From: Guus Sliepen <guus@tinc-vpn.org>
Date: Fri, 6 Nov 2015 07:48:35 +0000 (+0100)
Subject: Add ability to use proxies to connect to hostnames when there is no nameserver.
X-Git-Tag: release-1.0.27~25
X-Git-Url: https://git.tinc-vpn.org/git/browse?a=commitdiff_plain;h=776dbf88df1911ec379c2fece0089fd2f5c71021;p=tinc

Add ability to use proxies to connect to hostnames when there is no nameserver.

This adds support for SOCKS4a, and enhances the support for SOCKS5 and
HTTP.
---

diff --git a/src/Makefile.am b/src/Makefile.am
index 937800d3..ebd52abc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -40,6 +40,7 @@ tincd_SOURCES = \
 	protocol_misc.c \
 	protocol_key.c \
 	protocol_subnet.c \
+	proxy.c proxy.h \
 	raw_socket_device.c \
 	route.c route.h \
 	subnet.c subnet.h \
diff --git a/src/meta.c b/src/meta.c
index e62c3b7d..daa55e40 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -30,6 +30,7 @@
 #include "meta.h"
 #include "net.h"
 #include "protocol.h"
+#include "proxy.h"
 #include "utils.h"
 #include "xalloc.h"
 
@@ -160,6 +161,17 @@ bool receive_meta(connection_t *c) {
 	c->buflen += lenin;
 
 	while(lenin > 0) {
+		reqlen = 0;
+
+		/* Is it proxy metadata? */
+
+		if(c->allow_request == PROXY) {
+			reqlen = receive_proxy_meta(c, oldlen, lenin);
+			if(reqlen < 0)
+				return false;
+			goto consume;
+		}
+
 		/* Decrypt */
 
 		if(c->status.decryptin && !decrypted) {
@@ -177,74 +189,32 @@ bool receive_meta(connection_t *c) {
 
 		if(c->tcplen) {
 			if(c->tcplen <= c->buflen) {
-				if(!c->node) {
-					if(c->outgoing && proxytype == PROXY_SOCKS4 && c->allow_request == ID) {
-						if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
-							ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
-						} else {
-							logger(LOG_ERR, "Proxy request rejected");
-							return false;
-						}
-					} else if(c->outgoing && proxytype == PROXY_SOCKS5 && c->allow_request == ID) {
-						if(c->buffer[0] != 5) {
-							logger(LOG_ERR, "Invalid response from proxy server");
-							return false;
-						}
-						if(c->buffer[1] == (char)0xff) {
-							logger(LOG_ERR, "Proxy request rejected: unsuitable authentication method");
-							return false;
-						}
-						if(c->buffer[2] != 5) {
-							logger(LOG_ERR, "Invalid response from proxy server");
-							return false;
-						}
-						if(c->buffer[3] == 0) {
-							ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
-						} else {
-							logger(LOG_ERR, "Proxy request rejected");
-							return false;
-						}
-					} else {
-						logger(LOG_ERR, "c->tcplen set but c->node is NULL!");
-						abort();
-					}
-				} else {
-					if(c->allow_request == ALL) {
-						receive_tcppacket(c, c->buffer, c->tcplen);
-					} else {
-						logger(LOG_ERR, "Got unauthorized TCP packet from %s (%s)", c->name, c->hostname);
-						return false;
-					}
+				if(c->allow_request != ALL) {
+					logger(LOG_ERR, "Got unauthorized TCP packet from %s (%s)", c->name, c->hostname);
+					return false;
 				}
 
-				c->buflen -= c->tcplen;
-				lenin -= c->tcplen - oldlen;
-				memmove(c->buffer, c->buffer + c->tcplen, c->buflen);
-				oldlen = 0;
+				receive_tcppacket(c, c->buffer, c->tcplen);
+				reqlen = c->tcplen;
 				c->tcplen = 0;
-				continue;
-			} else {
-				break;
 			}
-		}
-
-		/* Otherwise we are waiting for a request */
-
-		reqlen = 0;
+		} else {
+			/* Otherwise we are waiting for a request */
 
-		for(i = oldlen; i < c->buflen; i++) {
-			if(c->buffer[i] == '\n') {
-				c->buffer[i] = '\0';	/* replace end-of-line by end-of-string so we can use sscanf */
-				reqlen = i + 1;
-				break;
+			for(i = oldlen; i < c->buflen; i++) {
+				if(c->buffer[i] == '\n') {
+					c->buffer[i] = '\0';	/* replace end-of-line by end-of-string so we can use sscanf */
+					c->reqlen = reqlen = i + 1;
+					break;
+				}
 			}
-		}
 
-		if(reqlen) {
-			c->reqlen = reqlen;
-			if(!receive_request(c))
+			if(reqlen && !receive_request(c))
 				return false;
+		}
 
+consume:
+		if(reqlen) {
 			c->buflen -= reqlen;
 			lenin -= reqlen - oldlen;
 			memmove(c->buffer, c->buffer + reqlen, c->buflen);
diff --git a/src/net.h b/src/net.h
index 0982020f..8de3a2c4 100644
--- a/src/net.h
+++ b/src/net.h
@@ -123,20 +123,6 @@ extern time_t now;
 extern int contradicting_add_edge;
 extern int contradicting_del_edge;
 
-extern char *proxyhost;
-extern char *proxyport;
-extern char *proxyuser;
-extern char *proxypass;
-typedef enum proxytype_t {
-	PROXY_NONE = 0,
-	PROXY_SOCKS4,
-	PROXY_SOCKS4A,
-	PROXY_SOCKS5,
-	PROXY_HTTP,
-	PROXY_EXEC,
-} proxytype_t;
-extern proxytype_t proxytype;
-
 extern volatile bool running;
 
 /* Yes, very strange placement indeed, but otherwise the typedefs get all tangled up */
diff --git a/src/net_setup.c b/src/net_setup.c
index 863616b7..50d5680a 100644
--- a/src/net_setup.c
+++ b/src/net_setup.c
@@ -39,6 +39,7 @@
 #include "netutl.h"
 #include "process.h"
 #include "protocol.h"
+#include "proxy.h"
 #include "route.h"
 #include "subnet.h"
 #include "utils.h"
@@ -47,12 +48,6 @@
 char *myport;
 devops_t devops;
 
-char *proxyhost;
-char *proxyport;
-char *proxyuser;
-char *proxypass;
-proxytype_t proxytype;
-
 bool read_rsa_public_key(connection_t *c) {
 	FILE *fp;
 	char *pubname;
diff --git a/src/net_socket.c b/src/net_socket.c
index c167c2f3..e63da754 100644
--- a/src/net_socket.c
+++ b/src/net_socket.c
@@ -31,6 +31,7 @@
 #include "net.h"
 #include "netutl.h"
 #include "protocol.h"
+#include "proxy.h"
 #include "utils.h"
 #include "xalloc.h"
 
@@ -354,8 +355,19 @@ static void do_outgoing_pipe(connection_t *c, char *command) {
 #endif
 }
 
+static bool is_valid_host_port(const char *host, const char *port) {
+	for(const char *p = host; *p; p++)
+		if(!isalnum(*p) && *p != '-' && *p != '.')
+			return false;
+
+	for(const char *p = port; *p; p++)
+		if(!isalnum(*p))
+			return false;
+
+	return true;
+}
+
 void do_outgoing_connection(connection_t *c) {
-	char *address, *port, *space;
 	struct addrinfo *proxyai = NULL;
 	int result;
 
@@ -375,6 +387,8 @@ begin:
 			return;
 		}
 
+		char *address, *port, *space;
+
 		get_config_string(c->outgoing->cfg, &address);
 
 		space = strchr(address, ' ');
@@ -387,11 +401,23 @@ begin:
 		}
 
 		c->outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
-		free(address);
-		free(port);
+
+		// If we cannot resolve the address, maybe we are using a proxy that can?
+		if(!c->outgoing->ai && proxytype != PROXY_NONE && is_valid_host_port(address, port)) {
+			memset(&c->address, 0, sizeof c->address);
+			c->address.sa.sa_family = AF_UNKNOWN;
+			c->address.unknown.address = address;
+			c->address.unknown.port = port;
+		} else {
+			free(address);
+			free(port);
+		}
 
 		c->outgoing->aip = c->outgoing->ai;
 		c->outgoing->cfg = lookup_config_next(c->config_tree, c->outgoing->cfg);
+
+		if(!c->outgoing->ai && proxytype != PROXY_NONE)
+			goto connect;
 	}
 
 	if(!c->outgoing->aip) {
@@ -404,6 +430,7 @@ begin:
 	memcpy(&c->address, c->outgoing->aip->ai_addr, c->outgoing->aip->ai_addrlen);
 	c->outgoing->aip = c->outgoing->aip->ai_next;
 
+connect:
 	if(c->hostname)
 		free(c->hostname);
 
diff --git a/src/netutl.c b/src/netutl.c
index 275c64f7..2abbe86d 100644
--- a/src/netutl.c
+++ b/src/netutl.c
@@ -33,7 +33,7 @@ bool hostnames = false;
   Return NULL on failure.
 */
 struct addrinfo *str2addrinfo(const char *address, const char *service, int socktype) {
-	struct addrinfo *ai, hint = {0};
+	struct addrinfo *ai = NULL, hint = {0};
 	int err;
 
 	hint.ai_family = addressfamily;
@@ -55,7 +55,7 @@ struct addrinfo *str2addrinfo(const char *address, const char *service, int sock
 }
 
 sockaddr_t str2sockaddr(const char *address, const char *port) {
-	struct addrinfo *ai, hint = {0};
+	struct addrinfo *ai = NULL, hint = {0};
 	sockaddr_t result;
 	int err;
 
diff --git a/src/protocol.c b/src/protocol.c
index b385fbc3..5d5518fd 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -125,20 +125,6 @@ void forward_request(connection_t *from) {
 bool receive_request(connection_t *c) {
 	int request;
 
-	if(c->outgoing && proxytype == PROXY_HTTP && c->allow_request == ID) {
-		if(!c->buffer[0] || c->buffer[0] == '\r')
-			return true;
-		if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
-			if(!strncmp(c->buffer + 9, "200", 3)) {
-				logger(LOG_DEBUG, "Proxy request granted");
-				return true;
-			} else {
-				logger(LOG_DEBUG, "Proxy request rejected: %s", c->buffer + 9);
-				return false;
-			}
-		}
-	}
-
 	if(sscanf(c->buffer, "%d", &request) == 1) {
 		if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 			ifdebug(META)
diff --git a/src/protocol.h b/src/protocol.h
index 6c46c726..54d03796 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -36,6 +36,7 @@
 /* Request numbers */
 
 typedef enum request_t {
+	PROXY = -2,
 	ALL = -1,					/* Guardian for allow_request */
 	ID = 0, METAKEY, CHALLENGE, CHAL_REPLY, ACK,
 	STATUS, ERROR, TERMREQ,
diff --git a/src/protocol_auth.c b/src/protocol_auth.c
index 971341f7..e54fe231 100644
--- a/src/protocol_auth.c
+++ b/src/protocol_auth.c
@@ -36,95 +36,10 @@
 #include "netutl.h"
 #include "node.h"
 #include "protocol.h"
+#include "proxy.h"
 #include "utils.h"
 #include "xalloc.h"
 
-static bool send_proxyrequest(connection_t *c) {
-	switch(proxytype) {
-		case PROXY_HTTP: {
-			char *host;
-			char *port;
-
-			sockaddr2str(&c->address, &host, &port);
-			send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
-			free(host);
-			free(port);
-			return true;
-		}
-		case PROXY_SOCKS4: {
-			if(c->address.sa.sa_family != AF_INET) {
-				logger(LOG_ERR, "Cannot connect to an IPv6 host through a SOCKS 4 proxy!");
-				return false;
-			}
-			char s4req[9 + (proxyuser ? strlen(proxyuser) : 0)];
-			s4req[0] = 4;
-			s4req[1] = 1;
-			memcpy(s4req + 2, &c->address.in.sin_port, 2);
-			memcpy(s4req + 4, &c->address.in.sin_addr, 4);
-			if(proxyuser)
-				strcpy(s4req + 8, proxyuser);
-			s4req[sizeof s4req - 1] = 0;
-			c->tcplen = 8;
-			return send_meta(c, s4req, sizeof s4req);
-		}
-		case PROXY_SOCKS5: {
-			int len = 3 + 6 + (c->address.sa.sa_family == AF_INET ? 4 : 16);
-			c->tcplen = 2;
-			if(proxypass)
-				len += 3 + strlen(proxyuser) + strlen(proxypass);
-			char s5req[len];
-			int i = 0;
-			s5req[i++] = 5;
-			s5req[i++] = 1;
-			if(proxypass) {
-				s5req[i++] = 2;
-				s5req[i++] = 1;
-				s5req[i++] = strlen(proxyuser);
-				strcpy(s5req + i, proxyuser);
-				i += strlen(proxyuser);
-				s5req[i++] = strlen(proxypass);
-				strcpy(s5req + i, proxypass);
-				i += strlen(proxypass);
-				c->tcplen += 2;
-			} else {
-				s5req[i++] = 0;
-			}
-			s5req[i++] = 5;
-			s5req[i++] = 1;
-			s5req[i++] = 0;
-			if(c->address.sa.sa_family == AF_INET) {
-				s5req[i++] = 1;
-				memcpy(s5req + i, &c->address.in.sin_addr, 4);
-				i += 4;
-				memcpy(s5req + i, &c->address.in.sin_port, 2);
-				i += 2;
-				c->tcplen += 10;
-			} else if(c->address.sa.sa_family == AF_INET6) {
-				s5req[i++] = 3;
-				memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
-				i += 16;
-				memcpy(s5req + i, &c->address.in6.sin6_port, 2);
-				i += 2;
-				c->tcplen += 22;
-			} else {
-				logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
-				return false;
-			}
-			if(i > len)
-				abort();
-			return send_meta(c, s5req, sizeof s5req);
-		}
-		case PROXY_SOCKS4A:
-			logger(LOG_ERR, "Proxy type not implemented yet");
-			return false;
-		case PROXY_EXEC:
-			return true;
-		default:
-			logger(LOG_ERR, "Unknown proxy type");
-			return false;
-	}
-}
-
 bool send_id(connection_t *c) {
 	if(proxytype && c->outgoing)
 		if(!send_proxyrequest(c))
diff --git a/src/proxy.c b/src/proxy.c
new file mode 100644
index 00000000..165d3f34
--- /dev/null
+++ b/src/proxy.c
@@ -0,0 +1,287 @@
+/*
+    proxy.c -- Proxy handling functions.
+    Copyright (C) 2015 Guus Sliepen <guus@tinc-vpn.org>
+
+    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.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "system.h"
+
+#include "connection.h"
+#include "logger.h"
+#include "meta.h"
+#include "netutl.h"
+#include "protocol.h"
+#include "proxy.h"
+#include "utils.h" //
+
+proxytype_t proxytype;
+char *proxyhost;
+char *proxyport;
+char *proxyuser;
+char *proxypass;
+
+static void update_address_ipv4(connection_t *c, void *address, void *port) {
+	sockaddrfree(&c->address);
+	memset(&c->address, 0, sizeof c->address);
+	c->address.sa.sa_family = AF_INET;
+	if(address)
+		memcpy(&c->address.in.sin_addr, address, sizeof(ipv4_t));
+	if(port)
+		memcpy(&c->address.in.sin_port, port, sizeof(uint16_t));
+	// OpenSSH -D returns all zero address, set it to 0.0.0.1 to prevent spamming ourselves.
+	if(!memcmp(&c->address.in.sin_addr, "\0\0\0\0", 4))
+		memcpy(&c->address.in.sin_addr, "\0\0\0\01", 4);
+}
+
+static void update_address_ipv6(connection_t *c, void *address, void *port) {
+	sockaddrfree(&c->address);
+	memset(&c->address, 0, sizeof c->address);
+	c->address.sa.sa_family = AF_INET6;
+	if(address)
+		memcpy(&c->address.in6.sin6_addr, address, sizeof(ipv6_t));
+	if(port)
+		memcpy(&c->address.in6.sin6_port, port, sizeof(uint16_t));
+	// OpenSSH -D returns all zero address, set it to 0100:: to prevent spamming ourselves.
+	if(!memcmp(&c->address.in6.sin6_addr, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16))
+		memcpy(&c->address.in6.sin6_addr, "\01\0\0\0\0\0\0\0", 8);
+}
+
+bool send_proxyrequest(connection_t *c) {
+	switch(proxytype) {
+	case PROXY_SOCKS4:
+		if(c->address.sa.sa_family != AF_INET) {
+			logger(LOG_ERR, "Can only connect to numeric IPv4 addresses through a SOCKS 4 proxy!");
+			return false;
+		}
+	case PROXY_SOCKS4A: {
+		if(c->address.sa.sa_family != AF_INET && c->address.sa.sa_family != AF_UNKNOWN) {
+			logger(LOG_ERR, "Can only connect to IPv4 addresses or hostnames through a SOCKS 4a proxy!");
+			return false;
+		}
+		int len = 9;
+		if(proxyuser)
+			len += strlen(proxyuser);
+		if(c->address.sa.sa_family == AF_UNKNOWN)
+			len += 1 + strlen(c->address.unknown.address);
+		char s4req[len];
+		s4req[0] = 4;
+		s4req[1] = 1;
+		if(c->address.sa.sa_family == AF_INET) {
+			memcpy(s4req + 2, &c->address.in.sin_port, 2);
+			memcpy(s4req + 4, &c->address.in.sin_addr, 4);
+		} else {
+			uint16_t port = htons(atoi(c->address.unknown.port));
+			memcpy(s4req + 2, &port, 2);
+			memcpy(s4req + 4, "\0\0\0\1", 4);
+			strcpy(s4req + (9 + (proxyuser ? strlen(proxyuser) : 0)), c->address.unknown.address);
+		}
+		if(proxyuser)
+			strcpy(s4req + 8, proxyuser);
+		else
+			s4req[8] = 0;
+		s4req[sizeof s4req - 1] = 0;
+		c->allow_request = PROXY;
+		return send_meta(c, s4req, sizeof s4req);
+	}
+
+	case PROXY_SOCKS5: {
+		int len = 3 + 6;
+		if(c->address.sa.sa_family == AF_INET) {
+			len += 4;
+		} else if(c->address.sa.sa_family == AF_INET6) {
+			len += 16;
+		} else if(c->address.sa.sa_family == AF_UNKNOWN) {
+			len += 1 + strlen(c->address.unknown.address);
+		} else {
+			logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
+			return false;
+		}
+		if(proxypass)
+			len += 3 + strlen(proxyuser) + strlen(proxypass);
+		char s5req[len];
+		int i = 0;
+		s5req[i++] = 5;
+		s5req[i++] = 1;
+		if(proxypass) {
+			s5req[i++] = 2;
+			s5req[i++] = 1;
+			s5req[i++] = strlen(proxyuser);
+			strcpy(s5req + i, proxyuser);
+			i += strlen(proxyuser);
+			s5req[i++] = strlen(proxypass);
+			strcpy(s5req + i, proxypass);
+			i += strlen(proxypass);
+		} else {
+			s5req[i++] = 0;
+		}
+		s5req[i++] = 5;
+		s5req[i++] = 1;
+		s5req[i++] = 0;
+		if(c->address.sa.sa_family == AF_INET) {
+			s5req[i++] = 1;
+			memcpy(s5req + i, &c->address.in.sin_addr, 4);
+			i += 4;
+			memcpy(s5req + i, &c->address.in.sin_port, 2);
+			i += 2;
+		} else if(c->address.sa.sa_family == AF_INET6) {
+			s5req[i++] = 4;
+			memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
+			i += 16;
+			memcpy(s5req + i, &c->address.in6.sin6_port, 2);
+			i += 2;
+		} else if(c->address.sa.sa_family == AF_UNKNOWN) {
+			s5req[i++] = 3;
+			int len = strlen(c->address.unknown.address);
+			s5req[i++] = len;
+			memcpy(s5req + i, c->address.unknown.address, len);
+			i += len;
+			uint16_t port = htons(atoi(c->address.unknown.port));
+			memcpy(s5req + i, &port, 2);
+			i += 2;
+		} else {
+			logger(LOG_ERR, "Unknown address family while trying to connect to SOCKS5 proxy");
+			return false;
+		}
+		if(i > len)
+			abort();
+		c->allow_request = PROXY;
+		return send_meta(c, s5req, sizeof s5req);
+	}
+
+	case PROXY_HTTP: {
+		char *host;
+		char *port;
+
+		sockaddr2str(&c->address, &host, &port);
+		send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
+		free(host);
+		free(port);
+		c->allow_request = PROXY;
+		return true;
+	}
+
+	case PROXY_EXEC:
+		return true;
+
+	default:
+		logger(LOG_ERR, "Unknown proxy type");
+		return false;
+	}
+}
+
+int receive_proxy_meta(connection_t *c, int start, int lenin) {
+	switch(proxytype) {
+	case PROXY_SOCKS4:
+	case PROXY_SOCKS4A:
+		if(c->buflen < 8)
+			return 0;
+		if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
+			if(c->address.sa.sa_family == AF_UNKNOWN)
+				update_address_ipv4(c, c->buffer + 4, c->buffer + 2);
+
+			ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
+			c->allow_request = ID;
+			return 8;
+		} else {
+			logger(LOG_ERR, "Proxy request rejected");
+			return -1;
+		}
+
+	case PROXY_SOCKS5:
+		if(c->buflen < 2)
+			return 0;
+		if(c->buffer[0] != 0x05 || c->buffer[1] == 0xff) {
+			logger(LOG_ERR, "Proxy authentication method rejected");
+			return -1;
+		}
+		int offset = 2;
+		if(c->buffer[1] == 0x02) {
+			if(c->buflen < 4)
+				return 0;
+			if(c->buffer[2] != 0x05 || c->buffer[3] != 0x00) {
+				logger(LOG_ERR, "Proxy username/password rejected");
+				return -1;
+			}
+			offset += 2;
+		}
+		if(c->buflen - offset < 7)
+			return 0;
+		if(c->buffer[offset] != 0x05  || c->buffer[offset + 1] != 0x00) {
+			logger(LOG_ERR, "Proxy request rejected");
+			return -1;
+		}
+		int replen = offset + 6;
+		switch(c->buffer[offset + 3]) {
+			case 0x01: // IPv4
+				if(c->address.sa.sa_family == AF_UNKNOWN)
+					update_address_ipv4(c, c->buffer + offset + 4, c->buffer + offset + 8);
+				replen += 4;
+				break;
+			case 0x03: // Hostname
+				if(c->address.sa.sa_family == AF_UNKNOWN)
+					update_address_ipv4(c, "\0\0\0\1", "\0\0");
+				replen += ((uint8_t *)c->buffer)[offset + 4];
+				break;
+			case 0x04: // IPv6
+				if(c->address.sa.sa_family == AF_UNKNOWN)
+					update_address_ipv6(c, c->buffer + offset + 4, c->buffer + offset + 20);
+				replen += 16;
+				break;
+			default:
+				logger(LOG_ERR, "Proxy reply malformed");
+				return -1;
+		}
+		if(c->buflen < replen) {
+			return 0;
+		} else {
+			ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
+			c->allow_request = ID;
+			return replen;
+		}
+
+	case PROXY_HTTP: {
+		char *p = memchr(c->buffer, '\n', c->buflen);
+		if(!p || p - c->buffer >= c->buflen)
+			return 0;
+		p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer));
+		if(!p)
+			return 0;
+
+		if(c->buflen < 9)
+			return 0;
+
+		if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
+			if(!strncmp(c->buffer + 9, "200", 3)) {
+				if(c->address.sa.sa_family == AF_UNKNOWN)
+					update_address_ipv4(c, "\0\0\0\1", "\0\0");
+				logger(LOG_DEBUG, "Proxy request granted");
+				replen = p  + 1 - c->buffer;
+				c->allow_request = ID;
+				return replen;
+			} else {
+				logger(LOG_ERR, "Proxy request rejected: %s", c->buffer + 9);
+				return false;
+			}
+		} else {
+			logger(LOG_ERR, "Proxy reply malformed");
+			return -1;
+		}
+	}
+
+	default:
+		abort();
+	}
+}
diff --git a/src/proxy.h b/src/proxy.h
new file mode 100644
index 00000000..a9829439
--- /dev/null
+++ b/src/proxy.h
@@ -0,0 +1,43 @@
+/*
+    proxy.h -- header for proxy.c
+    Copyright (C) 2015 Guus Sliepen <guus@tinc-vpn.org>
+
+    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.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef __TINC_PROXY_H__
+#define __TINC_PROXY_H__
+
+#include "connection.h"
+
+typedef enum proxytype_t {
+	PROXY_NONE = 0,
+	PROXY_SOCKS4,
+	PROXY_SOCKS4A,
+	PROXY_SOCKS5,
+	PROXY_HTTP,
+	PROXY_EXEC,
+} proxytype_t;
+
+extern proxytype_t proxytype;
+extern char *proxyhost;
+extern char *proxyport;
+extern char *proxyuser;
+extern char *proxypass;
+
+extern bool send_proxyrequest(struct connection_t *c);
+extern int receive_proxy_meta(struct connection_t *c, int start, int lenin);
+
+#endif