* make loopback address mapping configurable

* add loopback address mapping to udp server tunnel

ClientContext.cpp

@@ -493,6 +493,7 @@ namespace client
 					i2p::data::SigningKeyType sigType = section.second.get (I2P_SERVER_TUNNEL_SIGNATURE_TYPE, i2p::data::SIGNING_KEY_TYPE_ECDSA_SHA256_P256);
 					uint32_t maxConns = section.second.get(i2p::stream::I2CP_PARAM_STREAMING_MAX_CONNS_PER_MIN, i2p::stream::DEFAULT_MAX_CONNS_PER_MIN);
 					std::string address = section.second.get<std::string> (I2P_SERVER_TUNNEL_ADDRESS, "127.0.0.1");
+					bool mapToLoopback = section.second.get(I2P_SERVER_TUNNEL_MAPTOLOOPBACK, true);
 
 					// I2CP
 					std::map<std::string, std::string> options;							 
@@ -512,6 +513,10 @@ namespace client
 						auto localAddress = boost::asio::ip::address::from_string(address);
 						boost::asio::ip::udp::endpoint endpoint(boost::asio::ip::address::from_string(host), port);
 						I2PUDPServerTunnel * serverTunnel = new I2PUDPServerTunnel(name, localDestination, localAddress, endpoint, port);
+						if(!mapToLoopback) {
+							LogPrint(eLogInfo, "Clients: disabling loopback address mapping");
+						}
+						serverTunnel->SetMapToLoopback(mapToLoopback);
 						std::lock_guard<std::mutex> lock(m_ForwardsMutex);
 						if(m_ServerForwards.insert(
 							std::make_pair(
@@ -538,7 +543,9 @@ namespace client
 
 					LogPrint(eLogInfo, "Clients: Set Max Conns To ", maxConns);
 					serverTunnel->SetMaxConnsPerMinute(maxConns);
-					
+					if(!mapToLoopback)
+						LogPrint(eLogInfo, "Clients: disabling loopback address mapping");
+					serverTunnel->SetMapToLoopback(mapToLoopback);
           
 					if (accessList.length () > 0)
 					{

ClientContext.h

@@ -42,6 +42,7 @@ namespace client
 	const char I2P_SERVER_TUNNEL_GZIP[] = "gzip";
 	const char I2P_SERVER_TUNNEL_WEBIRC_PASSWORD[] = "webircpassword";
 	const char I2P_SERVER_TUNNEL_ADDRESS[] = "address";
+	const char I2P_SERVER_TUNNEL_MAPTOLOOPBACK[] = "maploopback";
 
 	class ClientContext
 	{

I2PTunnel.cpp

@@ -59,24 +59,38 @@ namespace client
 		Receive ();
 	}
 
-	void I2PTunnelConnection::Connect ()
+	static boost::asio::ip::address GetLoopbackAddressFor(const i2p::data::IdentHash & addr)
 	{
-		I2PTunnelSetSocketOptions(m_Socket);
-		if (m_Socket) {
-#ifdef __linux__ 			
+		boost::asio::ip::address_v4::bytes_type bytes;
+		const uint8_t * ident = addr;
+		bytes[0] = 127;
+		memcpy (bytes.data ()+1, ident, 3);
+		boost::asio::ip::address ourIP = boost::asio::ip::address_v4 (bytes);
+		return ourIP;
+	}
+	
+	static void MapToLoopback(const std::shared_ptr<boost::asio::ip::tcp::socket> & sock, const i2p::data::IdentHash & addr)
+	{
+
 		// bind to 127.x.x.x address 
 		// where x.x.x are first three bytes from ident
+		auto ourIP = GetLoopbackAddressFor(addr);
+		sock->bind (boost::asio::ip::tcp::endpoint (ourIP, 0));
+
+	}
 
+	void I2PTunnelConnection::Connect (bool mapToLoopback)
+	{
+		I2PTunnelSetSocketOptions(m_Socket);
+		if (m_Socket) {
+
+#ifdef __linux__
 			if (m_RemoteEndpoint.address ().is_v4 () &&
-				m_RemoteEndpoint.address ().to_v4 ().to_bytes ()[0] == 127)
+				m_RemoteEndpoint.address ().to_v4 ().to_bytes ()[0] == 127 && mapToLoopback)
 			{
 				m_Socket->open (boost::asio::ip::tcp::v4 ());
-				boost::asio::ip::address_v4::bytes_type bytes;
-				const uint8_t * ident = m_Stream->GetRemoteIdentity ()->GetIdentHash ();
-				bytes[0] = 127;
-				memcpy (bytes.data ()+1, ident, 3);
-				boost::asio::ip::address ourIP = boost::asio::ip::address_v4 (bytes);
-				m_Socket->bind (boost::asio::ip::tcp::endpoint (ourIP, 0));
+				auto ident = m_Stream->GetRemoteIdentity()->GetIdentHash();
+				MapToLoopback(m_Socket, ident);
 			}
 #endif
  			m_Socket->async_connect (m_RemoteEndpoint, std::bind (&I2PTunnelConnection::HandleConnect,
@@ -417,7 +431,7 @@ namespace client
 
 	I2PServerTunnel::I2PServerTunnel (const std::string& name, const std::string& address, 
 	    int port, std::shared_ptr<ClientDestination> localDestination, int inport, bool gzip): 
-		I2PService (localDestination), m_Name (name), m_Address (address), m_Port (port), m_IsAccessList (false)
+		I2PService (localDestination), m_MapToLoopback(true), m_Name (name), m_Address (address), m_Port (port), m_IsAccessList (false)
 	{
 		m_PortDestination = localDestination->CreateStreamingDestination (inport > 0 ? inport : port, gzip);
 	}
@@ -502,7 +516,7 @@ namespace client
 	{
 		auto conn = std::make_shared<I2PTunnelConnection> (this, stream, std::make_shared<boost::asio::ip::tcp::socket> (GetService ()), GetEndpoint ());
 		AddHandler (conn);
-		conn->Connect ();
+		conn->Connect (m_MapToLoopback);
 	}
 
 	I2PServerTunnelHTTP::I2PServerTunnelHTTP (const std::string& name, const std::string& address, 
@@ -581,8 +595,15 @@ namespace client
         return s;
       }
     }
+		boost::asio::ip::address addr;
 		/** create new udp session */
-    boost::asio::ip::udp::endpoint ep(m_LocalAddress, 0);
+		if(m_LocalAddress.is_loopback() && m_MapToLoopback) {
+			auto ident = from.GetIdentHash();
+			addr = GetLoopbackAddressFor(ident);
+		} else {
+			addr = m_LocalAddress;
+		}
+		boost::asio::ip::udp::endpoint ep(addr, 0);
     m_Sessions.push_back(std::make_shared<UDPSession>(ep, m_LocalDest, m_RemoteEndpoint, &ih, localPort, remotePort));
 		auto & back = m_Sessions.back();
 		return back;
@@ -627,6 +648,7 @@ namespace client
 	
 	I2PUDPServerTunnel::I2PUDPServerTunnel(const std::string & name, std::shared_ptr<i2p::client::ClientDestination> localDestination,
 		boost::asio::ip::address localAddress, boost::asio::ip::udp::endpoint forwardTo, uint16_t port) :
+		m_MapToLoopback(true),
 		m_Name(name),
 		m_LocalAddress(localAddress),
 		m_RemoteEndpoint(forwardTo)
@@ -768,8 +790,6 @@ namespace client
 				// found convo
 				if (len > 0) {
 					LogPrint(eLogDebug, "UDP Client: got ", len, "B from ", from.GetIdentHash().ToBase32());
-					uint8_t sendbuf[len];
-					memcpy(sendbuf, buf, len);
 					m_LocalSocket.send_to(boost::asio::buffer(buf, len), itr->second.first);
 					// mark convo as active
 					itr->second.second = i2p::util::GetMillisecondsSinceEpoch();

I2PTunnel.h

@@ -38,7 +38,7 @@ namespace client
 				const boost::asio::ip::tcp::endpoint& target, bool quiet = true); // from I2P
 			~I2PTunnelConnection ();
 			void I2PConnect (const uint8_t * msg = nullptr, size_t len = 0);
-			void Connect ();
+			void Connect (bool mapToLoopback = true);
 			
 		protected:
 
@@ -201,12 +201,15 @@ namespace client
 			std::vector<std::shared_ptr<DatagramSessionInfo> > GetSessions();
 			std::shared_ptr<ClientDestination> GetLocalDestination () const { return m_LocalDest; }
 
+			void SetMapToLoopback(bool mapToLoopback = true) { m_MapToLoopback = mapToLoopback; }
+
 		private:
 
 			void HandleRecvFromI2P(const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
 			UDPSessionPtr ObtainUDPSession(const i2p::data::IdentityEx& from, uint16_t localPort, uint16_t remotePort);
 
 		private:
+			bool m_MapToLoopback;
 			const std::string m_Name;
 			boost::asio::ip::address m_LocalAddress;
 			boost::asio::ip::udp::endpoint m_RemoteEndpoint;
@@ -264,6 +267,8 @@ namespace client
 
 			void SetAccessList (const std::set<i2p::data::IdentHash>& accessList); 
 
+			void SetMapToLoopback(bool mapToLoopback) { m_MapToLoopback = mapToLoopback; }
+
 			const std::string& GetAddress() const { return m_Address; }
 			int GetPort () const { return m_Port; };
 			uint16_t GetLocalPort () const { return m_PortDestination->GetLocalPort (); };
@@ -283,7 +288,7 @@ namespace client
 			virtual void CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream);
 
 		private:
-
+			bool m_MapToLoopback;
 			std::string m_Name, m_Address;
 			int m_Port;
 			boost::asio::ip::tcp::endpoint m_Endpoint;