[socks] try fix SOCKS5 upstream connection

Signed-off-by: R4SAS <r4sas@i2pmail.org>

libi2pd_client/SOCKS.cpp

@@ -30,6 +30,8 @@ namespace proxy
 	static const size_t SOCKS_FORWARDER_BUFFER_SIZE = 8192;
 
 	static const size_t SOCKS_UPSTREAM_SOCKS4A_REPLY_SIZE = 8;
+	static const size_t SOCKS_UPSTREAM_SOCKS5_INIT_REPLY_SIZE = 2;
+	static const size_t SOCKS_UPSTREAM_SOCKS5_CONNECT_REPLY_MIN_SIZE = 10;
 
 	struct SOCKSDnsAddress
 	{
@@ -127,7 +129,7 @@ namespace proxy
 			boost::asio::const_buffers_1 GenerateSOCKS5SelectAuth(authMethods method);
 			boost::asio::const_buffers_1 GenerateSOCKS4Response(errTypes error, uint32_t ip, uint16_t port);
 			boost::asio::const_buffers_1 GenerateSOCKS5Response(errTypes error, addrTypes type, const address &addr, uint16_t port);
-			boost::asio::const_buffers_1 GenerateUpstreamRequest();
+			boost::asio::const_buffers_1 GenerateUpstreamRequest(int version, bool initial);
 			bool Socks5ChooseAuth();
 			void SocksRequestFailed(errTypes error);
 			void SocksRequestSuccess();
@@ -139,7 +141,7 @@ namespace proxy
 
 			void SocksUpstreamSuccess();
 			void AsyncUpstreamSockRead();
-			void SendUpstreamRequest();
+			void SendUpstreamRequest(int version, bool initial);
 			void HandleUpstreamData(uint8_t * buff, std::size_t len);
 			void HandleUpstreamSockSend(const boost::system::error_code & ecode, std::size_t bytes_transfered);
 			void HandleUpstreamSockRecv(const boost::system::error_code & ecode, std::size_t bytes_transfered);
@@ -274,12 +276,27 @@ namespace proxy
 		return boost::asio::const_buffers_1(m_response, size);
 	}
 
-	boost::asio::const_buffers_1 SOCKSHandler::GenerateUpstreamRequest()
+	boost::asio::const_buffers_1 SOCKSHandler::GenerateUpstreamRequest(int version, bool initial)
 	{
 		size_t upstreamRequestSize = 0;
 		// TODO: negotiate with upstream
-		// SOCKS 4a
+		if (version == 5) // SOCKS5
-		m_upstream_request[0] = '\x04'; //version
+		{
+			if (initial)
+			{
+				m_upstream_request[0] = '\x05'; // VER
+				m_upstream_request[1] = 1;      // NAUTH
+				m_upstream_request[2] = 0;      // AUTH
+				upstreamRequestSize += 3;
+			}
+			else
+			{
+				return GenerateSOCKS5Response(SOCKS5_GEN_FAIL, m_addrtype, m_address, m_port); // dirty hack, SOCKS5_GEN_FAIL == 1, that's a "establish a TCP/IP stream connection" command
+			}
+		}
+		else if (version == 4) // SOCKS4a
+		{
+			m_upstream_request[0] = '\x04'; // VER
 			m_upstream_request[1] = m_cmd;
 			htobe16buf(m_upstream_request + 2, m_port);
 			m_upstream_request[4] = 0;
@@ -300,7 +317,8 @@ namespace proxy
 				// null terminate
 				m_upstream_request[++upstreamRequestSize] = 0;
 			} else {
-			LogPrint(eLogError, "SOCKS: BUG!!! m_addr.dns.sizs > max_socks_hostname - ( upstreamRequestSize + 1 ) )");
+				LogPrint(eLogError, "SOCKS: BUG!!! m_addr.dns.size > max_socks_hostname - ( upstreamRequestSize + 1 ) )");
+			}
 		}
 		return boost::asio::const_buffers_1(m_upstream_request, upstreamRequestSize);
 	}
@@ -417,6 +435,7 @@ namespace proxy
 			{
 				case GET_SOCKSV:
 					m_socksv = (SOCKSHandler::socksVersions) *sock_buff;
+					LogPrint(eLogInfo, "SOCKS: received version: ", ((int)*sock_buff));
 					switch (*sock_buff)
 					{
 						case SOCKS4:
@@ -715,7 +734,6 @@ namespace proxy
 		GetOwner()->AddHandler(forwarder);
 		forwarder->Start();
 		Terminate();
-
 	}
 
 	void SOCKSHandler::HandleUpstreamData(uint8_t * dataptr, std::size_t len)
@@ -723,7 +741,26 @@ namespace proxy
 		if (m_state == UPSTREAM_HANDSHAKE) {
 			m_upstream_response_len += len;
 			// handle handshake data
-			if (m_upstream_response_len < SOCKS_UPSTREAM_SOCKS4A_REPLY_SIZE) {
+			if (m_upstream_response_len == SOCKS_UPSTREAM_SOCKS5_INIT_REPLY_SIZE) {
+				if (m_upstream_response[0] == '\x05' && m_upstream_response[1] != AUTH_UNACCEPTABLE) {
+					LogPrint(eLogInfo, "SOCKS: upstream proxy: success greeting");
+					SendUpstreamRequest(m_socksv, false);
+				} else {
+					LogPrint(eLogError, "SOCKS: upstream proxy failure: no acceptable methods were offered");
+					SocksRequestFailed(SOCKS5_GEN_FAIL);
+				}
+			}
+			else if (m_upstream_response[0] == '\x05' && m_upstream_response_len >= SOCKS_UPSTREAM_SOCKS5_CONNECT_REPLY_MIN_SIZE)
+			{
+				uint8_t resp = m_upstream_response[1];
+				if (resp == SOCKS5_OK) {
+					SocksUpstreamSuccess();
+				} else {
+					LogPrint(eLogError, "SOCKS: upstream proxy failure: ", (int) resp);
+					SocksRequestFailed(SOCKS5_GEN_FAIL);
+				}
+			}
+			else if (m_upstream_response_len < SOCKS_UPSTREAM_SOCKS4A_REPLY_SIZE) {
 				// too small, continue reading
 				AsyncUpstreamSockRead();
 			} else if (len == SOCKS_UPSTREAM_SOCKS4A_REPLY_SIZE) {
@@ -748,12 +785,12 @@ namespace proxy
 		}
 	}
 
-	void SOCKSHandler::SendUpstreamRequest()
+	void SOCKSHandler::SendUpstreamRequest(int version, bool initial)
 	{
 		LogPrint(eLogInfo, "SOCKS: Negotiating with upstream proxy");
 		EnterState(UPSTREAM_HANDSHAKE);
 		if (m_upstreamSock) {
-			boost::asio::write(*m_upstreamSock, GenerateUpstreamRequest());
+			boost::asio::write(*m_upstreamSock, GenerateUpstreamRequest(version, initial));
 			AsyncUpstreamSockRead();
 		} else {
 			LogPrint(eLogError, "SOCKS: No upstream socket to send handshake to");
@@ -768,7 +805,7 @@ namespace proxy
 			return;
 		}
 		LogPrint(eLogInfo, "SOCKS: Connected to upstream proxy");
-		SendUpstreamRequest();
+		SendUpstreamRequest(m_socksv, true); // try SOCKS5 first
 	}
 
 	void SOCKSHandler::HandleUpstreamResolved(const boost::system::error_code & ecode, boost::asio::ip::tcp::resolver::iterator itr)