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forward server responses back to sender

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yrutschle 2020-12-04 16:31:52 +01:00
parent 1e33455fe7
commit a42d4f8049
1 changed files with 89 additions and 45 deletions
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134
sslh-fork.c
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@ -246,60 +246,104 @@ int get_empty_source(struct known_udp_source* ks, int ks_len)
/* Array to keep the UDP sources we have seen before */
struct known_udp_source udp_known_sources[MAX_UDP_SRC];
/* UDP listener: upon incoming packet, find where it should go */
void udp_listener(struct listen_endpoint* endpoint, int num_endpoints, int active_endpoint)
{
char data[65536]; /* TODO what's right, here? */
/* Process UDP coming from outside:
* If it's a new source, probe; otherwise, forward to previous target
* Returns: >= 0 sockfd of newly allocated socket, for new connections
* -1 otherwise
* */
int udp_extern_forward(int sockfd) {
char addr_str[NI_MAXHOST+1+NI_MAXSERV+1];
struct sockaddr src_addr;
struct addrinfo addrinfo;
struct known_udp_source* src;
ssize_t len;
socklen_t addrlen;
int i, res, target;
int res, target, out = -1;
char data[65536]; /* TODO what's right, here? */
fprintf(stderr, "recvfrom(%d)\n", getpid());
addrlen = sizeof(src_addr);
len = recvfrom(sockfd, data, sizeof(data), 0, &src_addr, &addrlen);
if (len < 0) {
perror("recvfrom");
return -1;
}
target = known_source(udp_known_sources, ARRAY_SIZE(udp_known_sources),
&src_addr, addrlen);
addrinfo.ai_addr = &src_addr;
addrinfo.ai_addrlen = addrlen;
if (cfg.verbose)
fprintf(stderr, "received %ld UDP from %d:%s\n", len, target, sprintaddr(addr_str, sizeof(addr_str), &addrinfo));
if (target == -1) {
target = get_empty_source(udp_known_sources, ARRAY_SIZE(udp_known_sources));
fprintf(stderr, "source target index %d\n", target);
if (target == -1) exit(0); /* TODO handle this properly */
/* A probe worked: save this as an active connection */
src = &udp_known_sources[target];
src->allocated = 1;
src->sockaddr = src_addr;
src->addrlen = addrlen;
/* TODO fill in time */
res = probe_buffer(data, len, &src->proto);
/* First version: if we can't work out the protocol from the first
* packet, drop it. Conceivably, we could store several packets to
* run probes on packet sets */
if (cfg.verbose) fprintf(stderr, "UDP probed: %d\n", res);
if (res != PROBE_MATCH) return -1;
src->target_sock = socket(src->proto->saddr->ai_family, SOCK_DGRAM, 0);
out = src->target_sock;
}
src = &udp_known_sources[target];
/* at this point src is the UDP connection */
res = sendto(src->target_sock, data, len, 0,
src->proto->saddr->ai_addr, src->proto->saddr->ai_addrlen);
fprintf(stderr, "sending %d to %s",
res, sprintaddr(data, sizeof(data), src->proto->saddr));
return out;
}
/* UDP listener: upon incoming packet, find where it should go */
void udp_listener(struct listen_endpoint* endpoint, int num_endpoints, int active_endpoint)
{
fd_set fds_r, fds_r_tmp;
char data[65536]; /* TODO what? */
int max_fd, res, sockfd, i;
struct known_udp_source* src;
FD_ZERO(&fds_r);
FD_SET(endpoint[active_endpoint].socketfd, &fds_r);
max_fd = endpoint[active_endpoint].socketfd + 1;
while (1) {
fprintf(stderr, "recvfrom(%d)\n", getpid());
addrlen = sizeof(src_addr);
len = recvfrom(endpoint[active_endpoint].socketfd, data, sizeof(data), 0, &src_addr, &addrlen);
if (len < 0) {
perror("recvfrom");
continue;
fds_r_tmp = fds_r;
res = select(max_fd + 1, &fds_r_tmp, NULL, NULL, NULL);
CHECK_RES_DIE(res, "select");
if (FD_ISSET(endpoint[active_endpoint].socketfd, &fds_r_tmp)) {
sockfd = udp_extern_forward(endpoint[active_endpoint].socketfd);
if (sockfd >= 0) {
FD_SET(sockfd, &fds_r);
max_fd = MAX(max_fd, sockfd);
}
} else {
for (i = 0; i < ARRAY_SIZE(udp_known_sources); i++) {
src = &udp_known_sources[i];
sockfd = src->target_sock;
if (FD_ISSET(sockfd, &fds_r_tmp)) {
res = recvfrom(sockfd, data, sizeof(data), 0, NULL, NULL);
fprintf(stderr, "recvfrom %d\n", res);
CHECK_RES_DIE(res, "udp_listener/recvfrom");
res = sendto(endpoint[active_endpoint].socketfd, data, res, 0,
&src->sockaddr, src->addrlen);
fprintf(stderr, "sendto %d to\n", res);
}
}
}
target = known_source(udp_known_sources, ARRAY_SIZE(udp_known_sources),
&src_addr, addrlen);
addrinfo.ai_addr = &src_addr;
addrinfo.ai_addrlen = addrlen;
if (cfg.verbose)
fprintf(stderr, "received %d UDP from %d:%s\n", len, target, sprintaddr(addr_str, sizeof(addr_str), &addrinfo));
if (target == -1) {
target = get_empty_source(udp_known_sources, ARRAY_SIZE(udp_known_sources));
fprintf(stderr, "source target index %d\n", target);
if (target == -1) exit(0); /* TODO handle this properly */
/* A probe worked: save this as an active connection */
src = &udp_known_sources[target];
src->allocated = 1;
src->sockaddr = src_addr;
src->addrlen = addrlen;
/* TODO fill in time */
res = probe_buffer(data, len, &src->proto);
/* First version: if we can't work out the protocol from the first
* packet, drop it. Conceivably, we could store several packets to
* run probes on packet sets */
if (cfg.verbose) fprintf(stderr, "UDP probed: %d\n", res);
if (res != PROBE_MATCH) continue;
src->target_sock = socket(src->proto->saddr->ai_family, SOCK_DGRAM, 0);
}
src = &udp_known_sources[target];
/* at this point src is the UDP connection */
res = sendto(src->target_sock, data, len, 0,
src->proto->saddr->ai_addr, src->proto->saddr->ai_addrlen);
fprintf(stderr, "sending %d to %s",
res, sprintaddr(data, sizeof(data), src->proto->saddr));
}
}