fix issues introduced with connection ordering

src/ip_voter.cpp

@@ -118,7 +118,9 @@ namespace libtorrent
 
 	address external_ip::external_address(address const& ip) const
 	{
-		return m_vote_group[ip.is_v6()].external_address();
+		address ext = m_vote_group[ip.is_v6()].external_address();
+		if (ip.is_v6() && ext == address_v4()) return address_v6();
+		return ext;
 	}
 }
 

src/session_impl.cpp

@@ -4830,11 +4830,27 @@ retry:
 		return boost::weak_ptr<torrent>();
 	}
 
+	// returns true if lhs is a better disconnect candidate than rhs
+	bool compare_disconnect_torrent(session_impl::torrent_map::value_type const& lhs
+		, session_impl::torrent_map::value_type const& rhs)
+	{
+		// a torrent with 0 peers is never a good disconnect candidate
+		// since there's nothing to disconnect
+		if ((lhs.second->num_peers() == 0) != (lhs.second->num_peers() == 0))
+			return lhs.second->num_peers() != 0;
+
+		// other than that, always prefer to disconnect peers from seeding torrents
+		// in order to not harm downloading ones
+		if (lhs.second->is_seed() != rhs.second->is_seed())
+			return lhs.second->is_seed();
+
+		return lhs.second->num_peers() > rhs.second->num_peers();
+	}
+
  	boost::weak_ptr<torrent> session_impl::find_disconnect_candidate_torrent()
  	{
-		aux::session_impl::torrent_map::iterator i = std::max_element(m_torrents.begin(), m_torrents.end()
-			, boost::bind(&torrent::num_peers, boost::bind(&session_impl::torrent_map::value_type::second, _1))
-			< boost::bind(&torrent::num_peers, boost::bind(&session_impl::torrent_map::value_type::second, _2)));
+		aux::session_impl::torrent_map::iterator i = std::min_element(m_torrents.begin(), m_torrents.end()
+			, boost::bind(&compare_disconnect_torrent, _1, _2));
 
 		TORRENT_ASSERT(i != m_torrents.end());
 		if (i == m_torrents.end()) return boost::shared_ptr<torrent>();

src/torrent.cpp

@@ -4328,7 +4328,8 @@ namespace libtorrent
 
 		if (ready_for_connections())
 		{
-			TORRENT_ASSERT(p->associated_torrent().lock().get() == this);
+			TORRENT_ASSERT(p->associated_torrent().lock().get() == NULL
+				|| p->associated_torrent().lock().get() == this);
 
 			if (p->is_seed())
 			{
@@ -5890,6 +5891,8 @@ namespace libtorrent
 			return false;
 		}
 
+		bool maybe_replace_peer = false;
+
 		if (m_connections.size() >= m_max_connections)
 		{
 			// if more than 10% of the connections are outgoing
@@ -5923,21 +5926,7 @@ namespace libtorrent
 			}
 			else
 			{
-				// now, find the lowest rank peer and disconnect that
-				// if it's lower rank than the incoming connection
-				peer_connection* peer = find_lowest_ranking_peer();
-
-				// TODO: if peer is a really good peer, maybe we shouldn't disconnect it
-				if (peer && peer->peer_rank() < p->peer_rank())
-				{
-					peer->disconnect(errors::too_many_connections);
-					p->peer_disconnected_other();
-				}
-				else
-				{
-					p->disconnect(errors::too_many_connections);
-					return false;
-				}
+				maybe_replace_peer = true;
 			}
 		}
 
@@ -5979,6 +5968,34 @@ namespace libtorrent
 		TORRENT_ASSERT(p->remote() == p->get_socket()->remote_endpoint(ec) || ec);
 #endif
 
+		TORRENT_ASSERT(p->peer_info_struct() != NULL);
+
+		// we need to do this after we've added the peer to the policy
+		// since that's when the peer is assigned its peer_info object,
+		// which holds the rank
+		if (maybe_replace_peer)
+		{
+			// now, find the lowest rank peer and disconnect that
+			// if it's lower rank than the incoming connection
+			peer_connection* peer = find_lowest_ranking_peer();
+
+			// TODO: if peer is a really good peer, maybe we shouldn't disconnect it
+			if (peer && peer->peer_rank() < p->peer_rank())
+			{
+				peer->disconnect(errors::too_many_connections);
+				p->peer_disconnected_other();
+			}
+			else
+			{
+				p->disconnect(errors::too_many_connections);
+				// we have to do this here because from the peer's point of
+				// it wasn't really attached to the torrent, but we do need
+				// to let policy know we're removing it
+				remove_peer(p);
+				return false;
+			}
+		}
+
 #if defined TORRENT_DEBUG && !defined TORRENT_DISABLE_INVARIANT_CHECKS
 		m_policy.check_invariant();
 #endif