set port in handshake based on source address (#3172)

include/libtorrent/aux_/session_impl.hpp

@@ -593,7 +593,11 @@ namespace aux {
 			std::uint16_t ssl_listen_port() const override;
 			std::uint16_t ssl_listen_port(listen_socket_t* sock) const;
 
+			// used by the DHT tracker, returns a UDP listen port
 			int get_listen_port(transport ssl, aux::listen_socket_handle const& s) override;
+			// used by peer connections, returns a TCP listen port
+			// or zero if no matching listen socket is found
+			int listen_port(transport ssl, address const& local_addr) override;
 
 			std::uint32_t get_tracker_key(address const& iface) const;
 

include/libtorrent/aux_/session_interface.hpp

@@ -43,6 +43,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/socket.hpp" // for tcp::endpoint
 #include "libtorrent/aux_/vector.hpp"
 #include "libtorrent/aux_/listen_socket_handle.hpp"
+#include "libtorrent/aux_/session_udp_sockets.hpp" // for transport
 #include "libtorrent/session_types.hpp"
 #include "libtorrent/flags.hpp"
 #include "libtorrent/link.hpp" // for torrent_list_index_t
@@ -201,6 +202,8 @@ namespace aux {
 		virtual std::uint16_t listen_port() const = 0;
 		virtual std::uint16_t ssl_listen_port() const = 0;
 
+		virtual int listen_port(aux::transport ssl, address const& local_addr) = 0;
+
 		virtual void for_each_listen_socket(std::function<void(aux::listen_socket_handle const&)> f) = 0;
 
 		// ask for which interface and port to bind outgoing peer connections on

src/bt_peer_connection.cpp

@@ -2084,11 +2084,18 @@ namespace {
 		entry handshake;
 		entry::dictionary_type& m = handshake["m"].dict();
 
+		std::shared_ptr<torrent> t = associated_torrent().lock();
+		TORRENT_ASSERT(t);
+
 		// if we're using a proxy, our listen port won't be useful
 		// anyway.
-		auto const port = m_ses.listen_port();
-		if (port != 0 && is_outgoing())
-			handshake["p"] = port;
+		if (is_outgoing())
+		{
+			auto const port = m_ses.listen_port(
+				t->is_ssl_torrent() ? aux::transport::ssl : aux::transport::plaintext
+				, local_endpoint().address());
+			if (port != 0) handshake["p"] = port;
+		}
 
 		// only send the port in case we bade the connection
 		// on incoming connections the other end already knows
@@ -2108,8 +2115,6 @@ namespace {
 #endif
 			handshake["yourip"] = remote_address;
 		handshake["reqq"] = m_settings.get_int(settings_pack::max_allowed_in_request_queue);
-		std::shared_ptr<torrent> t = associated_torrent().lock();
-		TORRENT_ASSERT(t);
 
 		m["upload_only"] = upload_only_msg;
 		m["ut_holepunch"] = holepunch_msg;

src/session_impl.cpp

@@ -5456,6 +5456,21 @@ namespace aux {
 		return socket->udp_external_port;
 	}
 
+	int session_impl::listen_port(transport const ssl, address const& local_addr)
+	{
+		auto socket = std::find_if(m_listen_sockets.begin(), m_listen_sockets.end()
+			, [&](std::shared_ptr<listen_socket_t> const& e)
+		{
+			auto const& listen_addr = e->external_address.external_address();
+			return e->ssl == ssl
+				&& (listen_addr == local_addr
+					|| (listen_addr.is_v4() == local_addr.is_v4() && listen_addr.is_unspecified()));
+		});
+		if (socket != m_listen_sockets.end())
+			return (*socket)->tcp_external_port;
+		return 0;
+	}
+
 	void session_impl::announce_lsd(sha1_hash const& ih, int port, bool broadcast)
 	{
 		// use internal listen port for local peers