added proxyprotocol documentation

Due to a mistype in errno checking, sslh-fork process died repeatedly
resulting to a complete denial of service on systems with no built-in
process supervisors, like FreeBSD.

Signed-off-by: Sergei Zhmylev <zhmylove@narod.ru>

.github/workflows/container-build.yaml

@@ -0,0 +1,63 @@
+name: Create and publish Container image
+
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - 'v*'
+  pull_request:
+    branches:
+      - master
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to Container registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: |
+            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=edge
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          platforms: linux/amd64,linux/386,linux/arm64,linux/arm/v6,linux/arm/v7
+          context: .
+          file: Dockerfile
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

.gitignore

@@ -3,8 +3,15 @@
 *.o
 cscope.*
 echosrv
+libsslh.a
 sslh-fork
 sslh-select
+sslh-ev
+systemd-sslh-generator
 sslh.8.gz
 tags
 version.h
+/config.status
+/config.log
+/config.h
+/Makefile

ChangeLog

@@ -1,3 +1,109 @@
+vNEXT:
+	Added `max_connections` setting to `listen` and
+	`protocol` configuration; see the
+	[guide](doc/max_connections.md) for more
+	information.
+
+	accept() is now disabled for some time when ulimit -n is reached.
+
+	Support proxyprotocol on incoming connections.
+
+	Fix proxyprotocol target field (Thanks to Github user 404-Not-Found)
+
+	Fix memory leak in regex probe.
+
+v2.2.4:
+	Fix CVE-2025-46806 for "Misaligned Memory Accesses in `is_openvpn_protocol()`"
+
+	Fix CVE-2025-46807 for "File Descriptor Exhaustion in sslh-select and sslh-ev"
+
+	Fix potential parsing of undefined data in syslog
+	probe (no CVE assigned)
+
+	Thanks to Matthias Gerstner of the SUSE security
+	team for the security review that found these
+	defects!
+
+v2.2.3:
+	Reverse older commit: version.h cannot be included
+	without breaking the build (everything recompiles
+	every time) and the release archive creation (which
+	relies on git tags).
+
+v2.2.2:
+	Fix potential vulnerability similar to CVE-2020-28935
+
+v2.2.1:
+	Added a boolean setting "is_unix" for listen and
+	protocol entries. This will use the 'host' setting
+	as a path name to a socket file, and connections
+	(listening or connecting) will be performed on Unix
+	socket instead of Internet sockets.
+
+	Support HAProxy's proxyprotocol on the backend
+	server side.
+
+	Lots of documentation about a new, simpler way to
+	perform transparent proxying.
+
+	New "verbose" option that overrides all other
+	verbose settings.
+
+v2.1.3:
+	Fix Landlock access to /etc/hosts.deny and
+	/etc/hosts.allow.
+
+v2.1.2:
+	Fix inetd mode.
+
+v2.1.1:
+	Various minor fixes.
+
+v2.1.0:
+	Support for the Landlock LSM. After initial setup,
+	sslh gives up all local file access rights.
+
+	Reintroduced --ssl as an alias to --tls.
+
+	Introduce autoconf to adapt to landlock presence.
+
+	Close connexion without error message if remote
+	client forcefully closes connexion, for Windows.
+
+v2.0.1:	
+	Fix resolve_on_forward setting, which would crash
+	sslh reliably.
+
+v2.0.0:
+v2.0:
+	New sslh-ev: this is functionally equivalent to
+	sslh-select (mono-process, only forks for specified
+	protocols), but based on libev, which should make it
+	scalable to large numbers of connections.
+
+	New log system: instead of --verbose with arbitrary
+	levels, there are now several message classes. Each
+	message class can be set to go to stderr, syslog, or
+	both. Classes are documented in example.cfg.
+
+	UDP connections are now managed in a hash to avoid
+	linear searches. The downside is that the number of
+	UDP connections is a hard limit, configurable with
+	the 'udp_max_connections', which defaults to 1024.
+	Timeouts are managed with lists.
+
+	inetd merges stderr output to what is sent to the
+	client, which is a security issue as it might give
+	information to an attacker. When inetd is activated,
+	stderr is forcibly closed.
+
+	New protocol-level option `resolve_on_forward`,
+	requests that target names are resolved at each
+	connection instead of at startup. Useful for dynamic
+	DNS situations. (Paul Schroeder/milkpirate)
+
+	New probe for MSRDP (akappner).
+
 v1.22: 17AUG2021
 	sslh-select now supports UDP protocols.
 	Probes specified in the `protocols`
@@ -12,7 +118,7 @@ v1.22: 17AUG2021
 	combined with incoming TLS with SNI.  UDP clients
 	and servers need to agree on the IPv4/IPv6 they use:
 	use the same protocol on all sides! Often, this
-	means explicitely using 'ip4-localhost'.
+	means explicitly using 'ip4-localhost'.
 	UDP sender-receiver pairs (connections, so to speak)
 	are kept for 60s, which can be changed with
 	`udp_timeout` in the configuration.
@@ -54,7 +160,7 @@ v1.21: 11JUL2020
 
 	Added TCP_FASTOPEN support for client sockets (if
 	tfo_ok is specified in their configuration) and for
-	listenint socket, if all client protocols support it.
+	listening socket, if all client protocols support it.
 	(Craig Andrews)
 
 	Added 'minlength' option to skip a probe if less
@@ -80,8 +186,8 @@ v1.20: 20NOV2018
 	Before, probes were tried in order, repeating on the
 	same probe as long it returned PROBE_AGAIN before
 	moving to the next one. This means a probe which
-	requires a lot of data (i.e. returne PROBE_AGAIN for
-	a long time) could prevent sucessful matches from 
+	requires a lot of data (i.e. return PROBE_AGAIN for
+	a long time) could prevent successful matches from 
 	subsequent probes. The configuration file needed to
 	take that into account.
 
@@ -142,7 +248,7 @@ v1.18:	29MAR2016
 v1.17: 	09MAR2015
 	Support RFC5952-style IPv6 addresses, e.g. [::]:443.
 
-	Transparant proxy support for FreeBSD.
+	Transparent proxy support for FreeBSD.
 	(Ruben van Staveren)
 
 	Using -F with no argument will try
@@ -171,7 +277,7 @@ v1.16:	11FEB2014
 
 	Libcap support: Keep only CAP_NET_ADMIN if started
 	as root with transparent proxying and dropping
-	priviledges (enable USELIBCAP in Makefile). This
+	privileges (enable USELIBCAP in Makefile). This
 	avoids having to mess with filesystem capabilities.
 	(Sebastian Schmidt/yath)
 
@@ -180,7 +286,7 @@ v1.16:	11FEB2014
 	actual errors if connections are dropped before
 	getting to getpeername).
 
-	Set IP_FREEDBIND if available to bind to addresses
+	Set IP_FREEBIND if available to bind to addresses
 	that don't yet exist.
 
 v1.15:	27JUL2013
@@ -265,7 +371,7 @@ v1.11: 21APR2012
 	--user isn't specified, just run as current user.
 
 	No longer create PID file by default, it should be
-	explicitely set with --pidfile.
+	explicitly set with --pidfile.
 
 	No longer log to syslog if in foreground. Logs are
 	instead output to stderr.
@@ -356,7 +462,7 @@ v1.8: 15JUL2011
 v1.7: 01FEB2010
 	Added CentOS init.d script (Andre Krajnik).
 
-	Fixed default ssl address inconsistancy, now
+	Fixed default ssl address inconsistency, now
 	defaults to "localhost:443" and fixed documentation
 	accordingly (pointed by Markus Schalke).
 

Dockerfile

@@ -1,23 +1,38 @@
-FROM alpine:latest as build
+ARG ALPINE_VERSION="latest"
+ARG TARGET_ARCH="library"
 
-ADD . /sslh
+FROM docker.io/${TARGET_ARCH}/alpine:${ALPINE_VERSION} AS build
 
-RUN \
-  apk add \
-    gcc \
-    libconfig-dev \
-    make \
-    musl-dev \
-    pcre-dev \
-    perl && \
-  cd /sslh && \
-  make sslh-select && \
-  strip sslh-select
+WORKDIR /sslh
 
-FROM alpine:latest
+RUN apk add --no-cache \
+        'gcc' \
+        'libconfig-dev' \
+        'make' \
+        'musl-dev' \
+        'pcre2-dev' \
+        'perl' \
+        ;
 
-COPY --from=build /sslh/sslh-select /sslh
+COPY . /sslh
 
-RUN apk --no-cache add libconfig pcre
+RUN ./configure && make sslh-select && strip sslh-select
 
-ENTRYPOINT [ "/sslh", "--foreground"]
+FROM docker.io/${TARGET_ARCH}/alpine:${ALPINE_VERSION}
+
+COPY --from=build "/sslh/sslh-select" "/usr/local/bin/sslh"
+RUN apk add --no-cache \
+        'libconfig' \
+        'pcre2' \
+        'iptables' \
+        'ip6tables' \
+        'libcap' \
+    && \
+    adduser -s '/bin/sh' -S -D sslh && \
+    setcap cap_net_bind_service,cap_net_raw+ep /usr/local/bin/sslh
+
+COPY "./container-entrypoint.sh" "/init"
+ENTRYPOINT [ "/init" ]
+
+# required for updating iptables
+USER root:root

Makefile.in

@@ -3,12 +3,14 @@ VERSION=$(shell ./genver.sh -r)
 
 # Configuration -- you probably need to `make clean` if you
 # change any of these
+
+# uncomment the following line to disable landlock
+# override undefine HAVE_LANDLOCK
+ENABLE_SANITIZER= # Enable ASAN/LSAN/UBSAN
 ENABLE_REGEX=1  # Enable regex probes
 USELIBCONFIG=1	# Use libconfig? (necessary to use configuration files)
-USELIBWRAP?=	# Use libwrap?
-USELIBCAP=	# Use libcap?
+USELIBEV=1	# Use libev?
 USESYSTEMD=     # Make use of systemd socket activation
-USELIBBSD?=     # Use libbsd (needed to update process name in `ps`)
 COV_TEST= 	# Perform test coverage?
 PREFIX?=/usr
 BINDIR?=$(PREFIX)/sbin
@@ -19,23 +21,28 @@ MAN=sslh.8.gz	# man page name
 # End of configuration -- the rest should take care of
 # itself
 
+ifneq ($(strip $(ENABLE_SANITIZER)),)
+    CFLAGS_SAN=-fsanitize=address -fsanitize=leak -fsanitize=undefined -fsanitize=alignment
+endif
+
 ifneq ($(strip $(COV_TEST)),)
     CFLAGS_COV=-fprofile-arcs -ftest-coverage
 endif
 
 CC ?= gcc
-CFLAGS ?=-Wall -DLIBPCRE -g $(CFLAGS_COV)
+AR ?= ar
+CFLAGS +=-Wall -O2 -DLIBPCRE -g $(CFLAGS_COV) $(CFLAGS_SAN)
 
-LIBS=-lm -lpcre2-8
-OBJS=sslh-conf.o common.o sslh-main.o probe.o tls.o argtable3.o udp-listener.o collection.o gap.o
+
+LIBS=-lm -lpcre2-8 @LIBS@
+OBJS=sslh-conf.o common.o log.o sslh-main.o probe.o tls.o argtable3.o collection.o gap.o tcp-probe.o landlock.o proxyprotocol.o
+OBJS_A=libsslh.a
+FORK_OBJS=sslh-fork.o $(OBJS_A)
+SELECT_OBJS=processes.o udp-listener.o sslh-select.o hash.o tcp-listener.o $(OBJS_A)
+EV_OBJS=processes.o udp-listener.o sslh-ev.o hash.o tcp-listener.o $(OBJS_A)
 
 CONDITIONAL_TARGETS=
 
-ifneq ($(strip $(USELIBWRAP)),)
-	LIBS:=$(LIBS) -lwrap
-	CPPFLAGS+=-DLIBWRAP
-endif
-
 ifneq ($(strip $(ENABLE_REGEX)),)
 	CPPFLAGS+=-DENABLE_REGEX
 endif
@@ -45,62 +52,65 @@ ifneq ($(strip $(USELIBCONFIG)),)
 	CPPFLAGS+=-DLIBCONFIG
 endif
 
-ifneq ($(strip $(USELIBCAP)),)
-	LIBS:=$(LIBS) -lcap
-	CPPFLAGS+=-DLIBCAP
-endif
-
 ifneq ($(strip $(USESYSTEMD)),)
         LIBS:=$(LIBS) -lsystemd
         CPPFLAGS+=-DSYSTEMD
 	CONDITIONAL_TARGETS+=systemd-sslh-generator
 endif
 
-ifneq ($(strip $(USELIBBSD)),)
-        LIBS:=$(LIBS) -lbsd
-        CPPFLAGS+=-DLIBBSD
+ifneq ($(strip $(USELIBEV)),)
+        CONDITIONAL_TARGETS+=sslh-ev
 endif
 
+all: sslh-fork sslh-select $(MAN) echosrv $(CONDITIONAL_TARGETS)
 
-all: sslh $(MAN) echosrv $(CONDITIONAL_TARGETS)
+%.o: %.c %.h version.h
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
-.c.o: *.h version.h
-	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
+$(OBJS_A): $(OBJS)
+	$(AR) rcs $(OBJS_A) $(OBJS)
 
 version.h:
 	./genver.sh >version.h
 
-sslh: sslh-fork sslh-select
+$(OBJS) $(FORK_OBJS) $(SELECT_OBJS) $(EV_OBJS): argtable3.h collection.h common.h gap.h hash.h log.h probe.h processes.h sslh-conf.h tcp-listener.h tcp-probe.h tls.h udp-listener.h version.h
 
-$(OBJS): version.h common.h collection.h sslh-conf.h gap.h
+
+c2s:
+	conf2struct sslhconf.cfg
+	conf2struct echosrv.cfg
 
 sslh-conf.c sslh-conf.h: sslhconf.cfg
-	conf2struct sslhconf.cfg
+	$(warning "sslhconf.cfg is more recent than sslh-conf.[ch]. Use `make c2s` to rebuild using `conf2struct`")
 
-sslh-fork: version.h $(OBJS) sslh-fork.o Makefile
-	$(CC) $(CFLAGS) $(LDFLAGS) -o sslh-fork sslh-fork.o $(OBJS) $(LIBS)
-	#strip sslh-fork
+sslh-fork: version.h Makefile $(FORK_OBJS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o sslh-fork $(FORK_OBJS) $(LIBS)
 
-sslh-select: version.h $(OBJS) sslh-select.o Makefile
-	$(CC) $(CFLAGS) $(LDFLAGS) -o sslh-select sslh-select.o $(OBJS) $(LIBS)
-	#strip sslh-select
+sslh-select: version.h $(SELECT_OBJS) Makefile
+	$(CC) $(CFLAGS) $(LDFLAGS) -o sslh-select $(SELECT_OBJS) $(LIBS)
+
+sslh-ev: version.h $(EV_OBJS) Makefile
+	$(CC) $(CFLAGS) $(LDFLAGS) -o sslh-ev $(EV_OBJS) $(LIBS) -lev
 
 systemd-sslh-generator: systemd-sslh-generator.o
 	$(CC) $(CFLAGS) $(LDFLAGS) -o systemd-sslh-generator systemd-sslh-generator.o -lconfig
 
 echosrv-conf.c echosrv-conf.h: echosrv.cfg
-	conf2struct echosrv.cfg
+	$(warning "echosrv.cfg is more recent than echosrv-conf.[ch]. Use `make c2s` to rebuild using `conf2struct`")
 
 echosrv: version.h echosrv-conf.c echosrv.o echosrv-conf.o argtable3.o
 	$(CC) $(CFLAGS) $(LDFLAGS) -o echosrv echosrv.o echosrv-conf.o argtable3.o $(LIBS)
 
+
+landlock.o: config.h
+
 $(MAN): sslh.pod Makefile
 	pod2man --section=8 --release=$(VERSION) --center=" " sslh.pod | gzip -9 - > $(MAN)
 
 # Create release: export clean tree and tag current
 # configuration
 release:
-	git archive master --prefix="sslh-$(VERSION)/" | gzip > /tmp/sslh-$(VERSION).tar.gz
+	git archive $(VERSION) --prefix="sslh-$(VERSION)/" | gzip > /tmp/sslh-$(VERSION).tar.gz
 	gpg --detach-sign --armor /tmp/sslh-$(VERSION).tar.gz
 
 # Build docker image
@@ -113,7 +123,7 @@ docker-clean:
 	yes | docker image prune
 
 # generic install: install binary and man page
-install: sslh $(MAN)
+install: sslh-fork $(MAN)
 	mkdir -p $(DESTDIR)/$(BINDIR)
 	mkdir -p $(DESTDIR)/$(MANDIR)
 	install -p sslh-fork $(DESTDIR)/$(BINDIR)/sslh
@@ -133,10 +143,10 @@ distclean: clean
 	rm -f tags sslh-conf.[ch] echosrv-conf.[ch] cscope.*
 
 clean:
-	rm -f sslh-fork sslh-select echosrv version.h $(MAN) systemd-sslh-generator *.o *.gcov *.gcno *.gcda *.png *.html *.css *.info
+	rm -f sslh-fork sslh-select $(CONDITIONAL_TARGETS) echosrv version.h $(MAN) systemd-sslh-generator *.o *.gcov *.gcno *.gcda *.png *.html *.css *.info
 
-tags:
-	ctags --globals -T *.[ch]
+tags: *.c *.h
+	ctags *.[ch]
 
 cscope:
 	-find . -name "*.[chS]" >cscope.files

README.md

@@ -11,7 +11,7 @@ protocol that can be tested using a regular expression, can
 be recognised. A typical use case is to allow serving
 several services on port 443 (e.g. to connect to SSH from
 inside a corporate firewall, which almost never block port
-443) while still serving HTTPS on that port. 
+443) while still serving HTTPS on that port.
 
 Hence `sslh` acts as a protocol demultiplexer, or a
 switchboard. With the SNI and ALPN probe, it makes a good
@@ -20,21 +20,72 @@ address.
 
 `sslh` has the bells and whistles expected from a mature
 daemon: privilege and capabilities dropping, inetd support,
-systemd support, transparent proxying, chroot, logging, 
-IPv4 and IPv6, TCP and UDP, a fork-based and a select-based 
-model, and more.
+systemd support, transparent proxying, support for HAProxy's
+proxyprotocol, chroot, logging, IPv4 and IPv6, TCP and UDP,
+a fork-based, a select-based model, and yet another based on
+libev for larger installations.
 
 Install
 =======
 
 Please refer to the [install guide](doc/INSTALL.md).
 
+Security
+========
+
+Matthias Gerstner from OpenSUSE has performed a code review
+of `sslh` from a security point of view, which revealed a
+number of problems, including two CVE. His findings have
+already been taken partly into account for the more critical
+ones. The [full
+review](https://security.opensuse.org/2025/06/13/sslh-denial-of-service-vulnerabilities.html)
+is well worth reading if you are using `sslh` in production.
+
+Part of the securing your installation involves configuring
+connection limits. This is described in [this
+guide](doc/max_connections.md).
 
 Configuration
 =============
 
 Please refer to the [configuration guide](doc/config.md).
 
+Transparent proxying
+--------------------
+
+Transparent proxying allows the target server to see the
+original client IP address, i.e. `sslh` becomes invisible.
+
+The same result can be achieved more easily by using
+`proxyprotocol` if the backend server supports it. This is a
+simple setting to add to the `sslh` protocol configuration,
+usually with an equivalently simple setting to add in
+the backend server configuration, so try that first. This is
+explained in a [separate document](doc/proxyprotocol.md).
+
+This means services behind `sslh` (Apache, `sshd` and so on)
+will see the external IP and ports as if the external world
+connected directly to them. This simplifies IP-based access
+control (or makes it possible at all), and makes it possible
+to use IP-based banning tools such as `fail2ban`.
+
+There are two methods. One uses additional virtual network
+interfaces. The principle and basic setup is described
+[here](doc/simple_transparent_proxy.md), with further
+scenarios described [there](doc/scenarios-for-simple-transparent-proxy.md).
+
+There is also a guide to use [podman](doc/podman.md).
+
+Another method uses iptable packet marking features, and is
+highly dependent on your network environment and
+infrastructure setup. There is no known generic approach,
+and if you do not find directions for your exact setup, you
+will probably need an extensive knowledge of network
+management and iptables setup".
+
+It is described in its own [document](doc/tproxy.md).
+In most cases, you will be better off following the first
+method.
 
 
 Docker image
@@ -44,45 +95,120 @@ How to use
 
 ---
 
-Build docker image
-
-    make docker
-
 
 ```bash
-docker container run \
+docker run \
+  --cap-add CAP_NET_RAW \
+  --cap-add CAP_NET_BIND_SERVICE \
   --rm \
   -it \
+  ghcr.io/yrutschle/sslh:latest \
+  --foreground \
   --listen=0.0.0.0:443 \
   --ssh=hostname:22 \
-  --tlshostname:443 \
-  sslh:latest
+  --tls=hostname:443
 ```
 
 docker-compose example
 
-```
----
+```yaml
 version: "3"
 
 services:
   sslh:
-    image: sslh:latest
+    image: ghcr.io/yrutschle/sslh:latest
     hostname: sslh
     ports:
-      - 443:443/tcp
-    command: --listen=0.0.0.0:443 --tlshostname:443 --openvpn=openvpn:1194
+      - 443:443
+    command: --foreground --listen=0.0.0.0:443 --tls=nginx:443 --openvpn=openvpn:1194
     depends_on:
       - nginx
       - openvpn
 
   nginx:
     image: nginx
-    hostname: nginx
+
+  openvpn:
+    image: openvpn
+```
+
+Transparent mode 1: using sslh container for networking
+
+_Note: For transparent mode to work, the sslh container must be able to reach your services via **localhost**_
+```yaml
+version: "3"
+
+services:
+  sslh:
+    build: https://github.com/yrutschle/sslh.git
+    container_name: sslh
+    environment:
+      - TZ=${TZ}
+    cap_add:
+      - NET_ADMIN
+      - NET_RAW
+      - NET_BIND_SERVICE
+    sysctls:
+      - net.ipv4.conf.default.route_localnet=1
+      - net.ipv4.conf.all.route_localnet=1
+    command: --transparent --foreground --listen=0.0.0.0:443 --tls=localhost:8443 --openvpn=localhost:1194
+    ports:
+      - 443:443 #sslh
+
+      - 80:80 #nginx
+      - 8443:8443 #nginx
+
+      - 1194:1194 #openvpn
+    extra_hosts:
+      - localbox:host-gateway
+    restart: unless-stopped
+
+  nginx:
+    image: nginx:latest
+    .....
+    network_mode: service:sslh #set nginx container to use sslh networking.
+    # ^^^ This is required. This makes nginx reachable by sslh via localhost
+  
+  openvpn:
+    image: openvpn:latest
+    .....
+    network_mode: service:sslh #set openvpn container to use sslh networking
+```
+
+Transparent mode 2: using host networking
+
+```yaml
+version: "3"
+
+services:
+  sslh:
+    build: https://github.com/yrutschle/sslh.git
+    container_name: sslh
+    environment:
+      - TZ=${TZ}
+    cap_add:
+      - NET_ADMIN
+      - NET_RAW
+      - NET_BIND_SERVICE
+    # must be set manually
+    #sysctls:
+    #  - net.ipv4.conf.default.route_localnet=1
+    #  - net.ipv4.conf.all.route_localnet=1
+    command: --transparent --foreground --listen=0.0.0.0:443 --tls=localhost:8443 --openvpn=localhost:1194
+    network_mode: host
+    restart: unless-stopped
+  
+  nginx:
+    image: nginx:latest
+    .....
+    ports:
+      - 8443:8443 # bind to docker host on port 8443
 
   openvpn:
     image: openvpn:latest
-    hostname: openvpn
+    .....
+    ports:
+      - 1194:1194 # bind to docker host on port 1194
 ```
 
 Comments? Questions?

argtable3.c

@@ -2876,9 +2876,9 @@ static void arg_file_resetfn(struct arg_file* parent) {
 static const char* arg_basename(const char* filename) {
     const char *result = NULL, *result1, *result2;
 
-    /* Find the last occurrence of eother file separator character. */
-    /* Two alternative file separator chars are supported as legal  */
-    /* file separators but not both together in the same filename.  */
+    /* Find the last occurrence of other file separator character. */
+    /* Two alternative file separator chars are supported as legal */
+    /* file separators but not both together in the same filename. */
     result1 = (filename ? strrchr(filename, FILESEPARATOR1) : NULL);
     result2 = (filename ? strrchr(filename, FILESEPARATOR2) : NULL);
 
@@ -2927,7 +2927,7 @@ static int arg_file_scanfn(struct arg_file* parent, const char* argval) {
     } else if (!argval) {
         /* a valid argument with no argument value was given. */
         /* This happens when an optional argument value was invoked. */
-        /* leave parent arguiment value unaltered but still count the argument. */
+        /* leave parent argument value unaltered but still count the argument. */
         parent->count++;
     } else {
         parent->filename[parent->count] = argval;
@@ -3173,7 +3173,7 @@ static int arg_int_scanfn(struct arg_int* parent, const char* argval) {
     } else if (!argval) {
         /* a valid argument with no argument value was given. */
         /* This happens when an optional argument value was invoked. */
-        /* leave parent arguiment value unaltered but still count the argument. */
+        /* leave parent argument value unaltered but still count the argument. */
         parent->count++;
     } else {
         long int val;
@@ -3813,8 +3813,8 @@ static const TRexChar* g_nnames[] = {_SC("NONE"),    _SC("OP_GREEDY"), _SC("OP_O
 #endif
 #define OP_GREEDY (MAX_CHAR + 1)  /*  * + ? {n} */
 #define OP_OR (MAX_CHAR + 2)
-#define OP_EXPR (MAX_CHAR + 3)       /* parentesis () */
-#define OP_NOCAPEXPR (MAX_CHAR + 4)  /* parentesis (?:) */
+#define OP_EXPR (MAX_CHAR + 3)       /* parenthesis () */
+#define OP_NOCAPEXPR (MAX_CHAR + 4)  /* parenthesis (?:) */
 #define OP_DOT (MAX_CHAR + 5)
 #define OP_CLASS (MAX_CHAR + 6)
 #define OP_CCLASS (MAX_CHAR + 7)
@@ -5313,7 +5313,7 @@ static void arg_parse_untagged(int argc, char** argv, struct arg_hdr** table, st
         }
     }
 
-    /* if a tenative error still remains at this point then register it as a proper error */
+    /* if a tentative error still remains at this point then register it as a proper error */
     if (errorlast) {
         arg_register_error(endtable, parentlast, errorlast, optarglast);
         optind++;
@@ -5384,7 +5384,7 @@ int arg_parse(int argc, char** argv, void** argtable) {
     /*
         Fill in the local copy of argv[]. We need a local copy
         because getopt rearranges argv[] which adversely affects
-        susbsequent parsing attempts.
+        subsequent parsing attempts.
         */
     for (i = 0; i < argc; i++)
         argvcopy[i] = argv[i];
@@ -5451,7 +5451,7 @@ static void arg_cat_option(char* dest, size_t ndest, const char* shortopts, cons
     if (shortopts) {
         char option[3];
 
-        /* note: option array[] is initialiazed dynamically here to satisfy   */
+        /* note: option array[] is initialized dynamically here to satisfy   */
         /* a deficiency in the watcom compiler wrt static array initializers. */
         option[0] = '-';
         option[1] = shortopts[0];
@@ -5509,7 +5509,7 @@ static void arg_cat_optionv(char* dest, size_t ndest, const char* shortopts, con
             /* "-a|-b|-c" */
             char shortopt[3];
 
-            /* note: shortopt array[] is initialiazed dynamically here to satisfy */
+            /* note: shortopt array[] is initialized dynamically here to satisfy */
             /* a deficiency in the watcom compiler wrt static array initializers. */
             shortopt[0] = '-';
             shortopt[1] = *c;
@@ -5881,7 +5881,7 @@ static void arg_print_formatted_ds(arg_dstr_t ds, const unsigned lmargin, const
  * Prints the glossary in strict GNU format.
  * Differences to arg_print_glossary() are:
  *   - wraps lines after 80 chars
- *   - indents lines without shortops
+ *   - indents lines without shortopts
  *   - does not accept formatstrings
  *
  * Contributed by Uli Fouquet
@@ -5956,7 +5956,7 @@ int arg_nullcheck(void** argtable) {
  * that entry were still allocated ok. Those subsequent allocations will not be
  * deallocated by arg_free().
  * Despite the unlikeliness of the problem occurring, and the even unlikelier event
- * that it has any deliterious effect, it is fixed regardless by replacing arg_free()
+ * that it has any deleterious effect, it is fixed regardless by replacing arg_free()
  * with the newer arg_freetable() function.
  * We still keep arg_free() for backwards compatibility.
  */

argtable3.h

@@ -87,7 +87,7 @@ typedef int(arg_comparefn)(const void* k1, const void* k2);
  * that particular arg_xxx arguments, performing post-parse checks, and
  * reporting errors.
  * These functions are private to the individual arg_xxx source code
- * and are the pointer to them are initiliased by that arg_xxx struct's
+ * and are the pointer to them are initialised by that arg_xxx struct's
  * constructor function. The user could alter them after construction
  * if desired, but the original intention is for them to be set by the
  * constructor and left unaltered.
@@ -95,7 +95,7 @@ typedef int(arg_comparefn)(const void* k1, const void* k2);
 typedef struct arg_hdr {
     char flag;             /* Modifier flags: ARG_TERMINATOR, ARG_HASVALUE. */
     const char* shortopts; /* String defining the short options */
-    const char* longopts;  /* String defiing the long options */
+    const char* longopts;  /* String defining the long options */
     const char* datatype;  /* Description of the argument data type */
     const char* glossary;  /* Description of the option as shown by arg_print_glossary function */
     int mincount;          /* Minimum number of occurences of this option accepted */

basic.cfg

@@ -1,29 +1,33 @@
 # This is a basic configuration file that should provide
 # sensible values for "standard" setup.
 
-verbose: 0;
-foreground: false;
-inetd: false;
-numeric: false;
-transparent: false;
+# You will find extensive examples with explanations in
+# example.cfg
+
 timeout: 2;
 user: "nobody";
 pidfile: "/var/run/sslh.pid";
-chroot: "/var/empty";
 
 
-# Change hostname with your external address name.
+# Change hostname with your external address name, or the IP
+# of the interface that receives connections
+# Default is to bind all interfaces. httpd can be started
+# first to bind on localhost, in which case sslh will bind
+# only other interfaces.
 listen:
 (
-    { host: "thelonious"; port: "443"; }
+    { host: "0.0.0.0"; port: "443"; },
+    { host: "[::]"; port: "443"; }
 );
 
+
+# Change to the protocols you want to forward to. The
+# defaults here are sensible for services running on
+# localhost
 protocols:
 (
      { name: "ssh"; service: "ssh"; host: "localhost"; port: "22"; fork: true; },
      { name: "openvpn"; host: "localhost"; port: "1194"; },
-     { name: "xmpp"; host: "localhost"; port: "5222"; },
-     { name: "http"; host: "localhost"; port: "80"; },
      { name: "tls"; host: "localhost"; port: "443"; log_level: 0; },
      { name: "anyprot"; host: "localhost"; port: "443"; }
 );

common.c

@@ -4,7 +4,6 @@
  * No code here should assume whether sockets are blocking or not.
  **/
 
-#define SYSLOG_NAMES
 #define _GNU_SOURCE
 #include <stddef.h>
 #include <stdarg.h>
@@ -13,10 +12,18 @@
 #include <sys/types.h>
 #include <ifaddrs.h>
 #include <netinet/in.h>
+#include <sys/un.h>
 
 #include "common.h"
 #include "probe.h"
+#include "log.h"
 #include "sslh-conf.h"
+#include "proxyprotocol.h"
+
+#if HAVE_LIBCAP
+#include <sys/capability.h>
+#include <sys/prctl.h>
+#endif
 
 /* Added to make the code compilable under CYGWIN
  * */
@@ -30,7 +37,7 @@
 #include <systemd/sd-daemon.h>
 #endif
 
-#ifdef LIBBSD
+#ifdef HAVE_LIBBSD
 #include <bsd/unistd.h>
 #endif
 
@@ -42,9 +49,7 @@ struct sslhcfg_item cfg;
 struct addrinfo *addr_listen = NULL; /* what addresses do we listen to? */
 
 
-static int do_syslog = 1; /* Should we syslog? controled by syslog_facility = "none" */
-
-#ifdef LIBWRAP
+#ifdef HAVE_LIBWRAP
 #include <tcpd.h>
 int allow_severity =0, deny_severity = 0;
 #endif
@@ -60,7 +65,7 @@ void check_res_dump(CR_ACTION act, int res, struct addrinfo *addr, char* syscall
     char buf[NI_MAXHOST];
 
     if (res == -1) {
-        fprintf(stderr, "%s:%s: %s\n",
+        print_message(msg_system_error, "%s:%s: %s\n",
                 sprintaddr(buf, sizeof(buf), addr),
                 syscall,
                 strerror(errno));
@@ -77,12 +82,12 @@ int get_fd_sockets(struct listen_endpoint *sockfd[])
 #ifdef SYSTEMD
     sd = sd_listen_fds(0);
     if (sd < 0) {
-      fprintf(stderr, "sd_listen_fds(): %s\n", strerror(-sd));
+      print_message(msg_system_error, "sd_listen_fds(): %s\n", strerror(-sd));
       exit(1);
     }
     if (sd > 0) {
       int i;
-      *sockfd = malloc(sd * sizeof(*sockfd[0]));
+      *sockfd = calloc(sd, sizeof(*sockfd[0]));
       CHECK_ALLOC(*sockfd, "malloc");
       for (i = 0; i < sd; i++) {
         (*sockfd)[i].socketfd = SD_LISTEN_FDS_START + i;
@@ -112,7 +117,7 @@ int make_listen_tfo(int s)
     return setsockopt(s, SOL_SOCKET, TCP_FASTOPEN, (char*)&qlen, sizeof(qlen));
 }
 
-/* Starts listening on a single address 
+/* Starts listening on a single address
  * Returns a socket filehandle, or dies with message in case of major error */
 int listen_single_addr(struct addrinfo* addr, int keepalive, int udp)
 {
@@ -157,17 +162,91 @@ int listen_single_addr(struct addrinfo* addr, int keepalive, int udp)
     return sockfd;
 }
 
+void print_inet_listen_info(int fd, const char* addr, 
+                            struct sslhcfg_listen_item* cfg)
+{
+    print_message(msg_config, "%d:\t%s\t[%s] [%s] [max_cnx: %d]\n", 
+                  fd, 
+                  addr,
+                  cfg->keepalive ? "keepalive" : "",
+                  cfg->is_udp ? "udp" : "",
+                  cfg->max_connections);
+}
+
+
+/* Start listening internet sockets for configuration entry 'index' 
+ * OUT: *sockfd[]: pointer to array of listen_endpoint object; we append new
+ * endpoints to that array
+ * IN: num_addr: how many entries are in sockfd[]
+ *     *cfg: configuration data for the endpoint we are adding
+ * Return: new value of num_addr
+ * */
+static int start_listen_inet(struct listen_endpoint *sockfd[], int num_addr, struct sslhcfg_listen_item* cfg)
+{
+    struct addrinfo *addr, *start_addr;
+    char buf[NI_MAXHOST];
+    int res;
+
+    res = resolve_split_name(&start_addr, cfg->host, cfg->port);
+    if (res) exit(4);
+
+    for (addr = start_addr; addr; addr = addr->ai_next) {
+        num_addr++;
+        *sockfd = realloc(*sockfd, num_addr * sizeof(*sockfd[0]));
+        memset(&(*sockfd)[num_addr-1], 0, sizeof((*sockfd)[num_addr-1]));
+        (*sockfd)[num_addr-1].socketfd = listen_single_addr(addr, cfg->keepalive, cfg->is_udp);
+        (*sockfd)[num_addr-1].type = cfg->is_udp ? SOCK_DGRAM : SOCK_STREAM;
+        (*sockfd)[num_addr-1].family = AF_INET;
+        (*sockfd)[num_addr-1].endpoint_cfg = cfg;
+        print_inet_listen_info((*sockfd)[num_addr-1].socketfd, 
+                               sprintaddr(buf, sizeof(buf), addr), 
+                               cfg);
+    }
+    freeaddrinfo(start_addr);
+    return num_addr;
+}
+
+/* Same, but for UNIX sockets */
+static int start_listen_unix(struct listen_endpoint *sockfd[], int num_addr, struct sslhcfg_listen_item* cfg)
+{
+    int fd = socket(AF_UNIX, cfg->is_udp ? SOCK_DGRAM : SOCK_STREAM, 0);
+    CHECK_RES_DIE(fd, "socket(AF_UNIX)");
+
+    int res = unlink(cfg->host);
+    if ((res == -1) && (errno != ENOENT)) {
+        print_message(msg_config_error, "unlink unix socket `%s':%d:%s\n", cfg->host, errno, strerror(errno));
+        exit(4);
+    }
+
+    struct sockaddr_un sun;
+    sun.sun_family = AF_UNIX;
+    strncpy(sun.sun_path, cfg->host, sizeof(sun.sun_path)-1);
+    printf("binding [%s]\n", sun.sun_path);
+    res = bind(fd, (struct sockaddr*)&sun, sizeof(sun));
+    CHECK_RES_DIE(res, "bind(AF_UNIX)");
+
+    res = listen(fd, 50);
+
+    num_addr++;
+    *sockfd = realloc(*sockfd, num_addr * sizeof(*sockfd[0]));
+    memset(&(*sockfd)[num_addr-1], 0, sizeof((*sockfd)[num_addr-1]));
+    (*sockfd)[num_addr-1].socketfd = fd;
+    (*sockfd)[num_addr-1].type = cfg->is_udp ? SOCK_DGRAM : SOCK_STREAM;
+    (*sockfd)[num_addr-1].family = AF_INET;
+    (*sockfd)[num_addr-1].endpoint_cfg = cfg;
+
+    return num_addr;
+}
+
+
 /* Starts listening sockets on specified addresses.
  * OUT: *sockfd[]  pointer to newly-allocated array of listen_endpoint objects
  * Returns number of addresses bound
    */
 int start_listen_sockets(struct listen_endpoint *sockfd[])
 {
-    struct addrinfo *addr, *start_addr;
-    char buf[NI_MAXHOST];
-    int i, res;
-    int num_addr = 0, keepalive = 0, udp = 0;
-    int sd_socks = 0;
+    int i;
+    int num_addr = 0, sd_socks = 0;
 
     sd_socks = get_fd_sockets(sockfd);
 
@@ -177,26 +256,14 @@ int start_listen_sockets(struct listen_endpoint *sockfd[])
 
     *sockfd = NULL;
 
-    if (cfg.verbose) fprintf(stderr, "Listening to:\n");
+    print_message(msg_config, "Listening to:\n");
 
     for (i = 0; i < cfg.listen_len; i++) {
-        keepalive = cfg.listen[i].keepalive;
-        udp = cfg.listen[i].is_udp;
-
-        res = resolve_split_name(&start_addr, cfg.listen[i].host, cfg.listen[i].port);
-        if (res) exit(4);
-
-        for (addr = start_addr; addr; addr = addr->ai_next) {
-            num_addr++;
-            *sockfd = realloc(*sockfd, num_addr * sizeof(*sockfd[0]));
-            (*sockfd)[num_addr-1].socketfd = listen_single_addr(addr, keepalive, udp);
-            (*sockfd)[num_addr-1].type = udp ? SOCK_DGRAM : SOCK_STREAM;
-            if (cfg.verbose)
-                fprintf(stderr, "%d:\t%s\t[%s] [%s]\n", (*sockfd)[num_addr-1].socketfd, sprintaddr(buf, sizeof(buf), addr),
-                        cfg.listen[i].keepalive ? "keepalive" : "",
-                        cfg.listen[i].is_udp ? "udp" : "");
+        if (cfg.listen[i].is_unix) {
+            num_addr = start_listen_unix(sockfd, num_addr, &cfg.listen[i]);
+        } else {
+            num_addr = start_listen_inet(sockfd, num_addr, &cfg.listen[i]);
         }
-        freeaddrinfo(start_addr);
     }
 
     return num_addr;
@@ -246,12 +313,17 @@ int is_same_machine(struct addrinfo* from)
 
 /* Transparent proxying: bind the peer address of fd to the peer address of
  * fd_from */
-#define IP_TRANSPARENT 19
+#ifndef IP_TRANSPARENT
+  #define IP_TRANSPARENT 19
+#endif
+#ifndef IP_BIND_ADDRESS_NO_PORT
+  #define IP_BIND_ADDRESS_NO_PORT 24
+#endif
 int bind_peer(int fd, int fd_from)
 {
     struct addrinfo from;
     struct sockaddr_storage ss;
-    int res, trans = 1;
+    int res, enable = 1, disable = 0;
 
     memset(&from, 0, sizeof(from));
     from.ai_addr = (struct sockaddr*)&ss;
@@ -265,23 +337,55 @@ int bind_peer(int fd, int fd_from)
     /* if the destination is the same machine, there's no need to do bind */
     if (is_same_machine(&from))
         return 0;
-    
+
 #ifndef IP_BINDANY /* use IP_TRANSPARENT */
-    res = setsockopt(fd, IPPROTO_IP, IP_TRANSPARENT, &trans, sizeof(trans));
+    res = setsockopt(fd, IPPROTO_IP, IP_TRANSPARENT, &enable, sizeof(enable));
     CHECK_RES_DIE(res, "setsockopt IP_TRANSPARENT");
+    res = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));
+    CHECK_RES_DIE(res, "setsockopt SO_REUSEADDR");
 #else
     if (from.ai_addr->sa_family==AF_INET) { /* IPv4 */
-        res = setsockopt(fd, IPPROTO_IP, IP_BINDANY, &trans, sizeof(trans));
+        res = setsockopt(fd, IPPROTO_IP, IP_BINDANY, &enable, sizeof(enable));
         CHECK_RES_RETURN(res, "setsockopt IP_BINDANY", res);
 #ifdef IPV6_BINDANY
     } else { /* IPv6 */
-        res = setsockopt(fd, IPPROTO_IPV6, IPV6_BINDANY, &trans, sizeof(trans));
+        res = setsockopt(fd, IPPROTO_IPV6, IPV6_BINDANY, &enable, sizeof(enable));
         CHECK_RES_RETURN(res, "setsockopt IPV6_BINDANY", res);
 #endif /* IPV6_BINDANY */
     }
 #endif /* IP_TRANSPARENT / IP_BINDANY */
     res = bind(fd, from.ai_addr, from.ai_addrlen);
-    CHECK_RES_RETURN(res, "bind", res);
+    if (res == -1) {
+        if (errno != EADDRINUSE) {
+            print_message(msg_system_error, "%s:%d:%s:%d:%s\n", __FILE__, __LINE__,
+                        "bind", errno, strerror(errno));
+            return res;
+        }
+        res = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &disable, sizeof(disable));
+        CHECK_RES_DIE(res, "setsockopt SO_REUSEADDR");
+        res = setsockopt(fd, IPPROTO_IP, IP_BIND_ADDRESS_NO_PORT, &enable, sizeof(enable));
+        CHECK_RES_RETURN(res, "setsockopt IP_BIND_ADDRESS_NO_PORT", res);
+        ((struct sockaddr_in *)from.ai_addr)->sin_port = 0;
+        res = bind(fd, from.ai_addr, from.ai_addrlen);
+        CHECK_RES_RETURN(res, "bind", res);
+        /*
+	 * There was a serious problem, when daisy-chaining programs using the same
+	 * ip transparent mechanism, as sslh uses. stunnel was mentioned in a previous 
+	 * comment. This problem should now be solved through the two methods, getting
+	 * a connection established:
+	 * In the first try, SO_REUSEADDR is set to socket, which will allow the same
+	 * IP-address:port tuple, as it is used by another application. The check for
+	 * inconsistency with other connections (same 4-value-tupel) is done at the 
+	 * moment, when the connection gets established.
+	 * If that fails, SO_REUSEADDR gets removed and IP_BIND_ADDRESS_NO_PORT get set.
+	 * This will search for a free port, which will not collide with current 
+	 * connections. Read more in this excellent blog-post: 
+	 * https://blog.cloudflare.com/how-to-stop-running-out-of-ephemeral-ports-and-start-to-love-long-lived-connections
+	 * The problem will still appear, if the another application in the daisy-chain
+	 * does not use similar mechanisms. In that case you must either pull this 
+	 * application at the beginning of the chain, or get it fixed.
+         */
+    }
 
     return 0;
 }
@@ -303,11 +407,8 @@ int set_nonblock(int fd)
 }
 
 
-/* Connect to first address that works and returns a file descriptor, or -1 if
- * none work.
- * If transparent proxying is on, use fd_from peer address on external address
- * of new file descriptor. */
-int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
+/* Connects to INET/INET6 domain sockets and return a fd */
+static int connect_inet(struct connection *cnx, int fd_from, connect_blocking blocking)
 {
     struct addrinfo *a, from;
     struct sockaddr_storage ss;
@@ -322,19 +423,23 @@ int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
     res = getpeername(fd_from, from.ai_addr, &from.ai_addrlen);
     CHECK_RES_RETURN(res, "getpeername", res);
 
+    if (cnx->proto->resolve_on_forward) {
+        resolve_split_name(&(cnx->proto->saddr), cnx->proto->host,
+                           cnx->proto->port);
+    }
     for (a = cnx->proto->saddr; a; a = a->ai_next) {
-        /* When transparent, make sure both connections use the same address family */
-        if (transparent && a->ai_family != from.ai_addr->sa_family)
+        /* When transparent or using proxyprotocol, make sure both 
+         * connections use the same address family (e.g. IP4 on both sides) */
+        if ((transparent || cnx->proto->proxyprotocol_is_present) && (a->ai_family != from.ai_addr->sa_family))
             continue;
-        if (cfg.verbose)
-            fprintf(stderr, "connecting to %s family %d len %d\n",
+        print_message(msg_connections_try, "trying to connect to %s family %d len %d\n",
                     sprintaddr(buf, sizeof(buf), a),
                     a->ai_addr->sa_family, a->ai_addrlen);
 
         /* XXX Needs to match ai_family from fd_from when being transparent! */
         fd = socket(a->ai_family, SOCK_STREAM, 0);
         if (fd == -1) {
-            log_message(LOG_ERR, "forward to %s failed:socket: %s\n",
+            print_message(msg_connections_error, "forward to %s failed:socket: %s\n",
                         cnx->proto->name, strerror(errno));
         } else {
             one = 1;
@@ -347,6 +452,7 @@ int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
 
             if (transparent) {
                 res = bind_peer(fd, fd_from);
+                if (res == -1) close(fd);
                 CHECK_RES_RETURN(res, "bind_peer", res);
             }
             res = connect(fd, a->ai_addr, a->ai_addrlen);
@@ -354,7 +460,7 @@ int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
             /* EINPROGRESS indicates it might take time. If it eventually
              * fails, it'll be caught as a failed read */
             if ((res == -1) && (errno != EINPROGRESS)) {
-                log_message(LOG_ERR, "forward to %s failed:connect: %s\n",
+                print_message(msg_connections_error, "forward to %s failed:connect: %s\n",
                                      cnx->proto->name, strerror(errno));
                 close(fd);
                 continue; /* Try the next address */
@@ -369,40 +475,123 @@ int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
     return -1;
 }
 
+/* Connects to AF_UNIX domain sockets */
+static int connect_unix(struct connection *cnx, int fd_from, connect_blocking blocking)
+{
+    struct sockaddr_storage ss;
+    struct sockaddr_un* sun = (struct sockaddr_un*)&ss;
+
+    int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    sun->sun_family = AF_UNIX;
+    strncpy(sun->sun_path, cnx->proto->host, sizeof(sun->sun_path)-1);
+
+    int res = connect(fd, (struct sockaddr*)sun, sizeof(*sun));
+    CHECK_RES_RETURN(res, "connect", res);
+
+    if (blocking == NON_BLOCKING) {
+        set_nonblock(fd);
+    }
+    return fd;
+}
+
+/* 
+ * Connect to the first backend server address that works and updates the *cnx
+ * object accordingly (in cnx->q[1].fd). Set that to -1 in case of failure.
+ *
+ * If transparent proxying is on, use fd_from peer address on external address
+ * of new file descriptor. 
+ * If proxyprotocol is used, write header on new backend server connection
+ * */
+void connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking)
+{
+    int fd;
+
+    if (cnx->proto->is_unix) {
+        fd = connect_unix(cnx, fd_from, blocking);
+    } else {
+        fd = connect_inet(cnx, fd_from, blocking);
+    }
+    cnx->q[1].fd = fd;
+
+    if (cnx->proto->proxyprotocol_is_present) {
+        if (cnx->proto->proxyprotocol) {
+            pp_write_header(cnx->proto->proxyprotocol, cnx);
+            /* If pp_write_header() fails, it already logs a message and there is
+             * nothing much we can do. The server side will probably close the
+             * connection */
+        } else {
+            /* proxyprotocol == 0 means we remove a proxyprotocol header from
+             * the client-side, and log PP information (as it will be lost
+             * after sslh) */
+            int pp_len = pp_log_connection(cnx->q[1].begin_deferred_data,
+                                           cnx->q[1].deferred_data_size);
+            if (pp_len > 0) {
+                defer_skip(&cnx->q[1], pp_len);
+            }
+        }
+    }
+}
+
 /* Store some data to write to the queue later */
-int defer_write(struct queue *q, void* data, int data_size)
+int defer_write(struct queue *q, void* data, ssize_t data_size)
 {
     char *p;
     ptrdiff_t data_offset = q->deferred_data - q->begin_deferred_data;
-    if (cfg.verbose)
-        fprintf(stderr, "**** writing deferred on fd %d\n", q->fd);
 
+    print_message(msg_fd, "writing deferred on fd %d\n", q->fd);
     p = realloc(q->begin_deferred_data, data_offset + q->deferred_data_size + data_size);
     CHECK_ALLOC(p, "realloc");
 
     q->begin_deferred_data = p;
     q->deferred_data = p + data_offset;
     p += data_offset + q->deferred_data_size;
-    q->deferred_data_size += data_size;
+    q->deferred_data_size += (int)data_size;
     memcpy(p, data, data_size);
 
     return 0;
 }
 
+/* skip (remove) some data from the head of the queue */
+void defer_skip(struct queue *q, ssize_t data_size)
+{
+    q->deferred_data += data_size;
+    q->deferred_data_size -= data_size;
+}
+
+/* Store some data to write *before* what's already in the queue */
+int defer_write_before(struct queue *q, void* data, ssize_t data_size)
+{
+    char *p;
+
+    print_message(msg_fd, "writing deferred to beginning on fd %d\n", q->fd);
+    p = malloc(q->deferred_data_size + data_size);
+    CHECK_ALLOC(p, "malloc");
+
+    memcpy(p, data, data_size);
+    memcpy(p + data_size, q->deferred_data, q->deferred_data_size);
+
+    free(q->begin_deferred_data);
+
+    q->begin_deferred_data = p;
+    q->deferred_data = p;
+    q->deferred_data_size += (int)data_size;
+
+    return 0;
+}
+
 /* tries to flush some of the data for specified queue
  * Upon success, the number of bytes written is returned.
  * Upon failure, -1 returned (e.g. connexion closed)
  * */
 int flush_deferred(struct queue *q)
 {
-    int n;
+    ssize_t n;
 
-    if (cfg.verbose)
-        fprintf(stderr, "flushing deferred data to fd %d\n", q->fd);
+    print_message(msg_fd, "flushing deferred data to fd %d\n", q->fd);
 
     n = write(q->fd, q->deferred_data, q->deferred_data_size);
     if (n == -1)
-        return n;
+        return (int)n;
 
     if (n == q->deferred_data_size) {
         /* All has been written -- release the memory */
@@ -413,10 +602,10 @@ int flush_deferred(struct queue *q)
     } else {
         /* There is data left */
         q->deferred_data += n;
-        q->deferred_data_size -= n;
+        q->deferred_data_size -= (int)n;
     }
 
-    return n;
+    return (int)n;
 }
 
 
@@ -430,11 +619,43 @@ void init_cnx(struct connection *cnx)
 
 void dump_connection(struct connection *cnx)
 {
-    printf("state: %d\n", cnx->state);
-    printf("0: fd %d, %d deferred\n", cnx->q[0].fd, cnx->q[0].deferred_data_size);
-    hexdump(cnx->q[0].deferred_data, cnx->q[0].deferred_data_size);
-    printf("1: fd %d, %d deferred\n", cnx->q[1].fd, cnx->q[1].deferred_data_size);
-    hexdump(cnx->q[1].deferred_data, cnx->q[1].deferred_data_size);
+    print_message(msg_int_error, "type: %s\n", cnx->type == SOCK_DGRAM ? "UDP" : "TCP");
+    print_message(msg_int_error, "state: %d\n", cnx->state);
+    print_message(msg_int_error, "0: fd %d, %d deferred\n", cnx->q[0].fd, cnx->q[0].deferred_data_size);
+    hexdump(msg_int_error, cnx->q[0].deferred_data, cnx->q[0].deferred_data_size);
+    print_message(msg_int_error, "1: fd %d, %d deferred\n", cnx->q[1].fd, cnx->q[1].deferred_data_size);
+    hexdump(msg_int_error, cnx->q[1].deferred_data, cnx->q[1].deferred_data_size);
+}
+
+
+/* *cnx must have its proto field probed already.
+ * If required, increment the connection count for this protocol.
+ * Returns 1 if connection count is exceeded, 0 otherwise */
+int inc_proto_connections(struct sslhcfg_protocols_item* proto)
+{
+    proto->num_connections++;
+    if (proto->max_connections_is_present) {
+        print_message(msg_connections, "Proto %s +1: %d/%d cnx\n",
+                      proto->name,
+                      proto->num_connections,
+                      proto->max_connections);
+        if (proto->num_connections > proto->max_connections) {
+            print_message(msg_connections_error, "%s: too many connections, dropping\n", proto->name);
+            return 1;
+        }
+    }
+    return 0;
+}
+
+void dec_proto_connections(struct sslhcfg_protocols_item* proto)
+{
+    if (proto) {
+        proto->num_connections--;
+        print_message(msg_connections, "Proto %s -1: %d/%d cnx\n",
+                      proto->name,
+                      proto->num_connections,
+                      proto->max_connections);
+    }
 }
 
 
@@ -450,7 +671,8 @@ void dump_connection(struct connection *cnx)
 int fd2fd(struct queue *target_q, struct queue *from_q)
 {
    char buffer[BUFSIZ];
-   int target, from, size_r, size_w;
+   int target, from;
+   ssize_t size_r, size_w;
 
    target = target_q->fd;
    from = from_q->fd;
@@ -459,11 +681,10 @@ int fd2fd(struct queue *target_q, struct queue *from_q)
    if (size_r == -1) {
        switch (errno) {
        case EAGAIN:
-           if (cfg.verbose)
-               fprintf(stderr, "reading 0 from %d\n", from);
            return FD_NODATA;
 
        case ECONNRESET:
+       case ENOTSOCK:
        case EPIPE:
            return FD_CNXCLOSED;
        }
@@ -496,7 +717,7 @@ int fd2fd(struct queue *target_q, struct queue *from_q)
 
    CHECK_RES_RETURN(size_w, "write", FD_CNXCLOSED);
 
-   return size_w;
+   return (int)size_w;
 }
 
 /* returns a string that prints the IP and port of the sockaddr */
@@ -505,13 +726,16 @@ char* sprintaddr(char* buf, size_t size, struct addrinfo *a)
    char host[NI_MAXHOST], serv[NI_MAXSERV];
    int res;
 
+   memset(host, 0, sizeof(host));
+   memset(serv, 0, sizeof(serv));
+
    res = getnameinfo(a->ai_addr, a->ai_addrlen,
                host, sizeof(host),
                serv, sizeof(serv),
                cfg.numeric ? NI_NUMERICHOST | NI_NUMERICSERV : 0 );
 
    if (res) {
-       log_message(LOG_ERR, "sprintaddr:getnameinfo: %s\n", gai_strerror(res));
+       print_message(msg_system_error, "sprintaddr:getnameinfo: %s\n", gai_strerror(res));
        /* Name resolution failed: do it numerically instead */
        res = getnameinfo(a->ai_addr, a->ai_addrlen,
                          host, sizeof(host),
@@ -519,7 +743,7 @@ char* sprintaddr(char* buf, size_t size, struct addrinfo *a)
                          NI_NUMERICHOST | NI_NUMERICSERV);
        /* should not fail but... */
        if (res) {
-           log_message(LOG_ERR, "sprintaddr:getnameinfo(NUM): %s\n", gai_strerror(res));
+           print_message(msg_system_error, "sprintaddr:getnameinfo(NUM): %s\n", gai_strerror(res));
            strcpy(host, "?");
            strcpy(serv, "?");
        }
@@ -531,7 +755,8 @@ char* sprintaddr(char* buf, size_t size, struct addrinfo *a)
 }
 
 /* Turns a hostname and port (or service) into a list of struct addrinfo
- * returns 0 on success, -1 otherwise and logs error
+ * On success, returns 0 
+ * On failure, returns -1 or one of getaddrinfo() codes
  */
 int resolve_split_name(struct addrinfo **out, char* host, char* serv)
 {
@@ -548,7 +773,7 @@ int resolve_split_name(struct addrinfo **out, char* host, char* serv)
    if (host[0] == '[') {
        end = strrchr(host, ']');
        if (!end) {
-           fprintf(stderr, "%s: no closing bracket in IPv6 address?\n", host);
+           print_message(msg_config_error, "%s: no closing bracket in IPv6 address?\n", host);
            return -1;
        }
        host++; /* skip first bracket */
@@ -557,7 +782,7 @@ int resolve_split_name(struct addrinfo **out, char* host, char* serv)
 
    res = getaddrinfo(host, serv, &hint, out);
    if (res)
-      log_message(LOG_ERR, "%s `%s:%s'\n", gai_strerror(res), host, serv);
+      print_message(msg_system_error, "resolve_split_name: %s `%s:%s'\n", gai_strerror(res), host, serv);
    return res;
 }
 
@@ -573,7 +798,7 @@ void resolve_name(struct addrinfo **out, char* fullname)
    /* Find port */
    char *sep = strrchr(fullname, ':');
    if (!sep) { /* No separator: parameter is just a port */
-      fprintf(stderr, "%s: names must be fully specified as hostname:port\n", fullname);
+      print_message(msg_config_error, "%s: names must be fully specified as hostname:port\n", fullname);
       exit(1);
    }
    serv = sep+1;
@@ -583,30 +808,13 @@ void resolve_name(struct addrinfo **out, char* fullname)
 
    res = resolve_split_name(out, host, serv);
    if (res) {
-      fprintf(stderr, "%s `%s'\n", gai_strerror(res), fullname);
+      print_message(msg_config_error, "%s `%s'\n", gai_strerror(res), fullname);
       if (res == EAI_SERVICE)
-         fprintf(stderr, "(Check you have specified all ports)\n");
+         print_message(msg_config_error, "(Check you have specified all ports)\n");
       exit(4);
    }
 }
 
-/* Log to syslog or stderr if foreground */
-void log_message(int type, const char* msg, ...)
-{
-    va_list ap;
-
-    va_start(ap, msg);
-    if (cfg.foreground)
-        vfprintf(stderr, msg, ap);
-    va_end(ap);
-
-    if (do_syslog) {
-        va_start(ap, msg);
-        vsyslog(type, msg, ap);
-        va_end(ap);
-    }
-}
-
 
 /* Fills a connection description; returns 0 on failure */
 int get_connection_desc(struct connection_desc* desc, const struct connection *cnx)
@@ -641,34 +849,10 @@ int get_connection_desc(struct connection_desc* desc, const struct connection *c
     return 1;
 }
 
-/* syslogs who connected to where 
- * desc: string description of the connection. if NULL, log_connection will
- * manage on its own
- * cnx: connection descriptor
- * */
-void log_connection(struct connection_desc* desc, const struct connection *cnx)
-{
-    struct connection_desc d;
-
-    if (cnx->proto->log_level < 1)
-        return;
-
-    if (!desc) {
-        desc = &d;
-        get_connection_desc(desc, cnx);
-    }
-
-    log_message(LOG_INFO, "%s:connection from %s to %s forwarded from %s to %s\n",
-                cnx->proto->name,
-                desc->peer,
-                desc->service,
-                desc->local,
-                desc->target);
-}
 
 void set_proctitle_shovel(struct connection_desc* desc, const struct connection *cnx)
 {
-#ifdef LIBBSD
+#ifdef HAVE_LIBBSD
     struct connection_desc d;
 
     if (!desc) {
@@ -693,7 +877,7 @@ void set_proctitle_shovel(struct connection_desc* desc, const struct connection
  */
 int check_access_rights(int in_socket, const char* service)
 {
-#ifdef LIBWRAP
+#ifdef HAVE_LIBWRAP
     union {
         struct sockaddr saddr;
         struct sockaddr_storage ss;
@@ -708,8 +892,7 @@ int check_access_rights(int in_socket, const char* service)
     /* extract peer address */
     res = getnameinfo(&peer.saddr, size, addr_str, sizeof(addr_str), NULL, 0, NI_NUMERICHOST);
     if (res) {
-        if (cfg.verbose)
-            fprintf(stderr, "getnameinfo(NI_NUMERICHOST):%s\n", gai_strerror(res));
+        print_message(msg_system_error, "getnameinfo(NI_NUMERICHOST):%s\n", gai_strerror(res));
         strcpy(addr_str, STRING_UNKNOWN);
     }
     /* extract peer name */
@@ -717,15 +900,12 @@ int check_access_rights(int in_socket, const char* service)
     if (!cfg.numeric) {
         res = getnameinfo(&peer.saddr, size, host, sizeof(host), NULL, 0, NI_NAMEREQD);
         if (res) {
-            if (cfg.verbose)
-                fprintf(stderr, "getnameinfo(NI_NAMEREQD):%s\n", gai_strerror(res));
+            print_message(msg_system_error, "getnameinfo(NI_NAMEREQD):%s\n", gai_strerror(res));
         }
     }
 
-    if (!hosts_ctl(service, host, addr_str, STRING_UNKNOWN)) {
-        if (cfg.verbose)
-            fprintf(stderr, "access denied\n");
-        log_message(LOG_INFO, "connection from %s(%s): access denied", host, addr_str);
+    if (!hosts_ctl((char*)service, host, addr_str, STRING_UNKNOWN)) {
+        print_message(msg_connections, "connection from %s(%s): access denied", host, addr_str);
         close(in_socket);
         return -1;
     }
@@ -733,16 +913,23 @@ int check_access_rights(int in_socket, const char* service)
     return 0;
 }
 
+volatile sig_atomic_t received_sigchld;
+
+void sig_sigchld(int sig)
+{
+    received_sigchld = 1;
+}
+
+
 void setup_signals(void)
 {
     int res;
     struct sigaction action;
 
-    /* Request no SIGCHLD is sent upon termination of
-     * the children */
+    /* Set SIGCHLD to sig_sigchld() */
     memset(&action, 0, sizeof(action));
-    action.sa_handler = NULL;
-    action.sa_flags = SA_NOCLDWAIT;
+    action.sa_handler = sig_sigchld;
+    action.sa_flags = SA_NOCLDSTOP;
     res = sigaction(SIGCHLD, &action, NULL);
     CHECK_RES_DIE(res, "sigaction");
 
@@ -757,42 +944,12 @@ void setup_signals(void)
     action.sa_handler = SIG_IGN;
     res = sigaction(SIGPIPE, &action, NULL);
     CHECK_RES_DIE(res, "sigaction");
-
 }
 
-/* Open syslog connection with appropriate banner;
- * banner is made up of basename(bin_name)+"[pid]" */
-void setup_syslog(const char* bin_name) {
-    char *name1, *name2;
-    int res, fn;
-
-    if (!strcmp(cfg.syslog_facility, "none")) {
-        do_syslog = 0;
-        return;
-    }
-
-    name1 = strdup(bin_name);
-    res = asprintf(&name2, "%s[%d]", basename(name1), getpid());
-    CHECK_RES_DIE(res, "asprintf");
-
-    for (fn = 0; facilitynames[fn].c_val != -1; fn++)
-        if (strcmp(facilitynames[fn].c_name, cfg.syslog_facility) == 0)
-            break;
-    if (facilitynames[fn].c_val == -1) {
-        fprintf(stderr, "Unknown facility %s\n", cfg.syslog_facility);
-        exit(1);
-    }
-
-    openlog(name2, LOG_CONS, facilitynames[fn].c_val);
-    free(name1);
-    /* Don't free name2, as openlog(3) uses it (at least in glibc) */
-
-    log_message(LOG_INFO, "%s %s started\n", server_type, VERSION);
-}
 
 /* Ask OS to keep capabilities over a setuid(nonzero) */
 void set_keepcaps(int val) {
-#ifdef LIBCAP
+#if HAVE_LIBCAP
     int res;
     res = prctl(PR_SET_KEEPCAPS, val, 0, 0, 0);
     if (res) {
@@ -805,7 +962,7 @@ void set_keepcaps(int val) {
 /* Returns true if anything requires transparent proxying. */
 static int use_transparent(void)
 {
-#ifdef LIBCAP
+#if HAVE_LIBCAP
     if (cfg.transparent)
         return 1;
 
@@ -821,7 +978,7 @@ static int use_transparent(void)
  * IN: cap_net_admin: set to 1 to set CAP_NET_RAW
  * */
 void set_capabilities(int cap_net_admin) {
-#ifdef LIBCAP
+#if HAVE_LIBCAP
     int res;
     cap_t caps;
     cap_value_t cap_list[10];
@@ -866,16 +1023,14 @@ void drop_privileges(const char* user_name, const char* chroot_path)
     if (user_name) {
         pw = getpwnam(user_name);
         if (!pw) {
-            fprintf(stderr, "%s: not found\n", user_name);
+            print_message(msg_config_error, "%s: not found\n", user_name);
             exit(2);
         }
-        if (cfg.verbose)
-            fprintf(stderr, "turning into %s\n", user_name);
+        print_message(msg_config, "turning into %s\n", user_name);
     }
 
     if (chroot_path) {
-        if (cfg.verbose)
-            fprintf(stderr, "chrooting into %s\n", chroot_path);
+        print_message(msg_config, "chrooting into %s\n", chroot_path);
 
         res = chroot(chroot_path);
         CHECK_RES_DIE(res, "chroot");
@@ -901,18 +1056,48 @@ void drop_privileges(const char* user_name, const char* chroot_path)
     }
 }
 
+
+#ifndef O_NOFOLLOW
+#define O_NOFOLLOW 0
+#endif
+
 /* Writes my PID */
 void write_pid_file(const char* pidfile)
 {
-    FILE *f;
+    int fd;
+    char pidbuf[32];
+    size_t len, written = 0;
+    ssize_t res;
 
-    f = fopen(pidfile, "w");
-    if (!f) {
-        perror(pidfile);
-        exit(3);
+    /* Format PID as string */
+    len = snprintf(pidbuf, sizeof(pidbuf), "%d\n", getpid());
+    if (len >= sizeof(pidbuf)) {
+        print_message(msg_system_error, "write_pid_file: PID string too long\n");
+        return;
     }
 
-    fprintf(f, "%d\n", getpid());
-    fclose(f);
-}
+    /* Open file with O_NOFOLLOW to prevent symlink attacks (Similar to CVE-2020-28935) */
+    fd = open(pidfile, O_WRONLY | O_CREAT | O_TRUNC | O_NOFOLLOW ,0644);
 
+    if (fd == -1) {
+        print_message(msg_system_error, "write_pid_file: %s: %s\n", pidfile, strerror(errno));
+        return;
+    }
+
+    /* Write PID to file with proper error handling */
+    while (written < len) {
+        res = write(fd, pidbuf + written, len - written);
+        if (res == -1) {
+            if (errno == EINTR || errno == EAGAIN)
+                continue;
+            print_message(msg_system_error, "write_pid_file: write: %s\n", strerror(errno));
+            break;
+        }
+        written += res;
+    }
+
+    /* Close file */
+    if (close(fd) == -1) {
+        print_message(msg_system_error, "write_pid_file: close: %s\n", strerror(errno));
+    }
+}

common.h

@@ -5,6 +5,7 @@
  * enough for the macros to adapt (http://support.microsoft.com/kb/111855)
  */
 #ifdef __CYGWIN__
+#undef FD_SETSIZE
 #define FD_SETSIZE 4096
 #endif
 
@@ -33,6 +34,11 @@
 #include <sys/capability.h>
 #endif
 
+#ifdef __APPLE__
+#include <AvailabilityMacros.h>
+#endif
+
+#include "config.h"
 #include "version.h"
 
 #define MAX(a, b)  (((a) > (b)) ? (a) : (b))
@@ -40,20 +46,20 @@
 
 #define CHECK_RES_DIE(res, str) \
     if (res == -1) {    \
-       fprintf(stderr, "%s:%d:", __FILE__, __LINE__); \
+       print_message(msg_system_error, "%s:%d:", __FILE__, __LINE__); \
        perror(str);     \
        exit(1);         \
     }
 
 #define CHECK_RES_RETURN(res, str, ret) \
     if (res == -1) {                                    \
-        log_message(LOG_CRIT, "%s:%d:%s:%d:%s\n", __FILE__, __LINE__, str, errno, strerror(errno));  \
+        print_message(msg_system_error, "%s:%d:%s:%d:%s\n", __FILE__, __LINE__, str, errno, strerror(errno));  \
         return ret;                                     \
     } 
 
 #define CHECK_ALLOC(a, str) \
     if (!a) { \
-        fprintf(stderr, "%s:%d:", __FILE__, __LINE__); \
+        print_message(msg_system_error, "%s:%d:", __FILE__, __LINE__); \
         perror(str); \
         exit(1); \
     }
@@ -83,9 +89,6 @@ enum connection_state {
     ST_SHOVELING   /* Connexion is established */
 };
 
-/* this is used to pass protocols through the command-line parameter parsing */
-#define PROT_SHIFT 1000  /* protocol options will be 1000, 1001, etc */
-
 /* A 'queue' is composed of a file descriptor (which can be read from or
  * written to), and a queue for deferred write data */
 struct queue {
@@ -95,11 +98,18 @@ struct queue {
     int deferred_data_size;
 };
 
+/* Double linked list for timeout management */
+typedef struct {
+    struct connection* head;
+    struct connection* tail;
+} dl_list;
+
 struct connection {
     int type;           /* SOCK_DGRAM | SOCK_STREAM */
     struct sslhcfg_protocols_item* proto; /* Where to connect to */
 
     /* SOCK_STREAM */
+    struct listen_endpoint* endpoint; /* Client-facing listen fd */
     enum connection_state state;
     time_t probe_timeout;
 
@@ -109,13 +119,16 @@ struct connection {
     struct queue q[2];
 
     /* SOCK_DGRAM */
-    struct sockaddr client_addr; /* Contains the remote client address */
+    struct sockaddr_storage client_addr; /* Contains the remote client address */
     socklen_t addrlen;
 
     int local_endpoint; /* Contains the local address */
 
     time_t last_active;
 
+    /* double linked list of timeouts */
+    struct connection *timeout_prev, *timeout_next;
+
     /* We need one local socket for each target server, so we know where to
      * forward server responses */
     int target_sock;  
@@ -125,6 +138,9 @@ struct connection {
 struct listen_endpoint {
     int socketfd;       /* file descriptor of listening socket */
     int type;           /* SOCK_DGRAM | SOCK_STREAM */
+    int family;         /* AF_INET | AF_UNIX */
+    int num_connections; /* How many active connections on this endpoint */
+    struct sslhcfg_listen_item* endpoint_cfg; /* the configuration item that corresponds to this endpoint */
 };
 
 #define FD_CNXCLOSED    0
@@ -147,7 +163,7 @@ typedef enum {
 /* common.c */
 void init_cnx(struct connection *cnx);
 int set_nonblock(int fd);
-int connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking);
+void connect_addr(struct connection *cnx, int fd_from, connect_blocking blocking);
 int fd2fd(struct queue *target, struct queue *from);
 char* sprintaddr(char* buf, size_t size, struct addrinfo *a);
 void resolve_name(struct addrinfo **out, char* fullname);
@@ -160,22 +176,36 @@ void setup_syslog(const char* bin_name);
 void drop_privileges(const char* user_name, const char* chroot_path);
 void set_capabilities(int cap_net_admin);
 void write_pid_file(const char* pidfile);
-void log_message(int type, const char* msg, ...);
 void dump_connection(struct connection *cnx);
+int inc_proto_connections(struct sslhcfg_protocols_item* cnx);
+void dec_proto_connections(struct sslhcfg_protocols_item* cnx);
 int resolve_split_name(struct addrinfo **out, char* hostname, char* port);
 
 int start_listen_sockets(struct listen_endpoint *sockfd[]);
 
-int defer_write(struct queue *q, void* data, int data_size);
+int defer_write(struct queue *q, void* data, ssize_t data_size);
+void defer_skip(struct queue *q, ssize_t data_size);
+int defer_write_before(struct queue *q, void* data, ssize_t data_size);
 int flush_deferred(struct queue *q);
 
 extern struct sslhcfg_item cfg;
 extern struct addrinfo *addr_listen;
 extern const char* server_type;
 
+#if defined(__APPLE__) && (MAC_OS_X_VERSION_MIN_REQUIRED < 1080)
+extern int hosts_ctl();
+#endif
+
 /* sslh-fork.c */
 void start_shoveler(int);
 
 void main_loop(struct listen_endpoint *listen_sockets, int num_addr_listen);
 
+/* landlock.c */
+void setup_landlock(void);
+
+
+/* sslh-fork.c or processes.c, depending on the model */
+void setup_sigchld(void);
+
 #endif

config.h.in

@@ -0,0 +1,21 @@
+
+
+#ifndef CONFIG_H
+/* Template for config.h, filled by `configure`. */
+
+/* Libwrap, to support host_ctl, /etc/allow and /etc/deny */
+#undef HAVE_LIBWRAP
+
+/* Landlock sandboxing Linux LSM */
+#undef HAVE_LANDLOCK
+
+/* Support for Proxy-protocol using libproxyprotocol */
+#undef HAVE_PROXYPROTOCOL
+
+/* libcap support, to use Linux capabilities */
+#undef HAVE_LIBCAP
+
+/* libbsd, to change process name */
+#undef HAVE_LIBBSD
+
+#endif

configure.ac

@@ -0,0 +1,20 @@
+
+dnl Use autoconf to generate the `configure` script from this and Makefile.in
+dnl This is awkardly adapted from https://github.com/edrosten/autoconf_tutorial
+dnl (all mistakes mine)
+
+AC_INIT
+AC_CONFIG_HEADERS(config.h)
+AC_CONFIG_FILES([Makefile])
+
+AC_CHECK_LIB([wrap], [hosts_ctl], [AC_DEFINE(HAVE_LIBWRAP) LIBS="$LIBS -lwrap" ], [])
+AC_CHECK_LIB([cap], [cap_get_proc], [AC_DEFINE(HAVE_LIBCAP) LIBS="$LIBS -lcap" ], [])
+AC_CHECK_LIB([bsd], [setproctitle], [AC_DEFINE(HAVE_LIBBSD) LIBS="$LIBS -lbsd" ], [])
+
+AC_CHECK_HEADERS(linux/landlock.h, AC_DEFINE(HAVE_LANDLOCK), [])
+AC_CHECK_HEADERS(proxy_protocol.h, [AC_DEFINE(HAVE_PROXYPROTOCOL) LIBS="$LIBS -lproxyprotocol" ], [])
+
+LIBS="$LIBS"
+AC_SUBST([LIBS])
+
+AC_OUTPUT

container-entrypoint.sh

@@ -0,0 +1,97 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL2-or-later
+#
+# Copyright (C) 2023 Olliver Schinagl <oliver@schinagl.nl>
+#
+# A beginning user should be able to docker run image bash (or sh) without
+# needing to learn about --entrypoint
+# https://github.com/docker-library/official-images#consistency
+
+set -eu
+
+bin='sslh'
+
+# run command if it is not starting with a "-" and is an executable in PATH
+if [ "${#}" -le 0 ] || \
+   [ "${1#-}" != "${1}" ] || \
+   [ -d "${1}" ] || \
+   ! command -v "${1}" > '/dev/null' 2>&1; then
+	entrypoint='true'
+fi
+
+unconfigure_iptables() { 
+	echo "Received SIG TERM/INT/KILL. Removing iptables / routing changes"
+
+	set +e # Don't exit if got error
+	set -x
+
+	iptables -t raw -D PREROUTING ! -i lo -d 127.0.0.0/8 -j DROP
+	iptables -t mangle -D POSTROUTING ! -o lo -s 127.0.0.0/8 -j DROP
+
+	iptables -t nat -D OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
+	iptables -t mangle -D OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+	ip rule del fwmark 0x1 lookup 100
+	ip route del local 0.0.0.0/0 dev lo table 100
+
+
+	if [ $(cat /proc/sys/net/ipv6/conf/all/disable_ipv6) -eq 0 ]; then
+		ip6tables -t raw -D PREROUTING ! -i lo -d ::1/128 -j DROP
+		ip6tables -t mangle -D POSTROUTING ! -o lo -s ::1/128 -j DROP
+		ip6tables -t nat -D OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
+		ip6tables -t mangle -D OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+		ip -6 rule del fwmark 0x1 lookup 100
+		ip -6 route del local ::/0 dev lo table 100
+	fi
+		
+	set -e
+	set +x
+}
+
+configure_iptables() {
+	echo "Configuring iptables and routing..."
+
+	set +e # Don't exit if got error
+	set -x
+	
+	iptables -t raw -A PREROUTING ! -i lo -d 127.0.0.0/8 -j DROP
+	iptables -t mangle -A POSTROUTING ! -o lo -s 127.0.0.0/8 -j DROP
+
+	iptables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN  -j CONNMARK --set-xmark 0x01/0x0f
+	iptables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+	ip rule add fwmark 0x1 lookup 100
+	ip route add local 0.0.0.0/0 dev lo table 100
+
+	if [ $(cat /proc/sys/net/ipv6/conf/all/disable_ipv6) -eq 0 ]; then
+		ip6tables -t raw -A PREROUTING ! -i lo -d ::1/128 -j DROP
+		ip6tables -t mangle -A POSTROUTING ! -o lo -s ::1/128 -j DROP
+		ip6tables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
+		ip6tables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+		ip -6 rule add fwmark 0x1 lookup 100
+		ip -6 route add local ::/0 dev lo table 100
+	fi
+	
+	set -e
+	set +x
+}
+
+for _args in "${@}" ; do
+	if [ "${_args:-}" = '--transparent' ] ; then
+		echo '--transparent flag is set'
+		configure_iptables
+		trap unconfigure_iptables TERM INT KILL
+		break
+	fi
+done
+
+# Drop privileges and run as sslh user
+sslh_cmd="${entrypoint:+${bin}} ${@}"
+echo "Executing with user 'sslh': ${sslh_cmd}"
+
+exec su - sslh -c "${sslh_cmd}" &
+wait "${!}"
+
+exit 0

doc/Daisy-Chaining-Transparency-Explained.md

@@ -0,0 +1,331 @@
+# Daisy-Chaining-Transparency #
+
+This documentation goes a level deeper, what happens in the operating system with IP-addresses, and why some combinations of programs are failing, when they use the same transparency method.
+
+There are situations, where you need to combine two applications, both working as ip-transparent proxies, to reach your goal. One example is, having nginx or stunnel as an proxytunnel-endpoint for tls tunneled ssh connections through https-proxies. An example for such a combination will be desribed at the end of this article.
+
+Unfortunately you will see a lot of errors popping out: **Address already in use**
+
+[This article from Cloudflare blog](https://blog.cloudflare.com/how-to-stop-running-out-of-ephemeral-ports-and-start-to-love-long-lived-connections) explains why this is happening, while it is describing the solution to another problem. However this is a close relative to our problem.
+
+Let us look to the following example: We have sslh (S) accepting connections from a client (C) and forwarding one of those connections to a man-in-the-middle (M), which finally forwards this connection to sshd. If everything works perfectly, we would like to see those connections.
+
+![Dataflow-Of-Daisy-Chain](./detailed-ip-transparency.png)
+
+But unfortunately we are receiving in many constellations errors, when M tries to open its connection to our final target sshd, here called T.
+
+Let us look more close, why that is happening. We need for this two terminal windows on the same server.
+
+### First example, uncooperative applications ###
+
+As the problem has nothing to do with transparency itself, but only of reuse of same IP-addresses and ports, we avoid the overhead of the additional capablities, to keep the example easy and clear.
+
+In the first terminal we are starting python3 and entering the following three lines:
+
+```
+user@host:~$ python3
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  
+>>> sock.bind(("192.168.255.254", 12345))
+>>> 
+```
+
+Now we are going to the second terminal window, and trying just the same:
+
+```
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  
+>>> sock.bind(("192.168.255.254", 12345))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+OSError: [Errno 98] Address already in use
+sock.bind(("192.168.255.254", 12346))  ##this however works!!
+```
+
+Here we are getting the error, which caused many of us hours of research.
+The problem is caused by the fact, that the kernel does not know at the moment of the bind()-call, how we want to use the socket. If we use this as a server socket, and will do a listen()-call as next, this will not work, as for server sockets, the two-value tuple ADDRESS:PORT needs to be unique only to the process, tied to this socket.
+
+That is the reason, that there are port ranges, reserved for servers, where the administrator is responsible not to assign the same port to two applications.
+
+But as server ports are coming from a range, which will not be used for client connections, a server can be sure, that if it is started at any time in the future, no outgoing client has used its port for an outbound connection.
+
+Clients are usually using ports from a so called [ephemeral port range](https://en.wikipedia.org/wiki/Ephemeral_port).
+
+However, for clients each connection is valid, as long as one value in the four-tuples describing the connection is different. In our example above, the two values from the destination are different, so this connection could be established (in theory) without conflicts.
+
+To make that happen, you need to deploy a special socket option to this socket, to explain, that we "know the risks" and we will reuse the ip-port combination.
+
+And, as we see from the second bind() in the second example, the error message: _**Address already in use**_ really means: _**Address:Port already in use**_
+
+### Taking Care, part I ###
+
+Ok, now we are entering our two terminals again, pressing Ctrl-D to finish python, and start a new session like this in both terminals:
+
+```
+user@host:~$ python3
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+>>> sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)  
+>>> sock.bind(("192.168.255.254", 12345))
+>>> 
+``` 
+
+And we will see, that the problem is solved, when both applications are taking care.
+
+### Taking Care, part II ###
+
+Ok, now we are going back to our terminals, pressing again Ctrl-D to finish python, and start new sessions like this:
+
+In the first terminal we repeat the input from our first example, without the setsockopt() call:
+
+```
+user@host:~$ python3
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  
+>>> sock.bind(("192.168.255.254", 12345))
+>>> 
+```
+
+in the second terminal, we enter our modified cooperative example:
+
+```
+user@host:~$ python3
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+>>> sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)  
+>>> sock.bind(("192.168.255.254", 12345))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+OSError: [Errno 98] Address already in use
+>>> 
+``` 
+
+Oops, here is our error again. And this is the reason, why I called this method "cooperative". As the first application has bound to that IP:PORT combination, without telling, that "it knows the risk", the kernel denies us, to use this combinations, as we may break the already active application. The first application is not "cooperative" :-(
+
+ Ok, but the kernel gives as some more possibilities: As we now get connections from a uncoperative application, we can no longer use the Client-IP-Port combination. We need to use a conflict free port for the client IP, to succeed. So lets get back to terminal 2 and continue after the error with the following commands:
+
+```
+user@host:~$ python3
+Python 3.11.2 (main, May  2 2024, 11:59:08) [GCC 12.2.0] on linux
+Type "help", "copyright", "credits" or "license" for more information.
+>>> import socket
+>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+>>> sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)  
+>>> sock.bind(("192.168.255.254", 12345))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+OSError: [Errno 98] Address already in use
+>>> sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 0)
+>>> sock.setsockopt(socket.SOL_IP, socket.IP_BIND_ADDRESS_NO_PORT, 1)
+>>> sock.bind(("192.168.255.254", 0))
+>>>
+```
+
+This last example makes it neccessary, that you use a recent version of the python3 socket library, as older versions, have the option _IP_BIND_ADDRESS_NO_PORT_ not yet defined.
+
+With his behaviour, we are telling the kernel, that the kernel should assign us a conflict free port address at latest possible moment, while calling connect().
+
+From `man ip`:
+
+```
+Inform the kernel to not reserve an ephemeral port when using bind(2)
+with a port number of 0. The port will later be automatically chosen
+at connect(2) time, in a way that allows sharing a source port as 
+long as the 4-tuple is unique.
+```
+
+Ok, now with those two actions an application is really ready for cooperative working in ip-transparent chains.
+
+If you are running in problems, with any kind of application, where you are redirecting transparent traffic to from sslh, check the following:
+
+- Are you using a recent version of sslh, having the described feature enabled
+- are you using the most recent version of the other application
+If you can confirm both checks, tell the maintainers of the other application, about possible fixes, and send them a link to this article.
+
+## Practical Use Of Daisy-Chaining: Proxytunnel Endpoint ##
+
+One reasons, why we want to combine two programs is related to the core functionality of sslh. You wish to hide your ssh connection behind a https port.
+
+But now you would like, to reach this port via the [proxy-tunnel application](https://github.com/proxytunnel/proxytunnel), though an restrictive http(s) proxy. This is in many cases, one of the few methods, to escape from restricted private networks, like in companies, schools and universities. Unfortunately, many of those proxy-servers will check, that the protocol leaving the proxy is really tls. Therefore you need and endpoint in your system, which will terminate the tls-connection and forward the encapsulated ssh stream to the sshd.  Sslh can't do tls termination, as this is not a core job of tls. One of the solutions tried here is stunnel. Stunnel can do transparency like sslh, but unfortunately belongs to the uncooperative ip-transparent programs. At the time of writing this article, you can use stunnel as the first-in-chain, and a very recent sslh as second in chain. But nginx (or openresty) is capable of this, however it prefers (at least in the tested versions), mostly the second way just selecting a new random port and not (always) preserving the original source port, what makes debugging of events much easier.
+
+
+```
+stream {
+  ssl_preread on;
+
+  map $ssl_preread_server_name $name {
+    default            master.yourdomain.top;
+    t1.yourdomain.top  t1.yourdomain.top;
+    t2.yourdomain.top  t2.yourdomain.top;
+    cryptic.foo.bar    location.selfsigned.cert;
+  }
+
+## $destination port :443 is assumed, beeing as real
+## webserver. Either anothe nginx http-server or apache 
+## or anything other ...
+  map $ssl_preread_server_name $dest {
+    default              192.168.255.254:443;
+    t1.yourdomain.top    192.168.255.254:443;
+    t2.yourdomain.top    192.168.255.254:444;
+    cryptic.foo.notexist 192.168.255.254:445;
+  }
+
+
+## this is the server, to handle incoming tcp streams
+## and dispatching them transparent to $dest
+## 192.168.255.254:1443 is the address, where
+## the front facing sslh sends traffic to
+  server {
+    listen 192.168.255.254:1443;
+    proxy_connect_timeout 5s;
+    proxy_timeout 3m;
+    proxy_bind $remote_addr transparent;
+    proxy_pass $dest;
+    ssl_preread on;
+  }
+
+  ## this is a basic endpoint for proxy-tunnel connections
+  server {
+    listen 192.168.255.254:444 ssl;
+    ssl_protocols TLSv1.2 TLSv1.3;
+    ssl_session_cache shared:SSL:10m;
+    ssl_session_timeout 10m;
+    ssl_prefer_server_ciphers on;
+    ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256";
+    ## give facl to the nginx user, see later in article
+    ssl_certificate /etc/letsencrypt/live/$name/fullchain.pem;
+    ssl_certificate_key /etc/letsencrypt/live/$name/privkey.pem;
+    ssl_dhparam  /etc/nginx/dhparam-nginx.pem;
+    ssl_session_cache shared:MySSL:10m;
+    ssl_session_tickets off;
+    proxy_connect_timeout 5s;
+    proxy_timeout 3m;
+    proxy_bind $remote_addr transparent;
+    proxy_pass 192.168.255.254:22 ;
+  }
+
+
+## this is a fancy destination, using some tricks, to fool
+## some proxies.
+  server {
+    listen 192.168.255.254:445 ssl;
+    ssl_protocols TLSv1.2 TLSv1.3;
+    ssl_session_cache shared:SSL:10m;
+    ssl_session_timeout 10m;
+    ssl_prefer_server_ciphers on;
+    ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256";
+    ## this points to a directory, containg a self signed certificate
+    ## created with CN and SAN to an not officially existing
+    ## domain, e.g. cryptic.foo.notexists
+    ssl_certificate /etc/nginx/$name/fullchain.pem;
+    ssl_certificate_key /etc/nginx/$name/privkey.pem;
+    ssl_dhparam  /etc/nginx/dhparam-nginx.pem;
+    ssl_session_cache shared:MySSL:10m;
+    ssl_session_tickets off;
+    ## additional trick: requiring client certificate authentication
+    ssl_client_certificate /etc/nginx/public.cert ;
+    ssl_verify_client on ;
+    proxy_connect_timeout 5s;
+    proxy_timeout 3m;
+    proxy_bind $remote_addr transparent;
+    proxy_pass 192.168.255.254:22;
+  }
+}
+```
+
+This nginx stream server shows a combination of different possibilities, how to establish an endpoint for proxytunnel or similar programs, to hide your ssh connection. Remember: Hiding ssh tunneled in tls does not neccessarly raise the security of your connection. In theory a combination of two methods may also lower the security. In addition there are more drawbacks: Such a connection needs more cpu on both ends for doing double crypto, and the throughput through he connection drops, as the ratio payload/header increases. the single ssh-packets are smaller, than usual.
+So it is not recommended for doing scp or sftp through such connections.
+
+### Nginx Configration Explained ###
+
+However, there are situations, where this is the only way, to reach your server.
+
+So we have now this nginx instance helping us out.
+
+The server stanza listening on _192.168.255.254:1443_ is the main process, accepting incoming connections forwarded from sslh. It prereads tls SNI names, to get destination information. When in the nginx-configuration a variable is used, which is set by an map action, the mapping takes place just in that moment, when the variable needs to be expanded.
+
+So we have either default values, in case there is no SNI, or values for individual SNI.
+
+The connection stream is than forwarded ip-transparent to a given destination, which is itself another nginx instance, defined in the configuration file.
+
+#### The Standard TLS-Termination ####
+
+The server stanza listening on _192.168.255.254:444_ is a very basic TLS terminating endpoint. In most cases, a proxy is happy with a destination like this. Here nginx just terminates the TLS connection and shovels the incoming packets over to sshd in ip-transparent way. The proxytunnel configuration for this target will look like:
+
+```
+host t2.yourdomain.top 
+  ProxyCommand /path/to/proxytunnel -e -p PROXY-IP:3128 -d t2.yourdomain.top:443
+  ServerAliveInterval 30
+```
+
+If you have no proxytunnel on your system, you can also use openssl. In this case the configuration looks like:
+
+```
+host t2-alias
+  ProxyCommand openssl s_client -proxy PROXY-IP:3128  -connect t2.yourdomain.top:443 
+  ServerAliveInterval 30
+```
+
+`ssh ts-alias` will use this configuration.
+
+One point from the above configuration needs further explanation, as we just refer to our common letsencrypt store, for certificates.
+
+##### Excurse To File ACLs #####
+
+We are using here our common letsencrypt certificate store, as copying certificates after renewal is a pain in the as and prone to errors.
+
+A small script makes sure, that all applications can read the certificates:
+
+```
+for i in  Debian-exim dovecot mail www-data nginx ; do
+  setfacl -Rdm u:$i:rX ./archive/
+  setfacl -Rdm u:$i:rX ./live/
+  setfacl -Rm u:$i:rX ./archive/
+  setfacl -Rm u:$i:rX ./live/
+  for file in $( find ./live ./archive -type l,f ) ; do
+    echo -e "$i $file set"
+    setfacl -m u:$i:r $file
+  done
+done
+```
+
+This script needs only to be run, when a new application user needs access.
+The first two lines are making sure (watch the **d**), that the given options
+on those directories will be the default for newly created files below.
+The uppercase **X** means, that **x**-access will only be granted to directories or files, having already **x** set for others.
+
+#### The Tricky TLS Termination ####
+
+The server stanza listening on _192.168.255.254:445_ is a more tricky TLS terminating endpoint. Some proxies are trying to inspect the destination, before letting you go. Some of them you can fool, others not.
+
+One trick can be to use an phantasy domain name with a self signed certificate, no dns server will ever resolve. As you are using this name as SNI name in your proxy-tunnel connection, it will work.  This can be also a way, to hide your sshd, if someone, who knows you are using sslh tries to find your sshd. As long, as this person does not get access to proxies you are using, this may help in some situations.
+
+Another trick is, requiring a client certificate for authentication. This is in each case the much better approach, as you can combine this also with official connected domain names. Without the client certificate no sshd!
+
+The client certificate does not increase the above mentioned ratio between payload and headers, as this is only used while establishing the TLS connection.
+
+It prevents however a proxy, doing a parallel sneak to your destination, to figure out what is behind. I have seen proxies letting you connect with this method, others are denying access.
+
+To access this endpoint, the proxytunnel configuration inside `~/.ssh/config`
+will look like:
+
+```
+host cryptic.foo.notexists
+  ProxyCommand /path/to/proxytunnel -e -c ~/public.cert -k ~/private.pem -C ~/myOwnCA.cert -p PROXY-IP:3128 -o cryptic.foo.notexists  -d t1.yourdomain.top:443
+  ServerAliveInterval 30
+```
+
+`-C` gives the certfile to your certificate used for selfsigning the server certificate. You can also set `-z` for not verifying the certificate, but that is not recommended! `t1.yourdomain.top` represents a valid domain name, where the listening sslh can be reached. This name is not taken for SNI, because **-o** sets our hidden SNI name. Whenever you enter `ssh cryptic.foo.notexists` you will get connected to your server!
+
+The best recommendation however is: Avoid self-signed certs, if you are not really sure what you are doing.
+

doc/FAQ.md

@@ -7,24 +7,25 @@ doesn't work, report how what was suggested here went.
 It's also worth reading [how to ask
 questions](http://www.catb.org/~esr/faqs/smart-questions.html)
 before posting on the mailing list or opening an issue in
-Github.
+GitHub.
 
 Getting more info
 =================
 
-In general, if something doesn't work, you'll want to run
-`sslh` with lots of logging, and the logging directly in
-the terminal (Otherwise, logs are sent to `syslog`, and
-usually end up in `/var/log/auth.log`). You will achieve
-this by running `sslh` in foreground with verbose:
+There are several `verbose` options that each enable a set
+of messages, each related to some event type. See
+`example.cfg` for a list of them.
+
+If something doesn't work, you'll want to run `sslh` with
+lots of logging, and the logging directly in the terminal
+(Otherwise, logs are sent to `syslog`, and usually end up in
+`/var/log/auth.log`). There is a general `--verbose` option
+that will allow you to enable all messages:
 
 ```
-sslh -v 1 -f -F myconfig.cfg
+sslh -v 3 -f -F myconfig.cfg
 ```
 
-Higher values of `verbose` produce more information. 1 is
-usually sufficient. 2 will also print incoming packets used
-for probing.
 
 forward to [PROBE] failed:connect: Connection refused
 =====================================================
@@ -167,3 +168,17 @@ protocols: (
                 ["^(GET|POST|PUT|OPTIONS|DELETE|HEADER) [^ ]* HTTP/[0-9.]*[\r\n]*Host: host_B.acme"] }
 );
 ```
+
+I get an error "Too many open files"
+====================================
+
+`sslh` used up all the file descriptors it can (1024 by default in Linux),
+which means it cannot create new connections. On some
+systems, you can increase the process limit with `ulimit -n
+2048` (for example). Maybe more usefully, you can limit the
+connection usage based on protocols or listening address, as
+described in the [max_connections](max_connections.md)
+guide.
+
+
+

doc/INSTALL.md

@@ -1,3 +1,13 @@
+Pre-built binaries
+==================
+
+Docker images of `master` and of the tagged versions are
+available directly from [Github](https://github.com/yrutschle/sslh/pkgs/container/sslh).
+
+Windows binaries for Cygwin are graciously produced by
+nono303 on his [repository](https://github.com/nono303/sslh).
+
+
 Compile and install
 ===================
 
@@ -6,115 +16,156 @@ Dependencies
 
 `sslh` uses:
 
-* [libconfig](http://www.hyperrealm.com/libconfig/). For
-  Debian this is contained in package `libconfig8-dev`. You
-can compile with or without it using USELIBCONFIG in the
-Makefile.
+* [libconfig](http://www.hyperrealm.com/libconfig/).
+  For Debian this is contained in package `libconfig-dev`.
+  You can compile with or without it using USELIBCONFIG in the Makefile.
 
 * [libwrap](http://packages.debian.org/source/unstable/tcp-wrappers).
-    For Debian, this is contained in packages
-`libwrap0-dev`. You
-can compile with or without it using USELIBWRAP in the
-Makefile.
+  For Debian, this is contained in packages `libwrap0-dev`.
+  Presence of libwrap is checked by the configure script.
 
-* [libsystemd](http://packages.debian.org/source/unstable/libsystemd-dev), in package `libsystemd-dev`.  You
-can compile with or without it using USESYSTEMD in the
-Makefile.
+* [libsystemd](http://packages.debian.org/source/unstable/libsystemd-dev), in package `libsystemd-dev`.
+  You can compile with or without it using USESYSTEMD in the Makefile.
 
-* [libcap](http://packages.debian.org/source/unstable/libcap-dev), in package `libcap-dev`. You can compile with or without it using USELIBCAP in the Makefile
+* [libcap](http://packages.debian.org/source/unstable/libcap-dev), in package `libcap-dev`.
+  Presence of libcap is checked by the configure script.
 
-* libbsd, to enable to change the process name (as shown in
-  `ps`, so each forked process shows what protocol and what
-  connection it is serving),
-which requires `libbsd` at runtime, and `libbsd-dev` at
-compile-time.
+* [libconfig++-dev](https://packages.debian.org/bookworm/libconfig++-dev), in package `lìbconfig++-dev`
+    
+* libbsd, to enable to change the process name (as shown in `ps`,
+  so each forked process shows what protocol and what connection it is serving),
+  which requires `libbsd` at runtime, and `libbsd-dev` at compile-time.
+  Presence of libbsd is checked by the configure script.
 
+* libpcre2, in package `libpcre2-dev`.
+  You can compile with or without it using ENABLE_REGEX in the Makefile.
+
+* libev-dev, in package `libev-dev`.
+  If you build a binary specifically and do not build `sslh-ev`, you don't need this.
+
+* [libproxyprotocol](https://github.com/kosmas-valianos/libproxyprotocol.git)
+  to support HAProxy's [ProxyProtocol](https://www.haproxy.org/download/2.3/doc/proxy-protocol.txt).
+  As this is not part of the distribution packages, set
+  C_INCLUDE_PATH, LD_LIBRARY_PATH, and LIBRARY_PATH to the appropriate
+  values:
+  ```
+    export C_INCLUDE_PATH=/home/user/src/libproxyprotocol/src 
+    export LD_LIBRARY_PATH=/home/user/src/libproxyprotocol/libs
+    export LIBRARY_PATH=/home/user/src/libproxyprotocol/libs
+  ```
 
 For OpenSUSE, these are contained in packages libconfig9 and
 libconfig-dev in repository
 <http://download.opensuse.org/repositories/multimedia:/libs/openSUSE_12.1/>
 
-For Fedora, you'll need packages `libconfig` and
-`libconfig-devel`:
+For Fedora, you'll need packages `libconfig` and `libconfig-devel`:
 
-	yum install libconfig libconfig-devel
+    yum install libconfig libconfig-devel
 
-If you want to rebuild `sslh-conf.c` (after a `make
-distclean` for example), you will also need to add
-[conf2struct](https://www.rutschle.net/tech/conf2struct/README.html)
+If you want to rebuild `sslh-conf.c` (after a `make distclean` for example),
+you will also need to add [conf2struct](https://www.rutschle.net/tech/conf2struct/README.html)
 (v1.5) to your path.
 
+The test scripts are written in Perl, and will require
+`IO::Socket::INET6` (`libio-socket-inet6-perl` in Debian).
+
+
 Compilation
 -----------
+First you have to run `./configure`  in the _**./sslh**_ directory. After this, 
+the Makefile is created, and you can do your configuration changes in the Makefile. 
+After each run of ./configure, those changes are gone and the Makefile is recreated.
 
-After this, the Makefile should work:
+There are a couple of configuration options at the beginning of the Makefile: 
 
-	make install
+* `# override undefine HAVE_LANDLOCK` if you uncomment this line, sslh will be compiled
+  without landlock. This works with gcc versions < 12. Otherwise, if your system has
+  linux/landlock.h in the include path, the configure script creates a _**config.h**_ file, 
+  which defines HAVE_LANDLOCK. It is not enough, to set this to 0, you must delete it, 
+  when you don't wish to have landlock in your binary.
+  
+* `USELIBWRAP` compiles support for host access control (see `hosts_access(3)`),
+  you will need `libwrap` headers and library to compile (`libwrap0-dev` in Debian).
 
-There are a couple of configuration options at the beginning
-of the Makefile: 
+* `USELIBCONFIG` compiles support for the configuration file.
+  You will need `libconfig` headers to compile (`libconfig8-dev` in Debian).
 
-* `USELIBWRAP` compiles support for host access control (see
-  `hosts_access(3)`), you will need `libwrap` headers and
-  library to compile (`libwrap0-dev` in Debian).
+* `USESYSTEMD` compiles support for using systemd socket activation.
+  You will need `systemd` headers to compile (`systemd-devel` in Fedora).
 
-* `USELIBCONFIG` compiles support for the configuration
-  file. You will need `libconfig` headers to compile
-  (`libconfig8-dev` in Debian).
+* `USELIBBSD` compiles support for updating the process name (as shown by `ps`).
 
-*  `USESYSTEMD` compiles support for using systemd socket activation.
-   You will need `systemd` headers to compile (`systemd-devel` in Fedora).
+* `USELIBCAP` compiles support for libcap, which allows to inherit capabilities to 
+  daughter-processes, which run as restricted users. You need this, when you wish to 
+  make sure, that the --user= parameter can be used, without setting capabilities etc.
+  to your binaries, to make this work.
+
+Now you can do either a plain `make` to create the binaries, or you can do an 
+`make install` to create the binaries and install them.
+
+
+Generating the configuration parser
+-----------------------------------
+
+The configuration file and command line parser is generated by `conf2struct`,
+from `sslhconf.cfg`, which generates `sslh-conf.c` and `sslh-conf.h`.
+The resulting files are included in the source
+so `sslh` can be built without `conf2struct` installed.
+
+Further, to prevent build issues,
+`sslh-conf.[ch]` has no dependency to `sslhconf.cfg` in the Makefile.
+In the event of adding configuration settings,
+they need to be regenerated using `make c2s`.
 
-* `USELIBBSD` compiles support for updating the process name (as shown
-  by `ps`).
 
 Binaries
 --------
 
-The Makefile produces two different executables: `sslh-fork`
-and `sslh-select`:
+The Makefile produces three different executables:
+`sslh-fork`, `sslh-select` and `sslh-ev`:
 
 * `sslh-fork` forks a new process for each incoming connection.
-It is well-tested and very reliable, but incurs the overhead
-of many processes.  
-If you are going to use `sslh` for a "small" setup (less than
-a dozen ssh connections and a low-traffic https server) then
-`sslh-fork` is probably more suited for you. 
+  It is well-tested and very reliable, but incurs the overhead of many processes.  
+  If you are going to use `sslh` for a "small" setup
+  (less than a dozen ssh connections and a low-traffic https server)
+  then `sslh-fork` is probably more suited for you.
 
-* `sslh-select` uses only one thread, which monitors all connections
-at once. It is more recent and less tested, but only incurs a 16
-byte overhead per connection. Also, if it stops, you'll lose all
-connections, which means you can't upgrade it remotely.  
-If you are going to use `sslh` on a "medium" setup (a few thousand ssh
-connections, and another few thousand ssl connections),
-`sslh-select` will be better.
+* `sslh-select` uses only one thread, which monitors all connections at once.
+  It only incurs a 16 byte overhead per connection.
+  Also, if it stops, you'll lose all connections,
+  which means you can't upgrade it remotely.
+  If you are going to use `sslh` on a "medium" setup (a few hundreds of connections),
+  or if you are on a system where forking is expensive (e.g. Windows),
+  `sslh-select` will be better.
 
-If you have a very large site (tens of thousands of connections),
-you'll need a vapourware version that would use libevent or
-something like that.
+* `sslh-ev` is similar to `sslh-select`, but uses `libev` as a backend.
+  This allows using specific kernel APIs that
+  allow to manage thousands of connections concurrently.
 
 
 Installation
 ------------
 
 * In general:
-
-		make
-		cp sslh-fork /usr/local/sbin/sslh
-		cp basic.cfg /etc/sslh.cfg
-                vi /etc/sslh.cfg
-
+  ```sh
+  ./configure
+  make
+  cp sslh-fork /usr/local/sbin/sslh
+  cp basic.cfg /etc/sslh.cfg
+  vi /etc/sslh.cfg
+  ```
 * For Debian:
-
-		cp scripts/etc.init.d.sslh /etc/init.d/sslh
-	
+  ```sh
+  cp scripts/etc.init.d.sslh /etc/init.d/sslh
+  ```
 * For CentOS:
+  ```sh
+  cp scripts/etc.rc.d.init.d.sslh.centos /etc/rc.d/init.d/sslh
+  ```
 
-		cp scripts/etc.rc.d.init.d.sslh.centos /etc/rc.d/init.d/sslh
-
-
-You might need to create links in /etc/rc<x>.d so that the server
+You might need to create links in `/etc/rc<x>.d` so that the server
 start automatically at boot-up, e.g. under Debian:
-
-	update-rc.d sslh defaults
+```sh
+update-rc.d sslh defaults
+```
 

doc/README.MacOSX

@@ -33,7 +33,7 @@ with launchctl or simply reboot.
 		<string>0.0.0.0:443</string>
 		<string>--ssh</string>
 		<string>localhost:22</string>
-		<string>--ssl</string>
+		<string>--tls</string>
 		<string>localhost:443</string>
 	</array>
 	<key>QueueDirectories</key>

doc/README.Windows.md

@@ -0,0 +1,72 @@
+It is possible to run `sslh` on Windows. The `fork` model
+should be avoided as it is very inefficient on Windows, but
+`sslh-select` and `sslh-ev` both work with good performance
+(prefer the latter, however).
+
+
+The following script downloads the latest cygwin, the latest version of sslh, and then compiles and copies the binaries with dependancies to an output folder.
+
+It may be needed to correct it from time to time, but it works. I use it in a virtual machine.
+Just retrieve WGET.EXE from https://eternallybored.org/misc/wget/ or git binaries.
+
+Copy the 3 files
+
+	GO.cmd
+	wget.exe
+	compile.sh
+	
+to C root folder, then execute **GO.cmd** with administrative rights.
+
+with **GO.cmd**
+
+	@ECHO OFF
+	CD /D "%~dp0"
+	
+	NET SESSION >NUL 2>&1
+	IF %ERRORLEVEL% NEQ 0 (
+	    ECHO Permission denied. This script must be run as an Administrator.
+	    ECHO:
+	    GOTO FIN
+	) ELSE (
+	    ECHO Running as Administrator.
+	    TIMEOUT /T 2 >NUL
+		wget --no-check-certificate https://www.cygwin.com/setup-x86_64.exe
+		IF NOT EXIST setup-x86_64.exe GOTO FIN
+		MKDIR C:\Z
+		setup-x86_64.exe -l C:\Z -s ftp://ftp.funet.fi/pub/mirrors/sourceware.org/pub/cygwin/ -q -P make -P git -P gcc-g++ -P autoconf -P automake -P libtool -P libpcre-devel -P libpcre2-devel -P bison -P libev-devel
+		MKDIR C:\cygwin64\home\user
+	COPY COMPILE.SH C:\cygwin64\home\user
+			START C:\cygwin64\bin\mintty.exe /bin/bash --login -i ~/compile.sh
+		START EXPLORER C:\zzSORTIE
+	)
+	:FIN
+	PAUSE
+	EXIT
+
+
+and **compile.sh**
+
+	# SAVE FILE TO UNIX FORMAT
+	# COPY IT IN C cygwin64 home user
+	git clone https://github.com/hyperrealm/libconfig.git
+	cd libconfig
+	autoreconf -fi
+	./configure
+	make
+	make install
+	cd ..
+	cp /usr/local/lib/libconfig.* /usr/lib
+	git clone https://github.com/yrutschle/sslh.git
+	cd sslh
+	make
+	cd ..
+	mkdir /cygdrive/c/zzSORTIE
+	cp ./sslh/sslh*.exe /cygdrive/c/zzSORTIE
+	cp /usr/local/bin/cygconfig-11.dll /cygdrive/c/zzSORTIE
+	cp /cygdrive/c/cygwin64/bin/cygwin1.dll /cygdrive/c/zzSORTIE
+	cp /cygdrive/c/cygwin64/bin/cygpcreposix-0.dll /cygdrive/c/zzSORTIE
+	cp /cygdrive/c/cygwin64/bin/cygpcre-1.dll /cygdrive/c/zzSORTIE
+	cp /cygdrive/c/cygwin64/bin/cygev-4.dll /cygdrive/c/zzSORTIE
+	cp /cygdrive/c/cygwin64/bin/cygpcre2-8-0.dll /cygdrive/c/zzSORTIE
+
+This method was contributed by lerenardo on [github](https://github.com/yrutschle/sslh/issues/196#issuecomment-1692805639).

doc/config.md

@@ -65,21 +65,21 @@ Configuration goes like this on the server side, using `stunnel3`:
   * `-f` for foreground/debugging
   * `-p` for specifying the key and certificate
   * `-d` for specifying which interface and port
-	we're listening to for incoming connexions
+	we're listening to for incoming connections
   * `-l` summons `sslh` in inetd mode.
 
 * sslh options:
   * `-i` for inetd mode
-  * `--http` to forward HTTP connexions to port 80,
-	and SSH connexions to port 22.
+  * `--http` to forward HTTP connections to port 80,
+	and SSH connections to port 22.
 
 Capabilities support
 --------------------
 
-On Linux (only?), you can compile sslh with `USELIBCAP=1` to
-make use of POSIX capabilities; this will save the required
-capabilities needed for transparent proxying for unprivileged
-processes.
+On Linux (only?), you can compile sslh with `USELIBCAP=1` set 
+in the Makefile to make use of POSIX capabilities; this will 
+save the required capabilities needed for transparent proxying 
+for unprivileged processes.
 
 Alternatively, you may use filesystem capabilities instead
 of starting sslh as root and asking it to drop privileges.
@@ -92,165 +92,18 @@ to the executable:
 
 	sudo setcap cap_net_bind_service,cap_net_raw+pe sslh-select
 
-Then you can run sslh-select as an unpriviledged user, e.g.:
+Then you can run sslh-select as an unprivileged user, e.g.:
 
 	sslh-select -p myname:443 --ssh localhost:22 --tls localhost:443
 
 Transparent proxy support
 -------------------------
 
-On Linux and FreeBSD you can use the `--transparent` option to
-request transparent proxying. This means services behind `sslh`
-(Apache, `sshd` and so on) will see the external IP and ports
-as if the external world connected directly to them. This
-simplifies IP-based access control (or makes it possible at
-all).
+Transparent proxying is described in its own
+[document](tproxy.md).
 
-You can refer to Sean Warn'ѕ [tutorial](tproxy.md) for a
-different set-up which enables transparent proxying between
-two different machines. The following may only work if
-`sslh` and the final servers are on the same machine.
-
-Note that getting this to work is very tricky and
-detail-dependant: depending on whether the target server and
-sslh are on the same machine, different machines, or
-different dockers, and tool versions, all seem to change the
-required network configuration somewhat. If it doesn't work,
-it's almost certain that the problem is not linked to `sslh`
-but to the network setup that surrounds it.
-
-Linux:
-
-`sslh` needs extended rights to perform this: you'll need to
-give it `CAP_NET_RAW` capabilities (see appropriate chapter)
-or run it as root (but don't do that).
-
-The firewalling tables also need to be adjusted as follows.
-I don't think it is possible to have `httpd` and `sslh` both listen to 443 in
-this scheme -- let me know if you manage that:
-
-	# Set route_localnet = 1 on all interfaces so that ssl can use "localhost" as destination
-	sysctl -w net.ipv4.conf.default.route_localnet=1
-	sysctl -w net.ipv4.conf.all.route_localnet=1
-
-	# DROP martian packets as they would have been if route_localnet was zero
-	# Note: packets not leaving the server aren't affected by this, thus sslh will still work
-	iptables -t raw -A PREROUTING ! -i lo -d 127.0.0.0/8 -j DROP
-	iptables -t mangle -A POSTROUTING ! -o lo -s 127.0.0.0/8 -j DROP
-
-	# Mark all connections made by ssl for special treatment (here sslh is run as user "sslh")
-	iptables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
-
-	# Outgoing packets that should go to sslh instead have to be rerouted, so mark them accordingly (copying over the connection mark)
-	iptables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
-
-	# Configure routing for those marked packets
-	ip rule add fwmark 0x1 lookup 100
-	ip route add local 0.0.0.0/0 dev lo table 100
-
-Tranparent proxying with IPv6 is similarly set up as follows:
-
-	# Set route_localnet = 1 on all interfaces so that ssl can use "localhost" as destination
-	# Not sure if this is needed for ipv6 though
-	sysctl -w net.ipv4.conf.default.route_localnet=1
-	sysctl -w net.ipv4.conf.all.route_localnet=1
-
-	# DROP martian packets as they would have been if route_localnet was zero
-	# Note: packets not leaving the server aren't affected by this, thus sslh will still work
-	ip6tables -t raw -A PREROUTING ! -i lo -d ::1/128 -j DROP
-	ip6tables -t mangle -A POSTROUTING ! -o lo -s ::1/128 -j DROP
-
-	# Mark all connections made by ssl for special treatment (here sslh is run as user "sslh")
-	ip6tables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
-
-	# Outgoing packets that should go to sslh instead have to be rerouted, so mark them accordingly (copying over the connection mark)
-	ip6tables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
-
-	# Configure routing for those marked packets
-	ip -6 rule add fwmark 0x1 lookup 100
-	ip -6 route add local ::/0 dev lo table 100
-
-Explanation:
-To be able to use `localhost` as destination in your sslh config along with transparent proxying
-you have to allow routing of loopback addresses as done above.
-This is something you usually should not do (see [this stackoverflow post](https://serverfault.com/questions/656279/how-to-force-linux-to-accept-packet-with-loopback-ip/656484#656484))
-The two `DROP` iptables rules emulate the behaviour of `route_localnet` set to off (with one small difference:
-allowing the reroute-check to happen after the fwmark is set on packets destined for sslh).
-See [this diagram](https://upload.wikimedia.org/wikipedia/commons/3/37/Netfilter-packet-flow.svg) for a good visualisation
-showing how packets will traverse the iptables chains.
-
-Note:
-You have to run `sslh` as dedicated user (in this example the user is also named `sslh`), to not mess up with your normal networking.
-These rules will allow you to connect directly to ssh on port
-22 (or to any other service behind sslh) as well as through sslh on port 443.
-
-Also remember that iptables configuration and ip routes and 
-rules won't be necessarily persisted after you reboot. Make 
-sure to save them properly. For example in CentOS7, you would 
-do `iptables-save > /etc/sysconfig/iptables`, and add both 
-`ip` commands to your `/etc/rc.local`.
-
-FreeBSD:
-
-Given you have no firewall defined yet, you can use the following configuration
-to have ipfw properly redirect traffic back to sslh
-
-	/etc/rc.conf
-	firewall_enable="YES"
-	firewall_type="open"
-	firewall_logif="YES"
-	firewall_coscripts="/etc/ipfw/sslh.rules"
-
-
-/etc/ipfw/sslh.rules
-
-	#! /bin/sh
-
-	# ssl
-	ipfw add 20000 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8443 to any out
-	ipfw add 20010 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8443 to any out
-
-	# ssh
-	ipfw add 20100 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8022 to any out
-	ipfw add 20110 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8022 to any out
-
-	# xmpp
-	ipfw add 20200 fwd 192.0.2.1,443 log tcp from 192.0.2.1 5222 to any out
-	ipfw add 20210 fwd 2001:db8::1,443 log tcp from 2001:db8::1 5222 to any out
-
-	# openvpn (running on other internal system)
-	ipfw add 20300 fwd 192.0.2.1,443 log tcp from 198.51.100.7 1194 to any out
-	ipfw add 20310 fwd 2001:db8::1,443 log tcp from 2001:db8:1::7 1194 to any out
-
-General notes:
-
-
-This will only work if `sslh` does not use any loopback
-addresses (no `127.0.0.1` or `localhost`), you'll need to use
-explicit IP addresses (or names):
-
-	sslh --listen 192.168.0.1:443 --ssh 192.168.0.1:22 --tls 192.168.0.1:4443
-
-This will not work:
-
-	sslh --listen 192.168.0.1:443 --ssh 127.0.0.1:22 --tls 127.0.0.1:4443
-    
-Transparent proxying means the target server sees the real
-origin address, so it means if the client connects using
-IPv6, the server must also support IPv6. It is easy to
-support both IPv4 and IPv6 by configuring the server
-accordingly, and setting `sslh` to connect to a name that
-resolves to both IPv4 and IPv6, e.g.:
-
-        sslh --transparent --listen <extaddr>:443 --ssh insideaddr:22
-
-        /etc/hosts:
-        192.168.0.1  insideaddr
-        201::::2     insideaddr
-
-Upon incoming IPv6 connection, `sslh` will first try to
-connect to the IPv4 address (which will fail), then connect
-to the IPv6 address.
+It might be easier to configure `sslh` to use Proxyprotocol
+if the backend server supports it.
 
 Systemd Socket Activation
 -------------------------
@@ -313,7 +166,7 @@ This parses the /etc/sslh.cfg (or /etc/sslh/sslh.cfg file if that exists
 instead) configuration file and dynamically generates a socket file to use.
 
 This will also merge with any sslh.socket.d drop in configuration but will be 
-overriden by a /etc/systemd/system/sslh.socket file.
+overridden by a /etc/systemd/system/sslh.socket file.
 
 To use the generator place it in /usr/lib/systemd/system-generators and then
 call systemctl daemon-reload after any changes to /etc/sslh.cfg to generate 
@@ -335,13 +188,24 @@ UDP
 ---
 
 `sslh` can perform demultiplexing on UDP packets as well.
-This only works with `sslh-select` (it is not possible to
+This does not work with `sslh-fork` (it is not possible to
 support UDP with a forking model). Specify a listening
 address and target protocols with `is_udp: true`. `sslh`
 will wait for incoming UDP packets, run the probes in the
 usual fashion, and forward packets to the appropriate
 target. `sslh` will then remember the association between
 remote host to target server for 60 seconds by default,
-which can be overriden with `udp_timeout`. This allows to
+which can be overridden with `udp_timeout`. This allows to
 process both single-datagram protocols such as DNS, and
 connection-based protocols such as QUIC.
+
+An example for supporting QUIC is shown in `example.cfg`.
+
+
+Limiting file descriptor consumption
+------------------------------------
+
+There are various mechanisms to limit the number of
+concurrent connections, which allows to limit the usage of
+file descriptor. This is described in a separate
+[guide](max_connections.md).

doc/max_connections.md

@@ -0,0 +1,64 @@
+Limiting the number of connections
+----------------------------------
+
+
+As a network-facing service, `sslh` can be attacked by very
+simple denial-of-service attacks by creating a lot of
+concurrent connections. Protecting against such attacks is
+complicated from the server side. This attack will cause
+`sslh` to create a large number of file handles, which can
+cause exgagerated resource consumption.
+
+In particular, when `sslh` runs into its file descriptor
+limit (as defined with `ulimit -n`), bad things happen: It
+becomes impossible to accept() new sockets efficiently
+(refer to libev's documentation, ["The special problem of
+ accept()ing when you can't"](http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#The_special_problem_of_accept_ing_wh)). Currently, when `sslh-ev` or
+`sslh-select` reaches its limit of file descriptors, it just
+stops accepting new connections altogether for a few
+seconds, hoping for the situation to get better soon. It is
+better to configure `sslh` to limit connections so the
+`ulimit` is never reached.
+
+Keep in mind that limiting the number of connections means
+that in case of an attack, the server resources are
+protected, but this might be at the expense of serving
+legitimate connections. In particular, in some cases this
+might mean SSH is no longer available.
+
+There are several mechanisms to limit the number of
+connections:
+
+- Use `ulimit` (see bash(3) or your shell's man page) to
+limit the number of file descriptors. (but then accepting
+new connections might fail for a while)
+
+Then, `sslh` provides several mechanisms to limit the number
+of concurrent connections, which in turns limits the number
+of file descriptors used.
+
+Essentially there are two ways to do this:
+
+- you can set `max_connections` per protocol, and `sslh`
+will drop connections after probing if the count is
+exceeded.  This should help in keeping SSH connections
+available even if an attacker is stuffing other protocols.
+
+- you can set `max_connections` for each `listen` entry. So
+the `sslh` process for each port will limit the number of
+concurrent connections to that port. This is similar to the
+`udp_max_connections` setting, but for TCP.
+
+`sslh-select` and `sslh-ev` support both limit types.
+
+`sslh-fork` has an explicit design goal to be as simple as
+possible, which makes it impossible to implement limits per
+protocol (because protocol probing is performed after the
+process has forked). Limits will only work for `listen`
+entries.
+
+As of sslh 2.2.5, this is an experimental feature and not
+all use cases have been tested. If 2.2.5 does not exist yet,
+you must be on the Git's head, so it is even more
+experimtental! Do not hesitate to send feedback if you
+notice inconsistent behaviour.

doc/podman.md

@@ -0,0 +1,120 @@
+Here is an example of deployment of sslh in transparent mode
+using ansible and podman, [submitted by Github user
+olegstepura](https://github.com/yrutschle/sslh/issues/448)
+
+```yaml
+# ansible podman task
+- name: "Create sslh-co pod"
+  containers.podman.podman_pod:
+    name: sslh-co # read as "sslh and company"
+    state: started
+    ports:
+      - "80:80"
+      - "443:444"
+      # ... (more ports if needed)
+    network:
+      - '{{ containers.config.network }}' # other services from this network can access containers in this network for example prometheus can read caddy metrics at sslh-co:2020, also caddy itself can connect to other services to act as a reverse proxy
+
+- name: "Create the sslh container"
+  containers.podman.podman_container:
+    name: sslh
+    image: "yrutschle/sslh:latest"
+    pod: sslh-co
+    capabilities:
+      - NET_RAW
+      - NET_BIND_SERVICE
+      - NET_ADMIN
+    sysctl:
+      net.ipv4.conf.default.route_localnet: 1
+      net.ipv4.conf.all.route_localnet: 1
+    expose:
+      - 444
+    volume:
+      # ... (make sure to mount config as you like)
+    command: --transparent -F/etc/sslh/sslh.cfg # parameter --transparent here is needed to trigger configure_iptables in init script
+   state: started
+
+- name: "Create the caddy container"
+  containers.podman.podman_container:
+    name: caddy
+    image: "lucaslorentz/caddy-docker-proxy:alpine" # regular caddy or nginx image will also work
+    pod: sslh-co
+    expose:
+      - 80
+      - 443
+      - 2020 # metrics, since caddy-docker-proxy uses :2019 internally
+    volume:
+      # ... (mount your configs and other stuff here)
+      - "/var/run/podman/podman.sock:/var/run/docker.sock"
+    state: started
+  notify: podman restart sslh
+
+- name: "Create the SSH proxy to host container"
+  containers.podman.podman_container:
+    name: ssh-proxy
+    image: "alpine/socat:latest"
+    pod: sslh-co
+    expose:
+      - 222
+    command: TCP-LISTEN:222,fork TCP:host.containers.internal:22
+    state: started
+```
+
+```ini
+# sslh config
+foreground: true;
+inetd: false;
+numeric: true;
+transparent: true;
+timeout: 5;
+
+listen:
+(
+    { host: "0.0.0.0"; port: "444"; keepalive: true; },
+);
+
+protocols:
+(
+  {
+    name: "ssh";
+    service: "ssh";
+    host: "localhost";
+    port: "222";
+    fork: true;
+  },
+  {
+    name: "http";
+    host: "localhost";
+    port: "80";
+  },
+  {
+    name: "tls";
+    host: "localhost";
+    port: "443";
+  },
+);
+```
+
+I omitted caddy configs here as it's not important. Some unrelated container configs were also dropped.
+In the example above `sslh`, `caddy` and `ssh-proxy` are 3 containers in the same pod, all listening on `localhost`. SSLH has to listen on `444` because caddy already listens on `443` and it's more complex to reconfigure caddy port because of let's encrypt (caddy itself "thinks" it is bound to your host interface).
+
+Scheme of port mapping is (all containers share same `localhost`):
+```
+host 443 → pod 444 (sslh) → pod 443 (caddy)
+```
+- podman connects host `443` port to pod's `444` port
+- `sslh` listens `444` on `localhost`, reroutes tls to `caddy` on `localhost:443`
+- `caddy` listens `443` on `localhost` (reverse-proxies to other apps on private network)
+Reverse-proxied services get correct IP in `X-Forwarded-For` header.
+
+Takeaways:
+- `net.ipv4.conf.default.route_localnet` is setup only in container, not on host, which is nice.
+- same with iptables and route rules applied by `init` script in sslh container
+- `sslh` proxy to other services in the private network will not work (because transparent mode is enabled) even if that other service does not need real IP
+	- with transparent mode all services that `sslh` will connect to should be attached to this pod making it listen on `localhost` of the pod
+	- ports of containers should not clash
+	- ports should be published on pod level, not on containers
+	- containers should not be configured to connect to custom networks
+- because of the above proxying ssh to host will also not work out of the box, `sslh` should connect to `localhost` and not to a random IP. While adding another proxy as a container to the same pod sounds like an overkill I don't see any other solution, so `socat` is used as an additional proxy.
+- `reverse_proxy` by caddy to other containers in the same custom network (as pod is attached to) works (e.g. caddy can connect to other IPs from custom network). `socat` can also connect to host and/or other containers in custom network.
+

doc/proxyprotocol.md

@@ -0,0 +1,120 @@
+Using Proxyprotocol with sslh
+=============================
+
+HAProxy defined the [Proxy protocol](https://www.haproxy.com/documentation/haproxy-configuration-tutorials/proxying-essentials/client-ip-preservation/enable-proxy-protocol/), where a proxy adds external connection information directly inside the TCP connection, for the backend server to get. This achieves the same goal as transparent proxying, while requiring no networking knowledge and no administration rights.
+
+Instead, the protocol needs to be supported in the servers.
+Many do, e.g. Apache (with the `RemoteIPProxyProtocol` setting).
+
+`sslh` supports this protocol both on the client and the
+server side.
+
+Proxyprotocol on the server side
+--------------------------------
+
+Presumably that's the most common setup, with `sslh` being
+the client-facing proxy in front of the backend server.
+Support is enabled by adding the `proxyprotocol: [1|2]`
+setting in the target protocol:
+
+```
+listen:
+(
+    { host: "localhost"; port: "443"; }
+);
+
+protocols:
+(
+     { name: "ssh";  host: "localhost"; port: "2222"; },
+     { name: "tls";  host: "localhost"; port: "8080"; proxyprotocol: 2; }
+     );
+);
+```
+
+Here `sslh` listens on port 443. It forwards `ssh`
+connections to port 2222 without touching them (which means sshd does not see the external data) (Apparently openssh does not as of september 2025 support Proxyprotocol).
+It forwards `tls` to port 8080, adding a proxy-protocol v2
+header which allows Apache (configured with RemoteIPProxyProtocol) to log the external IP and port.
+
+
+```
+                   203.0.113.4:443           :2222
+   Client -----------------> sslh -------------> sshd
+ 198.51.100.42:2342             |              logs: 127.0.0.1:<local port>
+                                |
+                                |            :8080
+                                \--pp v2-------> apache
+                                               logs: 198.51.100.42:2342
+
+```
+
+The `proxyprotocol` setting can be set to 1 or 2, which
+selects the appropriate protocol version. Version 2 being
+more efficient, this is what you should use unless you have
+good reasons to use version 1 (e.g. your backend server only
+supports v1, an unlikely scenario).
+
+
+Proxyprotocol on the client side
+--------------------------------
+
+`sslh` also supports Proxy-protocol on incoming connections.
+These are so-called "client side", but you should not enable
+proxy-protocol on an Internet-facing server. Instead, this
+can be useful if `sslh` is located behind another proxy that
+adds proxy-protocol headers, e.g. HAProxy.
+
+This is enabled by adding `proxyprotocol: true` to a
+`listen` statement:
+
+```
+listen:
+(
+    { host: "localhost"; port: "443"; proxyprotocol: true; }
+);
+
+protocols:
+(
+     { name: "ssh";  host: "localhost"; port: "2222"; proxyprotocol: 0; },
+     { name: "tls";  host: "localhost"; port: "8080"; }
+     );
+);
+```
+
+In that case, `sslh` expects to find a proxyprotocol header
+on all incoming connections. It ignores the header to
+perform its usual protocol detection. 
+
+If the target protocol
+specified nothing, the connection is passed untouched, i.e.
+the proxyprotocol header is forwarded as usual: here, Apache
+on 8080 will receive the proxyprotocol header.
+
+If the target protocol specifies `proxyprotocol: 0`, then
+`sslh` removes the proxyprotocol header, and logs an
+additional message with the connection information extracted
+from the header. Here, `sslh` logs the external information
+for ssh connections, removes the header, and forwards the
+connection to sshd. `sshd` does not support proxyprotocol,
+and logs a connection coming from the local IP address.
+
+
+```
+              203.0.113.4:443                                   :2222
+   Client ---------> HaProxy ----pp v2---------> sslh -------------> sshd
+ 198.51.100.42:2342                                 |                  logs: 127.0.0.1:<local port>
+                                                    | sslh logs: 198.51.100.42:2342 to localhost:2222
+                                                    |
+                                                    |            :8080
+                                                    \--pp v2-------> apache
+                                                                       logs: 198.51.100.42:2342
+                                           sslh logs: local connection
+```
+
+`sslh` always logs the 'real' network information, here the
+local addresses, and only logs the proxyprotocol information
+when it removes the header. It is not necessary to log the
+proxyprotocol information when the target server will
+receive it (as it is then the target server's job to log the
+external IP address).
+

doc/scenarios-for-simple-transparent-proxy.md

@@ -0,0 +1,51 @@
+# Three Scenarios for the simple transparent proxy setup #
+
+![Simple Transparent Proxy Examples](./sslh-examples-v3.png)
+
+## Introduction ##
+The first example is the configuration, which was described in the previous document. I omitted the loopback interface "lo" in those diagrams, trying not no overload the picture. 
+The connections have two different endings, showing the direction of the opening connection (SYN flag) and the answer connection (SYN-ACK flags). This is important, as the traffic in the transparent proxy setup flows somewhat unexpected.
+
+## Example 1 ##
+The first example shows the setup, which is described in the [previous document](./simple_transparent_proxy.md). You see the Client connecting to sslh (red connection). When sslh accepts this connection, the SYN-ACK packet is send back to the client, which sends the first data packet(s) together with the ACK for the SYN-ACK. So the bidirectional tcp connection is fully open.
+Sslh opens now the blue connection to sshd and needs for that elevation rights, as it uses the clients IP address as its own address for opening this connection. Now things are becoming complicated: Sshd send back the first packet with SYN-ACK flags (green line), addressed to the clients IP (dotted line). As already described, that would go wrong, so our routing trick makes this packet beeing deflected back to sslh, so this tcp connection is also opened. But we have here now an asymetric behaviour, that the read and write pathes of the tcp connection are going different routes.
+The sslh process shuffles now all the bytes coming from sshd from the green line to the red line, vice versa for the packets from the client.
+
+## Example 2 ##
+In this example sshd is running on another server. No matter, if this is docker, kvm, virtualbox or another physical host, connected with an ethernet cable. Here we need no dummy interface, so we need another way, to configure our routing deflection.  The principle is the same: We need to force packets coming back from sshd going to sslh and not directly back to the client.
+In this case its your decision, where those rules will be tied in, options are:
+
+* the startscript of sslh
+* the docker or kvm configuration
+* the configuration of the outgoing interface
+
+Its two lines you need:
+```
+ip rule add from SSHD_ADDRESS/32 table sslh
+ip route add local 0.0.0.0/0 dev lo table sslh
+```
+On the sshd host, we need no additional rules, as all traffic is coming back to our sslh host, because this is in this setting the default gateway.  The only thing, we need to do: Assign a unique IP address only for sshd and all other services, you wish to hide behind sslh and host on this device.
+
+There are two ways, how you can add multiple ip addresses to one device. The new _**ip addr add**_ supports multiple add statements to one and the same interface name. So you can just duplicate the interface stancas in the _**/etc/network/interfaces**_ configuration. The problem with this method is, that some older managment tools, like ifconfig are unable to show the additional addresses. So when you are used to some older tools, you may configure sub-interfaces like eth0:1.
+However my recommendation is, migrate to new tools, get used to it, as old tools don't show you the whole configuration!
+
+## Example 3 ##
+This is now the extended version of the previous example. The target host has another path back to the client, as there is a default route to another interface. Now we need **TWO** routing deflections, one on the sslh host, like in scenario 2, and one on the sshd target host.
+The routing setup on the target host looks like:
+* Add an routing table name for the deflection table in _**/etc/iproute2/rt_tables**_
+* Find a location, where you will hook the two routing rules in
+```
+ip rule add from SSHD_ADDRESS/32 table sslh_routeback
+ip route add default via SERVER1_ETH1_IP dev eth0 table sslh_routeback
+
+```
+This is setting up a default route for all traffic, originating from the ip address sshd (or any other service) is using, back to the host, hosting sslh. On that host, those packets will be deflected again with the same rule from scenario 2.
+
+Be aware, that scenario 3 can look very different and the picture above shows only one of those setups. Each configuration, where packets from the target system can find their way back, without beeing forcibly routed through the sslh hosting system, belongs into this category. This are e.g. virtual machines or containers, having interfaces in the same network, like the sslh hosting system. Even, when they look in some drawings embedded in their host, as soon, as they have network interfaces, allowing a direct connection to the client, it is scenario 3!
+
+## Modifications ##
+Now you can think about many modifications, but the tools will be the same, for all other thinkable scenarios. You must always make sure, that packets from foreign hosts, will find their way back to the sslh host. So if the chain consists of three or four servers, all need the deflection rules. 
+
+## Important Finding On Routing ##
+When I went ahead and wrote in my first drawings the warning, that the kernel in scenario 2 and 3 needs to have forwarding in place, I finally tested, that this is not true. **Both scenarios are working without kernel forwarding beeing activated!**
+The background:  The deflecting routing table cames into the game, before the kernel has to made the decision, that packets with non local ip addresses in source and destination must be forwarded. After the routing rule deliveres the packet to sslh and sslh rewrites the source ip, the packet is treated as local, and can pass the system.

doc/simple_transparent_proxy.md

@@ -0,0 +1,136 @@
+# Transparent Proxy Configuration Using IP Routing#
+This documentation is another explanation of the transparent proxy with the goal, beeing secure and minimalistic. Besides this documentation will explain, how and why this configuration works.
+The explanation will only describe the connection to sshd, so the target sshd can be replace with any other target service, sslh supports.
+
+## Introduction in the data flow ##
+This chapter can be skipped, if you just like to configure things fast.
+This chapter is a little excurse to the dataflow. First point of all is something, which you will unfortunately not see in the nice routing diagrams for iptables or netfilter-tables (nft) like: [Iptables at wikipedia](https://upload.wikimedia.org/wikipedia/commons/thumb/3/37/Netfilter-packet-flow.svg/2560px-Netfilter-packet-flow.svg.png), [Netfilter Flow](https://wiki.nftables.org/wiki-nftables/index.php/Netfilter_hooks#Netfilter_hooks_into_Linux_networking_packet_flows).
+
+Packets from local application talking to other local applications are routed through the loopback-interface. They leave postrouting to lo and reentering from there prerouting, without passing ingress/egress.
+This has nothing to do with the "**route_localnet = 1**" trick, which only makes, that the the local ip range 10.0.0.0/8 gets routed!
+As you can read in many articles, this is nothing you should do, as you may bring your system at risk, because it allows to leak packets from outside to applications, which feel themselves secure, by using those unroutable addresses.
+
+#### A Simple Simulation ####
+You can prove this behaviour with a simple test:
+```
+# In one terminal start socat as a local echo server
+# this is simulating sshd
+
+socat TCP4-LISTEN:2000,bind=SERVER_IP,fork EXEC:cat
+
+# In the next terminal start another instance of socat,
+# simulating sslh
+
+socat TCP-LISTEN:3000,bind=SERVER_IP,fork TCP:SERVER_IP:2000
+
+# In another terminal you can watch the traffic on lo
+
+tcpdump -i lo port 2000
+
+# In the last terminal talk to the echo server
+telnet SERVER_IP 2000
+```
+You will see your traffic on lo, but not on eth0, if you retry the tcpdump there.
+
+If you setup sslh as non transparent proxy, it will just work, as what we have seen.  
+
+#### Going Transparent ####
+
+In case of transparent proxy however, sslh uses some tricks, to reuse the clients IP on its outgoing interface to sshd. It opens the interface in raw mode, so it either needs to be started as root and drop privileges after binding, or you will need to give some capabilities to the sslh binary (cap_net_bind_service,cap_net_raw+ep), if you will start it as restricted user.
+In this setup we continue, with dropping priviledges.
+
+Doing so, you can send packets to the sshd, listening on another interface, but, the answer packets from sshd will get routed back to the client. This however will not work, as the client would refuse those packets, because they don't belong to a tcp session, the client opened. In most cases those packets would even not reach the client, as source ip addresses from private address space, will be blocked by most internet routers and connection providers.
+
+So its mandatory, to use some tricks, to get those packets back to sslh. All configurations, I have seen so far, are using two components for that. They bind sshd to lo, and than they introduce some firewall rules, to mark packets, originating from the sshd port on lo, so that those packets can be routed in a next step -based on that marking- back to sslh.
+
+##### Drawbacks From Using loopback #####
+This idea has some serious drawbacks: First, you need to allow routing of the local address space, 127.0.0.0/8, with kernel configurations. Search for the string "net.ipv4.conf.default.route_localnet" and you will find lot of articles, why you should not do this.
+By allowing this, you need additional firewall rules, dropping martian packets, which otherwise would get routed to the internet from other applications, running on lo, not aware, that their traffic could be routed.  You need further firewall rules, blocking incoming packets to loopback addresses, as otherwise some applications (especially udp) could be the goal of some bad traffic.
+
+##### Using A Dedicated Interface #####
+So this configuration makes use of a own interface, just for the services, where sslh should hide the traffic for. We use a interface of the dummy kernel module, which was designed just for this case.  It is an interface, beeing there, having no cable connection or whatsever, but applications can bind to it. We assign to this interface just a /32 private address, as this interface is not part of any network.
+
+Doing so, we can avoid all the hassle with marking certain packets, coming from the single applications, sslh has to hide, as we now just route ALL traffic from this specific interface by its ip to sslh.
+We need one routing rule and one routing table, this covers as many targets sslh will serve on this interface, without adding additional rules for adding apache, openvpn and others.
+
+We need no firewall rules, preventing martians, as this single routing rule will deadroute all traffic from this interface, if sslh is not catching it up.
+
+We only need firewall protection for this specific ip address, when we have activated ip forwarding on that system.  If the system is no router and needs no forwarding, there is no protection needed.
+
+## Finally The Configuration ##
+
+As described, we need as a first step a dedicated interface, just for the services, sslh should hide. Its possible, to generate individual interfaces for different configurations, however, that makes things again more complex and has no advantages seen so far.
+
+### Named Routing Table ###
+As we configure the needed routing rules in the interface configuration, we need to define a name for the sslh routing table first.
+Using named routing tables helps, understanding the routing configuration, as a name indicates, why this routing table is configured.
+To do so go to  _**/etc/iproute2/rt_tables**_ and add a line
+
+```
+ 111     sslh
+```
+With newer versions of iproute2 the /etc/iproute2 directory with the embedded templates got no longer installed. The cause maybe, that the example names, which were not used in any configuration, generated confusion. However, once you need those files, generate them and they will be honoured. You still can use just numbers for your routing table. But doing this, and having more than one routing table, you need a list, which numer belongs to which configuration. 
+And seeing in the output from `ip route list table all ` the tables names instead just numbers is worth creating the file.
+
+### Dummy Interface ###
+Now we configure our dedicated interface.
+In the file _**/etc/network/interfaces**_, we place this entry:
+```
+auto dummy0
+iface dummy0 inet static
+    address 192.168.255.254/32
+    pre-up modprobe dummy
+    ## Attention! with kernels, not automatically creating a dummy0
+    ## interface after module loading the following line should be:
+    ## pre-up modprobe dummy; if [ ! -e /sys/class/net/dummy0 ]; then ip link add dummy0 type dummy ; fi
+    post-up ip rule add from 192.168.255.254 table sslh
+    post-up ip route add local 0.0.0.0/0 dev dummy0 table sslh
+    pre-down ip route del local 0.0.0.0/0 dev dummy0 table sslh
+    pre-down ip rule del from 192.168.255.254 table sslh
+```
+As long, as your system has no other interfaces with private address-space, or is routing such addresses, you can continue with the given example. Otherwise you need to select a conflict free address.
+If you are updating a older current configuration, make sure, that you have no longer insecure localnet routing in place:
+```
+ sysctl  net.ipv4.conf.default.route_localnet  
+ sysctl net.ipv4.conf.all.route_localnet
+```
+should both report "0"! 
+
+
+### Explanation Of The Routing Rules ###
+The two routing rules in the dummy0 interface configuration are the key for this configuration.
+
+The first line is an routing rule entry, routing everything coming from the dummy0 ip source address to a special routing table _**sslh**_. 
+
+The next line generates this table implicitly, by inserting a single rule, routing everything from that ip address to dummy0.
+
+Opposite to other firewall based configurations, we have those rules now tied to the dummy0 device, dedicated to the hidden services.
+When this interface comes up, the routing rules are making sure, that no martian packets can leave the system, by some processes using this IP address. When the interface goes down, we delete those rules.
+Also the startup script needs lo longer special treatment for the transparent mode.
+
+
+#### SSLH Default Configuration ####
+And finally you need to configute _**/etc/default/sslh**_ with the right settings for all the services, sslh should work for.
+```
+DAEMON_OPTS="--user sslh --listen SERVER_IP:443 --transparent  \
+             --ssh 192.168.255.254:22 --tls 192.168.255.254:443 \
+             --pidfile /var/run/sslh/sslh.pid"
+```
+
+#### Systemd #### 
+This setup is now startup agnostic. As we don't need special treatment in the startup script, the sysV based init scripts will just work, like the systemd scripts. Nothing needs to be modified, when going transparent.
+
+#### Remote Setups ####
+This concept can also be adapted for several setups, where the sshd (or any other target service) is running in a container, kvm-virtual machine, etc.
+Precondition is, that the target system is the next hop and uses the sslh-hosting system as default gateway. In addition you need to bind an additional ip-address, solely used for sshd on the corresponding interface.
+Than you can adapt the routing rule, routing traffic coming back from this ip to the sslh-routing-table.
+Its also possible, to forward to an next hop system, which has its own default gateway back, bypassing the sslh-host.
+In this case, you need to add a special route back to the sslh host, for all traffic with the sshd source ip address. This can be done similar to the two rules described above:
+```
+  # first define a name for the table in /etc/iproute2/rt_tables e.g. sslh-routeback
+  ip rule add from IPADRESS-OF-SERVIE table sslh-routeback
+  ip route add default via IPADDRESS-OF_SSLH-HOST dev eth0 table sslh-routeback
+```
+The details are depending on your network settings. Als long, as the forward chain to the hidden service passes systems under your control, you can add backroutes on each system in that route. Precondition: The used ip address produces no conflict on those systems.
+
+[I added a second document](./scenarios-for-simple-transparent-proxy.md), describing three possible scenarios in detail. Those three scenarios should cover all setups related to transparent proxying. 

doc/tproxy.md

@@ -1,17 +1,177 @@
-Transparent Proxy to Two Hosts
-==============================
+# Transparent proxy using packet marking
+
+Before reading further, make sure you try to set up
+transparent proxying using [IP routing](simple_transparent_proxy.md).
+It is conceptually easier to understand, cleaner, and more
+portable.
+
+Using this method is very tricky and
+detail-dependant: depending on whether the target server and
+sslh are on the same machine, different machines, or
+different dockers, and tool versions, all seem to change the
+required network configuration somewhat. If it doesn't work,
+it's almost certain that the problem is not linked to `sslh`
+but to the network setup that surrounds it. If in trouble,
+it might be worth trying to set up the network rules
+with a simpler server than `sslh`, such as
+[`socat`](http://www.dest-unreach.org/socat/)
+
+
+Users have tried to do at least the following:
+
+  * `sslh` and the target servers run on the same host (see [below](#transparent-proxy-to-one-host))
+  * `sslh` runs on a host, and the target servers run on LXC or dockers running on the same host. No known working setup.
+  * `sslh` runs on a host, and the target servers run on different hosts on the same local network(see [below](#transparent-proxy-to-two-hosts))
+  * `sslh` runs on a host, and the target servers run on a different host on a different network (there is a [usecase](https://github.com/yrutschle/sslh/issues/295) for this). No known working setup, and it's unclear it is possible.
+
+
+## Transparent proxy to one host
+
+### Linux
+
+`sslh` needs extended rights to perform this: you'll need to
+give it `CAP_NET_RAW` capabilities (see appropriate chapter)
+or run it as root (but don't do that).
+
+The firewalling tables also need to be adjusted as follows.
+I don't think it is possible to have `httpd` and `sslh` both listen to 443 in
+this scheme -- let me know if you manage that:
+
+	# Set route_localnet = 1 on all interfaces so that ssl can use "localhost" as destination
+	sysctl -w net.ipv4.conf.default.route_localnet=1
+	sysctl -w net.ipv4.conf.all.route_localnet=1
+
+	# DROP martian packets as they would have been if route_localnet was zero
+	# Note: packets not leaving the server aren't affected by this, thus sslh will still work
+	iptables -t raw -A PREROUTING ! -i lo -d 127.0.0.0/8 -j DROP
+	iptables -t mangle -A POSTROUTING ! -o lo -s 127.0.0.0/8 -j DROP
+
+	# Mark all connections made by ssl for special treatment (here sslh is run as user "sslh")
+	iptables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
+
+	# Outgoing packets that should go to sslh instead have to be rerouted, so mark them accordingly (copying over the connection mark)
+	iptables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+	# Configure routing for those marked packets
+	ip rule add fwmark 0x1 lookup 100
+	ip route add local 0.0.0.0/0 dev lo table 100
+
+Transparent proxying with IPv6 is similarly set up as follows:
+
+	# Set route_localnet = 1 on all interfaces so that ssl can use "localhost" as destination
+	# Not sure if this is needed for ipv6 though
+	sysctl -w net.ipv4.conf.default.route_localnet=1
+	sysctl -w net.ipv4.conf.all.route_localnet=1
+
+	# DROP martian packets as they would have been if route_localnet was zero
+	# Note: packets not leaving the server aren't affected by this, thus sslh will still work
+	ip6tables -t raw -A PREROUTING ! -i lo -d ::1/128 -j DROP
+	ip6tables -t mangle -A POSTROUTING ! -o lo -s ::1/128 -j DROP
+
+	# Mark all connections made by ssl for special treatment (here sslh is run as user "sslh")
+	ip6tables -t nat -A OUTPUT -m owner --uid-owner sslh -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x01/0x0f
+
+	# Outgoing packets that should go to sslh instead have to be rerouted, so mark them accordingly (copying over the connection mark)
+	ip6tables -t mangle -A OUTPUT ! -o lo -p tcp -m connmark --mark 0x01/0x0f -j CONNMARK --restore-mark --mask 0x0f
+
+	# Configure routing for those marked packets
+	ip -6 rule add fwmark 0x1 lookup 100
+	ip -6 route add local ::/0 dev lo table 100
+
+Explanation:
+To be able to use `localhost` as destination in your sslh config along with transparent proxying
+you have to allow routing of loopback addresses as done above.
+This is something you usually should not do (see [this stackoverflow post](https://serverfault.com/questions/656279/how-to-force-linux-to-accept-packet-with-loopback-ip/656484#656484))
+The two `DROP` iptables rules emulate the behaviour of `route_localnet` set to off (with one small difference:
+allowing the reroute-check to happen after the fwmark is set on packets destined for sslh).
+See [this diagram](https://upload.wikimedia.org/wikipedia/commons/3/37/Netfilter-packet-flow.svg) for a good visualisation
+showing how packets will traverse the iptables chains.
+
+Note:
+You have to run `sslh` as dedicated user (in this example the user is also named `sslh`), to not mess up with your normal networking.
+These rules will allow you to connect directly to ssh on port
+22 (or to any other service behind sslh) as well as through sslh on port 443.
+
+Also remember that iptables configuration and ip routes and 
+rules won't be necessarily persisted after you reboot. Make 
+sure to save them properly. For example in CentOS7, you would 
+do `iptables-save > /etc/sysconfig/iptables`, and add both 
+`ip` commands to your `/etc/rc.local`.
+
+### FreeBSD
+
+Given you have no firewall defined yet, you can use the following configuration
+to have ipfw properly redirect traffic back to sslh
+
+	/etc/rc.conf
+	firewall_enable="YES"
+	firewall_type="open"
+	firewall_logif="YES"
+	firewall_coscripts="/etc/ipfw/sslh.rules"
+
+
+/etc/ipfw/sslh.rules
+
+	#! /bin/sh
+
+	# ssl
+	ipfw add 20000 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8443 to any out
+	ipfw add 20010 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8443 to any out
+
+	# ssh
+	ipfw add 20100 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8022 to any out
+	ipfw add 20110 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8022 to any out
+
+	# xmpp
+	ipfw add 20200 fwd 192.0.2.1,443 log tcp from 192.0.2.1 5222 to any out
+	ipfw add 20210 fwd 2001:db8::1,443 log tcp from 2001:db8::1 5222 to any out
+
+	# openvpn (running on other internal system)
+	ipfw add 20300 fwd 192.0.2.1,443 log tcp from 198.51.100.7 1194 to any out
+	ipfw add 20310 fwd 2001:db8::1,443 log tcp from 2001:db8:1::7 1194 to any out
+
+General notes:
+
+
+This will only work if `sslh` does not use any loopback
+addresses (no `127.0.0.1` or `localhost`), you'll need to use
+explicit IP addresses (or names):
+
+	sslh --listen 192.168.0.1:443 --ssh 192.168.0.1:22 --tls 192.168.0.1:4443
+
+This will not work:
+
+	sslh --listen 192.168.0.1:443 --ssh 127.0.0.1:22 --tls 127.0.0.1:4443
+    
+Transparent proxying means the target server sees the real
+origin address, so it means if the client connects using
+IPv6, the server must also support IPv6. It is easy to
+support both IPv4 and IPv6 by configuring the server
+accordingly, and setting `sslh` to connect to a name that
+resolves to both IPv4 and IPv6, e.g.:
+
+        sslh --transparent --listen <extaddr>:443 --ssh insideaddr:22
+
+        /etc/hosts:
+        192.168.0.1  insideaddr
+        201::::2     insideaddr
+
+Upon incoming IPv6 connection, `sslh` will first try to
+connect to the IPv4 address (which will fail), then connect
+to the IPv6 address.
+
+
+## Transparent Proxy to Two Hosts
 
 Tutorial by Sean Warner.  19 June 2019 20:35
 
-Aim
----
+### Aim
 
 * Show that `sslh` can transparently proxy requests from the internet to services on two separate hosts that are both on the same LAN.
 * The IP address of the client initiating the request is what the destination should see… and not the IP address of the host that `sslh` is running on, which is what happens when `sslh` is not running in transparent mode.
 * The solution here only works for my very specific use-case but hopefully others can adapt it to suits their needs.
 
-Overview of my Network
-----------------------
+### Overview of my Network
 
 Two Raspberry Pis on my home LAN:
 * Pi A: 192.168.1.124 – `sslh` (Port 4433), Apache2 web server for https (port 443), `stunnel` (port 4480) to decrypt ssh traffic and forward to SSH server (also on Pi A at Port 1022)
@@ -20,8 +180,7 @@ Two Raspberry Pis on my home LAN:
 
 ![Architecture](tproxy.svg)
 
-`sslh` build
-------------
+### `sslh` build
  
 `sslh` Version: sslh v1.19c-2-gf451cc8-dirty.
 
@@ -47,8 +206,7 @@ MAN=sslh.8.gz          # man page name
 # itself
 ```
  
-systemd setup
--------------
+### systemd setup
 
 Create an sslh systemd service file...
 ```
@@ -83,8 +241,7 @@ Start it again to test…
 # systemctl start sslh
 ```
  
-Configure `sslh`
-----------------
+### Configure `sslh`
 
 First stop `sslh` then open the config file and replace with below, save and start `sslh` again
 ```
@@ -123,8 +280,7 @@ protocols:
 );
 ```
  
-Configure `stunnel`
--------------------
+### Configure `stunnel`
 
 First stop `stunnel` then open the config file and replace with below, save and start `stunnel` again
 ```
@@ -151,8 +307,7 @@ connect = 192.168.1.124:1022
 TIMEOUTclose  = 0
 ```
  
-Configure iptables for Pi A
---------------------------
+### Configure iptables for Pi A
 
 The `_add.sh` script creates the rules, the `_rm.sh` script removes the rules.
 They will be lost if you reboot but there are ways to make them load again on start-up..
@@ -194,8 +349,7 @@ Now run the "add" script on Pi A!
 # piA_tproxy_rm.sh
 ```
  
-Configure iptables for Pi B
---------------------------
+## Configure iptables for Pi B
 
 ```
 # nano /usr/local/sbin/piB_tproxy_add.sh
@@ -235,8 +389,8 @@ Now run the "add" script on Pi B!
 # piB_tproxy_rm.sh
 ```
  
-Testing
--------
+### Testing
+
 * Getting to sshd on PiA
 
 I did this test using 4G from my phone (outside the LAN)

echo_test.cfg

@@ -0,0 +1,12 @@
+
+# TODO: c2s does not warn if udp: 1 (instead of 'true')
+
+udp: true;
+
+prefix: "hello";
+
+listen: "localhost:9000";
+
+listen-host: "localhost";
+listen-port: "9000";
+

echosrv-conf.c

@@ -1,8 +1,8 @@
 /* Generated by conf2struct (https://www.rutschle.net/tech/conf2struct/README)
- * on Fri Aug 13 18:03:20 2021. 
+ * on Fri Aug 29 20:43:29 2025. 
 
 # conf2struct: generate libconf parsers that read to structs
-# Copyright (C) 2018-2021  Yves Rutschle
+# Copyright (C) 2018-2024  Yves Rutschle
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -36,6 +36,8 @@
 #include <stdlib.h>
 #include <stddef.h>
 #include <stdio.h>
+#include <stdarg.h>
+#include <setjmp.h>
 #include "echosrv-conf.h"
 #include "argtable3.h"
 #ifdef LIBPCRE
@@ -216,6 +218,19 @@ char* config_error_text(config_t* c) {
 }
 #endif
 
+static jmp_buf c2s_asprintf_fail;
+
+static int c2s_asprintf(char **restrict strp, const char *restrict fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap,fmt);
+    int res = vasprintf(strp, fmt, ap);
+    va_end(ap);
+    if (res == -1) longjmp(c2s_asprintf_fail, res);
+    return res;
+}
+
 /* This is the same as config_setting_lookup_string() except
 it allocates a new string which belongs to the caller */
 static int myconfig_setting_lookup_stringcpy(
@@ -226,7 +241,7 @@ static int myconfig_setting_lookup_stringcpy(
     const char* str;
     *value = NULL;
     if (config_setting_lookup_string(setting, name, &str) == CONFIG_TRUE) {
-        asprintf(value, "%s", str);
+        c2s_asprintf(value, "%s", str);
         return CONFIG_TRUE;
     } else {
         return CONFIG_FALSE;
@@ -310,7 +325,7 @@ static int settingcpy(config_type type, void* target, const config_setting_t* se
         break;
 
     case CFG_STRING:
-        asprintf(&str, "%s", config_setting_get_string(setting));
+        c2s_asprintf(&str, "%s", config_setting_get_string(setting));
         val.def_string = str;
         *(char**)target = val.def_string;
         break;
@@ -353,7 +368,7 @@ static int clcpy(config_type type, void* target, const void* cl_arg)
         break;
 
     case CFG_STRING:
-        asprintf(&str, "%s", (*(struct arg_str**)cl_arg)->sval[0]);
+        c2s_asprintf(&str, "%s", (*(struct arg_str**)cl_arg)->sval[0]);
         val.def_string = str;
         *(char**)target = val.def_string;
         break;
@@ -765,7 +780,7 @@ static int read_block_setval(void* target,
             /* setting is present in cfg, look it up */
             if (lookup_typed_ud(cfg, target, desc) != CONFIG_TRUE) {
                 TRACE_READ((" but wrong type (expected %s) ", type2str[desc->type]));
-                asprintf(errmsg, "Option \"%s\" wrong type, expected %s\n", 
+                c2s_asprintf(errmsg, "Option \"%s\" wrong type, expected %s\n", 
                     desc->name, type2str[desc->type]);
                 return 0;
             }
@@ -822,7 +837,7 @@ static int read_block(config_setting_t* cfg, void* target, struct config_desc* d
         set = read_block_setval(target, cfg, desc, errmsg);
 
         if (!set && desc->mandatory) {
-            asprintf(errmsg, "Mandatory option \"%s\" not found", desc->name);
+            c2s_asprintf(errmsg, "Mandatory option \"%s\" not found", desc->name);
             return 0;
         }
 
@@ -980,13 +995,13 @@ static int regcompmatch_posix( regmatch_t* pmatch,
         int errlen = regerror(res, &preg, NULL, 0);
         regerr = malloc(errlen);
         regerror(res, &preg, regerr, errlen);
-        asprintf(errmsg, "compiling pattern /%s/:%s", arg->regex, regerr);
+        c2s_asprintf(errmsg, "compiling pattern /%s/:%s", arg->regex, regerr);
         free(regerr);
         return 0;
     }
     res = regexec(&preg, arg_cl->sval[arg_index], MAX_MATCH, &pmatch[0], 0);
     if (res) {
-        asprintf(errmsg, "--%s %s: Illegal argument", 
+        c2s_asprintf(errmsg, "--%s %s: Illegal argument", 
         arg_cl->hdr.longopts, 
         arg->regex); 
         return 0;
@@ -1012,7 +1027,7 @@ static int regcompmatch_pcre2( regmatch_t* pmatch,
     pcre = pcre2_compile((PCRE2_SPTR8)arg->regex, PCRE2_ZERO_TERMINATED, 0, &error, &error_offset, NULL);
     if (!pcre) {
         pcre2_get_error_message(error, err_str, sizeof(err_str));
-        asprintf(errmsg, "compiling pattern /%s/:%d: %s at offset %ld\n",
+        c2s_asprintf(errmsg, "compiling pattern /%s/:%d: %s at offset %ld\n",
                 arg->regex, error, err_str, error_offset);
         return 0;
     }
@@ -1022,7 +1037,7 @@ static int regcompmatch_pcre2( regmatch_t* pmatch,
                           0, 0, matches, NULL);
     if (res < 0) {
         pcre2_get_error_message(res, err_str, sizeof(err_str));
-        asprintf(errmsg, "matching %s =~ /%s/:%d: %s\n", 
+        c2s_asprintf(errmsg, "matching %s =~ /%s/:%d: %s\n", 
                           arg_cl->sval[arg_index], arg->regex, res, err_str);
         return 0;
     }
@@ -1111,13 +1126,13 @@ static int c2s_parse_file(const char* filename, config_t* c, char**errmsg)
     /* Read config file */
     if (config_read_file(c, filename) == CONFIG_FALSE) {
         if (config_error_line(c) != 0) {
-           asprintf(errmsg, "%s:%d:%s", 
+           c2s_asprintf(errmsg, "%s:%d:%s", 
                     filename,
                     config_error_line(c),
                     config_error_text(c));
            return 0;
         }
-        asprintf(errmsg, "%s:%s", filename, config_error_text(c));
+        c2s_asprintf(errmsg, "%s:%s", filename, config_error_text(c));
         return 0;
     }
     return 1;
@@ -1128,23 +1143,23 @@ static void scalar_to_string(char** strp, config_setting_t* s)
 {
     switch(config_setting_type(s)) {
     case CONFIG_TYPE_INT:
-        asprintf(strp, "%d\n", config_setting_get_int(s));
+        c2s_asprintf(strp, "%d\n", config_setting_get_int(s));
         break;
 
     case CONFIG_TYPE_BOOL:
-        asprintf(strp, "%s\n", config_setting_get_bool(s) ?  "[true]" : "[false]" );
+        c2s_asprintf(strp, "%s\n", config_setting_get_bool(s) ?  "[true]" : "[false]" );
         break;
 
     case CONFIG_TYPE_INT64:
-        asprintf(strp, "%lld\n", config_setting_get_int64(s));
+        c2s_asprintf(strp, "%lld\n", config_setting_get_int64(s));
         break;
 
     case CONFIG_TYPE_FLOAT:
-        asprintf(strp, "%lf\n", config_setting_get_float(s));
+        c2s_asprintf(strp, "%lf\n", config_setting_get_float(s));
         break;
 
     case CONFIG_TYPE_STRING:
-        asprintf(strp, "%s\n", config_setting_get_string(s));
+        c2s_asprintf(strp, "%s\n", config_setting_get_string(s));
         break;
 
     default: /* This means a bug */
@@ -1172,9 +1187,9 @@ static int cfg_as_string(config_setting_t* parent, const char* path, char** strp
 
         if(config_setting_is_list(parent) ||
            config_setting_is_array(parent)) {
-            asprintf(&subpath, "%s[%d]%s", path, config_setting_index(child), name);
+            c2s_asprintf(&subpath, "%s[%d]%s", path, config_setting_index(child), name);
         } else {
-            asprintf(&subpath, "%s/%s", path, name);
+            c2s_asprintf(&subpath, "%s/%s", path, name);
         }
 
         if (config_setting_is_scalar(child)) {
@@ -1182,12 +1197,12 @@ static int cfg_as_string(config_setting_t* parent, const char* path, char** strp
 
             /* Add value to the output string  */
             if (*strp) {
-                asprintf(&old, "%s", *strp);
+                c2s_asprintf(&old, "%s", *strp);
                 free(*strp);
             }  else {
-                asprintf(&old, "%s", "");
+                c2s_asprintf(&old, "%s", "");
             }
-            asprintf(strp, "%s%s:%s", old, subpath, value);
+            c2s_asprintf(strp, "%s%s:%s", old, subpath, value);
             free(value);
             free(old);
 
@@ -1224,6 +1239,14 @@ int echocfg_cl_parse(int argc, char* argv[], struct echocfg_item* cfg)
 
     };
 
+    /* Set up failure handler in case asprintf() runs out of
+    * memory */
+    ;
+    if (setjmp(c2s_asprintf_fail)) {
+        fprintf(stderr, "asprintf: probably out of memory\n");
+        return -1;
+    }
+
     /* Parse command line */
     nerrors = arg_parse(argc, argv, argtable);
     if (nerrors) {

echosrv-conf.h

@@ -1,8 +1,8 @@
 /* Generated by conf2struct (https://www.rutschle.net/tech/conf2struct/README)
- * on Fri Aug 13 18:03:20 2021. 
+ * on Fri Aug 29 20:43:29 2025. 
 
 # conf2struct: generate libconf parsers that read to structs
-# Copyright (C) 2018-2021  Yves Rutschle
+# Copyright (C) 2018-2024  Yves Rutschle
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without

echosrv.c

@@ -1,6 +1,6 @@
 /* echosrv: a simple line echo server with optional prefix adding.
  *
- * echsrv --listen localhost6:1234 --prefix "ssl: "
+ * echosrv --listen localhost6:1234 --prefix "ssl: "
  *
  * This will bind to 1234, and echo every line pre-pending "ssl: ". This is
  * used for testing: we create several such servers with different prefixes,
@@ -26,7 +26,6 @@
 #include <pwd.h>
 #include <syslog.h>
 #include <libgen.h>
-#include <getopt.h>
 #include <errno.h>
 
 #define cfg sslhcfg
@@ -62,9 +61,10 @@ void check_res_dump(int res, struct addrinfo *addr, char* syscall)
 
 void start_echo(int fd)
 {
-    int res;
+    ssize_t res;
     char buffer[1 << 20];
-    int ret, prefix_len;
+    ssize_t ret;
+    size_t prefix_len;
     int first = 1;
 
     prefix_len = strlen(cfg.prefix);
@@ -100,7 +100,10 @@ void tcp_echo(struct listen_endpoint* listen_socket)
 {
     while (1) {
         int in_socket = accept(listen_socket->socketfd, 0, 0);
-        CHECK_RES_DIE(in_socket, "accept");
+        if (in_socket == -1) {
+            perror("tcp_echo:accept");
+            exit(1);
+        }
 
         if (!fork())
         {
@@ -109,6 +112,7 @@ void tcp_echo(struct listen_endpoint* listen_socket)
             exit(0);
         }
         close(in_socket);
+        waitpid(-1, NULL, WNOHANG);
     }
 }
 
@@ -147,7 +151,7 @@ void udp_echo(struct listen_endpoint* listen_socket)
 
     while (1) {
         addrlen = sizeof(src_addr);
-        size_t len = recvfrom(listen_socket->socketfd, 
+        ssize_t len = recvfrom(listen_socket->socketfd,
                            data + prefix_len,
                            sizeof(data) - prefix_len,
                            0,
@@ -158,11 +162,11 @@ void udp_echo(struct listen_endpoint* listen_socket)
             perror("recvfrom");
         }
         *(data + prefix_len + len) = 0;
-        fprintf(stderr, "%ld: %s\n", len, data + prefix_len);
+        fprintf(stderr, "%zd %s\n", len, data + prefix_len);
 
         print_udp_xchange(listen_socket->socketfd, &src_addr, addrlen);
 
-        int res = sendto(listen_socket->socketfd,
+        ssize_t res = sendto(listen_socket->socketfd,
                          data,
                          len + prefix_len,
                          0,
@@ -318,9 +322,6 @@ int start_listen_sockets(struct listen_endpoint *sockfd[])
 
 int main(int argc, char *argv[])
 {
-
-   extern char *optarg;
-   extern int optind;
    int num_addr_listen;
 
    struct listen_endpoint *listen_sockets;

echoѕrv-conf.h

@@ -0,0 +1,109 @@
+/* Generated by conf2struct (https://www.rutschle.net/tech/conf2struct/README)
+ * on Sat Nov  7 09:19:26 2020. 
+
+# conf2struct: generate libconf parsers that read to structs
+# Copyright (C) 2018-2019  Yves Rutschle
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice,
+#    this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+*/
+ 
+#ifndef C2S_SSLHCFG_H
+#define C2S_SSLHCFG_H
+#ifdef LIBCONFIG
+#    include <libconfig.h>
+#endif
+
+
+#include "probe.h"
+#include  <sys/types.h>
+#include  <sys/socket.h>
+#include  <netdb.h>
+
+struct sslhcfg_listen_item {
+	char*	host;
+	char*	port;
+	int	keepalive;
+};
+
+struct sslhcfg_protocols_item {
+	char*	name;
+	char*	host;
+	char*	port;
+	int	service_is_present;
+	char*	service;
+	int	fork;
+	int	tfo_ok;
+	int	log_level;
+	int	keepalive;
+	size_t	sni_hostnames_len;
+	char** sni_hostnames;
+	size_t	alpn_protocols_len;
+	char** alpn_protocols;
+	size_t	regex_patterns_len;
+	char** regex_patterns;
+	int	minlength_is_present;
+	int	minlength;
+	T_PROBE*	probe;
+	struct addrinfo*	saddr;
+	void*	data;
+};
+
+struct sslhcfg_item {
+	char*	prefix;
+	int	verbose;
+	int	foreground;
+	int	inetd;
+	int	numeric;
+	int	transparent;
+	int	timeout;
+	int	user_is_present;
+	char*	user;
+	int	pidfile_is_present;
+	char*	pidfile;
+	int	chroot_is_present;
+	char*	chroot;
+	char*	syslog_facility;
+	char*	on_timeout;
+	size_t	listen_len;
+	struct sslhcfg_listen_item* listen;
+	size_t	protocols_len;
+	struct sslhcfg_protocols_item* protocols;
+};
+
+int sslhcfg_parse_file(
+        const char* filename,
+        struct sslhcfg_item* sslhcfg, 
+        const char** errmsg);
+
+void sslhcfg_fprint(
+    FILE* out,
+    struct sslhcfg_item *sslhcfg,
+    int depth);
+
+int sslhcfg_cl_parse(
+    int argc,
+    char* argv[],
+    struct sslhcfg_item *sslhcfg);
+
+#endif

example.cfg

@@ -3,7 +3,6 @@
 # not be used as a starting point for a working
 # configuration. Instead use basic.cfg.
 
-verbose: 0;
 foreground: true;
 inetd: false;
 numeric: false;
@@ -13,6 +12,34 @@ user: "nobody";
 pidfile: "/var/run/sslh.pid";
 chroot: "/var/empty";
 
+# Logging configuration
+# Value: 1: stdout; 2: syslog; 3: stdout+syslog; 4: logfile; ...; 7: all
+# Defaults are indicated here, and should be sensible. Generally, you want *-error
+# to be always enabled, to know if something is going wrong.
+# Each option relates to a different set of messages.
+verbose-config: 0; #  print configuration at startup
+verbose-config-error: 3;  # print configuration errors
+verbose-connections: 3; # trace established incoming address to forward address
+verbose-connections-error: 3; # connection errors
+verbose-connections-try: 0; # connection attempts towards targets
+verbose-fd: 0; # file descriptor activity, open/close/whatnot
+verbose-packets: 0; # hexdump packets on which probing is done
+verbose-probe-info: 0; # what's happening during the probe process
+verbose-probe-error: 3; # failures and problems during probing
+verbose-system-error: 3; # system call problem, i.e.  malloc, fork, failing
+verbose-int-error: 3; # internal errors, the kind that should never happen
+
+# This one is special and overrides all previous options if
+# set, as a quick way to get "as much as possible"
+#verbose: 3;
+
+# Specify a path to the logfile.
+#logfile: "/var/log/sslh.log"
+
+# Specify the number of concurrent UDP connection that can
+# be managed (default 1024)
+udp_max_connections: 16;
+
 # Specify which syslog facility to use (names for your
 # system are usually defined in /usr/include/*/sys/syslog.h
 # or equivalent)
@@ -22,11 +49,18 @@ syslog_facility: "auth";
 
 # List of interfaces on which we should listen
 # Options:
+# host: name of the interface to listen to
+# port: name of the service to listen to
+# is_udp: listen in the UDP domain (default is TCP)
+# is_unix: listen in the UNIX socket domain (default is TCP)
+# keepalive: set TCP_KEEPALIVE
+# max_connections: drop incoming connections after this count
 listen:
 (
-    { host: "thelonious"; port: "443"; },
+    { host: "thelonious"; port: "443"; max_connections: 5; },
     { host: "thelonious"; port: "8080"; keepalive: true; },
-    { host: "thelonious"; is_udp: true; port: "443" }
+    { host: "thelonious"; is_udp: true; port: "443"; },
+    { host: "/tmp/unix_socket"; is_unix: true; port: ""; }
 );
 
 # List of protocols
@@ -42,18 +76,32 @@ listen:
 #   keepalive:  Should TCP keepalive be on or off for that
 #               connection (default is off)
 #   fork: Should a new process be forked for this protocol?
-#         (only useful for sslh-select)
+#         (only useful for sslh-select and sslh-ev)
+#   max_connections: further connections for this protocol
+#         will be rejected once the limit is reached. Does not
+#         work with sslh-fork.
 #   tfo_ok: Set to true if the server supports TCP FAST OPEN
+#   resolve_on_forward: Set to true if server address should be resolved on
+#         (every) newly incoming connection (again)
 #   transparent: Set to true to proxy this protocol
 #         transparently (server sees the remote client IP
 #         address). Same as the global option, but per-protocol
+#   is_unix: [true|false] connect to a UNIX socket. The host
+#         field becomes the pathname to the socket, and the port
+#         field is unused (but necessary).
+#   proxyprotocol: <1|2>; When connecting to the backend
+#         server, a proxyprotocol header of the specified
+#         version will be added, containing the client's
+#         connection information.
 #
 #  Probe-specific options:
 # (sslh will try each probe in order they are declared, and
 # connect to the first that matches.)
 #
 #       tls:
-#               sni_hostnames:  list of FQDN for that target
+#               sni_hostnames:  list of FQDN for that target. Each name can
+#               include wildcard following glob(7) rules.
+
 #               alpn_protocols: list of ALPN protocols for that target, see:
 #               https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids
 #
@@ -69,12 +117,18 @@ listen:
 #               that target.
 #   
 # You can specify several of 'regex' and 'tls'.
+#
+# If you want to filter on incoming IP addresses, you can
+# use libwrap which will use /etc/hosts.allow and
+# /etc/hosts.deny.
  
 protocols:
 (
      { name: "ssh"; service: "ssh"; host: "localhost"; port: "22"; 
        keepalive: true; fork: true; tfo_ok: true },
-     { name: "http"; host: "localhost"; port: "80"; },
+
+# UNIX socket to a local NGINX. The socket name is in  'host'; 'port' is necessary but not used.
+     { name: "http"; is_unix: true; host: "/tmp/nginx.sock"; port: ""; },
 
 # match BOTH ALPN/SNI
      { name: "tls"; host: "localhost"; port: "5223"; alpn_protocols: [ "xmpp-client" ]; sni_hostnames: [ "im.somethingelse.net" ]; log_level: 0; tfo_ok: true },
@@ -98,7 +152,7 @@ protocols:
                       udp_timeout: 20;  # Time after which the "connection" is forgotten
                       regex_patterns: [ "hello" ]; },
 # Forward Teamspeak3 (Voice only)
-     { name: "regex"; host: "localhost"; is_udp: true; port: "9987"; regex_patterns: [ "TS3INIT1" ]; },
+     { name: "teamspeak"; host: "localhost"; is_udp: true; port: "9987"; },
 # Forward IETF QUIC-50 ("Q050" -> "\x51\x30\x35\x30")
 # Remember that the regex needs to be adjusted for every supported QUIC version.
      { name: "regex"; host: "localhost"; is_udp: true; port: "4433"; regex_patterns: [ "\x51\x30\x35\x30" ]; },

gap.c

@@ -31,11 +31,6 @@
 #include "gap.h"
 
 
-typedef struct gap_array {
-    int len; /* Number of elements in array */
-    void** array;
-} gap_array;
-
 /* Allocate one page-worth of elements */
 static int gap_len_alloc(int elem_size)
 {
@@ -53,7 +48,10 @@ gap_array* gap_init(int len)
     gap->len = gap_len_alloc(elem_size);
     if (gap->len < len) gap->len = len;
     gap->array = malloc(gap->len * elem_size);
-    if (!gap->array) return NULL;
+    if (!gap->array) {
+        free(gap);
+        return NULL;
+    }
 
     for (int i = 0; i < gap->len; i++)
         gap->array[i] = NULL;
@@ -61,12 +59,12 @@ gap_array* gap_init(int len)
     return gap;
 }
 
-void* gap_get(gap_array* gap, int index)
+void gap_set_hardlimit(gap_array* gap, int index)
 {
-    return gap->array[index];
+    gap->hardlimit = index;
 }
 
-static int gap_extend(gap_array* gap)
+int gap_extend(gap_array* gap)
 {
     int elem_size = sizeof(gap->array[0]);
     int new_length = gap->len + gap_len_alloc(elem_size);
@@ -84,17 +82,6 @@ static int gap_extend(gap_array* gap)
     return 0;
 }
 
-int gap_set(gap_array* gap, int index, void* ptr)
-{
-    while (index >= gap->len) {
-        int res = gap_extend(gap);
-        if (res == -1) return -1;
-    }
-
-    gap->array[index] = ptr;
-    return 0;
-}
-
 void gap_destroy(gap_array* gap) 
 {
     free(gap->array);
@@ -106,7 +93,11 @@ void gap_destroy(gap_array* gap)
  * is considered len elements long.
  * A poor man's list, if you will. Currently only used to remove probing
  * connections, so it only copies a few pointers at most.
- * Returns -1 if ptr was not found */
+ * Returns:
+ * -1 if ptr was not found 
+ * -2 if `len` is inconsistent with gap->len (i.e. trying to shift beyond the
+ * end of the array)
+ * */
 int gap_remove_ptr(gap_array* gap, void* ptr, int len)
 {
     int start, i;
@@ -120,7 +111,10 @@ int gap_remove_ptr(gap_array* gap, void* ptr, int len)
     else
         return -1;
 
-    for (i = start; i < len; i++) {
+    if (gap->len < len)
+        return -2;
+
+    for (i = start; i < len - 1; i++) {
         gap->array[i] = gap->array[i+1];
     }
 

gap.h

@@ -4,10 +4,47 @@
 typedef struct gap_array gap_array;
 
 gap_array* gap_init(int len);
-void* gap_get(gap_array* gap, int index);
-int gap_set(gap_array* gap, int index, void* ptr);
+void gap_set_hardlimit(gap_array* ga, int index);
+static void* gap_get(gap_array* gap, int index);
+static int gap_set(gap_array* gap, int index, void* ptr);
 void gap_destroy(gap_array* gap);
 
 int gap_remove_ptr(gap_array* gap, void* ptr, int len);
 
+/* Private declarations to allow inlining.
+ * Don't assume my implementation. */
+typedef struct gap_array {
+    int len; /* Number of elements in array (corresponds to the number of pages allocated) */
+    int hardlimit; /* Maximum index allowed after which sets will fail; 0 means no limit */
+    void** array;
+} gap_array;
+
+int gap_extend(gap_array* gap);
+
+static inline int __attribute__((unused)) gap_set(gap_array* gap, int index, void* ptr)
+{
+    if (gap->hardlimit && (index > gap->hardlimit))
+        return -1;
+
+    while (index >= gap->len) {
+        int res = gap_extend(gap);
+        if (res == -1) return -1;
+    }
+
+    gap->array[index] = ptr;
+    return 0;
+}
+
+static inline void* __attribute__((unused)) gap_get(gap_array* gap, int index)
+{
+    /* sslh-ev routinely reads before it writes. It's not clear if it should be
+     * its job to check the length (and add a gap_getlen()), or if it should be
+     * gap_get()'s job. This will do for now */
+    if (index >= gap->len) return NULL;
+
+    if (gap->hardlimit && (index > gap->hardlimit)) return NULL;
+
+    return gap->array[index];
+}
+
 #endif

genver.sh

@@ -10,14 +10,14 @@ fi
 if [ ! -d .git ] || ! `(git status | grep -q "On branch") 2> /dev/null`; then
         # If we don't have git, we can't work out what
         # version this is. It must have been downloaded as a
-        # zip file. 
-        
+        # zip file.
+
         # If downloaded from the release page, the directory
         # has the version number.
         release=`pwd | sed s/.*sslh-// | grep "[[:digit:]]"`
-        
+
         if [ "x$release" = "x" ]; then
-            # If downloaded from the head, Github creates the
+            # If downloaded from the head, GitHub creates the
             # zip file with all files dated from the last
             # change: use the Makefile's modification time as a
             # release number
@@ -28,7 +28,7 @@ fi
 if [ -d .git ] && head=`git rev-parse --verify HEAD 2>/dev/null`; then
 	# generate the version info based on the tag
 	release=`(git describe --tags || git --describe || git describe --all --long) \
-		2>/dev/null | tr -d '\n'`
+		2>/dev/null | tr -s '/' '-' | tr -d '\n'`
 
 	# Are there uncommitted changes?
 	git update-index --refresh --unmerged > /dev/null

hash.c

@@ -0,0 +1,246 @@
+/* 
+ * a fixed-sized hash
+ *
+# Copyright (C) 2022  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+#
+# */
+
+
+/*  * The hash is open-addressing, linear search, robin-hood insertion, with 
+ * backward shift deletion. References:
+ * https://codecapsule.com/2013/11/11/robin-hood-hashing/
+ * https://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/
+ * This means items are reordered upon insertion and deletion, and the hash
+ * is well-ordered at all times with no tombstones.
+ *
+ * Each pointer is either:
+ * - to a connection struct
+ * - FREE (NULL) if not allocated
+ *
+ * */
+
+#include <stdlib.h>
+#include <stddef.h>
+
+#if HASH_DEBUG
+#include <stdio.h>
+#include <string.h>
+#endif
+
+#include "gap.h"
+
+#if 0
+#define DEBUG 1
+#include <stdio.h>
+#endif
+
+typedef void* hash_item;
+
+typedef struct hash hash;
+#include "hash.h"
+
+static void* const FREE = NULL;
+
+
+/* Define DEBUG adds two functions:
+ * hash_dump() that prints the hash to a file as text
+ * hash_item_print() takes a pointer to a function that prints a hash item
+ * See test suite in hashtest/ for an example
+ *  */
+#if 0
+#define HASH_DEBUG 1
+#endif
+
+struct hash {
+    int hash_size;      /* Max number of items in the hash */
+    int item_cnt;       /* Number of items in the hash */
+    gap_array* data;
+
+    hash_make_key_fn hash_make_key;
+    hash_cmp_item_fn cmp_item;
+#ifdef HASH_DEBUG
+    void (*hash_item_print)(FILE* out, hash_item item);
+#endif
+};
+
+
+
+static int hash_make_key(hash* h, hash_item item)
+{
+    return h->hash_make_key(item) % h->hash_size;
+}
+
+
+hash* hash_init(int hash_size, hash_make_key_fn make_key, hash_cmp_item_fn cmp_item)
+{
+    hash* h = malloc(sizeof(*h));
+    if (!h) return NULL;
+
+    h->hash_size = hash_size;
+    h->item_cnt = 0;
+    h->data = gap_init(hash_size);
+    h->hash_make_key = make_key;
+    h->cmp_item = cmp_item;
+
+    return h;
+}
+
+/* Return the index following i in h */
+static int hash_next_index(hash* h, int i)
+{
+    return (i + 1) % h->hash_size;
+}
+
+/* Returns the index in h of specified address, -1 if not found 
+ * item is an item object that must return the target wanted index and for
+ * which comparison with the searched object will succeed.
+ * */
+static int hash_find_index(hash* h, hash_item item)
+{
+    hash_item cnx;
+    int index = hash_make_key(h, item);
+    int cnt = 0;
+
+    cnx = gap_get(h->data, index);
+#ifdef DEBUG
+    fprintf(stderr, "searching %d\n", index);
+#endif
+    while (cnx != FREE) {
+        if (cnt++ > h->hash_size) return -1;
+
+        if (!h->cmp_item(cnx, item))
+            break;
+
+        index = hash_next_index(h, index);
+        cnx = gap_get(h->data, index);
+#ifdef DEBUG
+        fprintf(stderr, "searching %d\n", index);
+#endif
+    } 
+    if (cnx == FREE) return -1;
+    return index;
+}
+
+hash_item hash_find(hash* h, hash_item item)
+{
+    int index = hash_find_index(h, item);
+    if (index == -1) return NULL;
+    hash_item out = gap_get(h->data, index);
+    return out;
+}
+
+
+/* Returns DIB: distance to initial bucket */
+static int distance(int current_index, hash* h, hash_item item)
+{
+    int wanted_index = hash_make_key(h, item);
+    if (wanted_index <= current_index)
+        return current_index - wanted_index;
+    else
+        return current_index - wanted_index + h->hash_size;
+}
+
+
+int hash_insert(hash* h, hash_item new)
+{
+    int bubble_wanted_index = hash_make_key(h, new);
+    int index = bubble_wanted_index;
+    gap_array* hash = h->data;
+
+    if (h->item_cnt == h->hash_size)
+        return -1;
+
+    hash_item curr_item = gap_get(hash, index);
+    while (curr_item) {
+        if (distance(index, h, curr_item) < distance(index, h, new)) {
+            gap_set(h->data, index, new);
+#if DEBUG
+            fprintf(stderr, "intermediate insert at %d\n", index);
+#endif
+            new = curr_item;
+        }
+
+        index = hash_next_index(h, index);
+        curr_item = gap_get(hash, index);
+    }
+
+#if DEBUG
+    fprintf(stderr, "final insert at %d\n", index);
+#endif
+    gap_set(hash, index, new);
+    h->item_cnt++;
+
+    return 0;
+}
+
+/* Remove cnx from the hash */
+int hash_remove(hash* h, hash_item item)
+{
+    gap_array* hash = h->data;
+
+    int index = hash_find_index(h, item);
+    if (index == -1) return -1; /* Tried to remove something that isn't there */
+
+    while (1) {
+        int next_index = hash_next_index(h, index);
+        hash_item next = gap_get(h->data, next_index);
+        if ((next == FREE) || (distance(next_index, h, next) == 0)) {
+            h->item_cnt--;
+            gap_set(hash, index, FREE);
+            return 0;
+        }
+
+        gap_set(hash, index, next);
+
+        index = hash_next_index(h, index);;
+    }
+    return 0;
+}
+
+/******************************************************************************/
+#if HASH_DEBUG
+void hash_item_print(hash* h, void fn(FILE*, hash_item))
+{
+    h->hash_item_print = fn;
+}
+
+
+void hash_dump(hash* h, char* filename)
+{
+    FILE* out = fopen(filename, "w");
+
+    if (!out) {
+        perror(filename);
+        exit(1);
+    }
+    
+    fprintf(out, "<hash elem=%d>\n", h->item_cnt);
+    for (int i = 0; i < h->hash_size; i++) {
+        hash_item item = gap_get(h->data, i);
+
+        fprintf(out, "\t%d:", i);
+        if (item)
+            h->hash_item_print(out, item);
+        else
+            fprintf(out, "<empty>");
+        fprintf(out, "\n");
+    }
+    fprintf(out, "</hash>\n");
+    fclose(out);
+}
+#endif

hash.h

@@ -0,0 +1,26 @@
+#ifndef HASH_H
+#define HASH_H
+
+/* You will need to typedef a pointer type to hash_item before including this
+ * .h */
+
+/* Function that returns a key (index) for a given item. The key must be always
+ * the same for an item. It doesn't need to be bounded (hash.c masks it for you) */
+typedef int (*hash_make_key_fn)(hash_item item);
+
+/* Function that compares two items: returns 0 if they are the same */
+typedef int (*hash_cmp_item_fn)(hash_item item1, hash_item item2);
+
+hash* hash_init(int hash_size, hash_make_key_fn make_key, hash_cmp_item_fn cmp_item);
+
+int hash_insert(hash* h, hash_item new);
+int hash_remove(hash* h, hash_item item);
+
+/* Returns the hash item that matches specification (meaning the
+ * comparison function returns true for cmp(x, item), or NULL if not found */
+hash_item hash_find(hash* h, hash_item item);
+
+
+void hash_dump(hash* h, char* filename); /* For development only */
+
+#endif

hashtest/Makefile

@@ -0,0 +1,7 @@
+
+CFLAGS=-DHASH_DEBUG -O2 -Wall
+OBJ=../hash.o ../gap.o htest.o
+
+htest: $(OBJ)
+	$(CC) -o htest $(OBJ)
+

hashtest/delete.tst

@@ -0,0 +1,8 @@
+# Basic delete
+a 10 aa
+a 10 ab
+a 10 ac
+a 20 ba
+a 21 bb
+
+d 21 bb

hashtest/delete.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=4>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:aa
+	11:10:ab
+	12:10:ac
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:20:ba
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/delete_at_end.tst

@@ -0,0 +1,9 @@
+# Delete inside a block with nothing after
+
+a 10 aa
+a 10 ab
+a 12 ac
+a 13 ad
+a 14 ae
+
+d 14 ae

hashtest/delete_at_end.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=4>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:aa
+	11:10:ab
+	12:12:ac
+	13:13:ad
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/delete_below_floor.tst

@@ -0,0 +1,9 @@
+# wrap-around and delete below floor
+a 2 ba
+a 30 aa
+a 30 ab
+a 30 ac
+a 30 ad
+a 2 bb
+
+d 30 ab

hashtest/delete_below_floor.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=5>
+	0:30:ad
+	1:<empty>
+	2:2:ba
+	3:2:bb
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ac
+</hash>

hashtest/delete_discont.tst

@@ -0,0 +1,10 @@
+# delete in a discontinuous block
+
+a 10 aa
+a 11 ab
+a 12 ac
+a 14 ad
+a 10 bc
+
+d 11 ab
+

hashtest/delete_discont.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=4>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:aa
+	11:10:bc
+	12:12:ac
+	13:<empty>
+	14:14:ad
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/delete_empty.tst

@@ -0,0 +1,11 @@
+# Delete an unexisting element. And on an empty hash
+
+a 10 aa
+
+d 10 ab
+d 12 bc
+
+# Empty for real
+d 10 aa
+
+d 10 aa

hashtest/delete_empty.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=0>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/delete_full.tst

@@ -0,0 +1,39 @@
+# delete on a full hash
+
+# First, fill the hash :-)
+
+a 0 aa
+a 1 ab
+a 2 ac
+a 3 ad
+a 4 ae
+a 5 af
+a 6 ag 
+a 7 ah
+a 8 ai
+a 9 af
+a 10 ba
+a 11 bb
+a 12 bc
+a 13 bd
+a 14 be 
+a 15 bf
+a 16 bg
+a 17 bh
+a 18 bi
+a 19 bj
+a 20 ca
+a 21 cb
+a 22 cd
+a 23 ce
+a 24 cf
+a 25 cg
+a 26 ch
+a 27 ci
+a 28 cj
+a 29 ck
+a 30 da
+a 31 db
+
+
+d 21 cb

hashtest/delete_full.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=31>
+	0:0:aa
+	1:1:ab
+	2:2:ac
+	3:3:ad
+	4:4:ae
+	5:5:af
+	6:6:ag
+	7:7:ah
+	8:8:ai
+	9:9:af
+	10:10:ba
+	11:11:bb
+	12:12:bc
+	13:13:bd
+	14:14:be
+	15:15:bf
+	16:16:bg
+	17:17:bh
+	18:18:bi
+	19:19:bj
+	20:20:ca
+	21:<empty>
+	22:22:cd
+	23:23:ce
+	24:24:cf
+	25:25:cg
+	26:26:ch
+	27:27:ci
+	28:28:cj
+	29:29:ck
+	30:30:da
+	31:31:db
+</hash>

hashtest/delete_middle.tst

@@ -0,0 +1,10 @@
+# Delete inside a block with something discontinuous
+
+a 10 aa
+a 10 ab
+a 12 ac
+a 13 ad
+a 14 ae
+
+# ab shifts, ac and next doesn't
+d 10 aa

hashtest/delete_middle.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=4>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:ab
+	11:<empty>
+	12:12:ac
+	13:13:ad
+	14:14:ae
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/delete_wrap.tst

@@ -0,0 +1,8 @@
+# Basic delete when wrapping, between wrap and floor
+a 30 aa
+a 30 ab
+a 30 ac
+a 30 ba
+a 30 bb
+
+d 30 ac

hashtest/delete_wrap.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=4>
+	0:30:ba
+	1:30:bb
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ab
+</hash>

hashtest/delete_wrap_at_end.tst

@@ -0,0 +1,10 @@
+# Delete inside a block with wrapping, with something after
+
+a 30 aa
+a 30 ab
+a 30 ac
+a 1 ad
+a 3 ae
+
+# shift ad but not ae
+d 14 ae

hashtest/delete_wrap_at_end.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=5>
+	0:30:ac
+	1:1:ad
+	2:<empty>
+	3:3:ae
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ab
+</hash>

hashtest/delete_wrap_below_floor.tst

@@ -0,0 +1,8 @@
+# delete before wrap
+a 30 aa
+a 30 ab
+a 30 ac
+a 30 ad
+
+# shift ac and ad
+d 30 ab

hashtest/delete_wrap_below_floor.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=3>
+	0:30:ad
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ac
+</hash>

hashtest/delete_wrap_discont.tst

@@ -0,0 +1,11 @@
+# Delete with wrapping in discontinuous group
+
+a 30 aa
+a 30 ab
+a 30 ac
+a 31 ad
+a 2 ba
+a 3 bb
+
+# shift ac and ad but not ba and bb
+d 30 ab

hashtest/delete_wrap_discont.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=5>
+	0:31:ad
+	1:<empty>
+	2:2:ba
+	3:3:bb
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ac
+</hash>

hashtest/htest.c

@@ -0,0 +1,116 @@
+/* Wee testing program from the hash code:
+ * htest <script> <dump>
+ *
+ * scripts are a list of operations:
+ * a $index $string
+ * => add an element at specified index
+ * d $index $string
+ * => remove an element
+ * s $index $string
+ * => prints the actual element index, if it's there
+ *
+ * The hash is dumped to the dump file at each iteration.
+ */
+
+
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+
+
+/* tests have been written for a hash that holds 32 items */
+#define HASH_SIZE 32
+
+#define STR_LENGTH 16
+struct hash_item {
+    int wanted_index;
+    char str[STR_LENGTH];
+};
+
+typedef struct hash_item* hash_item;
+
+#include "../hash.h"
+
+
+
+static int cmp_item(hash_item item1, hash_item item2)
+{
+    return strcmp(item1->str, item2->str);
+}
+
+
+static int hash_make_key(hash_item item)
+{
+    return item->wanted_index;
+}
+
+
+static void htest_next_key(FILE* f, char* action, int* key, char str[STR_LENGTH])
+{
+
+    int res = 0;
+    while ((res != 3) && (res != EOF))
+        res = fscanf(f, "%c %d %s\n", action, key, str);
+    if (res == EOF) exit(0);
+}
+
+static void item_print(FILE* out, hash_item item)
+{
+    fprintf(out, "%d:%s", item->wanted_index, item->str);
+}
+
+int main(int argc, char* argv[])
+{
+    hash* h = hash_init(HASH_SIZE, &hash_make_key, &cmp_item);
+    char action;
+    hash_item item;
+    int line = 0;
+    FILE* f;
+
+    hash_item_print(h, item_print);
+
+    if (argc != 3) {
+        fprintf(stderr, "Usage: htest <script file> <dump file>\n");
+        exit(1);
+    }
+    char* script_file = argv[1];
+    char* dump_file = argv[2];
+    f = fopen(argv[1], "r");
+    if (!f) {
+        perror(script_file);
+        exit(1);
+    }
+
+    while (1) {
+        item= malloc(sizeof(*item));
+        action = ' ';
+
+        line++;
+        htest_next_key(f, &action, &item->wanted_index, item->str);
+        fprintf(stderr, "action %d: %c %d %s\n", line, action, item->wanted_index, item->str);
+
+        switch (action) {
+        case 'a': /* add */
+            fprintf(stderr, "inserting [%s] at %d\n", item->str, item->wanted_index);
+            hash_insert(h, item);
+            break;
+
+        case 'd': /* del */
+            fprintf(stderr, "removing [%s] at %d\n", item->str, item->wanted_index);
+            hash_remove(h, item);
+            break;
+
+        case 's': /* search */
+            fprintf(stderr, "searching\n");
+            struct hash_item* found = hash_find(h, item);
+            fprintf(stderr, "searching %d[%s]: %p\n", item->wanted_index, item->str, found);
+            break;
+
+        case 'q': /* quit */
+            exit(1);
+        }
+        hash_dump(h, dump_file);
+    }
+    return 0;
+}

hashtest/insert.tst

@@ -0,0 +1,6 @@
+# Basic insertions
+a 10 aa
+a 10 ab
+a 10 ac
+a 20 ba
+a 21 bb

hashtest/insert.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=5>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:aa
+	11:10:ab
+	12:10:ac
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:20:ba
+	21:21:bb
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/insert_discont.tst

@@ -0,0 +1,8 @@
+# insert and bubble with single empty space
+
+a 10 aa
+a 11 ab
+a 12 ac
+a 14 ad
+a 10 bc
+

hashtest/insert_discont.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=5>
+	0:<empty>
+	1:<empty>
+	2:<empty>
+	3:<empty>
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:10:aa
+	11:10:bc
+	12:11:ab
+	13:12:ac
+	14:14:ad
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:<empty>
+	31:<empty>
+</hash>

hashtest/insert_full.tst

@@ -0,0 +1,40 @@
+# Insert on a full hash
+
+# First, fill the hash :-)
+
+a 0 aa
+a 1 ab
+a 2 ac
+a 3 ad
+a 4 ae
+a 5 af
+a 6 ag 
+a 7 ah
+a 8 ai
+a 9 af
+a 10 ba
+a 11 bb
+a 12 bc
+a 13 bd
+a 14 be 
+a 15 bf
+a 16 bg
+a 17 bh
+a 18 bi
+a 19 bj
+a 20 ca
+a 21 cb
+a 22 cd
+a 23 ce
+a 24 cf
+a 25 cg
+a 26 ch
+a 27 ci
+a 28 cj
+a 29 ck
+a 30 da
+a 31 db
+
+# it's full!
+a 20 zz
+a 31 za

hashtest/insert_full.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=32>
+	0:0:aa
+	1:1:ab
+	2:2:ac
+	3:3:ad
+	4:4:ae
+	5:5:af
+	6:6:ag
+	7:7:ah
+	8:8:ai
+	9:9:af
+	10:10:ba
+	11:11:bb
+	12:12:bc
+	13:13:bd
+	14:14:be
+	15:15:bf
+	16:16:bg
+	17:17:bh
+	18:18:bi
+	19:19:bj
+	20:20:ca
+	21:21:cb
+	22:22:cd
+	23:23:ce
+	24:24:cf
+	25:25:cg
+	26:26:ch
+	27:27:ci
+	28:28:cj
+	29:29:ck
+	30:30:da
+	31:31:db
+</hash>

hashtest/insert_full_floor.tst

@@ -0,0 +1,7 @@
+# wrap-around and insert at full floor
+a 2 ba
+a 30 aa
+a 30 ab
+a 30 ac
+a 30 ad
+a 2 bb

hashtest/insert_full_floor.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=6>
+	0:30:ac
+	1:30:ad
+	2:2:ba
+	3:2:bb
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ab
+</hash>

hashtest/insert_wrap.tst

@@ -0,0 +1,7 @@
+# wrap-around and insert above floor
+a 30 aa
+a 30 ab
+a 30 ac
+a 30 ad
+a 0 ba
+a 0 bb

hashtest/insert_wrap.tst.ref

@@ -0,0 +1,34 @@
+<hash elem=6>
+	0:30:ac
+	1:30:ad
+	2:0:ba
+	3:0:bb
+	4:<empty>
+	5:<empty>
+	6:<empty>
+	7:<empty>
+	8:<empty>
+	9:<empty>
+	10:<empty>
+	11:<empty>
+	12:<empty>
+	13:<empty>
+	14:<empty>
+	15:<empty>
+	16:<empty>
+	17:<empty>
+	18:<empty>
+	19:<empty>
+	20:<empty>
+	21:<empty>
+	22:<empty>
+	23:<empty>
+	24:<empty>
+	25:<empty>
+	26:<empty>
+	27:<empty>
+	28:<empty>
+	29:<empty>
+	30:30:aa
+	31:30:ab
+</hash>

hashtest/mkrand.pl

@@ -0,0 +1,41 @@
+#! /usr/bin/perl
+
+# Creates a script of random accesses and deletes
+
+use strict;
+
+
+my $i = 0;
+sub mkstr {
+    $i++;
+    return chr(ord('a') + ($i / 26) % 26) . chr(ord('a') + $i % 26);
+}
+
+my @elems;
+
+
+sub add_elem {
+    my $val = int(rand(32));
+    my $str = mkstr($val);
+    push @elems, "$val $str";
+    print "a $val $str\n";
+}
+
+sub del_elem {
+    my $remove = splice(@elems, rand @elems, 1);
+    print "d $remove\n";
+}
+
+while (1) {
+    if (@elems < 5) {
+        add_elem;
+    } elsif (@elems > 28) {
+        del_elem;
+    } else {
+        if (rand() < .5) {
+            add_elem;
+        } else {
+            del_elem;
+        }
+    }
+}

hashtest/run

@@ -0,0 +1,30 @@
+#! /usr/bin/perl -w
+
+# This runs all the tests.
+
+# Tests scripts are in *.tst files.
+# Corresponding output is put in *.out.
+# Reference output is put in *.ref.
+# Any discrepancy will be reported!
+
+use strict;
+
+my @res;
+foreach my $fn (`ls *.tst`) {
+    chomp $fn;
+    my $cmd = "./htest $fn $fn.out";
+    print "$cmd\n";
+    `$cmd`;
+    my $res = system("diff -u $fn.ref $fn.out");
+    push @res, [$fn, ($res == 0 ? "OK" : "*KO*")];
+}
+
+format =
+@<<<<<<<<<<<<<<<<<<<<<<<<<< @>>>
+$_->[0], $_->[1]
+.
+
+
+#format_name STDOUT test_result;
+map { write; } @res;
+

landlock.c

@@ -0,0 +1,186 @@
+/*
+ * Setup a sandbox using the Landlock LSM, if available.
+
+# Copyright (C) 2023  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+#
+*/
+
+#include "config.h"
+#include "log.h"
+
+#ifdef HAVE_LANDLOCK
+
+#define _GNU_SOURCE
+#include <linux/landlock.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+
+/* Ubuntu 22.04 does not have this symbol */
+#ifndef LANDLOCK_ACCESS_FS_REFER
+#define LANDLOCK_ACCESS_FS_REFER			(1ULL << 13)
+#endif
+
+#ifndef landlock_create_ruleset
+static inline int
+landlock_create_ruleset(const struct landlock_ruleset_attr *const attr,
+			const size_t size, const __u32 flags)
+{
+	return syscall(__NR_landlock_create_ruleset, attr, size, flags);
+}
+#endif
+
+#ifndef landlock_add_rule
+static inline int landlock_add_rule(const int ruleset_fd,
+				    const enum landlock_rule_type rule_type,
+				    const void *const rule_attr,
+				    const __u32 flags)
+{
+	return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr,
+		       flags);
+}
+#endif
+
+#ifndef landlock_restrict_self
+static inline int landlock_restrict_self(const int ruleset_fd,
+					 const __u32 flags)
+{
+	return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
+}
+#endif
+
+typedef enum {
+    LL_TREE,
+    LL_FILE
+} ll_obj_type;
+
+static int add_path_ro(int ruleset_fd, ll_obj_type otype, const char* path)
+{
+    int fd = open(path, O_PATH | O_CLOEXEC);
+    if (fd < 0) {
+        print_message(msg_config_error, "Landlock: Failed to open %s: %s\n", path, strerror(errno));
+        return -1;
+    }
+
+    struct landlock_path_beneath_attr path_beneath = {
+        .allowed_access = (otype == LL_TREE ? LANDLOCK_ACCESS_FS_READ_DIR : 0 ) |
+                          LANDLOCK_ACCESS_FS_READ_FILE,
+        .parent_fd = fd,
+    };
+
+    int res = landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0);
+    if (res) {
+        print_message(msg_config_error, "Landlock: Failed to update the ruleset with \"%s\": %s\n",
+                path, strerror(errno));
+        close(path_beneath.parent_fd);
+        return -1;
+    }
+
+    // close helper handle
+    close(fd);
+
+    return 0;
+}
+
+
+static int add_libs(int ruleset_fd)
+{
+    /* Access to libraries, to be able to fork */
+    add_path_ro(ruleset_fd, LL_TREE, "/lib");
+    add_path_ro(ruleset_fd, LL_TREE, "/usr/lib");
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/ld.so.cache");  /* To avoid searching all libs... */
+    return 0;
+}
+
+static int add_resolv(int ruleset_fd)
+{
+    /* Files to resolve names (required when dynamic resolution is used) */
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/hosts");
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/resolv.conf");
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/nsswitch.conf");
+    return 0;
+}
+
+static int add_libwrap(int ruleset_fd)
+{
+    /* Files for libwrap */
+#ifdef LIBWRAP
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/hosts.allow");
+    add_path_ro(ruleset_fd, LL_FILE, "/etc/hosts.deny");
+#endif
+
+    return 0;
+}
+
+
+
+void setup_landlock(void)
+{
+    __u64 restrict_rules = 
+        LANDLOCK_ACCESS_FS_EXECUTE |
+        LANDLOCK_ACCESS_FS_READ_FILE |
+        LANDLOCK_ACCESS_FS_READ_DIR |
+        LANDLOCK_ACCESS_FS_WRITE_FILE |
+        LANDLOCK_ACCESS_FS_REMOVE_DIR |
+        LANDLOCK_ACCESS_FS_REMOVE_FILE |
+        LANDLOCK_ACCESS_FS_MAKE_CHAR |
+        LANDLOCK_ACCESS_FS_MAKE_DIR |
+        LANDLOCK_ACCESS_FS_MAKE_REG |
+        LANDLOCK_ACCESS_FS_MAKE_SOCK |
+        LANDLOCK_ACCESS_FS_MAKE_FIFO |
+        LANDLOCK_ACCESS_FS_MAKE_BLOCK |
+        LANDLOCK_ACCESS_FS_MAKE_SYM |
+        LANDLOCK_ACCESS_FS_REFER;
+
+    struct landlock_ruleset_attr ruleset_attr = {
+        .handled_access_fs = restrict_rules
+    };
+
+    /* ruleset_addr.handled_access_fs contains all rights that will be restricted
+     * unless explicitly added */
+    int ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+    if (ruleset_fd < 0) {
+        print_message(msg_config_error, "Landlock: Failed to create a ruleset");
+        return;
+    }
+
+
+    /* Add all the paths we need */
+    add_libs(ruleset_fd);
+    add_resolv(ruleset_fd);
+    add_libwrap(ruleset_fd);
+
+    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+        print_message(msg_config_error, "Landlock: Failed to restrict privileges");
+        return;
+    }
+    if (landlock_restrict_self(ruleset_fd, 0)) {
+        print_message(msg_config_error, "Landlock: Failed to enforce ruleset");
+        return;
+    }
+    close(ruleset_fd);
+
+    print_message(msg_config, "Landlock: all restricted\n");
+}
+
+#else /* HAVE_LANDLOCK */
+void setup_landlock(void)
+{
+    print_message(msg_config, "Landlock: not built in\n");
+    return;
+}
+#endif /* HAVE_LANDLOCK */

log.c

@@ -0,0 +1,211 @@
+/*
+# log: processing of all outgoing messages
+#
+# Copyright (C) 2007-2021  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+
+*/
+
+
+#define SYSLOG_NAMES
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include "sslh-conf.h"
+#include "common.h"
+#include "log.h"
+
+msg_info msg_config = {
+    LOG_INFO,
+    &cfg.verbose_config
+};
+
+msg_info msg_config_error = {
+    LOG_ERR,
+    &cfg.verbose_config_error
+};
+
+msg_info msg_fd = {
+    LOG_DEBUG,
+    &cfg.verbose_fd
+};
+
+/* Internal errors: inconsistent states, impossible values, things that should never happen, and are therefore the sign of memory corruption: hence the LOG_CRIT */
+msg_info msg_int_error = {
+    LOG_CRIT,
+    &cfg.verbose_system_error
+};
+
+/* System errors: when the system around us fails us: memory allocation, fork, ... */
+msg_info msg_system_error = {
+    LOG_ERR,
+    &cfg.verbose_system_error
+};
+
+msg_info msg_packets = {
+    LOG_INFO,
+    &cfg.verbose_packets
+};
+
+/* additional info when attempting outgoing connections */
+msg_info msg_connections_try = {
+    LOG_DEBUG,
+    &cfg.verbose_connections_try
+};
+
+/* Connection information and failures (e.g. forbidden by policy) */
+msg_info msg_connections = {
+    LOG_INFO,
+    &cfg.verbose_connections
+};
+
+/* Connection failures, e.g. target server not present */
+msg_info msg_connections_error = {
+    LOG_ERR,
+    &cfg.verbose_connections_error
+};
+
+
+/* comment the probing process */
+msg_info msg_probe_info = {
+    LOG_INFO,
+    &cfg.verbose_probe_info
+};
+
+/* probing errors, e.g. inconsistent data in connections */
+msg_info msg_probe_error = {
+    LOG_ERR,
+    &cfg.verbose_probe_error
+};
+
+
+
+/* Bitmasks in verbose-* values */
+#define MSG_STDOUT 1
+#define MSG_SYSLOG 2
+#define MSG_FILE   4
+
+static FILE* logfile_fp = NULL;
+
+/* Prints a message to stderr and/or syslog if appropriate */
+void print_message(msg_info info, const char* str, ...)
+{
+    va_list ap;
+
+    if ((*info.verbose & MSG_STDOUT) && ! cfg.inetd) {
+        va_start(ap, str);
+        vfprintf(stderr, str, ap);
+        va_end(ap);
+    }
+
+    if (*info.verbose & MSG_SYSLOG) {
+        va_start(ap, str);
+        vsyslog(info.log_level, str, ap);
+        va_end(ap);
+    }
+
+    if (*info.verbose & MSG_FILE && logfile_fp != NULL) {
+        va_start(ap, str);
+        vfprintf(logfile_fp, str, ap);
+        fflush(logfile_fp);
+        va_end(ap);
+    }
+}
+
+static int do_syslog = 1; /* Should we syslog? controled by syslog_facility = "none" */
+
+/* Open syslog connection with appropriate banner;
+ * banner is made up of basename(bin_name)+"[pid]" */
+void setup_syslog(const char* bin_name) {
+    char *name1, *name2;
+    int res, fn;
+
+    if (!strcmp(cfg.syslog_facility, "none")) {
+        do_syslog = 0;
+        return;
+    }
+
+    name1 = strdup(bin_name);
+    res = asprintf(&name2, "%s[%d]", basename(name1), getpid());
+    CHECK_RES_DIE(res, "asprintf");
+
+    for (fn = 0; facilitynames[fn].c_val != -1; fn++)
+        if (strcmp(facilitynames[fn].c_name, cfg.syslog_facility) == 0)
+            break;
+    if (facilitynames[fn].c_val == -1) {
+        fprintf(stderr, "Unknown facility %s\n", cfg.syslog_facility);
+        exit(1);
+    }
+
+    openlog(name2, LOG_CONS, facilitynames[fn].c_val);
+    free(name1);
+    /* Don't free name2, as openlog(3) uses it (at least in glibc) */
+}
+
+void setup_logfile()
+{
+    if (cfg.logfile == NULL)
+    {
+        return;
+    }
+
+    logfile_fp = fopen(cfg.logfile, "a");
+    if (logfile_fp == NULL)
+    {
+        fprintf(stderr, "Could not open logfile %s for writing: %s\n", cfg.logfile, strerror(errno));
+        exit(1);
+    }
+}
+
+void close_logfile()
+{
+    if (logfile_fp != NULL)
+    {
+        fclose(logfile_fp);
+        logfile_fp = NULL;
+    }
+}
+
+/* syslogs who connected to where 
+ * desc: string description of the connection. if NULL, log_connection will
+ * manage on its own
+ * cnx: connection descriptor
+ * */
+void log_connection(struct connection_desc* desc, const struct connection *cnx)
+{
+    struct connection_desc d;
+
+    if (cnx->proto->log_level < 1)
+        return;
+
+    if (!desc) {
+        desc = &d;
+        if (!get_connection_desc(desc, cnx)) {
+            print_message(msg_connections, "%s: lost incoming connection\n",
+                          cnx->proto->name);
+            return;
+        }
+    }
+
+    print_message(msg_connections, "%s:connection from %s to %s forwarded from %s to %s\n",
+                cnx->proto->name,
+                desc->peer,
+                desc->service,
+                desc->local,
+                desc->target);
+}

log.h

@@ -0,0 +1,36 @@
+#ifndef LOG_H
+#define LOG_H
+
+#include "common.h"
+
+void setup_syslog(const char* bin_name);
+
+void setup_logfile();
+
+void close_logfile();
+
+void log_connection(struct connection_desc* desc, const struct connection *cnx);
+
+typedef struct s_msg_info{
+    int log_level;
+    int *verbose;
+} msg_info;
+
+void print_message(msg_info info, const char* str, ...);
+extern msg_info msg_config;
+extern msg_info msg_config_error;
+
+extern msg_info msg_fd;
+extern msg_info msg_packets;
+
+extern msg_info msg_int_error;
+extern msg_info msg_system_error;
+
+extern msg_info msg_connections_try;
+extern msg_info msg_connections_error;
+extern msg_info msg_connections;
+
+extern msg_info msg_probe_info;
+extern msg_info msg_probe_error;
+
+#endif /* LOG_H */

probe.c

@@ -1,7 +1,7 @@
 /*
 # probe.c: Code for probing protocols
 #
-# Copyright (C) 2007-2019  Yves Rutschle
+# Copyright (C) 2007-2021  Yves Rutschle
 # 
 # This program is free software; you can redistribute it
 # and/or modify it under the terms of the GNU General Public
@@ -21,17 +21,16 @@
 
 #define _GNU_SOURCE
 #include <stdio.h>
-#ifdef ENABLE_REGEX
-#define PCRE2_CODE_UNIT_WIDTH 8
-#include <pcre2.h>
-#endif
+#include <regex.h>
 #include <ctype.h>
 #include "probe.h"
+#include "log.h"
 
 
 
 static int is_ssh_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_openvpn_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
+static int is_wireguard_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_tinc_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_xmpp_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_http_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
@@ -39,6 +38,8 @@ static int is_tls_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_
 static int is_adb_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_socks5_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_syslog_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
+static int is_teamspeak_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
+static int is_msrdp_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item*);
 static int is_true(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto) { return 1; }
 
 /* Table of protocols that have a built-in probe
@@ -47,6 +48,7 @@ static struct protocol_probe_desc builtins[] = {
     /* description  probe  */
     { "ssh",        is_ssh_protocol},
     { "openvpn",    is_openvpn_protocol },
+    { "wireguard",  is_wireguard_protocol },
     { "tinc",       is_tinc_protocol },
     { "xmpp",       is_xmpp_protocol },
     { "http",       is_http_protocol },
@@ -54,6 +56,8 @@ static struct protocol_probe_desc builtins[] = {
     { "adb",        is_adb_protocol },
     { "socks5",     is_socks5_protocol },
     { "syslog",     is_syslog_protocol },
+    { "teamspeak",  is_teamspeak_protocol },
+    { "msrdp",      is_msrdp_protocol },
     { "anyprot",    is_true }
 };
 
@@ -81,33 +85,38 @@ struct sslhcfg_protocols_item* timeout_protocol(void)
 
 /* From http://grapsus.net/blog/post/Hexadecimal-dump-in-C */
 #define HEXDUMP_COLS 16
-void hexdump(const char *mem, unsigned int len)
+void hexdump(msg_info msg_info, const char *mem, unsigned int len)
 {
     unsigned int i, j;
+    char str[10 + HEXDUMP_COLS * 4 + 2];
+    int c = 0; /* index in str */
 
     for(i = 0; i < len + ((len % HEXDUMP_COLS) ? (HEXDUMP_COLS - len % HEXDUMP_COLS) : 0); i++)
     {
         /* print offset */
         if(i % HEXDUMP_COLS == 0)
-            fprintf(stderr, "0x%06x: ", i);
+            c += sprintf(&str[c], "0x%06x: ", i);
 
         /* print hex data */
         if(i < len)
-            fprintf(stderr, "%02x ", 0xFF & mem[i]);
+            c += sprintf(&str[c], "%02x ", 0xFF & mem[i]);
         else /* end of block, just aligning for ASCII dump */
-            fprintf(stderr, "   ");
+            c+= sprintf(&str[c], "   ");
 
         /* print ASCII dump */
         if(i % HEXDUMP_COLS == (HEXDUMP_COLS - 1)) {
             for(j = i - (HEXDUMP_COLS - 1); j <= i; j++) {
                 if(j >= len) /* end of block, not really printing */
-                    fputc(' ', stderr);
+                    str[c++] = ' ';
                 else if(isprint(mem[j])) /* printable char */
-                    fputc(0xFF & mem[j], stderr);
+                    str[c++] = 0xFF & mem[j];
                 else /* other char */
-                    fputc('.', stderr);
+                    str[c++] = '.';
             }
-            fputc('\n', stderr);
+            str[c++] = '\n';
+            str[c++] = 0;
+            print_message(msg_info, "%s", str);
+            c = 0;
         }
     }
 }
@@ -131,15 +140,77 @@ static int is_ssh_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_
  * http://www.fengnet.com/book/vpns%20illustrated%20tunnels%20%20vpnsand%20ipsec/ch08lev1sec5.html
  * and OpenVPN ssl.c, ssl.h and options.c
  */
+#define OVPN_OPCODE_MASK 0xF8
+#define OVPN_CONTROL_HARD_RESET_CLIENT_V1  (0x01 << 3)
+#define OVPN_CONTROL_HARD_RESET_CLIENT_V2  (0x07 << 3)
+#define OVPN_CONTROL_HARD_RESET_CLIENT_V3  (0x0A << 3)
+#define OVPN_HMAC_128 16
+#define OVPN_HMAC_160 20
+#define OVPN_HARD_RESET_PACKET_ID_OFFSET(hmac_size) (9 + hmac_size)
 static int is_openvpn_protocol (const char*p,ssize_t len, struct sslhcfg_protocols_item* proto)
 {
     int packet_len;
 
-    if (len < 2)
-        return PROBE_AGAIN;
+    if (proto->is_udp == 0)
+    {
+        if (len < 2)
+            return PROBE_AGAIN;
 
-    packet_len = ntohs(*(uint16_t*)p);
-    return packet_len == len - 2;
+        packet_len = ntohs(*(uint16_t*)p);
+        return packet_len == len - 2;
+    } else {
+        if (len < 1)
+            return PROBE_NEXT;
+
+        printf("opcode: %d\n", (p[0] & OVPN_OPCODE_MASK) >> 3);
+
+        if ((p[0] & OVPN_OPCODE_MASK) != OVPN_CONTROL_HARD_RESET_CLIENT_V1 &&
+            (p[0] & OVPN_OPCODE_MASK) != OVPN_CONTROL_HARD_RESET_CLIENT_V2 &&
+            (p[0] & OVPN_OPCODE_MASK) != OVPN_CONTROL_HARD_RESET_CLIENT_V3
+            )
+            return PROBE_NEXT;
+
+        /* The detection pattern above may not be reliable enough.
+         * Check the packet id: OpenVPN sents five initial packets
+         * whereas the packet id is increased with every transmitted datagram.
+         */
+
+        if (len <= OVPN_HARD_RESET_PACKET_ID_OFFSET(OVPN_HMAC_128) + sizeof(uint32_t))
+            return PROBE_NEXT;
+
+        uint32_t i;
+        /* OVPN_HMAC_128 is unaligned, which requires special care e.g. on ARM */
+        memcpy(&i, (p + OVPN_HARD_RESET_PACKET_ID_OFFSET(OVPN_HMAC_128)), sizeof(i));
+        i = ntohl(i);
+        if (i <= 5u)
+            return PROBE_MATCH;
+
+        if (len <= OVPN_HARD_RESET_PACKET_ID_OFFSET(OVPN_HMAC_160) + sizeof(uint32_t))
+            return PROBE_NEXT;
+
+        memcpy(&i, (p + OVPN_HARD_RESET_PACKET_ID_OFFSET(OVPN_HMAC_160)), sizeof(i));
+        i = ntohl(i);
+        if (i <= 5u)
+            return PROBE_MATCH;
+
+        return PROBE_NEXT;
+    }
+}
+
+static int is_wireguard_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto)
+{
+    if (proto->is_udp == 0)
+        return PROBE_NEXT;
+
+    // Handshake Init: 148 bytes
+    if (len != 148)
+        return PROBE_NEXT;
+
+    // Handshake Init: p[0] = 0x01, p[1..3] = 0x000000 (reserved)
+    if (ntohl(*(uint32_t*)p) != 0x01000000)
+        return PROBE_NEXT;
+
+    return PROBE_MATCH;
 }
 
 /* Is the buffer the beginning of a tinc connections?
@@ -260,7 +331,7 @@ static int is_adb_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_
     if (len < min_data_packet_size + sizeof(empty_message))
         return PROBE_AGAIN;
 
-    if (memcmp(&p[0], empty_message, sizeof(empty_message)))
+    if (memcmp(&p[0], empty_message, sizeof(empty_message)) != 0)
         return PROBE_NEXT;
 
     return probe_adb_cnxn_message(&p[sizeof(empty_message)]);
@@ -299,80 +370,128 @@ static int is_socks5_protocol(const char *p_in, ssize_t len, struct sslhcfg_prot
     return PROBE_MATCH;
 }
 
+/* ******************
+ * is_syslog_protocol 
+ * */
+static regex_t syslog_preg;
+static int configured_syslog_regex = 0;
+
+static void config_syslog_regex(void)
+{
+    /* two patterns for syslog messages:
+     * <12> My message
+     * 15 <12> My message
+     * 12 is 'priority', 1 to 3 digits (RFC4234)
+     * 15 is 'message length', a TCP-only option (RFC6587)
+     */
+    int res = regcomp(&syslog_preg, "^([0-9]{1,3} )?<[0-9]{1,3}>", REG_EXTENDED);
+    if (res) {
+        print_message(msg_system_error, "regcomp");
+        exit(1);
+    }
+    configured_syslog_regex = 1;
+}
+
 static int is_syslog_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto)
 {
-    int res, i, j;
+    char buf[len+1];
 
-    res = sscanf(p, "<%d>", &i);
-    if (res == 1) return 1;
+    if (!configured_syslog_regex) config_syslog_regex();
 
-    res = sscanf(p, "%d <%d>", &i, &j);
-    if (res == 2) return 1;
+    strncpy(buf, p, len);
+    buf[len] = 0;
 
-    return 0;
+    return (regexec(&syslog_preg, buf, (size_t)0, NULL, 0) == 0);
 }
 
+static int is_teamspeak_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto)
+{
+    if (len < 8)
+        return PROBE_NEXT;
+
+    return !strncmp(p, "TS3INIT1", len);
+}
+
+static int is_msrdp_protocol(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto)
+{
+    char version;
+    char packet_len;
+    if (len < 7)
+        return PROBE_NEXT;
+    version=*p;
+    if (version!=0x03)
+        return 0;
+    packet_len = ntohs(*(uint16_t*)(p+2));
+    return packet_len == len;
+}
+
+#ifdef ENABLE_REGEX
+pcre2_match_data* probe_regex_matches;
+#endif
+
 static int regex_probe(const char *p, ssize_t len, struct sslhcfg_protocols_item* proto)
 {
 #ifdef ENABLE_REGEX
     pcre2_code**probe = (pcre2_code**)proto->data;
-    pcre2_match_data* matches;
 
-    matches = pcre2_match_data_create(1, NULL);
 
     for (; *probe; probe++) {
-        int res = pcre2_match(*probe, (PCRE2_SPTR8)p, len, 0, 0, matches, NULL);
+        int res = pcre2_match(*probe, (PCRE2_SPTR8)p, len, 0, 0, probe_regex_matches, NULL);
         if (res >= 0) return 1;
 
     }
     return 0;
 #else
     /* Should never happen as we check when loading config file */
-    fprintf(stderr, "FATAL: regex probe called but not built in\n");
+    print_message(msg_int_error, "FATAL: regex probe called but not built in\n");
     exit(5);
 #endif
 }
 
 /* Run all the probes on a buffer
+ * buf, len: buffer to test on
+ * proto_in, proto_len: array of protocols to try
+ * proto_out: protocol that matched
+ *
  * Returns
- *      PROBE_AGAIN if not enough data, and set *proto to NULL
- *      PROBE_MATCH if protocol is identified, in which case *proto is set to
+ *      PROBE_AGAIN if not enough data, and set *proto_out to NULL
+ *      PROBE_MATCH if protocol is identified, in which case *proto_out is set to
  *      point to the appropriate protocol
  * */
-int probe_buffer(char* buf, int len, struct sslhcfg_protocols_item** proto)
+int probe_buffer(char* buf, int len,
+                 struct sslhcfg_protocols_item** proto_in,
+                 int proto_len,
+                 struct sslhcfg_protocols_item** proto_out
+                 )
 {
     struct sslhcfg_protocols_item* p;
     int i, res, again = 0;
 
-    if (cfg.verbose > 1) {
-        fprintf(stderr, "hexdump of incoming packet:\n");
-        hexdump(buf, len);
-    }
-
-    *proto = NULL;
-    for (i = 0; i < cfg.protocols_len; i++) {
+    *proto_out = NULL;
+    for (i = 0; i < proto_len; i++) {
         char* probe_str[3] = {"PROBE_NEXT", "PROBE_MATCH", "PROBE_AGAIN"};
-        p = &cfg.protocols[i];
+        p = proto_in[i];
 
         if (! p->probe) continue;
 
-        if (cfg.verbose) fprintf(stderr, "probing for %s\n", p->name);
+        print_message(msg_probe_info, "probing for %s\n", p->name);
 
         /* Don't probe last protocol if it is anyprot (and store last protocol) */
-        if ((i == cfg.protocols_len - 1) && (!strcmp(p->name, "anyprot")))
+        if ((i == proto_len - 1) && (!strcmp(p->name, "anyprot")))
             break;
 
         if (p->minlength_is_present && (len < p->minlength )) {
-            fprintf(stderr, "input too short, %d bytes but need %d\n", len , p->minlength);
+            print_message(msg_probe_info, "input too short, %d bytes but need %d\n", 
+                          len , p->minlength);
             again++;
             continue;
         }
 
         res = p->probe(buf, len, p);
-        if (cfg.verbose) fprintf(stderr, "probed for %s: %s\n", p->name, probe_str[res]);
+        print_message(msg_probe_info, "probed for %s: %s\n", p->name, probe_str[res]);
 
         if (res == PROBE_MATCH) {
-            *proto = p;
+            *proto_out = p;
             return PROBE_MATCH;
         }
         if (res == PROBE_AGAIN)
@@ -382,37 +501,14 @@ int probe_buffer(char* buf, int len, struct sslhcfg_protocols_item** proto)
         return PROBE_AGAIN;
 
     /* Everything failed: match the last one */
-    *proto = &cfg.protocols[cfg.protocols_len-1];
-    return PROBE_MATCH;
-}
 
-/*
- * Read the beginning of data coming from the client connection and check if
- * it's a known protocol.
- * Return PROBE_AGAIN if not enough data, or PROBE_MATCH if it succeeded in
- * which case cnx->proto is set to the appropriate protocol.
- */
-int probe_client_protocol(struct connection *cnx)
-{
-    char buffer[BUFSIZ];
-    ssize_t n;
-
-    n = read(cnx->q[0].fd, buffer, sizeof(buffer));
-    /* It's possible that read() returns an error, e.g. if the client
-     * disconnected between the previous call to select() and now. If that
-     * happens, we just connect to the default protocol so the caller of this
-     * function does not have to deal with a specific  failure condition (the
-     * connection will just fail later normally). */
-
-    if (n > 0) {
-        defer_write(&cnx->q[1], buffer, n);
-        return probe_buffer(cnx->q[1].begin_deferred_data,
-                            cnx->q[1].deferred_data_size,
-                            &cnx->proto);
+    if (proto_len == 0) {
+        /* This should be caught by configuration sanity checks, but just in
+         * case, die gracefully rather than segfaulting */
+        print_message(msg_int_error, "Received traffic on transport that has no target\n");
+        exit(0);
     }
-
-    /* read() returned an error, so just connect to the last protocol to die */
-    cnx->proto = &cfg.protocols[cfg.protocols_len-1];
+    *proto_out = proto_in[proto_len-1];
     return PROBE_MATCH;
 }
 

probe.h

@@ -5,6 +5,8 @@
 
 #include "common.h"
 #include "tls.h"
+#include "log.h"
+#include "proxyprotocol.h"
 
 typedef enum {
     PROBE_NEXT,  /* Enough data, probe failed -- it's some other protocol */
@@ -47,8 +49,12 @@ void set_protocol_list(struct sslhcfg_protocols_item*);
  */
 int probe_client_protocol(struct connection *cnx);
 
-/* Probe, but on a buffer */
-int probe_buffer(char* buf, int len, struct sslhcfg_protocols_item** proto);
+/* Probe on a buffer */
+int probe_buffer(char* buf, int len,
+                 struct sslhcfg_protocols_item** proto_in,
+                 int proto_len,
+                 struct sslhcfg_protocols_item** proto_out
+                 );
 
 /* set the protocol to connect to in case of timeout */
 void set_ontimeout(const char* name);
@@ -59,6 +65,13 @@ void set_ontimeout(const char* name);
  */
 struct sslhcfg_protocols_item* timeout_protocol(void);
 
-void hexdump(const char*, unsigned int);
+void hexdump(msg_info, const char*, unsigned int);
+
+#ifdef ENABLE_REGEX
+#define PCRE2_CODE_UNIT_WIDTH 8
+#include <pcre2.h>
+extern pcre2_match_data* probe_regex_matches;
+#endif
+
 
 #endif

processes.c

@@ -0,0 +1,203 @@
+/* 
+  Processes that are common to sslh-ev and sslh-select
+ 
+# Copyright (C) 2021-2025  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+
+*/
+
+#include "udp-listener.h"
+#include "tcp-listener.h"
+#include "processes.h"
+#include "probe.h"
+#include "log.h"
+
+/* Struct to keep track of an association of a forked PID to its
+ * listening socket and its protocol */
+struct pid2proto {
+    pid_t pid;
+    struct listen_endpoint* endpoint;
+    struct sslhcfg_protocols_item* proto;
+};
+
+
+int tidy_connection(struct connection *cnx, struct loop_info* fd_info)
+{
+    int i;
+
+    for (i = 0; i < 2; i++) {
+        if (cnx->q[i].fd != -1) {
+            print_message(msg_fd, "closing fd %d\n", cnx->q[i].fd);
+
+            watchers_del_read(fd_info->watchers, cnx->q[i].fd);
+            watchers_del_write(fd_info->watchers, cnx->q[i].fd);
+            close(cnx->q[i].fd);
+            if (cnx->q[i].deferred_data)
+                free(cnx->q[i].deferred_data);
+        }
+    }
+
+    if (cnx->type == SOCK_DGRAM)
+        udp_tidy(cnx, fd_info);
+
+    if (gap_remove_ptr(fd_info->probing_list, cnx, fd_info->num_probing) != -1)
+        fd_info->num_probing--;
+
+    dec_proto_connections(cnx->proto);
+    dec_listen_connections(cnx->endpoint);
+
+    collection_remove_cnx(fd_info->collection, cnx);
+    return 0;
+}
+
+
+
+/* Process a connection that is active in read */
+
+void cnx_read_process(struct loop_info* fd_info, int fd)
+{
+    cnx_collection* collection = fd_info->collection;
+    struct connection* cnx = collection_get_cnx_from_fd(collection, fd);
+    switch (cnx->type)  {
+    case SOCK_STREAM:
+        tcp_read_process(fd_info, fd);
+        break;
+
+    case SOCK_DGRAM:
+        udp_s2c_forward(cnx);
+        break;
+
+    default:
+        print_message(msg_int_error, "cnx_read_process: Illegal connection type %d\n", cnx->type);
+        dump_connection(cnx);
+        exit(1);
+    }
+}
+
+
+/* Process a connection that accepts a socket
+ * (For UDP, this means all traffic coming from remote clients)
+ * Returns new connection object, or NULL
+ * */
+struct connection* cnx_accept_process(struct loop_info* fd_info, struct listen_endpoint* listen_socket)
+{
+    int fd = listen_socket->socketfd;
+    int type = listen_socket->type;
+    struct connection* cnx;
+
+    udp_timeouts(fd_info);
+
+    switch (type) {
+    case SOCK_STREAM:
+        cnx = accept_new_connection(listen_socket, fd_info);
+        if (!cnx) return NULL;
+
+        break;
+
+    case SOCK_DGRAM:
+        cnx = udp_c2s_forward(fd, fd_info);
+        if (!cnx) return NULL;
+        break;
+
+    default:
+        print_message(msg_int_error, "Inconsistent cnx type: %d\n", type);
+        exit(1);
+    }
+
+    int new_fd = cnx->q[0].fd;
+    watchers_add_read(fd_info->watchers, new_fd);
+    return cnx;
+}
+
+
+
+typedef struct pid2proto* hash_item;
+#include "hash.h"
+
+static int pid_make_key(hash_item item) 
+{
+    return item->pid;
+}
+
+static int pid_cmp(hash_item item1, hash_item item2)
+{
+    return item1->pid != item2->pid;
+}
+
+/* When a child has died, update the counts appropriately */
+void decrease_forked_connection(struct loop_info* loop, pid_t pid) {
+    struct pid2proto p2p = { .pid = pid };
+    struct pid2proto* found = hash_find(loop->pid2proto, &p2p);
+    dec_proto_connections(found->proto);
+    dec_listen_connections(found->endpoint);
+
+    hash_remove(loop->pid2proto, found);
+    free(found);
+}
+
+
+typedef struct pid2proto* hash_item;
+#include "hash.h"
+void remember_child_data(struct loop_info* fd_info,
+                         struct connection* cnx, pid_t pid)
+{
+    struct pid2proto* pid2proto = malloc(sizeof(*pid2proto));
+    pid2proto->pid = pid;
+    pid2proto->proto = cnx->proto;
+    pid2proto->endpoint = cnx->endpoint;
+    if (hash_insert(fd_info->pid2proto, pid2proto)) {
+        /* TODO something if it fails */
+    }
+}
+
+static int max_forking_connections(void)
+{
+    int max_cnx = 0;
+    for (int i = 0; i < cfg.protocols_len; i++) {
+        if (cfg.protocols[i].fork)
+            max_cnx += cfg.protocols[i].max_connections;
+    }
+    return max_cnx;
+}
+
+static int next_power_of_two(int n)
+{
+    n |= (n >> 16);
+    n |= (n >> 4);
+    n |= (n >> 2);
+    n |= (n >> 1);
+    return n + 1;
+}
+
+void loop_init(struct loop_info* loop, int num_addr_listen)
+{
+    memset(loop, 0, sizeof(*loop));
+    loop->collection = collection_init(0);
+    loop->probing_list = gap_init(0);
+    CHECK_ALLOC(loop->probing_list, "gap_init");
+
+    udp_init(loop);
+    tcp_init();
+
+    loop->num_addr_listen = num_addr_listen;
+
+    int max_forks = next_power_of_two(max_forking_connections());
+    loop->pid2proto = hash_init(2 * max_forks, pid_make_key, pid_cmp);
+    CHECK_ALLOC(loop->pid2proto, "hash_init");
+}
+
+

processes.h

@@ -0,0 +1,49 @@
+#ifndef PROCESSES_H
+#define PROCESSES_H
+
+#include "common.h"
+#include "collection.h"
+#include "gap.h"
+
+/* Provided by event loop, sslh-ev or sslh-select, for implementation-dependant
+ * data */
+typedef struct watchers watchers; 
+
+typedef void hash;
+
+/* Global state for a loop */
+struct loop_info {
+    int num_probing;     /* Number of connections currently probing 
+                          * We use this to know if we need to time out of
+                          * select() */
+    gap_array* probing_list;  /* Pointers to cnx that are in probing mode */
+
+    hash* hash_sources; /* UDP remote sources previously encountered */
+
+    hash* pid2proto; /* to follow which forked PID is processing what protocol for connection count */
+
+    watchers* watchers;
+    int num_addr_listen;  /* How many listen endpoints do we have here */
+
+    cnx_collection* collection; /* Collection of connections linked to this loop */
+};
+
+void cnx_read_process(struct loop_info* fd_info, int fd);
+struct connection* cnx_accept_process(struct loop_info* fd_info, struct listen_endpoint* listen_socket);
+
+int tidy_connection(struct connection *cnx, struct loop_info* fd_info);
+void loop_init(struct loop_info* loop, int num_addr_listen);
+
+void remember_child_data(struct loop_info* fd_info, 
+                         struct connection* cnx, pid_t pid);
+void decrease_forked_connection(struct loop_info* loop, pid_t pid);
+
+/* These must be declared in the loop handler, sslh-ev or sslh-select */
+void watchers_add_read(watchers* w, int fd);
+void watchers_del_read(watchers* w, int fd);
+void watchers_add_write(watchers* w, int fd);
+void watchers_del_write(watchers* w, int fd);
+
+void watcher_sigchld(struct loop_info* fd_info, struct connection* cnx, pid_t pid);
+
+#endif

proxyprotocol.c

@@ -0,0 +1,169 @@
+/*
+# proxyprotocol: Support for HAProxy's proxyprotocol
+#
+# Copyright (C) 2025  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+
+*/
+
+#include "config.h"
+
+#ifdef HAVE_PROXYPROTOCOL
+
+#include <proxy_protocol.h>
+#include "common.h"
+#include "log.h"
+
+
+/* Converts socket family to libproxyprotocol family */
+static int family_to_pp(int af_family)
+{
+    switch (af_family) {
+    case AF_INET:
+        return ADDR_FAMILY_INET;
+
+    case AF_INET6:
+        return ADDR_FAMILY_INET6;
+
+    case AF_UNIX:
+        return ADDR_FAMILY_UNIX;
+
+    default:
+        print_message(msg_int_error, "Unknown internal socket family %d\n", af_family);
+        return -1;
+    }
+}
+
+typedef char libpp_addr[108]; /* This is hardcoded in libproxyprotocol/proxy_protocol.h */
+
+
+typedef enum {
+    PEER,
+    SOCK
+} sockpeer_t;
+
+/* Fills *addr, *host and *serv with the connection information corresponding
+ * to fd. sockpeer indicates if if is filled with the remote, or local, part of
+ * the socket.
+ * *host is the IP address as string and *serv is the service (port)
+ * */
+static int get_info(int fd, sockpeer_t sockpeer, struct addrinfo* addr, libpp_addr* host, uint16_t* serv)
+{
+    char serv_str[NI_MAXSERV];
+    int res;
+
+    if (sockpeer == PEER) {
+        res = getpeername(fd, addr->ai_addr, &addr->ai_addrlen);
+        CHECK_RES_RETURN(res, "getpeername", -1);
+    } else {
+        res = getsockname(fd, addr->ai_addr, &addr->ai_addrlen);
+        CHECK_RES_RETURN(res, "getsockname", -1);
+    }
+
+    res = getnameinfo(addr->ai_addr, addr->ai_addrlen,
+                      (char*)host, sizeof(*host),
+                      serv_str, sizeof(serv_str),
+                      NI_NUMERICHOST | NI_NUMERICSERV );
+    if (res != 0) {
+        print_message(msg_system_error, "getnameinfo: %s\n", gai_strerror(res));
+        return -1;
+    }
+
+    *serv = atoi(serv_str);
+
+    return 0;
+}
+
+
+
+int pp_write_header(int pp_version, struct connection* cnx)
+{
+    pp_info_t pp_info_in_v1 = {
+        .transport_protocol = TRANSPORT_PROTOCOL_STREAM,
+    };
+    uint16_t pp1_hdr_len;
+    int32_t error;
+
+    struct sockaddr_storage ss;
+    struct addrinfo addr;
+    int res;
+
+    addr.ai_addr = (struct sockaddr*)&ss;
+    addr.ai_addrlen = sizeof(ss);
+
+    res = get_info(cnx->q[0].fd, PEER,
+             &addr,
+             &pp_info_in_v1.src_addr,
+             &pp_info_in_v1.src_port);
+    if (res == -1) return -1;
+    pp_info_in_v1.address_family = family_to_pp(addr.ai_addr->sa_family);
+
+    res = get_info(cnx->q[1].fd, SOCK,
+             &addr,
+             &pp_info_in_v1.dst_addr,
+             &pp_info_in_v1.dst_port
+            );
+    if (res == -1) return -1;
+
+    uint8_t *pp1_hdr = pp_create_hdr(pp_version, &pp_info_in_v1, &pp1_hdr_len, &error);
+
+    if (!pp1_hdr) {
+        print_message(msg_system_error, "pp_create_hrd:%d:%s\n", error, pp_strerror(error));
+        return -1;
+    }
+    defer_write_before(&cnx->q[1], pp1_hdr, pp1_hdr_len);
+
+    pp_info_clear(&pp_info_in_v1);
+    free(pp1_hdr);
+
+    return 0;
+}
+
+/* Logs the connection data in the pp header and return header length */
+int pp_log_connection(char* buffer, ssize_t buffer_len)
+{
+    pp_info_t pp_info;
+
+    int header_len = pp_parse_hdr((uint8_t*)buffer, buffer_len, &pp_info);
+
+    if (header_len > 0) {
+    print_message(msg_connections, "client had proxyprotocol info: %s:%d to %s:%d not forwarded to server\n",
+                  pp_info.src_addr, pp_info.src_port,
+                  pp_info.dst_addr, pp_info.dst_port);
+    } else {
+        print_message(msg_connections, "no proxyprotocol data found on client side, forwarding as is\n");
+        header_len = 0;
+    }
+
+    return header_len;
+}
+
+int pp_header_len(char* buffer, int buffer_len)
+{
+    pp_info_t pp_info;
+
+    int header_len = pp_parse_hdr((uint8_t*)buffer, buffer_len, &pp_info);
+
+    print_message(msg_probe_info, "proxyprotocol header %d bytes found\n", header_len);
+    
+    if (header_len < 0) header_len = 0;
+
+    return header_len;
+}
+
+
+#endif /* HAVE_PROXYPROTOCOL */

proxyprotocol.h

@@ -0,0 +1,21 @@
+#ifndef PROXYPROTOCOL_H
+#define PROXYPROTOCOL_H
+
+
+#if HAVE_PROXYPROTOCOL
+
+
+int pp_write_header(int pp_version, struct connection* cnx);
+int pp_log_connection(char* buffer, ssize_t buffer_len);
+int pp_header_len(char* buffer, int len);
+
+
+#else /* HAVE_PROXYPROTOCOL */
+
+static inline int pp_write_header(int pp_version, struct connection* cnx) { return 0; }
+static int pp_log_connection(char* buffer, ssize_t buffer_len) { return 0; }
+static inline int pp_header_len(char*, int) { return 0; }
+
+#endif /* HAVE_PROXYPROTOCOL */
+
+#endif /* PROXYPROTOCOL_H */

scripts/etc-init.d-sslh-debian-modified.sslh

@@ -0,0 +1,186 @@
+#! /bin/sh
+### BEGIN INIT INFO
+# Provides:          sslh
+# Required-Start:    $remote_fs $syslog $network
+# Required-Stop:     $remote_fs $syslog $network
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: ssl/ssh multiplexer
+# Description:       sslh lets one accept both HTTPS and SSH connections on the
+#                    same port. It makes it possible to connect to an SSH server
+#                    on port 443 (e.g. from inside a corporate firewall) while
+#                    still serving HTTPS on that port.
+### END INIT INFO
+
+# Original Author: Guillaume Delacour <gui@iroqwa.org>
+# modified and optimized for current sslh-fork 
+
+# Do NOT "set -e"
+
+# PATH should only include /usr/* if it runs after the mountnfs.sh script
+PATH=/sbin:/usr/sbin:/bin:/usr/bin
+DESC="ssl/ssh multiplexer"
+NAME=sslh
+DAEMON=/usr/sbin/$NAME
+DAEMON_OPTS=""
+PIDFILE=/var/run/sslh/$NAME.pid
+SCRIPTNAME=/etc/init.d/$NAME
+RUN=yes
+
+
+# If you want to use a configuration file, put -F/path/to/sslh.cfg
+# into /etc/default/sslh DAEMON_OPTS
+# Read configuration variable file if it is present
+[ -r /etc/default/$NAME ] && . /etc/default/$NAME
+
+
+
+# Load the VERBOSE setting and other rcS variables
+. /lib/init/vars.sh
+
+# Define LSB log_* functions.
+# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
+# and status_of_proc is working.
+. /lib/lsb/init-functions
+
+# Exit if the package is not installed
+if [ -x "$DAEMON" ] 
+then
+  echo "Can not start \"$DAEMON\", path not available"
+  log_failure_msg "Can not start \"$DAEMON\", path not available"
+fi
+
+
+#
+# Function that starts the daemon/service
+#
+do_start()
+{
+        # Return
+        #   0 if daemon has been started
+        #   1 if daemon was already running
+        #   2 if daemon could not be started
+    
+  # Use this if you want the user to explicitly set 'RUN' in
+  # /etc/default/
+  if [ "$RUN" != "yes" ]
+  then
+      echo "$NAME disabled, please adjust the configuration to your needs "
+      log_failure_msg "and then set RUN to 'yes' in /etc/default/$NAME to enable it."
+      return 2
+  fi
+    
+        # sslh write the pid as sslh user
+        if [ ! -d /var/run/sslh/ ]
+        then
+                mkdir -p /var/run/sslh
+                chown sslh:sslh /var/run/sslh
+        fi
+
+        start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \
+                || return 1
+        start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON -- \
+                $DAEMON_OPTS \
+                || return 2
+        # Add code here, if necessary, that waits for the process to be ready
+        # to handle requests from services started subsequently which depend
+        # on this one.  As a last resort, sleep for some time.
+}
+
+#
+# Function that stops the daemon/service
+#
+do_stop()
+{
+        # Return
+        #   0 if daemon has been stopped
+        #   1 if daemon was already stopped
+        #   2 if daemon could not be stopped
+        #   other if a failure occurred
+        start-stop-daemon --stop --quiet --retry=TERM/45/KILL/5 --pidfile $PIDFILE --name $NAME
+        RETVAL="$?"
+        [ "$RETVAL" = 2 ] && return 2
+  # As long, as the started sslh is sslh-fork, don't kill the still existing 
+  # connections. You may need the following construct for sslh-ev and sslh-select,
+  # as sslh has currently no function reloading its configuration.
+
+  # Wait for children to finish too if this is a daemon that forks
+        # and if the daemon is only ever run from this initscript.
+        # If the above conditions are not satisfied then add some other code
+        # that waits for the process to drop all resources that could be
+        # needed by services started subsequently.  A last resort is to
+        # sleep for some time.
+        #start-stop-daemon --stop --quiet --oknodo --retry=0/30/KILL/5 --exec $DAEMON
+        #[ "$?" = 2 ] && return 2
+        # Many daemons don't delete their pidfiles when they exit.
+        rm -f $PIDFILE
+        return "$RETVAL"
+}
+
+#
+# Function that sends a SIGHUP to the daemon/service
+# don't activate this, as this kills only the leading process
+# of sslh-fork, and the spawned worker stays connected listening.
+# After that, the Owner of the PID from PIDFILE is gone, the
+# listening connection is still blocked
+# sslh can't reload its configuration as of Aug 2024
+#do_reload() {
+        #
+        # If the daemon can reload its configuration without
+        # restarting (for example, when it is sent a SIGHUP),
+        # then implement that here.
+        #
+#       start-stop-daemon --stop --signal 1 --quiet --pidfile $PIDFILE --name $NAME
+#       return 0
+#}
+
+case "$1" in
+  start)
+        # check if sslh is launched via inetd
+        if [ -f /etc/inetd.conf ] && [ $(egrep -q "^https.*/usr/sbin/sslh" /etc/inetd.conf|wc -l) -ne 0 ]
+        then
+                echo "sslh is started from inetd."
+                exit 1
+        fi
+
+        log_daemon_msg "Starting $DESC" "$NAME"
+        do_start
+        case "$?" in
+                0|1) log_end_msg 0 ;;
+                2) log_end_msg 1 ;;
+        esac
+        ;;
+  stop)
+        log_daemon_msg "Stopping $DESC" "$NAME"
+        do_stop
+        case "$?" in
+                0|1) log_end_msg 0 ;;
+                2) log_end_msg 1 ;;
+        esac
+        ;;
+  status)
+       status_of_proc "$DAEMON" "$NAME" && exit 0 || exit $?
+       ;;
+  restart|force-reload)
+        log_daemon_msg "Restarting $DESC" "$NAME"
+        do_stop
+        case "$?" in
+          0|1)
+                do_start
+                case "$?" in
+                        0) log_end_msg 0 ;;
+                        1) log_end_msg 1 ;; # Old process is still running
+                        *) log_end_msg 1 ;; # Failed to start
+                esac
+                ;;
+          *)
+                # Failed to stop
+                log_end_msg 1
+                ;;
+        esac
+        ;;
+  *)
+        echo "Usage: $SCRIPTNAME {start|stop|status|restart}" >&2
+        exit 3
+        ;;
+esac

scripts/etc.sysconfig.sslh

@@ -18,7 +18,7 @@
 #CONFIG=/etc/sslh.cfg
 
 #
-# Extra option to pass on comand line
+# Extra option to pass on command line
 # Those can supersede configuration file settings
 # 
 #OPTIONS=

scripts/fail2ban/sslh-ssh.conf

@@ -8,7 +8,7 @@
 # but many connection attempts from the same
 # origin is reason enough to block.
 #
-# Verion: 2014-03-28
+# Version: 2014-03-28
 
 [INCLUDES]
 
@@ -16,7 +16,7 @@
 
 [Definition]
 
-failregex = ^.+ sslh\[.+\]: connection from <HOST>:.+ to .+ forwarded
+failregex = ^.+ sslh\[.+\]: ssh:connection from <HOST>:.+ to .+ forwarded
 from .+ to .+:ssh\s*$
 
 ignoreregex =

scripts/systemd.sslh-select@.service

@@ -0,0 +1,27 @@
+[Unit]
+Description=SSL/SSH multiplexer (select mode) for %I
+After=network.target
+
+[Service]
+EnvironmentFile=/etc/default/sslh
+ExecStart=/usr/sbin/sslh-select -F/etc/sslh/%I.cfg -f $DAEMON_OPTS
+KillMode=process
+#Hardening
+PrivateTmp=true
+CapabilityBoundingSet=CAP_NET_BIND_SERVICE
+AmbientCapabilities=CAP_NET_BIND_SERVICE
+SecureBits=noroot-locked
+ProtectSystem=strict
+ProtectHome=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectControlGroups=true
+MountFlags=private
+NoNewPrivileges=true
+PrivateDevices=true
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+MemoryDenyWriteExecute=true
+DynamicUser=true
+
+[Install]
+WantedBy=multi-user.target

scripts/systemd.sslh@.service

@@ -1,10 +1,10 @@
 [Unit]
-Description=SSL/SSH multiplexer
+Description=SSL/SSH multiplexer (fork mode) for %I
 After=network.target
 
 [Service]
-EnvironmentFile=/etc/conf.d/sslh
-ExecStart=/usr/sbin/sslh --foreground $DAEMON_OPTS
+EnvironmentFile=/etc/default/sslh
+ExecStart=/usr/sbin/sslh -F/etc/sslh/%I.cfg -f $DAEMON_OPTS
 KillMode=process
 #Hardening
 PrivateTmp=true

sslh-conf.h

@@ -1,8 +1,8 @@
 /* Generated by conf2struct (https://www.rutschle.net/tech/conf2struct/README)
- * on Tue Aug 24 13:53:04 2021. 
+ * on Fri Aug 29 20:43:29 2025. 
 
 # conf2struct: generate libconf parsers that read to structs
-# Copyright (C) 2018-2021  Yves Rutschle
+# Copyright (C) 2018-2024  Yves Rutschle
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -43,8 +43,12 @@
 struct sslhcfg_listen_item {
 	char*	host;
 	char*	port;
+	int	max_connections_is_present;
+	int	max_connections;
 	int	is_udp;
+	int	is_unix;
 	int	keepalive;
+	int	proxyprotocol;
 };
 
 struct sslhcfg_protocols_item {
@@ -53,13 +57,17 @@ struct sslhcfg_protocols_item {
 	char*	port;
 	int	service_is_present;
 	char*	service;
+	int	is_unix;
 	int	is_udp;
 	int	udp_timeout;
 	int	fork;
 	int	tfo_ok;
 	int	transparent;
+	int	resolve_on_forward;
 	int	log_level;
 	int	keepalive;
+	int	max_connections_is_present;
+	int	max_connections;
 	size_t	sni_hostnames_len;
 	char** sni_hostnames;
 	size_t	alpn_protocols_len;
@@ -68,19 +76,35 @@ struct sslhcfg_protocols_item {
 	char** regex_patterns;
 	int	minlength_is_present;
 	int	minlength;
+	int	proxyprotocol_is_present;
+	int	proxyprotocol;
 	T_PROBE*	probe;
 	struct addrinfo*	saddr;
 	void*	data;
+	unsigned int	num_connections;
+	dl_list	timeouts;
 };
 
 struct sslhcfg_item {
 	int	verbose;
+	int	verbose_config;
+	int	verbose_config_error;
+	int	verbose_connections;
+	int	verbose_connections_try;
+	int	verbose_connections_error;
+	int	verbose_fd;
+	int	verbose_packets;
+	int	verbose_probe_info;
+	int	verbose_probe_error;
+	int	verbose_system_error;
+	int	verbose_int_error;
 	int	version;
 	int	foreground;
 	int	inetd;
 	int	numeric;
 	int	transparent;
 	int	timeout;
+	int	udp_max_connections;
 	int	user_is_present;
 	char*	user;
 	int	pidfile_is_present;
@@ -88,6 +112,8 @@ struct sslhcfg_item {
 	int	chroot_is_present;
 	char*	chroot;
 	char*	syslog_facility;
+	int	logfile_is_present;
+	char*	logfile;
 	char*	on_timeout;
 	char*	prefix;
 	size_t	listen_len;

sslh-ev.c

@@ -0,0 +1,229 @@
+/*
+   sslh-ev: mono-processus server based on libev
+
+# Copyright (C) 2021  Yves Rutschle
+# 
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later
+# version.
+# 
+# This program is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE.  See the GNU General Public License for more
+# details.
+# 
+# The full text for the General Public License is here:
+# http://www.gnu.org/licenses/gpl.html
+
+*/
+
+#include <stdlib.h>
+#include <ev.h>
+#include "gap.h"
+#include "log.h"
+#include "udp-listener.h"
+#include "tcp-listener.h"
+
+
+const char* server_type = "sslh-ev";
+
+static struct ev_loop* loop;
+
+/* Libev watchers */
+struct watchers {
+    /* one set of ev_io for read, one for write, indexed by file descriptor */
+    gap_array *ev_ior, *ev_iow;
+
+    struct listen_endpoint* listen_sockets;
+    gap_array* fd2ls;  /* Array indexed by file descriptor, pointing to listen_sockets */
+};
+
+static void cnx_read_cb(EV_P_ ev_io *w, int revents);
+static void cnx_write_cb(EV_P_ ev_io *w, int wevents);
+static void cnx_accept_cb(EV_P_ ev_io *w, int revents);
+
+/*******************************************************************************/
+/* Helper functions */
+
+/* Enable all accept() watchers */
+static void start_accept_watchers(watchers* w, int num_addr_listen) 
+{
+    for (int i = 0; i < num_addr_listen; i++) {
+        ev_io* io = gap_get(w->ev_ior, i);
+        ev_io_start(EV_A_  io);
+    }
+}
+
+/* Disable all accept() watchers */
+static void stop_accept_watchers(watchers* w, int num_addr_listen)
+{
+    for (int i = 0; i < num_addr_listen; i++) {
+        ev_io* io = gap_get(w->ev_ior, i);
+        ev_io_stop(EV_A_  io);
+    }
+}
+
+/*******************************************************************************/
+
+static void watchers_init(watchers** w, struct listen_endpoint* listen_sockets, 
+                          int num_addr_listen)
+{
+    *w = malloc(sizeof(**w));
+    (*w)->ev_ior = gap_init(num_addr_listen);
+    (*w)->ev_iow = gap_init(num_addr_listen);
+    (*w)->listen_sockets = listen_sockets;
+    (*w)->fd2ls = gap_init(0);
+
+    /* Create watchers for listen sockets */
+    for (int i = 0; i < num_addr_listen; i++) {
+        ev_io* io = malloc(sizeof(*io));
+
+        ev_io_init(io, &cnx_accept_cb, listen_sockets[i].socketfd, EV_READ);
+        gap_set((*w)->ev_ior, i, io);
+        gap_set((*w)->fd2ls, listen_sockets[i].socketfd, &listen_sockets[i]);
+        set_nonblock(listen_sockets[i].socketfd);
+    }
+    start_accept_watchers(*w, num_addr_listen);
+}
+
+void watchers_add_read(watchers* w, int fd)
+{
+    ev_io* io = gap_get(w->ev_ior, fd);
+    if (!io) {
+        io = malloc(sizeof(*io));
+        ev_io_init(io, &cnx_read_cb, fd, EV_READ);
+        ev_io_set(io, fd, EV_READ);
+
+        gap_set(w->ev_ior, fd, io);
+    }
+    ev_io_start(loop, io);
+}
+
+void watchers_del_read(watchers* w, int fd)
+{
+    ev_io* io = gap_get(w->ev_ior, fd);
+    if (io) ev_io_stop(EV_A_ io);
+}
+
+void watchers_add_write(watchers* w, int fd)
+{
+    ev_io* io = gap_get(w->ev_iow, fd);
+    if (!io) {
+        io = malloc(sizeof(*io));
+        ev_io_init(io, &cnx_write_cb, fd, EV_WRITE);
+        ev_io_set(io, fd, EV_WRITE);
+
+        gap_set(w->ev_iow, fd, io);
+    }
+    ev_io_start(loop, io);
+}
+
+void watchers_del_write(watchers* w, int fd)
+{
+    ev_io* io = gap_get(w->ev_iow, fd);
+    if (io) ev_io_stop(EV_A_ io);
+}
+
+/* /watchers */
+
+#include "processes.h"
+
+/* Libev callbacks */
+static void cnx_read_cb(EV_P_ ev_io *w, int revents)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+    cnx_read_process(info, w->fd);
+}
+
+static void cnx_write_cb(EV_P_ ev_io *w, int wevents)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+    cnx_write_process(info, w->fd);
+}
+
+/* Timer expired: destroy timer, restart the accept watchers */
+static void restart_accept_cb( EV_P_ ev_timer *timer, int revents)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+
+    ev_timer_stop(EV_A_ timer);
+    free(timer);
+
+    start_accept_watchers(info->watchers, info->num_addr_listen);
+}
+
+/* Stop the accept() io watchers, start a timer
+ */
+static void temporary_stop_accept_watchers(ev_io* io)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+
+    ev_timer* timer = malloc(sizeof(*timer));
+    stop_accept_watchers(info->watchers, info->num_addr_listen);
+    ev_timer_init(timer, &restart_accept_cb, 1, 0);
+    ev_timer_start(EV_A_ timer);
+}
+
+/* The accept() callback, called when there is READ activity.
+ *
+ * accept()ing when the process as reached its file descriptor limit (ulimit -n) is can of worms with no solution (see libev's manual "The special problem of accept()ing when you can't").
+ * When that happens, the strategy is: Disable all listening sockets, start a 1
+ * second timer, enable all listening sockets. This is terrible, but apparently
+ * the best we can do */
+static void cnx_accept_cb(EV_P_ ev_io *w, int revents)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+    if (!cnx_accept_process(info, gap_get(info->watchers->fd2ls, w->fd))) {
+        switch (errno) {
+        case EMFILE:
+        case ENFILE:  /* Not sure ENFILE should be included here */
+            /* cancel accepting for a while */
+            temporary_stop_accept_watchers(w);
+
+        default:
+            break;
+        }
+    }
+}
+
+
+void sigchld_cb(EV_P_ ev_child *w, int revents)
+{
+    struct loop_info* info = ev_userdata(EV_A);
+    ev_child_stop(EV_A_ w);
+
+    decrease_forked_connection(info, w->pid);
+    free(w);
+}
+
+void watcher_sigchld(struct loop_info* fd_info, struct connection* cnx, pid_t pid)
+{
+    ev_child* cw = malloc(sizeof(*cw));
+
+    ev_child_init(cw, sigchld_cb, pid, 0);
+    ev_child_start(EV_DEFAULT_ cw);
+}
+
+
+void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
+{
+    struct loop_info ev_info;
+    loop = EV_DEFAULT;
+
+    loop_init(&ev_info, num_addr_listen);
+
+    watchers_init(&ev_info.watchers, listen_sockets, num_addr_listen);
+    ev_set_userdata(EV_A_ &ev_info);
+
+    ev_run(EV_A_ 0);
+}
+
+void start_shoveler(int listen_socket) {
+    print_message(msg_config_error, "inetd mode is not supported in libev mode\n");
+    exit(1);
+}
+
+

sslh-fork.c

@@ -1,7 +1,7 @@
 /*
    sslh-fork: forking server
 
-# Copyright (C) 2007-2021  Yves Rutschle
+# Copyright (C) 2007-2025  Yves Rutschle
 # 
 # This program is free software; you can redistribute it
 # and/or modify it under the terms of the GNU General Public
@@ -23,9 +23,10 @@
 #include "common.h"
 #include "probe.h"
 #include "sslh-conf.h"
-#include "udp-listener.h"
+#include "tcp-probe.h"
+#include "log.h"
 
-#ifdef LIBBSD
+#if HAVE_LIBBSD
 #include <bsd/unistd.h>
 #endif
 
@@ -58,8 +59,7 @@ int shovel(struct connection *cnx)
           if (FD_ISSET(cnx->q[i].fd, &fds)) {
               res = fd2fd(&cnx->q[1-i], &cnx->q[i]);
               if (res == FD_CNXCLOSED) {
-                  if (cfg.verbose) 
-                      fprintf(stderr, "%s %s", i ? "client" : "server", "socket closed\n");
+                  print_message(msg_fd, "%s %s", i ? "client" : "server", "socket closed\n");
                   return res;
               }
           }
@@ -74,7 +74,6 @@ void start_shoveler(int in_socket)
    fd_set fds;
    struct timeval tv;
    int res = PROBE_AGAIN;
-   int out_socket;
    struct connection cnx;
    struct connection_desc desc;
 
@@ -99,8 +98,7 @@ void start_shoveler(int in_socket)
        } else {
            /* Timed out: it's necessarily SSH */
            cnx.proto = timeout_protocol();
-           if (cfg.verbose) 
-               log_message(LOG_INFO, "timed out, connect to %s\n", cnx.proto->name);
+           print_message(msg_fd, "timed out, connect to %s\n", cnx.proto->name);
            break;
        }
    }
@@ -111,13 +109,11 @@ void start_shoveler(int in_socket)
    }
 
    /* Connect the target socket */
-   out_socket = connect_addr(&cnx, in_socket, BLOCKING);
-   CHECK_RES_DIE(out_socket, "connect");
+   connect_addr(&cnx, in_socket, BLOCKING);
+   CHECK_RES_DIE(cnx.q[1].fd, "connect");
 
    set_capabilities(0);
 
-   cnx.q[1].fd = out_socket;
-
    get_connection_desc(&desc, &cnx);
    log_connection(&desc, &cnx);
    set_proctitle_shovel(&desc, &cnx);
@@ -127,10 +123,9 @@ void start_shoveler(int in_socket)
    shovel(&cnx);
 
    close(in_socket);
-   close(out_socket);
+   close(cnx.q[1].fd);
    
-   if (cfg.verbose)
-      fprintf(stderr, "connection closed down\n");
+   print_message(msg_fd, "connection closed down\n");
 
    exit(0);
 }
@@ -149,7 +144,7 @@ void stop_listeners(int sig)
 
 void set_listen_procname(struct listen_endpoint *listen_socket)
 {
-#ifdef LIBBSD
+#if HAVE_LIBBSD
     int res;
     struct addrinfo addr;
     struct sockaddr_storage ss;
@@ -165,6 +160,42 @@ void set_listen_procname(struct listen_endpoint *listen_socket)
 #endif
 }
 
+static void mask_sigchld(void)
+{
+    struct sigaction action;
+
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = NULL;
+    action.sa_flags = SA_NOCLDWAIT;
+    int res = sigaction(SIGCHLD, &action, NULL);
+    CHECK_RES_DIE(res, "sigaction");
+}
+
+
+extern volatile sig_atomic_t received_sigchld;
+/* EINTR, so we probably received a signal; check if it's SIGCHLD */
+static void process_signals(struct listen_endpoint* endpoint)
+{
+    int chld;
+    if (received_sigchld) {
+        received_sigchld = 0;
+        do {
+            chld = waitpid(-1, NULL, WNOHANG);
+            CHECK_RES_RETURN(chld, "waitpid", );
+            if (chld) {
+                endpoint->num_connections--;
+                print_message(msg_fd, "child died, %d concurrent connections remaining\n", endpoint->num_connections);
+            }
+        } while (chld);
+    }
+}
+
+/* At least MacOS does not know these two options, so define them to something
+ * equivalent for our use case */
+#ifndef ENONET
+#define ENONET EWOULDBLOCK
+#endif
+/* /MacOS kludge */
 
 /* TCP listener: connections, fork a child for each new connection 
  * IN: 
@@ -179,10 +210,42 @@ void tcp_listener(struct listen_endpoint* endpoint, int num_endpoints, int activ
 
     while (1) {
         in_socket = accept(endpoint[active_endpoint].socketfd, 0, 0);
-        if (cfg.verbose) fprintf(stderr, "accepted fd %d\n", in_socket);
+        if (in_socket == -1) {
+            print_message(msg_system_error, "%s:%d:%s:%d:%s\n",
+                          __FILE__, __LINE__, "accept", errno, strerror(errno));
+            switch(errno) {
+            case ENETDOWN:  /* accept(2) cites all these errnos as "you should retry" */
+            case EPROTO:
+            case ENOPROTOOPT:
+            case EHOSTDOWN:
+            case ENONET:
+            case EHOSTUNREACH:
+            case EOPNOTSUPP:
+            case ENETUNREACH:
+            case ECONNABORTED:
+                continue;
+
+            case EINTR:
+                process_signals(endpoint);
+                continue;
+
+            default:  /* Otherwise, it's something wrong in our parameters, we fail */
+                return;
+            }
+        }
+        endpoint->num_connections++;
+        print_message(msg_fd, "accepted fd %d (%d concurrent connections)\n", in_socket, endpoint->num_connections);
+        if ((endpoint->endpoint_cfg->max_connections_is_present) 
+            && (endpoint->num_connections > endpoint->endpoint_cfg->max_connections)) 
+        {
+            print_message(msg_fd, "too many connection, reclosing fd %d\n", in_socket);
+            endpoint->num_connections--;
+            close(in_socket);
+            continue;
+        }
 
         switch(fork()) {
-        case -1: log_message(LOG_ERR, "fork failed: err %d: %s\n", errno, strerror(errno));
+        case -1: print_message(msg_system_error, "fork failed: err %d: %s\n", errno, strerror(errno));
                  break;
 
         case 0: /* In child process */
@@ -209,24 +272,30 @@ void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
     listener_pid = malloc(listener_pid_number * sizeof(listener_pid[0]));
     CHECK_ALLOC(listener_pid, "malloc");
 
+    tcp_init();
+
     /* Start one process for each listening address */
     for (i = 0; i < num_addr_listen; i++) {
         listener_pid[i] = fork();
         switch(listener_pid[i]) {
         /* Log if fork() fails for some reason */
-        case -1: log_message(LOG_ERR, "fork failed: err %d: %s\n", errno, strerror(errno));
+        case -1: print_message(msg_system_error, "fork failed: err %d: %s\n", errno, strerror(errno));
                  break;
         /* We're in the child, we have work to do  */
         case 0:
             set_listen_procname(&listen_sockets[i]);
             if (listen_sockets[i].type == SOCK_DGRAM)
-                log_message(LOG_ERR, "UDP not (yet?) supported in sslh-fork\n");
+                print_message(msg_config_error, "UDP not supported in sslh-fork\n");
             else
                 tcp_listener(listen_sockets, num_addr_listen, i);
+
+            exit(0);
 	    break;
 
-	/* We're in the parent, we don't need to do anything */
+	/* We're in the parent, which does nothing but wait to be killed by
+         * SIGTERM, which it will send to its children */
 	default:
+            mask_sigchld();
 	    break;
         }
     }
@@ -243,7 +312,7 @@ void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
     wait(NULL);
 }
 
-/* The actual main is in common.c: it's the same for both version of
+/* The actual main() is in sslh_main.c: it's the same for all versions of
  * the server
  */
 

sslh-main.c

@@ -30,18 +30,24 @@
 #include <pcre2.h>
 #endif
 
-#ifdef LIBBSD
+#include "common.h"
+#include "probe.h"
+#include "log.h"
+#include "tcp-probe.h"
+
+#if HAVE_LIBBSD
 #include <bsd/unistd.h>
 #endif
 
-#include "common.h"
-#include "probe.h"
+#if HAVE_LIBCAP
+#include <sys/capability.h>
+#endif
 
 /* Constants for options that have no one-character shorthand */
 #define OPT_ONTIMEOUT   257
 
 static void printcaps(void) {
-#ifdef LIBCAP
+#if HAVE_LIBCAP
     cap_t caps;
     char* desc;
     ssize_t len;
@@ -50,7 +56,7 @@ static void printcaps(void) {
 
     desc = cap_to_text(caps, &len);
 
-    fprintf(stderr, "capabilities: %s\n", desc);
+    print_message(msg_config, "capabilities: %s\n", desc);
 
     cap_free(caps);
     cap_free(desc);
@@ -59,34 +65,55 @@ static void printcaps(void) {
 
 static void printsettings(void)
 {
-    char buf[NI_MAXHOST];
+    char buf[NI_MAXHOST + 256]; /* 256 > " family %d %d" for reasonable ints */
     int i;
     struct sslhcfg_protocols_item *p;
     
     for (i = 0; i < cfg.protocols_len; i++ ) {
         p = &cfg.protocols[i];
-        fprintf(stderr,
-                "%s addr: %s. libwrap service: %s log_level: %d family %d %d [%s] [%s] [%s]\n",
-                p->name, 
-                sprintaddr(buf, sizeof(buf), p->saddr), 
-                p->service,
-                p->log_level,
-                p->saddr->ai_family,
-                p->saddr->ai_addr->sa_family,
-                p->keepalive ? "keepalive" : "",
-                p->fork ? "fork" : "",
-                p->transparent ? "transparent" : ""
-                );
+        if (p->is_unix) {
+            sprintf(buf, "unix socket: %s", p->host);
+        } else {
+            if (p->resolve_on_forward) {
+                strcpy(buf, "resolve on forward: ");
+                size_t len = strlen(buf);
+                sprintf(buf+len, "%s:%s", p->host, p->port);
+            } else {
+                sprintaddr(buf, sizeof(buf), p->saddr);
+                size_t len = strlen(buf);
+                sprintf(buf+len, " family %d %d",
+                        p->saddr->ai_family,
+                        p->saddr->ai_addr->sa_family);
+            }
+        }
+        print_message(msg_config, 
+                      "%s addr: %s. max_cnx: %d libwrap service: %s log_level: %d [%s] [%s] [%s] pp:%d\n",
+                      p->name, 
+                      buf,
+                      p->max_connections,
+                      p->service,
+                      p->log_level,
+                      p->keepalive ? "keepalive" : "",
+                      p->fork ? "fork" : "",
+                      p->transparent ? "transparent" : "",
+                      p->proxyprotocol_is_present ? p->proxyprotocol : -1
+                     );
     }
-    fprintf(stderr, "timeout: %d\non-timeout: %s\n", cfg.timeout,
-            timeout_protocol()->name);
+    print_message(msg_config, 
+                  "timeout: %d\n"
+                  "on-timeout: %s\n"
+                  "UDP hash size: %d\n", 
+                  cfg.timeout,
+                  timeout_protocol()->name,
+                  cfg.udp_max_connections);
 }
 
 
 static void setup_regex_probe(struct sslhcfg_protocols_item *p)
 #ifdef ENABLE_REGEX
 {
-    int num_patterns, i, error;
+    size_t num_patterns, i;
+    int error;
     pcre2_code** pattern_list;
     PCRE2_SIZE error_offset;
     PCRE2_UCHAR8 err_str[120];
@@ -103,11 +130,12 @@ static void setup_regex_probe(struct sslhcfg_protocols_item *p)
                                         &error, &error_offset, NULL);
         if (!pattern_list[i]) {
             pcre2_get_error_message(error, err_str, sizeof(err_str));
-            fprintf(stderr, "compiling pattern /%s/:%d:%s at offset %ld\n",
+            print_message(msg_config_error, "compiling pattern /%s/:%d:%s at offset %ld\n",
                     p->regex_patterns[i], error, err_str, error_offset);
             exit(1);
         }
     }
+    probe_regex_matches = pcre2_match_data_create(1, NULL);
 }
 #else
 {
@@ -115,6 +143,36 @@ static void setup_regex_probe(struct sslhcfg_protocols_item *p)
 }
 #endif
 
+/* Perform some fixups on configuration after reading it.
+ * if verbose is present, override all other verbose options
+ */
+void config_finish(struct sslhcfg_item* cfg)
+{
+    if (cfg->verbose) {
+        cfg->verbose_config = cfg->verbose;
+	cfg->verbose_config_error = cfg->verbose;
+	cfg->verbose_connections = cfg->verbose;
+	cfg->verbose_connections_try = cfg->verbose;
+	cfg->verbose_connections_error = cfg->verbose;
+	cfg->verbose_fd = cfg->verbose;
+	cfg->verbose_packets = cfg->verbose;
+	cfg->verbose_probe_info = cfg->verbose;
+	cfg->verbose_probe_error = cfg->verbose;
+	cfg->verbose_system_error = cfg->verbose;
+	cfg->verbose_int_error = cfg->verbose;
+    }
+}
+
+/* Checks that the UNIX socket specified exists and is accessible
+ * Dies otherwise
+ */
+static void check_access_unix_socket(struct sslhcfg_protocols_item* p)
+{
+    /* TODO */
+    return;
+}
+
+
 /* For each protocol in the configuration, resolve address and set up protocol
  * options if required
  */
@@ -123,14 +181,21 @@ static void config_protocols()
     int i;
     for (i = 0; i < cfg.protocols_len; i++) {
         struct sslhcfg_protocols_item* p = &(cfg.protocols[i]);
-        if (resolve_split_name(&(p->saddr), p->host, p->port)) {
-            fprintf(stderr, "cannot resolve %s:%s\n", p->host, p->port);
+
+        if (p->is_unix) {
+            check_access_unix_socket(p);
+        } else if (
+            !p->resolve_on_forward &&
+            resolve_split_name(&(p->saddr), p->host, p->port)
+        ) {
+            print_message(msg_config_error, "cannot resolve %s:%s\n",
+                          p->host, p->port);
             exit(4);
         }
 
         p->probe = get_probe(p->name);
         if (!p->probe) {
-            fprintf(stderr, "%s: probe unknown\n", p->name);
+            print_message(msg_config_error, "%s: probe unknown\n", p->name);
             exit(1);
         }
 
@@ -149,43 +214,89 @@ static void config_protocols()
                                   (const char**) cfg.protocols[i].alpn_protocols,
                                   cfg.protocols[i].alpn_protocols_len);
         }
+
+        p->timeouts.head = NULL;
+        p->timeouts.tail = NULL;
     }
 }
 
 
-void config_sanity_check(struct sslhcfg_item* cfg) {
-    if (!cfg->protocols_len) {
-        fprintf(stderr, "At least one target protocol must be specified.\n");
-        exit(2);
-    }
+void config_sanity_check(struct sslhcfg_item* cfg)
+{
+    size_t i;
 
 /* If compiling with systemd socket support no need to require listen address */
 #ifndef SYSTEMD
     if (!cfg->listen_len && !cfg->inetd) {
-        fprintf(stderr, "No listening address specified; use at least one -p option\n");
+        print_message(msg_config_error, "No listening address specified; use at least one -p option\n");
         exit(1);
     }
 #endif
+
+    for (i = 0; i < cfg->protocols_len; ++i) {
+        if (strcmp(cfg->protocols[i].name, "tls") != 0) {
+            if (cfg->protocols[i].sni_hostnames_len) {
+                print_message(msg_config_error, "name: \"%s\"; host: \"%s\"; port: \"%s\": "
+                              "Config option sni_hostnames is only applicable for tls\n",
+                              cfg->protocols[i].name, cfg->protocols[i].host, cfg->protocols[i].port);
+                exit(1);
+            }
+            if (cfg->protocols[i].alpn_protocols_len) {
+                print_message(msg_config_error, "name: \"%s\"; host: \"%s\"; port: \"%s\": "
+                              "Config option alpn_protocols is only applicable for tls\n",
+                              cfg->protocols[i].name, cfg->protocols[i].host, cfg->protocols[i].port);
+                exit(1);
+            }
+        }
+
+        if (cfg->protocols[i].is_udp) {
+            if (cfg->protocols[i].tfo_ok) {
+                print_message(msg_config_error, "name: \"%s\"; host: \"%s\"; port: \"%s\": "
+                              "Config option tfo_ok is not applicable for udp connections\n",
+                              cfg->protocols[i].name, cfg->protocols[i].host, cfg->protocols[i].port);
+                exit(1);
+            }
+        } else {
+            if (!strcmp(cfg->protocols[i].name, "wireguard")) {
+                print_message(msg_config_error, "Wireguard works only with UDP\n");
+                exit(1);
+            }
+        }
+    }
 }
 
+/* Connect stdin, stdout, stderr to /dev/null. It is better to keep them around
+ * so they do not get re-used by socket descriptors, and accidently used by
+ * some library code.
+ */
+void close_std(void)
+{
+    int newfd;
+
+    if ((newfd = open("/dev/null", O_RDWR))) {
+        dup2 (newfd, STDIN_FILENO);
+        dup2 (newfd, STDOUT_FILENO);
+        dup2 (newfd, STDERR_FILENO);
+        /* close the helper handle, as this is now unnecessary */
+        close(newfd);
+    } else {
+        print_message(msg_system_error, "Error closing standard filehandles for background daemon\n");
+    }
+}
 
 int main(int argc, char *argv[], char* envp[])
 {
-
-   extern char *optarg;
-   extern int optind;
    int res, num_addr_listen;
    struct listen_endpoint *listen_sockets;
 
-#ifdef LIBBSD
+#if HAVE_LIBBSD
    setproctitle_init(argc, argv, envp);
 #endif
 
    memset(&cfg, 0, sizeof(cfg));
    res = sslhcfg_cl_parse(argc, argv, &cfg);
    if (res) exit(6);
-   if (cfg.verbose > 3)
-       sslhcfg_fprint(stderr, &cfg, 0);
+   config_finish(&cfg);
 
    if (cfg.version) {
        printf("%s %s\n", server_type, VERSION);
@@ -197,25 +308,26 @@ int main(int argc, char *argv[], char* envp[])
 
    if (cfg.inetd)
    {
-       cfg.verbose = 0;
+       close(fileno(stderr)); /* Make sure no error will go to client */
+       tcp_init();
        start_shoveler(0);
        exit(0);
    }
 
-   if (cfg.verbose)
-       printsettings();
+   printsettings();
 
    num_addr_listen = start_listen_sockets(&listen_sockets);
 
 #ifdef SYSTEMD
    if (num_addr_listen < 1) {
-     fprintf(stderr, "No listening sockets found, restart sockets or specify addresses in config\n");
+     print_message(msg_config_error, "No listening sockets found, restart sockets or specify addresses in config\n");
      exit(1);
     }
 #endif
 
    if (!cfg.foreground) {
        if (fork() > 0) exit(0); /* Detach */
+       close_std();
 
        /* New session -- become group leader */
        if (getuid() == 0) {
@@ -232,13 +344,22 @@ int main(int argc, char *argv[], char* envp[])
    /* Open syslog connection before we drop privs/chroot */
    setup_syslog(argv[0]);
 
+   /* Open log file for writing */
+   setup_logfile();
+
    if (cfg.user || cfg.chroot)
        drop_privileges(cfg.user, cfg.chroot);
+   setup_landlock();
 
-   if (cfg.verbose)
-       printcaps();
+   printcaps();
+
+   print_message(msg_config, "%s %s started\n", server_type, VERSION);
 
    main_loop(listen_sockets, num_addr_listen);
 
+   close_logfile();
+
+   free(listen_sockets);
+
    return 0;
 }

sslh-select.c

@@ -25,483 +25,161 @@
  * https://daniel.haxx.se/docs/poll-vs-select.html suggests that over a few
  * hundred file descriptors, both become very slow, so there is little
  * incentive to move to poll() to support more than FD_SETSIZE (which is 1024
- * on many Linux. To support large numbers of descriptors, either use the fork
- * version, or we'll have to write a new version based on libev. */
+ * on many Linux. To support large numbers of descriptors efficiently, either use sslh-fork
+ * or sslh-ev. */
 
 #define __LINUX__
 
-#include <limits.h>
-
 #include "common.h"
 #include "probe.h"
+#include "tcp-listener.h"
 #include "udp-listener.h"
 #include "collection.h"
+#include "processes.h"
 #include "gap.h"
-
-static int debug = 0;
+#include "log.h"
 
 const char* server_type = "sslh-select";
 
-/* Global state for a select() loop */
-struct select_info {
-    int max_fd;   /* Highest fd number to pass to select() */
-
-    int num_probing;     /* Number of connections currently probing 
-                          * We use this to know if we need to time out of
-                          * select() */
-    gap_array* probing_list;  /* Pointers to cnx that are in probing mode */
-
+/* watcher type for a select() loop */
+struct watchers {
     fd_set fds_r, fds_w;  /* reference fd sets (used to init working copies) */
-    cnx_collection* collection; /* Collection of connections linked to this loop */
-
-    time_t next_timeout; /* time at which next UDP connection times out */
+    int max_fd;   /* Highest fd number to pass to select() */
 };
 
 
-
-static int tidy_connection(struct connection *cnx, struct select_info* fd_info)
+static void watchers_init(watchers** w, struct listen_endpoint* listen_sockets,
+                          int num_addr_listen)
 {
-    int i;
-    fd_set* fds = &fd_info->fds_r;
-    fd_set* fds2 = &fd_info->fds_w;
+    *w = malloc(sizeof(**w));
+    CHECK_ALLOC(*w, "malloc");
 
-    for (i = 0; i < 2; i++) {
-        if (cnx->q[i].fd != -1) {
-            if (cfg.verbose)
-                fprintf(stderr, "closing fd %d\n", cnx->q[i].fd);
+    memset(*w, 0, sizeof(**w));
+    FD_ZERO(&(*w)->fds_r);
+    FD_ZERO(&(*w)->fds_w);
 
-            FD_CLR(cnx->q[i].fd, fds);
-            FD_CLR(cnx->q[i].fd, fds2);
-            close(cnx->q[i].fd);
-            if (cnx->q[i].deferred_data)
-                free(cnx->q[i].deferred_data);
-        }
+    for (int i = 0; i < num_addr_listen; i++) {
+        watchers_add_read(*w, listen_sockets[i].socketfd);
+        set_nonblock(listen_sockets[i].socketfd);
     }
-    collection_remove_cnx(fd_info->collection, cnx);
-    return 0;
 }
 
+void watchers_add_read(watchers* w, int fd)
+{
+    FD_SET(fd, &w->fds_r); 
+    if (fd + 1 > w->max_fd)
+        w->max_fd = fd + 1;
+}
+
+void watchers_del_read(watchers* w, int fd)
+{
+    FD_CLR(fd, &w->fds_r);
+}
+
+void watchers_add_write(watchers* w, int fd)
+{
+    FD_SET(fd, &w->fds_w); 
+    if (fd > w->max_fd)
+        w->max_fd = fd + 1;
+}
+
+void watchers_del_write(watchers* w, int fd)
+{
+    FD_CLR(fd, &w->fds_w);
+}
+
+void watcher_sigchld(struct loop_info* fd_info, struct connection* cnx, pid_t pid)
+{
+    /* Nothing to do, watcher is processed in the event loop when select() is
+     * interrupted by the signal */
+}
+
+/* /end watchers */
+
+
+/* Enable all accept() watchers */
+static void start_accept_watchers(watchers* w, struct listen_endpoint* listen_sockets, int num_addr_listen)
+{
+    for (int i = 0; i < num_addr_listen; i++) {
+        watchers_add_read(w, listen_sockets[i].socketfd);
+    }
+}
+
+/* Disable all accept() watchers */
+static void stop_accept_watchers(watchers* w, struct listen_endpoint* listen_sockets, int num_addr_listen)
+{
+    for (int i = 0; i < num_addr_listen; i++) {
+        watchers_del_read(w, listen_sockets[i].socketfd);
+    }
+}
+
+static void temporary_stop_accept_watchers(
+                                    watchers* w,
+                                    struct listen_endpoint* listen_sockets,
+                                    int num_addr_listen)
+{
+    stop_accept_watchers(w, listen_sockets, num_addr_listen);
+    alarm(2);
+}
+
+/* Check if SIGCHLD was received, find which PID and reap appropriately */
+extern volatile sig_atomic_t received_sigchld;
+static void sigchld_process(struct loop_info* loop)
+{
+    int chld;
+    if (received_sigchld) {
+        received_sigchld = 0;
+        do {
+            chld = waitpid(-1, NULL, WNOHANG);
+            CHECK_RES_RETURN(chld, "waitpid", );
+            if (chld) {
+                decrease_forked_connection(loop, chld);
+            }
+        } while (chld);
+    }
+}
+
+volatile sig_atomic_t received_sigalrm;
+void sig_sigalrm(int sig)
+{
+    received_sigalrm = 1;
+}
+
+static void setup_sigalrm(void)
+{
+    int res;
+    struct sigaction action;
+
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = sig_sigalrm;
+    res = sigaction(SIGALRM, &action, NULL);
+    CHECK_RES_DIE(res, "sigaction");
+}
+
+
+static void sigalrm_process(watchers* w, struct listen_endpoint* listen_sockets, int num_addr_listen)
+{
+    if (received_sigalrm) {
+        received_sigalrm = 0;
+        start_accept_watchers(w, listen_sockets, num_addr_listen);
+    }
+}
+
+
 /* if fd becomes higher than FD_SETSIZE, things won't work so well with FD_SET
  * and FD_CLR. Need to drop connections if we go above that limit */
-static int fd_is_in_range(int fd) {
+static int fd_out_of_range(int fd) {
     if (fd >= FD_SETSIZE) {
-        log_message(LOG_ERR, "too many open file descriptor to monitor them all -- dropping connection\n");
-        return 0;
+        print_message(msg_system_error, "too many open file descriptor to monitor them all -- dropping connection\n");
+        return 1;
     }
-    return 1;
-}
-
-/* Accepts a connection from the main socket and assigns it to an empty slot.
- * If no slots are available, allocate another few. If that fails, drop the
- * connexion */
-static struct connection* accept_new_connection(int listen_socket, struct cnx_collection *collection)
-{
-    int in_socket, res;
-
-
-    if (cfg.verbose) fprintf(stderr, "accepting from %d\n", listen_socket);
-
-    in_socket = accept(listen_socket, 0, 0);
-    CHECK_RES_RETURN(in_socket, "accept", NULL);
-
-    if (!fd_is_in_range(in_socket)) {
-        close(in_socket);
-        return NULL;
-    }
-
-    res = set_nonblock(in_socket);
-    if (res == -1) {
-        close(in_socket);
-        return NULL;
-    }
-
-    struct connection* cnx = collection_alloc_cnx_from_fd(collection, in_socket);
-    if (!cnx) {
-        close(in_socket);
-        return NULL;
-    }
-
-    return cnx;
+    return 0;
 }
 
 
-/* Connect queue 1 of connection to SSL; returns new file descriptor */
-static int connect_queue(struct connection* cnx,
-                         struct select_info* fd_info)
-{
-    struct queue *q = &cnx->q[1];
-
-    q->fd = connect_addr(cnx, cnx->q[0].fd, NON_BLOCKING);
-    if ((q->fd != -1) && fd_is_in_range(q->fd)) {
-        log_connection(NULL, cnx);
-        flush_deferred(q);
-        if (q->deferred_data) {
-            FD_SET(q->fd, &fd_info->fds_w);
-            FD_CLR(cnx->q[0].fd, &fd_info->fds_r);
-        }
-        FD_SET(q->fd, &fd_info->fds_r);
-        collection_add_fd(fd_info->collection, cnx, q->fd);
-        return q->fd;
-    } else {
-        tidy_connection(cnx, fd_info);
-        return -1;
-    }
-}
-
-/* shovels data from active fd to the other
-   returns after one socket closed or operation would block
- */
-static void shovel(struct connection *cnx, int active_fd, struct select_info* fd_info)
-{
-    struct queue *read_q, *write_q;
-
-    read_q = &cnx->q[active_fd];
-    write_q = &cnx->q[1-active_fd];
-
-    if (cfg.verbose)
-        fprintf(stderr, "activity on fd%d\n", read_q->fd);
-
-    switch(fd2fd(write_q, read_q)) {
-    case -1:
-    case FD_CNXCLOSED:
-        tidy_connection(cnx, fd_info);
-        break;
-
-    case FD_STALLED:
-        FD_SET(write_q->fd, &fd_info->fds_w);
-        FD_CLR(read_q->fd, &fd_info->fds_r);
-        break;
-
-    default: /* Nothing */
-        break;
-    }
-}
-
-/* shovels data from one fd to the other and vice-versa
-   returns after one socket closed
- */
-static void shovel_single(struct connection *cnx)
-{
-   fd_set fds_r, fds_w;
-   int res, i;
-   int max_fd = MAX(cnx->q[0].fd, cnx->q[1].fd) + 1;
-
-   FD_ZERO(&fds_r);
-   FD_ZERO(&fds_w);
-   while (1) {
-      for (i = 0; i < 2; i++) {
-         if (cnx->q[i].deferred_data_size) {
-            FD_SET(cnx->q[i].fd, &fds_w);
-            FD_CLR(cnx->q[1-i].fd, &fds_r);
-         } else {
-            FD_CLR(cnx->q[i].fd, &fds_w);
-            FD_SET(cnx->q[1-i].fd, &fds_r);
-         }
-      }
-
-      res = select(
-                   max_fd,
-                   &fds_r,
-                   &fds_w,
-                   NULL,
-                   NULL
-                  );
-      CHECK_RES_DIE(res, "select");
-
-      for (i = 0; i < 2; i++) {
-          if (FD_ISSET(cnx->q[i].fd, &fds_w)) {
-              res = flush_deferred(&cnx->q[i]);
-              if ((res == -1) && ((errno == EPIPE) || (errno == ECONNRESET))) {
-                  if (cfg.verbose)
-                      fprintf(stderr, "%s socket closed\n", i ? "server" : "client");
-                  return;
-              }
-          }
-          if (FD_ISSET(cnx->q[i].fd, &fds_r)) {
-              res = fd2fd(&cnx->q[1-i], &cnx->q[i]);
-              if (!res) {
-                  if (cfg.verbose)
-                      fprintf(stderr, "socket closed\n");
-                  return;
-              }
-          }
-      }
-   }
-}
-
-/* Child process that makes internal connection and proxies
- */
-static void connect_proxy(struct connection *cnx)
-{
-    int in_socket;
-    int out_socket;
-
-    /* Minimize the file descriptor value to help select() */
-    in_socket = dup(cnx->q[0].fd);
-    if (in_socket == -1) {
-        in_socket = cnx->q[0].fd;
-    } else {
-        close(cnx->q[0].fd);
-        cnx->q[0].fd = in_socket;
-    }
-
-    /* Connect the target socket */
-    out_socket = connect_addr(cnx, in_socket, BLOCKING);
-    CHECK_RES_DIE(out_socket, "connect");
-
-    cnx->q[1].fd = out_socket;
-
-    log_connection(NULL, cnx);
-
-    shovel_single(cnx);
-
-    close(in_socket);
-    close(out_socket);
-
-    if (cfg.verbose)
-        fprintf(stderr, "connection closed down\n");
-
-    exit(0);
-}
-
-/* Removes cnx from probing list */
-static void remove_probing_cnx(struct select_info* fd_info, struct connection* cnx)
-{
-    gap_remove_ptr(fd_info->probing_list, cnx, fd_info->num_probing);
-    fd_info->num_probing--;
-}
-
-static void add_probing_cnx(struct select_info* fd_info, struct connection* cnx)
-{
-    gap_set(fd_info->probing_list, fd_info->num_probing, cnx);
-    fd_info->num_probing++;
-}
 
 
-/* Process read activity on a socket in probe state 
- * IN/OUT cnx: connection data, updated if connected
- * IN/OUT info: updated if connected
- * */
 
-static void probing_read_process(struct connection* cnx,
-                                 struct select_info* fd_info)
-{
-    int res;
-
-    /* If timed out it's SSH, otherwise the client sent
-     * data so probe the protocol */
-    if ((cnx->probe_timeout < time(NULL))) {
-        cnx->proto = timeout_protocol();
-        if (cfg.verbose) 
-            log_message(LOG_INFO, 
-                        "timed out, connect to %s\n", 
-                        cnx->proto->name);
-    } else {
-        res = probe_client_protocol(cnx);
-        if (res == PROBE_AGAIN)
-            return;
-    }
-
-    remove_probing_cnx(fd_info, cnx);
-    cnx->state = ST_SHOVELING;
-
-    /* libwrap check if required for this protocol */
-    if (cnx->proto->service &&
-        check_access_rights(cnx->q[0].fd, cnx->proto->service)) {
-        tidy_connection(cnx, fd_info);
-        res = -1;
-    } else if (cnx->proto->fork) {
-        switch (fork()) {
-        case 0:  /* child */
-            /* TODO: close all file descriptors except 2 */
-            /* free(cnx); */
-            connect_proxy(cnx);
-            exit(0);
-        case -1: log_message(LOG_ERR, "fork failed: err %d: %s\n", errno, strerror(errno));
-                 break;
-        default: /* parent */
-                 break;
-        }
-        tidy_connection(cnx, fd_info);
-        res = -1;
-    } else {
-        res = connect_queue(cnx, fd_info);
-    }
-
-    if (res >= fd_info->max_fd)
-        fd_info->max_fd = res + 1;;
-}
-
-
-/* Returns the queue index that contains the specified file descriptor */
-int active_queue(struct connection* cnx, int fd)
-{
-    if (cnx->q[0].fd == fd) return 0;
-    if (cnx->q[1].fd == fd) return 1;
-
-    log_message(LOG_ERR, "file descriptor %d not found in connection object\n", fd);
-    return -1;
-}
-
-/* Process a connection that is active in read */
-static void tcp_read_process(struct select_info* fd_info,
-                             int fd)
-{
-    if (debug) fprintf(stderr, "cnx_read_process fd %d\n", fd);
-
-    cnx_collection* collection = fd_info->collection;
-    struct connection* cnx = collection_get_cnx_from_fd(collection, fd);
-    /* Determine active queue (0 or 1): if fd is that of q[1], active_q = 1,
-     * otherwise it's 0 */
-    int active_q = active_queue(cnx, fd);
-
-    switch (cnx->state) {
-
-    case ST_PROBING:
-        if (active_q == 1) {
-            fprintf(stderr, "Activity on fd2 while probing, impossible\n");
-            dump_connection(cnx);
-            exit(1);
-        }
-
-        probing_read_process(cnx, fd_info);
-
-        break;
-
-    case ST_SHOVELING:
-        shovel(cnx, active_q, fd_info);
-        break;
-
-    default: /* illegal */
-        log_message(LOG_ERR, "Illegal connection state %d\n", cnx->state);
-        dump_connection(cnx);
-        exit(1);
-    }
-}
-
-static void cnx_read_process(struct select_info* fd_info, int fd)
-{
-    cnx_collection* collection = fd_info->collection;
-    struct connection* cnx = collection_get_cnx_from_fd(collection, fd);
-    switch (cnx->type)  {
-    case SOCK_STREAM:
-        tcp_read_process(fd_info, fd);
-        break;
-
-    case SOCK_DGRAM:
-        udp_s2c_forward(cnx);
-        break;
-
-    default:
-        log_message(LOG_ERR, "cnx_read_process: Illegal connection type %d\n", cnx->type);
-        dump_connection(cnx);
-        exit(1);
-    }
-
-}
-
-/* Process a connection that is active in write */
-static void cnx_write_process(struct select_info* fd_info, int fd)
-{
-    if (debug) fprintf(stderr, "cnx_write_process fd %d\n", fd);
-
-    struct connection* cnx = collection_get_cnx_from_fd(fd_info->collection, fd);
-    int res;
-    int queue = active_queue(cnx, fd);
-
-    res = flush_deferred(&cnx->q[queue]);
-    if ((res == -1) && ((errno == EPIPE) || (errno == ECONNRESET))) {
-        if (cnx->state == ST_PROBING) remove_probing_cnx(fd_info, cnx);
-        tidy_connection(cnx, fd_info);
-    } else {
-        /* If no deferred data is left, stop monitoring the fd 
-         * for write, and restart monitoring the other one for reads*/
-        if (!cnx->q[queue].deferred_data_size) {
-            FD_CLR(cnx->q[queue].fd, &fd_info->fds_w);
-            FD_SET(cnx->q[1-queue].fd, &fd_info->fds_r);
-        }
-    }
-}
-
-/* Process a connection that accepts a socket
- * (For UDP, this means all traffic coming from remote clients)
- * */
-void cnx_accept_process(struct select_info* fd_info, struct listen_endpoint* listen_socket)
-{
-    int fd = listen_socket->socketfd;
-    int type = listen_socket->type;
-    struct connection* cnx;
-    int new_fd;
-
-    if (debug) fprintf(stderr, "cnx_accept_process fd %d\n", fd);
-
-    switch (type) {
-    case SOCK_STREAM:
-        cnx = accept_new_connection(fd, fd_info->collection);
-
-        if (cnx) {
-            add_probing_cnx(fd_info, cnx);
-            new_fd = cnx->q[0].fd;
-        }
-        break;
-
-    case SOCK_DGRAM:
-        new_fd = udp_c2s_forward(fd, fd_info->collection, fd_info->max_fd);
-        fprintf(stderr, "new_fd %d\n", new_fd);
-        if (new_fd == -1)
-            return;
-        break;
-
-    default:
-        log_message(LOG_ERR, "Inconsistent cnx type: %d\n", type);
-        exit(1);
-        return;
-    }
-
-    FD_SET(new_fd, &fd_info->fds_r);
-    if (new_fd >= fd_info->max_fd)
-        fd_info->max_fd = new_fd + 1;
-
-}
-
-/* Check all connections to see if a UDP connections has timed out, then free
- * it. At the same time, keep track of the closest, next timeout. Only do the
- * search through connections if that timeout actually happened. If the
- * connection that would have timed out has had activity, it doesn't matter: we
- * go through connections to find the next timeout, which was needed anyway. */
-static void udp_timeouts(struct select_info* fd_info)
-{
-    time_t now = time(NULL);
-
-    if (now < fd_info->next_timeout) return;
-
-    time_t next_timeout = INT_MAX;
-
-    for (int i = 0; i < fd_info->max_fd; i++) {
-        /* if it's either in read or write set, there is a connection
-         * behind that file descriptor */
-        if (FD_ISSET(i, &fd_info->fds_r) || FD_ISSET(i, &fd_info->fds_w)) {
-            struct connection* cnx = collection_get_cnx_from_fd(fd_info->collection, i);
-            if (cnx) {
-                time_t timeout = udp_timeout(cnx);
-                if (!timeout) continue; /* Not a UDP connection */
-                if (cnx && (timeout <= now)) {
-                    if (cfg.verbose > 3)
-                        fprintf(stderr, "timed out UDP %d\n", cnx->target_sock);
-                    close(cnx->target_sock);
-                    FD_CLR(i, &fd_info->fds_r);
-                    FD_CLR(i, &fd_info->fds_w);
-                    collection_remove_cnx(fd_info->collection, cnx);
-                } else {
-                    if (timeout < next_timeout) next_timeout = timeout;
-                }
-            }
-        }
-    }
-
-    if (next_timeout != INT_MAX)
-        fd_info->next_timeout = next_timeout;
-}
 
 /* Main loop: the idea is as follow:
  * - fds_r and fds_w contain the file descriptors to monitor in read and write
@@ -519,57 +197,63 @@ static void udp_timeouts(struct select_info* fd_info)
  */
 void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
 {
-    struct select_info fd_info = {0};
+    struct loop_info fd_info;
     fd_set readfds, writefds; /* working read and write fd sets */
     struct timeval tv;
     int i, res;
 
-    fd_info.num_probing = 0; 
-    FD_ZERO(&fd_info.fds_r);
-    FD_ZERO(&fd_info.fds_w);
-    fd_info.probing_list = gap_init(0);
+    setup_sigalrm();
+    loop_init(&fd_info, num_addr_listen);
 
-    for (i = 0; i < num_addr_listen; i++) {
-        FD_SET(listen_sockets[i].socketfd, &fd_info.fds_r); 
-        set_nonblock(listen_sockets[i].socketfd);
-    }
-    fd_info.max_fd = listen_sockets[num_addr_listen-1].socketfd + 1;
+    watchers_init(&fd_info.watchers, listen_sockets, num_addr_listen);
 
-    fd_info.collection = collection_init(fd_info.max_fd);
+    fd_info.collection = collection_init(fd_info.watchers->max_fd);
 
     while (1)
     {
         memset(&tv, 0, sizeof(tv));
         tv.tv_sec = cfg.timeout;
 
-        memcpy(&readfds, &fd_info.fds_r, sizeof(readfds));
-        memcpy(&writefds, &fd_info.fds_w, sizeof(writefds));
+        memcpy(&readfds, &fd_info.watchers->fds_r, sizeof(readfds));
+        memcpy(&writefds, &fd_info.watchers->fds_w, sizeof(writefds));
 
-        if (cfg.verbose)
-            fprintf(stderr, "selecting... max_fd=%d num_probing=%d\n", 
-                                          fd_info.max_fd, fd_info.num_probing);
-        res = select(fd_info.max_fd, &readfds, &writefds, 
+        print_message(msg_fd, "selecting... max_fd=%d num_probing=%d\n",
+                                          fd_info.watchers->max_fd, fd_info.num_probing);
+        res = select(fd_info.watchers->max_fd, &readfds, &writefds,
                      NULL, fd_info.num_probing ? &tv : NULL);
         if (res < 0)
             perror("select");
 
-
-        /* UDP timeouts: clear out connections after some idle time */
-        udp_timeouts(&fd_info);
-
         /* Check main socket for new connections */
         for (i = 0; i < num_addr_listen; i++) {
             if (FD_ISSET(listen_sockets[i].socketfd, &readfds)) {
-                cnx_accept_process(&fd_info, &listen_sockets[i]);
-
                 /* don't also process it as a read socket */
                 FD_CLR(listen_sockets[i].socketfd, &readfds);
+
+                struct connection* new_cnx;
+                while ((new_cnx = cnx_accept_process(&fd_info, &listen_sockets[i]))) {
+                    if (fd_out_of_range(new_cnx->q[0].fd))
+                        tidy_connection(new_cnx, &fd_info);
+                }
+                /* if accept() returns with ENFILE, disable listen for a second */
+                switch (errno) {
+                case EMFILE:
+                case ENFILE:  /* Not sure ENFILE should be included here */
+                    temporary_stop_accept_watchers(fd_info.watchers, listen_sockets, num_addr_listen);
+                    break;
+
+                default: break;
+                }
+
             }
         }
 
         /* Check all sockets for write activity */
-        for (i = 0; i < fd_info.max_fd; i++) {
-            if (FD_ISSET(i, &writefds)) {
+        for (i = 0; i < fd_info.watchers->max_fd; i++) {
+            /* Check if it's active AND currently monitored (if a connection
+             * died, it gets tidied, which closes both sockets, but writefs does
+             * not know about that */
+            if (FD_ISSET(i, &writefds) && FD_ISSET(i, &fd_info.watchers->fds_w)) {
                 cnx_write_process(&fd_info, i);
             }
         }
@@ -578,38 +262,41 @@ void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
         for (i = 0; i < fd_info.num_probing; i++) {
             struct connection* cnx = gap_get(fd_info.probing_list, i);
             if (!cnx || cnx->state != ST_PROBING) {
-                log_message(LOG_ERR, "Inconsistent probing: cnx=%0xp\n", cnx);
+                print_message(msg_int_error, "Inconsistent probing: cnx=0x%p\n", cnx);
                 if (cnx)
-                    log_message(LOG_ERR, "Inconsistent probing: state=%d\n", cnx);
+                    print_message(msg_int_error, "Inconsistent probing: state=%d\n", cnx->state);
                 exit(1);
             }
             if (cnx->probe_timeout < time(NULL)) {
-                if (cfg.verbose)
-                    fprintf(stderr, "timeout slot %d\n", i);
+                print_message(msg_fd, "timeout slot %d\n", i);
                 probing_read_process(cnx, &fd_info);
             }
         }
 
         /* Check all sockets for read activity */
-        for (i = 0; i < fd_info.max_fd; i++) {
+        for (i = 0; i < fd_info.watchers->max_fd; i++) {
             /* Check if it's active AND currently monitored (if a connection
              * died, it gets tidied, which closes both sockets, but readfs does
              * not know about that */
-            if (FD_ISSET(i, &readfds) && FD_ISSET(i, &fd_info.fds_r)) {
+            if (FD_ISSET(i, &readfds) && FD_ISSET(i, &fd_info.watchers->fds_r)) {
                 cnx_read_process(&fd_info, i);
             }
         }
+
+        /* Process if signals occured */
+        sigchld_process(&fd_info);
+        sigalrm_process(fd_info.watchers, listen_sockets, num_addr_listen);
     }
 }
 
 
 void start_shoveler(int listen_socket) {
-    fprintf(stderr, "inetd mode is not supported in select mode\n");
+    print_message(msg_config_error, "inetd mode is not supported in select mode\n");
     exit(1);
 }
 
 
-/* The actual main is in common.c: it's the same for both version of
+/* The actual main is in sslh-main.c: it's the same for all versions of
  * the server
  */
 

sslh.pod

@@ -6,7 +6,7 @@
 
 =head1 SYNOPSIS
 
-sslh [B<-F>I<config file>] [B<-t> I<num>] [B<--transparent>] [B<-p> I<listening address> [B<-p> I<listening address> ...]  [B<--tls> I<target address for TLS>] [B<--ssh> I<target address for SSH>] [B<--openvpn> I<target address for OpenVPN>] [B<--http> I<target address for HTTP>] [B<--xmpp> I<target address for XMPP>] [B<--tinc> I<target address for TINC>] [B<--anyprot> I<default target address>] [B<--on-timeout> I<protocol name>] [B<-u> I<username>] [B<-C> I<chroot>] [B<-P> I<pidfile>] [-v] [-i] [-V] [-f] [-n]
+sslh [B<-F>I<config file>] [B<-t> I<num>] [B<--transparent>] [B<-p> I<listening address> [B<-p> I<listening address> ...]  [B<--tls> I<target address for TLS>] [B<--ssh> I<target address for SSH>] [B<--openvpn> I<target address for OpenVPN>] [B<--http> I<target address for HTTP>] [B<--xmpp> I<target address for XMPP>] [B<--tinc> I<target address for TINC>] [B<--anyprot> I<default target address>] [B<--on-timeout> I<protocol name>] [B<-u> I<username>] [B<-C> I<chroot>] [B<-P> I<pidfile>] [B<-v> I<n>] [-i] [-V] [-f] [-n]
 
 =head1 DESCRIPTION
 
@@ -14,7 +14,7 @@ B<sslh> accepts connections on specified ports, and forwards
 them further based on tests performed on the first data
 packet sent by the remote client.
 
-Probes for HTTP, SSL, SSH, OpenVPN, tinc, XMPP are
+Probes for HTTP, TLS, SSH, OpenVPN, tinc, XMPP are
 implemented, and any other protocol that can be tested using
 a regular expression, can be recognised. A typical use case
 is to allow serving several services on port 443 (e.g. to
@@ -102,8 +102,10 @@ clients wait for the server to send its banner.
 
 Makes B<sslh> behave as a transparent proxy, i.e. the
 receiving service sees the original client's IP address.
-This works on Linux only and involves B<iptables> settings.
-Refer to the README for more information.
+This works on Linux only and involves B<iproute2> settings.
+In some cases also B<iptables/nftables> settings are needed.
+Refer to the README or L<https://github.com/ftasnetamot/sslh/blob/2014-08-16--close-filehandles-with-detach/doc/simple_transparent_proxy.md>
+for more information.
 
 =item B<-p> I<listening address>, B<--listen> I<listening address>
 
@@ -123,10 +125,11 @@ Note that you can set B<sslh> to listen on I<ext_ip:443> and
 B<httpd> to listen on I<localhost:443>: this allows clients
 inside your network to just connect directly to B<httpd>.
 
-Also, B<sslh> probes for SSLv3 (or TLSv1) handshake and will
+Also, B<sslh> probes for TLS handshakes and will
 reject connections from clients requesting SSLv2. This is
-compliant with RFC6176 which prohibits the usage of SSLv2. If
-you wish to accept SSLv2, use B<--anyprot> instead.
+compliant with RFC6176 which prohibits the usage of SSLv2. 
+If you wish to accept SSLv2, use B<--anyprot> instead.
+
 
 =item B<--ssh> I<target address>
 
@@ -164,9 +167,10 @@ specified on the command line, this should be specified
 last. If no default is specified, B<sslh> will forward
 unknown protocols to the first protocol specified.
 
-=item B<-v>, B<--verbose>
+=item B<-v>, B<--verbose> I<n>
 
-Increase verboseness.
+Override all verboseness. Refer to B<example.cfg> for all
+verbose sub-options.
 
 =item B<-n>, B<--numeric>
 
@@ -233,8 +237,8 @@ detailed explanation of the variables used by B<sslh>.
 =head1 SEE ALSO
 
 The latest version is available from
-L<http://www.rutschle.net/tech/sslh>, and can be tracked
-from L<http://freecode.com/projects/sslh>.
+L<https://github.com/yrutschle/sslh>. There you can find a more
+detailed and recent documentation.
 
 =head1 AUTHOR