use a key loader function to move file reading out of auth

auth.go

@@ -1,14 +1,12 @@
 package sshchat
 
 import (
-	"bufio"
 	"crypto/sha256"
 	"crypto/subtle"
 	"encoding/csv"
 	"errors"
 	"fmt"
 	"net"
-	"os"
 	"strings"
 	"sync"
 	"time"
@@ -18,6 +16,10 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+// KeyLoader loads public keys, e.g. from an authorized_keys file.
+// It must return a nil slice on error.
+type KeyLoader func() ([]ssh.PublicKey, error)
+
 // ErrNotAllowlisted Is the error returned when a key is checked that is not allowlisted,
 // when allowlisting is enabled.
 var ErrNotAllowlisted = errors.New("not allowlisted")
@@ -53,16 +55,17 @@ func newAuthAddr(addr net.Addr) string {
 // Auth stores lookups for bans, allowlists, and ops. It implements the sshd.Auth interface.
 // If the contained passphrase is not empty, it complements a allowlist.
 type Auth struct {
-	passphraseHash  []byte
-	allowlistModeMu sync.RWMutex
+	passphraseHash []byte
+	bannedAddr     *set.Set
+	bannedClient   *set.Set
+	banned         *set.Set
+	allowlist      *set.Set
+	ops            *set.Set
+
+	settingsMu      sync.RWMutex
 	allowlistMode   bool
-	bannedAddr      *set.Set
-	bannedClient    *set.Set
-	banned          *set.Set
-	allowlist       *set.Set
-	ops             *set.Set
-	opFile          string
-	allowlistFile   string
+	opLoader        KeyLoader
+	allowlistLoader KeyLoader
 }
 
 // NewAuth creates a new empty Auth.
@@ -77,14 +80,14 @@ func NewAuth() *Auth {
 }
 
 func (a *Auth) AllowlistMode() bool {
-	a.allowlistModeMu.RLock()
-	defer a.allowlistModeMu.RUnlock()
+	a.settingsMu.RLock()
+	defer a.settingsMu.RUnlock()
 	return a.allowlistMode
 }
 
 func (a *Auth) SetAllowlistMode(value bool) {
-	a.allowlistModeMu.Lock()
-	defer a.allowlistModeMu.Unlock()
+	a.settingsMu.Lock()
+	defer a.settingsMu.Unlock()
 	a.allowlistMode = value
 }
 
@@ -174,10 +177,19 @@ func (a *Auth) IsOp(key ssh.PublicKey) bool {
 	return a.ops.In(authkey)
 }
 
-// LoadOpsFromFile reads a file in authorized_keys format and makes public keys operators
-func (a *Auth) LoadOpsFromFile(path string) error {
-	a.opFile = path
-	return fromFile(path, func(key ssh.PublicKey) { a.Op(key, 0) })
+// LoadOps sets the public keys form loader to operators and saves the loader for later use
+func (a *Auth) LoadOps(loader KeyLoader) error {
+	a.settingsMu.Lock()
+	a.opLoader = loader
+	a.settingsMu.Unlock()
+	return a.ReloadOps()
+}
+
+// ReloadOps sets the public keys from a loader saved in the last call to operators
+func (a *Auth) ReloadOps() error {
+	a.settingsMu.RLock()
+	defer a.settingsMu.RUnlock()
+	return addFromLoader(a.opLoader, a.Op)
 }
 
 // Allowlist will set a public key as a allowlisted user.
@@ -199,10 +211,30 @@ func (a *Auth) Allowlist(key ssh.PublicKey, d time.Duration) {
 	}
 }
 
-// LoadAllowlistFromFile reads a file in authorized_keys format and allowlists public keys
-func (a *Auth) LoadAllowlistFromFile(path string) error {
-	a.allowlistFile = path
-	return fromFile(path, func(key ssh.PublicKey) { a.Allowlist(key, 0) })
+// LoadAllowlist adds the public keys from the loader to the allowlist and saves the loader for later use
+func (a *Auth) LoadAllowlist(loader KeyLoader) error {
+	a.settingsMu.Lock()
+	a.allowlistLoader = loader
+	a.settingsMu.Unlock()
+	return a.ReloadAllowlist()
+}
+
+//  LoadAllowlist adds the public keys from a loader saved in a previous call to the allowlist
+func (a *Auth) ReloadAllowlist() error {
+	a.settingsMu.RLock()
+	defer a.settingsMu.RUnlock()
+	return addFromLoader(a.allowlistLoader, a.Allowlist)
+}
+
+func addFromLoader(loader KeyLoader, adder func(ssh.PublicKey, time.Duration)) error {
+	if loader == nil {
+		return nil
+	}
+	keys, err := loader()
+	for _, key := range keys {
+		adder(key, 0)
+	}
+	return err
 }
 
 // Ban will set a public key as banned.
@@ -309,29 +341,3 @@ func (a *Auth) BanQuery(q string) error {
 
 	return nil
 }
-
-func fromFile(path string, handler func(ssh.PublicKey)) error {
-	if path == "" {
-		return nil
-	}
-
-	file, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		key, _, _, _, err := ssh.ParseAuthorizedKey(scanner.Bytes())
-		if err != nil {
-			if err.Error() == "ssh: no key found" {
-				// TODO: do we really want to always ignore this?
-				continue // Skip line
-			}
-			return err
-		}
-		handler(key)
-	}
-	return nil
-}

cmd/ssh-chat/cmd.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -12,6 +13,7 @@ import (
 	"github.com/alexcesaro/log"
 	"github.com/alexcesaro/log/golog"
 	flags "github.com/jessevdk/go-flags"
+	"golang.org/x/crypto/ssh"
 
 	sshchat "github.com/shazow/ssh-chat"
 	"github.com/shazow/ssh-chat/chat"
@@ -139,12 +141,12 @@ func main() {
 		auth.SetPassphrase(options.Passphrase)
 	}
 
-	err = auth.LoadOpsFromFile(options.Admin)
+	err = auth.LoadOps(loaderFromFile(options.Admin, logger))
 	if err != nil {
 		fail(5, "Failed to load admins: %v\n", err)
 	}
 
-	err = auth.LoadAllowlistFromFile(options.Allowlist)
+	err = auth.LoadAllowlist(loaderFromFile(options.Allowlist, logger))
 	if err != nil {
 		fail(6, "Failed to load allowlist: %v\n", err)
 	}
@@ -188,3 +190,33 @@ func main() {
 	<-sig // Wait for ^C signal
 	fmt.Fprintln(os.Stderr, "Interrupt signal detected, shutting down.")
 }
+
+func loaderFromFile(path string, logger *golog.Logger) sshchat.KeyLoader {
+	if path == "" {
+		return nil
+	}
+	return func() ([]ssh.PublicKey, error) {
+		file, err := os.Open(path)
+		if err != nil {
+			return nil, err
+		}
+		defer file.Close()
+
+		var keys []ssh.PublicKey
+		scanner := bufio.NewScanner(file)
+		for scanner.Scan() {
+			key, _, _, _, err := ssh.ParseAuthorizedKey(scanner.Bytes())
+			if err != nil {
+				if err.Error() == "ssh: no key found" {
+					continue // Skip line
+				}
+				return nil, err
+			}
+			keys = append(keys, key)
+		}
+		if keys == nil {
+			logger.Warning("file", path, "contained no keys")
+		}
+		return keys, nil
+	}
+}

host.go

@@ -798,7 +798,7 @@ func (h *Host) InitCommands(c *chat.Commands) {
 		if args[0] == "flush" {
 			h.auth.allowlist.Clear()
 		}
-		return h.auth.LoadAllowlistFromFile(h.auth.allowlistFile)
+		return h.auth.ReloadAllowlist()
 	}
 
 	allowlistReverify := func(room *chat.Room) []string {