socks4a proxy support (like socks4 with remote DNS)

Fixes trac ticket 995 https://bugs.bitlbee.org/bitlbee/ticket/995

This is slightly pointless for the suggested use case (tor), since with
socks5 we already send a hostname instead of an IP address.

Either way, it was easy to implement, so I hope it helps.

6 files changed, 35 insertions, 7 deletions

diff --git a/conf.c b/conf.c
index 845731b2..ac02f1b1 100644
--- a/conf.c
+++ b/conf.c
@@ -294,6 +294,8 @@ static int conf_loadini(conf_t *conf, char *file)
 					proxytype = PROXY_SOCKS4;
 				} else if (url->proto == PROTO_SOCKS5) {
 					proxytype = PROXY_SOCKS5;
+				} else if (url->proto == PROTO_SOCKS4A) {
+					proxytype = PROXY_SOCKS4A;
 				}
 
 				g_free(url);
diff --git a/lib/proxy.c b/lib/proxy.c
index 4028f750..c4f75772 100644
--- a/lib/proxy.c
+++ b/lib/proxy.c
@@ -293,6 +293,7 @@ static gboolean s4_canwrite(gpointer data, gint source, b_input_condition cond)
 	struct PHB *phb = data;
 	socklen_t len;
 	int error = ETIMEDOUT;
+	gboolean is_socks4a = (proxytype == PROXY_SOCKS4A);
 
 	if (phb->inpa > 0) {
 		b_event_remove(phb->inpa);
@@ -303,8 +304,7 @@ static gboolean s4_canwrite(gpointer data, gint source, b_input_condition cond)
 	}
 	sock_make_blocking(source);
 
-	/* XXX does socks4 not support host name lookups by the proxy? */
-	if (!(hp = gethostbyname(phb->host))) {
+	if (!is_socks4a && !(hp = gethostbyname(phb->host))) {
 		return phb_close(phb);
 	}
 
@@ -312,15 +312,30 @@ static gboolean s4_canwrite(gpointer data, gint source, b_input_condition cond)
 	packet[1] = 1;
 	packet[2] = phb->port >> 8;
 	packet[3] = phb->port & 0xff;
-	packet[4] = (unsigned char) (hp->h_addr_list[0])[0];
-	packet[5] = (unsigned char) (hp->h_addr_list[0])[1];
-	packet[6] = (unsigned char) (hp->h_addr_list[0])[2];
-	packet[7] = (unsigned char) (hp->h_addr_list[0])[3];
+	if (is_socks4a) {
+		packet[4] = 0;
+		packet[5] = 0;
+		packet[6] = 0;
+		packet[7] = 1;
+	} else {
+		packet[4] = (unsigned char) (hp->h_addr_list[0])[0];
+		packet[5] = (unsigned char) (hp->h_addr_list[0])[1];
+		packet[6] = (unsigned char) (hp->h_addr_list[0])[2];
+		packet[7] = (unsigned char) (hp->h_addr_list[0])[3];
+	}
 	packet[8] = 0;
 	if (write(source, packet, 9) != 9) {
 		return phb_close(phb);
 	}
 
+	if (is_socks4a) {
+		size_t host_len = strlen(phb->host) + 1; /* include the \0 */
+
+		if (write(source, phb->host, host_len) != host_len) {
+			return phb_close(phb);
+		}
+	}
+
 	phb->inpa = b_input_add(source, B_EV_IO_READ, s4_canread, phb);
 
 	return FALSE;
@@ -505,7 +520,7 @@ int proxy_connect(const char *host, int port, b_event_handler func, gpointer dat
 		return proxy_connect_none(host, port, phb);
 	} else if (proxytype == PROXY_HTTP) {
 		return proxy_connect_http(host, port, phb);
-	} else if (proxytype == PROXY_SOCKS4) {
+	} else if (proxytype == PROXY_SOCKS4 || proxytype == PROXY_SOCKS4A) {
 		return proxy_connect_socks4(host, port, phb);
 	} else if (proxytype == PROXY_SOCKS5) {
 		return proxy_connect_socks5(host, port, phb);
diff --git a/lib/proxy.h b/lib/proxy.h
index 9688aaa6..eaf31375 100644
--- a/lib/proxy.h
+++ b/lib/proxy.h
@@ -39,6 +39,7 @@
 #define PROXY_HTTP 1
 #define PROXY_SOCKS4 2
 #define PROXY_SOCKS5 3
+#define PROXY_SOCKS4A 4
 
 extern char proxyhost[128];
 extern int proxyport;
diff --git a/lib/url.c b/lib/url.c
index 38515669..082e3586 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -47,6 +47,8 @@ int url_set(url_t *url, const char *set_url)
 			url->proto = PROTO_SOCKS4;
 		} else if (g_strncasecmp(set_url, "socks5", i - set_url) == 0) {
 			url->proto = PROTO_SOCKS5;
+		} else if (g_strncasecmp(set_url, "socks4a", i - set_url) == 0) {
+			url->proto = PROTO_SOCKS4A;
 		} else {
 			return 0;
 		}
diff --git a/lib/url.h b/lib/url.h
index 4caf13d7..66abcd03 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -29,6 +29,7 @@
 #define PROTO_HTTPS     5
 #define PROTO_SOCKS4    3
 #define PROTO_SOCKS5    4
+#define PROTO_SOCKS4A   5
 #define PROTO_DEFAULT   PROTO_HTTP
 
 typedef struct url {
diff --git a/protocols/purple/purple.c b/protocols/purple/purple.c
index b00d3078..a24b064a 100644
--- a/protocols/purple/purple.c
+++ b/protocols/purple/purple.c
@@ -121,6 +121,12 @@ static void purple_init(account_t *acc)
 
 		purple_blist_load();
 		purple_prefs_load();
+
+		if (proxytype == PROXY_SOCKS4A) {
+			/* do this here after loading prefs. yes, i know, it sucks */
+			purple_prefs_set_bool("/purple/proxy/socks4_remotedns", TRUE);
+		}
+
 		dir_fixed = TRUE;
 	}
 
@@ -1403,6 +1409,7 @@ void purple_initmodule()
 	if (proxytype != PROXY_NONE) {
 		PurpleProxyInfo *pi = purple_global_proxy_get_info();
 		switch (proxytype) {
+		case PROXY_SOCKS4A:
 		case PROXY_SOCKS4:
 			purple_proxy_info_set_type(pi, PURPLE_PROXY_SOCKS4);
 			break;