fix to allow hostnames for peers in tracker responses

docs/manual.rst

@@ -1471,7 +1471,8 @@ use_interface()
 
 ``use_interface()`` sets the network interface this torrent will use when it opens outgoing
 connections. By default, it uses the same interface as the session_ uses to listen on. The
-parameter can be a string containing an ip-address or a hostname.
+parameter must be a string containing an ip-address (either an IPv4 or IPv6 address). If
+the string does not conform to this format and exception is thrown.
 
 
 info_hash()

include/libtorrent/torrent.hpp

@@ -363,9 +363,14 @@ namespace libtorrent
 		// the download. It will post an event, disconnect
 		// all seeds and let the tracker know we're finished.
 		void completed();
-		
+
 		// this is the asio callback that is called when a name
-		// lookup for a web seed is completed.
+		// lookup for a PEER is completed.
+		void on_peer_name_lookup(asio::error_code const& e, tcp::resolver::iterator i
+			, peer_id pid);
+
+		// this is the asio callback that is called when a name
+		// lookup for a WEB SEED is completed.
 		void on_name_lookup(asio::error_code const& e, tcp::resolver::iterator i
 			, std::string url, tcp::endpoint proxy);
 

src/torrent.cpp

@@ -592,17 +592,29 @@ namespace libtorrent
 			if (i->pid == m_ses.get_peer_id())
 				continue;
 
-			tcp::endpoint a(address::from_string(i->ip), i->port);
+			try
-
-			if (m_ses.m_ip_filter.access(a.address()) & ip_filter::blocked)
 			{
+				tcp::endpoint a(address::from_string(i->ip), i->port);
+
+				if (m_ses.m_ip_filter.access(a.address()) & ip_filter::blocked)
+				{
 #if defined(TORRENT_VERBOSE_LOGGING) || defined(TORRENT_LOGGING)
-				debug_log("blocked ip from tracker: " + i->ip);
+					debug_log("blocked ip from tracker: " + i->ip);
 #endif
-				continue;
+					continue;
-			}
+				}
 			
-			m_policy->peer_from_tracker(a, i->pid);
+				m_policy->peer_from_tracker(a, i->pid);
+			}
+			catch (std::exception&)
+			{
+				// assume this is because we got a hostname instead of
+				// an ip address from the tracker
+
+				tcp::resolver::query q(i->ip, boost::lexical_cast<std::string>(i->port));
+				m_host_resolver.async_resolve(q, m_ses.m_strand.wrap(
+					bind(&torrent::on_peer_name_lookup, shared_from_this(), _1, _2, i->pid)));
+			}	
 		}
 
 		if (m_ses.m_alerts.should_post(alert::info))
@@ -616,6 +628,29 @@ namespace libtorrent
 		m_got_tracker_response = true;
 	}
 
+	void torrent::on_peer_name_lookup(asio::error_code const& e, tcp::resolver::iterator host
+		, peer_id pid) try
+	{
+		session_impl::mutex_t::scoped_lock l(m_ses.m_mutex);
+
+		INVARIANT_CHECK;
+
+		if (e || host == tcp::resolver::iterator() ||
+			m_ses.is_aborted()) return;
+
+		if (m_ses.m_ip_filter.access(host->endpoint().address()) & ip_filter::blocked)
+		{
+#if defined(TORRENT_VERBOSE_LOGGING) || defined(TORRENT_LOGGING)
+			debug_log("blocked ip from tracker: " + host->endpoint().address().to_string());
+#endif
+			return;
+		}
+			
+		m_policy->peer_from_tracker(*host, pid);
+	}
+	catch (std::exception&)
+	{}
+
 	size_type torrent::bytes_left() const
 	{
 		// if we don't have the metadata yet, we