possible dangling pointer fix in broadcast_socket

include/libtorrent/broadcast_socket.hpp

@@ -117,6 +117,9 @@ namespace libtorrent
 		void open_multicast_socket(io_service& ios, address const& addr
 			, bool loopback, error_code& ec);
 
+		// if we're aborting, destruct the handler and return true
+		bool maybe_abort();
+
 		// these sockets are used to
 		// join the multicast group (on each interface)
 		// and receive multicast messages
@@ -128,6 +131,18 @@ namespace libtorrent
 		std::list<socket_entry> m_unicast_sockets;
 		udp::endpoint m_multicast_endpoint;
 		receive_handler_t m_on_receive;
+
+		// the number of outstanding async operations
+		// we have on these sockets. The m_on_receive
+		// handler may not be destructed until this reaches
+		// 0, since it may be holding references to
+		// the broadcast_socket itself.
+		int m_outstanding_operations;
+		// when set to true, we're trying to shut down
+		// don't initiate new operations and once the
+		// outstanding counter reaches 0, destruct
+		// the handler object
+		bool m_abort;
 	};
 }
 	

src/broadcast_socket.cpp

@@ -217,6 +217,8 @@ namespace libtorrent
 		, bool loopback)
 		: m_multicast_endpoint(multicast_endpoint)
 		, m_on_receive(handler)
+		, m_outstanding_operations(0)
+		, m_abort(false)
 	{
 		TORRENT_ASSERT(is_multicast(m_multicast_endpoint.address()));
 
@@ -279,6 +281,7 @@ namespace libtorrent
 #endif
 		s->async_receive_from(asio::buffer(se.buffer, sizeof(se.buffer))
 			, se.remote, boost::bind(&broadcast_socket::on_receive, this, &se, _1, _2));
+		++m_outstanding_operations;
 	}
 
 	void broadcast_socket::open_unicast_socket(io_service& ios, address const& addr
@@ -305,6 +308,7 @@ namespace libtorrent
 #endif
 		s->async_receive_from(asio::buffer(se.buffer, sizeof(se.buffer))
 			, se.remote, boost::bind(&broadcast_socket::on_receive, this, &se, _1, _2));
+		++m_outstanding_operations;
 	}
 
 	void broadcast_socket::send(char const* buffer, int size, error_code& ec, int flags)
@@ -365,14 +369,31 @@ namespace libtorrent
 #if defined TORRENT_ASIO_DEBUGGING
 		complete_async("broadcast_socket::on_receive");
 #endif
-		if (ec || bytes_transferred == 0 || !m_on_receive) return;
+		TORRENT_ASSERT(m_outstanding_operations > 0);
+		--m_outstanding_operations;
+
+		if (ec || bytes_transferred == 0 || !m_on_receive)
+		{
+			maybe_abort();
+			return;
+		}
 		m_on_receive(s->remote, s->buffer, bytes_transferred);
+
+		if (maybe_abort()) return;
 		if (!s->socket) return;
 #if defined TORRENT_ASIO_DEBUGGING
 		add_outstanding_async("broadcast_socket::on_receive");
 #endif
 		s->socket->async_receive_from(asio::buffer(s->buffer, sizeof(s->buffer))
 			, s->remote, boost::bind(&broadcast_socket::on_receive, this, s, _1, _2));
+		++m_outstanding_operations;
+	}
+
+	bool broadcast_socket::maybe_abort()
+	{
+		if (m_abort && m_outstanding_operations == 0)
+			m_on_receive.clear();
+		return m_abort;
 	}
 
 	void broadcast_socket::close()
@@ -380,7 +401,8 @@ namespace libtorrent
 		std::for_each(m_sockets.begin(), m_sockets.end(), boost::bind(&socket_entry::close, _1));
 		std::for_each(m_unicast_sockets.begin(), m_unicast_sockets.end(), boost::bind(&socket_entry::close, _1));
 
-		m_on_receive.clear();
+		m_abort = true;
+		maybe_abort();
 	}
 }
 

src/session_impl.cpp

@@ -1598,9 +1598,9 @@ namespace aux {
 		m_i2p_conn.close(ec);
 #endif
 		m_queued_for_checking.clear();
-		if (m_lsd) m_lsd->close();
+		stop_lsd();
-		if (m_upnp) m_upnp->close();
+		stop_upnp();
-		if (m_natpmp) m_natpmp->close();
+		stop_natpmp();
 #ifndef TORRENT_DISABLE_DHT
 		if (m_dht)
 		{