made the handshake timeout configurable and defaults to 10 seconds

include/libtorrent/session_settings.hpp

@@ -111,6 +111,7 @@ namespace libtorrent
 			, initial_picker_threshold(4)
 			, allowed_fast_set_size(10)
 			, max_outstanding_disk_bytes_per_connection(64 * 1024)
+			, handshake_timeout(10)
 #ifndef TORRENT_DISABLE_DHT
 			, use_dht_as_fallback(true)
 #endif
@@ -270,6 +271,11 @@ namespace libtorrent
 		// to not completely disrupt normal downloads.
 		int max_outstanding_disk_bytes_per_connection;
 
+		// the number of seconds to wait for a handshake
+		// response from a peer. If no response is received
+		// within this time, the peer is disconnected.
+		int handshake_timeout;
+
 #ifndef TORRENT_DISABLE_DHT
 		// while this is true, the dht will note be used unless the
 		// tracker is online

src/peer_connection.cpp

@@ -3000,13 +3000,12 @@ namespace libtorrent
 			return true;
 		}
 
-		// if it takes more than 5 seconds to receive
-		// handshake, disconnect
-		if (in_handshake() && d > seconds(5))
+		// do not stall waiting for a handshake
+		if (in_handshake() && d > seconds(m_ses.settings().handshake_timeout))
 		{
 #ifdef TORRENT_VERBOSE_LOGGING
-			(*m_logger) << time_now_string() << " *** NO HANDSHAKE [ "
-				<< total_seconds(d) << " seconds ago ] ***\n";
+			(*m_logger) << time_now_string() << " *** NO HANDSHAKE [ waited "
+				<< total_seconds(d) << " seconds ] ***\n";
 #endif
 			return true;
 		}