added support to bind outgoing connections to specific ports (might be useful to do traffic shaping)

include/libtorrent/aux_/session_impl.hpp

@@ -375,6 +375,8 @@ namespace libtorrent
 			void stop_natpmp();
 			void stop_upnp();
 
+			int next_port();
+
 			// handles delayed alerts
 			alert_manager m_alerts;
 
@@ -551,6 +553,10 @@ namespace libtorrent
 			void second_tick(asio::error_code const& e);
 			ptime m_last_tick;
 
+			// when outgoing_ports is configured, this is the
+			// port we'll bind the next outgoing socket to
+			int m_next_port;
+
 #ifndef TORRENT_DISABLE_DHT
 			boost::intrusive_ptr<dht::dht_tracker> m_dht;
 			dht_settings m_dht_settings;

include/libtorrent/session_settings.hpp

@@ -126,6 +126,7 @@ namespace libtorrent
 			, auto_upload_slots(true)
 			, cache_size(512)
 			, cache_expiry(60)
+			, outgoing_ports(0,0)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -332,6 +333,12 @@ namespace libtorrent
 		// idle in the cache before it's forcefully flushed
 		// to disk. Default is 60 seconds.
 		int cache_expiry;
+
+		// if != (0, 0), this is the range of ports that
+		// outgoing connections will be bound to. This
+		// is useful for users that have routers that
+		// allow QoS settings based on local port.
+		std::pair<int, int> outgoing_ports;
 	};
 	
 #ifndef TORRENT_DISABLE_DHT