expose UPnP and NAT-PMP mapping in session object

ChangeLog

@@ -1,3 +1,4 @@
+	* expose UPnP and NAT-PMP mapping in session object
 	* DHT refactoring and support for storing arbitrary data with put
 	* support building on android
 	* improved support for web seeds that don't support keep-alive

include/libtorrent/session.hpp

@@ -879,6 +879,15 @@ namespace libtorrent
  		void start_upnp();
 		void stop_upnp();
 
+		enum protocol_type { udp = 1, tcp = 2 };
+
+		// add_port_mapping adds a port forwarding on UPnP and/or NAT-PMP,
+		// whichever is enabled. The return value is a handle referring to
+		// the port mapping that was just created. Pass it to delete_port_mapping()
+		// to remove it.
+		int add_port_mapping(protocol_type t, int external_port, int local_port);
+		void delete_port_mapping(int handle);
+
 		// Starts and stops the NAT-PMP service. When started, the listen port and the DHT
 		// port are attempted to be forwarded on the router through NAT-PMP.
 		// 

src/session.cpp

@@ -1160,6 +1160,16 @@ namespace libtorrent
 	{
 		TORRENT_ASYNC_CALL(start_upnp);
 	}
+
+	int session::add_port_mapping(protocol_type t, int external_port, int local_port)
+	{
+		TORRENT_SYNC_CALL_RET3(add_port_forward, int, t, external_port, local_port);
+	}
+
+	void session::delete_port_mapping(int handle)
+	{
+		TORRENT_ASYNC_CALL1(delete_port_forward, handle);
+	}
 	
 	void session::stop_lsd()
 	{

src/session_impl.cpp

@@ -6173,6 +6173,24 @@ retry:
 		return u;
 	}
 
+	int session_impl::add_port_mapping(protocol_type t, int external_port
+		, int local_port)
+	{
+		int ret = 0;
+		if (m_upnp) ret = m_upnp->add_mapping(t, external_port
+			, internal_port);
+		if (m_natpmp) ret = m_natpmp->add_mapping(t, external_port
+			, internal_port);
+		return ret;
+	}
+
+	void session_impl::delete_port_mapping(int handle)
+	{
+		int ret = 0;
+		if (m_upnp) ret = m_upnp->delete_mapping(handle);
+		if (m_natpmp) ret = m_natpmp->delete_mapping(handle);
+	}
+
 	void session_impl::stop_lsd()
 	{
 		if (m_lsd.get())