merged udp tracker fix from RC_0_16

ChangeLog

@@ -5,6 +5,8 @@
 	* fix uTP edge case where udp socket buffer fills up
 	* fix nagle implementation in uTP
 
+	* fix UDP trackers trying all endpoints behind the hostname
+
 0.16.4 release
 
 	* raise the default number of torrents allowed to announce to trackers to 1600

include/libtorrent/tracker_manager.hpp

@@ -225,7 +225,7 @@ namespace libtorrent
 			, io_service& ios
 			, boost::weak_ptr<request_callback> r);
 
-		boost::shared_ptr<request_callback> requester();
+		boost::shared_ptr<request_callback> requester() const;
 		virtual ~tracker_connection() {}
 
 		tracker_request const& tracker_req() const { return m_req; }

include/libtorrent/udp_tracker_connection.hpp

@@ -108,12 +108,18 @@ namespace libtorrent
 		bool on_announce_response(char const* buf, int size);
 		bool on_scrape_response(char const* buf, int size);
 
+		// wraps tracker_connection::fail
+		void fail(error_code const& ec, int code = -1
+			, char const* msg = "", int interval = 0, int min_interval = 0);
+
 		void send_udp_connect();
 		void send_udp_announce();
 		void send_udp_scrape();
 
 		virtual void on_timeout(error_code const& ec);
 
+		udp::endpoint pick_target_endpoint() const;
+
 //		tracker_manager& m_man;
 
 		bool m_abort;

src/tracker_manager.cpp

@@ -156,7 +156,7 @@ namespace libtorrent
 		, m_req(req)
 	{}
 
-	boost::shared_ptr<request_callback> tracker_connection::requester()
+	boost::shared_ptr<request_callback> tracker_connection::requester() const
 	{
 		return m_requester.lock();
 	}

src/udp_tracker_connection.cpp

@@ -132,6 +132,26 @@ namespace libtorrent
 			, settings.tracker_receive_timeout);
 	}
 
+	void udp_tracker_connection::fail(error_code const& ec, int code
+		, char const* msg, int interval, int min_interval)
+	{
+		// m_target failed. remove it from the endpoint list
+		std::list<tcp::endpoint>::iterator i = std::find(m_endpoints.begin()
+			, m_endpoints.end(), tcp::endpoint(m_target.address(), m_target.port()));
+
+		if (i != m_endpoints.end()) m_endpoints.erase(i);
+
+		// if that was the last one, fail the whole announce
+		if (m_endpoints.empty())
+			tracker_connection::fail(ec, code, msg, interval, min_interval);
+
+		// pick another target endpoint and try again
+		m_target = pick_target_endpoint();
+
+		m_ses.m_io_service.post(boost::bind(
+			&udp_tracker_connection::start_announce, self()));
+	}
+
 	void udp_tracker_connection::name_lookup(error_code const& error
 		, tcp::resolver::iterator i)
 	{
@@ -191,8 +211,17 @@ namespace libtorrent
 			return;
 		}
 		
-		std::list<tcp::endpoint>::iterator iter = m_endpoints.begin();
-		m_target = udp::endpoint(iter->address(), iter->port());
+		m_target = pick_target_endpoint();
+
+		if (cb) cb->m_tracker_address = tcp::endpoint(m_target.address(), m_target.port());
+
+		start_announce();
+	}
+
+	udp::endpoint udp_tracker_connection::pick_target_endpoint() const
+	{
+		std::list<tcp::endpoint>::const_iterator iter = m_endpoints.begin();
+		udp::endpoint target = udp::endpoint(iter->address(), iter->port());
 
 		if (bind_interface() != address_v4::any())
 		{
@@ -202,10 +231,11 @@ namespace libtorrent
 
 			if (iter == m_endpoints.end())
 			{
-				TORRENT_ASSERT(m_target.address().is_v4() != bind_interface().is_v4());
+				TORRENT_ASSERT(target.address().is_v4() != bind_interface().is_v4());
+				boost::shared_ptr<request_callback> cb = requester();
 				if (cb)
 				{
-					char const* tracker_address_type = m_target.address().is_v4() ? "IPv4" : "IPv6";
+					char const* tracker_address_type = target.address().is_v4() ? "IPv4" : "IPv6";
 					char const* bind_address_type = bind_interface().is_v4() ? "IPv4" : "IPv6";
 					char msg[200];
 					snprintf(msg, sizeof(msg)
@@ -219,13 +249,11 @@ namespace libtorrent
 			}
 			else
 			{
-				m_target = udp::endpoint(iter->address(), iter->port());
+				target = udp::endpoint(iter->address(), iter->port());
 			}
 		}
 
-		if (cb) cb->m_tracker_address = tcp::endpoint(m_target.address(), m_target.port());
-
-		start_announce();
+		return target;
 	}
 
 	void udp_tracker_connection::start_announce()