add SOCKS upstream proxy support (socks4/socks5)

original patch submitted in 2006 to debian mailing list:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=392848%29#12

this version was rebased to git and updated by Russ Dill <russ.dill@gmail.com>
in 2015 (the original patch used a different config file format).

as discussed in #40.

commit message by @rofl0r.

1 files changed, 90 insertions, 3 deletions

diff --git a/src/reqs.c b/src/reqs.c
index 990152a..a3d8162 100644
--- a/src/reqs.c
+++ b/src/reqs.c
@@ -61,9 +61,11 @@
 #ifdef UPSTREAM_SUPPORT
 #  define UPSTREAM_CONFIGURED() (config.upstream_list != NULL)
 #  define UPSTREAM_HOST(host) upstream_get(host, config.upstream_list)
+#  define UPSTREAM_IS_HTTP(conn) (conn->upstream_proxy != NULL && conn->upstream_proxy->type == HTTP_TYPE)
 #else
 #  define UPSTREAM_CONFIGURED() (0)
 #  define UPSTREAM_HOST(host) (NULL)
+#  define UPSTREAM_IS_HTTP(up) (0)
 #endif
 
 /*
@@ -853,10 +855,10 @@ process_client_headers (struct conn_s *connptr, hashmap_t hashofheaders)
         /*
          * Don't send headers if there's already an error, if the request was
          * a stats request, or if this was a CONNECT method (unless upstream
-         * proxy is in use.)
+         * http proxy is in use.)
          */
         if (connptr->server_fd == -1 || connptr->show_stats
-            || (connptr->connect_method && (connptr->upstream_proxy == NULL))) {
+            || (connptr->connect_method && ! UPSTREAM_IS_HTTP(connptr))) {
                 log_message (LOG_INFO,
                              "Not sending client headers to remote machine");
                 return 0;
@@ -1265,6 +1267,88 @@ static void relay_connection (struct conn_s *connptr)
         return;
 }
 
+static int
+connect_to_upstream_proxy(struct conn_s *connptr, struct request_s *request)
+{
+	int len;
+	char buff[512]; /* won't use more than 7 + 255 */
+	unsigned short port;
+	struct hostent *host;
+	struct upstream *cur_upstream = connptr->upstream_proxy;
+
+	log_message(LOG_CONN,
+		    "Established connection to %s proxy \"%s\" using file descriptor %d.",
+		    proxy_type_name(cur_upstream->type), cur_upstream->host, connptr->server_fd);
+
+	if (cur_upstream->type == SOCKS4_TYPE) {
+
+		buff[0] = 4; /* socks version */
+		buff[1] = 1; /* connect command */
+		port = htons(request->port);
+		memcpy(&buff[2], &port, 2); /* dest port */
+		host = gethostbyname(request->host);
+		memcpy(&buff[4], host->h_addr_list[0], 4); /* dest ip */
+		buff[8] = 0; /* user */
+		if (9 != safe_write(connptr->server_fd, buff, 9))
+			return -1;
+		if (8 != safe_read(connptr->server_fd, buff, 8))
+			return -1;
+		if (buff[0]!=0 || buff[1]!=90)
+			return -1;
+
+	} else if (cur_upstream->type == SOCKS5_TYPE) {
+
+		/* init */
+		buff[0] = 5; /* socks version */
+		buff[1] = 1; /* number of methods  */
+		buff[2] = 0; /* no auth method */
+		if (3 != safe_write(connptr->server_fd, buff, 3))
+			return -1;
+		if (2 != safe_read(connptr->server_fd, buff, 2))
+			return -1;
+		if (buff[0]!=5 || buff[1]!=0)
+			return -1;
+		/* connect */
+		buff[0] = 5; /* socks version */
+		buff[1] = 1; /* connect */
+		buff[2] = 0; /* reserved */
+		buff[3] = 3; /* domainname */
+		len=strlen(request->host);
+		if(len>255)
+			return -1;
+		buff[4] = len; /* length of domainname */
+		memcpy(&buff[5], request->host, len); /* dest ip */
+		port = htons(request->port);
+		memcpy(&buff[5+len], &port, 2); /* dest port */
+		if (7+len != safe_write(connptr->server_fd, buff, 7+len))
+			return -1;
+		if (4 != safe_read(connptr->server_fd, buff, 4))
+			return -1;
+		if (buff[0]!=5 || buff[1]!=0)
+			return -1;
+		switch(buff[3]) {
+			case 1: len=4; break; /* ip v4 */
+			case 4: len=16; break; /* ip v6 */
+			case 3: /* domainname */
+				if (1 != safe_read(connptr->server_fd, buff, 1))
+					return -1;
+				len = buff[0]; /* max = 255 */
+				break;
+			default: return -1;
+		}
+		if (2+len != safe_read(connptr->server_fd, buff, 2+len))
+			return -1;
+	} else {
+		return -1;
+	}
+
+	if (connptr->connect_method)
+		return 0;
+
+	return establish_http_connection(connptr, request);
+}
+
+
 /*
  * Establish a connection to the upstream proxy server.
  */
@@ -1308,6 +1392,9 @@ connect_to_upstream (struct conn_s *connptr, struct request_s *request)
                 return -1;
         }
 
+	if (cur_upstream->type != HTTP_TYPE)
+		return connect_to_upstream_proxy(connptr, request);
+
         log_message (LOG_CONN,
                      "Established connection to upstream proxy \"%s\" "
                      "using file descriptor %d.",
@@ -1527,7 +1614,7 @@ void handle_connection (int fd)
                 goto fail;
         }
 
-        if (!(connptr->connect_method && (connptr->upstream_proxy == NULL))) {
+        if (!connptr->connect_method || UPSTREAM_IS_HTTP(connptr)) {
                 if (process_server_headers (connptr) < 0) {
                         update_stats (STAT_BADCONN);
                         goto fail;