func (nn *netNotifiee) Disconnected(n inet.Network, v inet.Conn) {
	// undo the setting of addresses to peer.ConnectedAddrTTL we did
	ids := nn.IDService()
	ps := ids.Host.Peerstore()
	addrs := ps.Addrs(v.RemotePeer())
	ps.SetAddrs(v.RemotePeer(), addrs, peer.RecentlyConnectedAddrTTL)
}

func (ids *IDService) consumeObservedAddress(observed []byte, c inet.Conn) {
	if observed == nil {
		return
	}

	maddr, err := ma.NewMultiaddrBytes(observed)
	if err != nil {
		log.Debugf("error parsing received observed addr for %s: %s", c, err)
		return
	}

	// we should only use ObservedAddr when our connection's LocalAddr is one
	// of our ListenAddrs. If we Dial out using an ephemeral addr, knowing that
	// address's external mapping is not very useful because the port will not be
	// the same as the listen addr.
	ifaceaddrs, err := ids.Host.Network().InterfaceListenAddresses()
	if err != nil {
		log.Infof("failed to get interface listen addrs", err)
		return
	}

	log.Debugf("identify identifying observed multiaddr: %s %s", c.LocalMultiaddr(), ifaceaddrs)
	if !addrInAddrs(c.LocalMultiaddr(), ifaceaddrs) {
		// not in our list
		return
	}

	// ok! we have the observed version of one of our ListenAddresses!
	log.Debugf("added own observed listen addr: %s --> %s", c.LocalMultiaddr(), maddr)
	ids.observedAddrs.Add(maddr, c.RemoteMultiaddr())
}

func (ids *IDService) IdentifyConn(c inet.Conn) {
	ids.currmu.Lock()
	if wait, found := ids.currid[c]; found {
		ids.currmu.Unlock()
		log.Debugf("IdentifyConn called twice on: %s", c)
		<-wait // already identifying it. wait for it.
		return
	}
	ids.currid[c] = make(chan struct{})
	ids.currmu.Unlock()

	s, err := c.NewStream()
	if err != nil {
		log.Debugf("error opening initial stream for %s", ID)
		log.Event(context.TODO(), "IdentifyOpenFailed", c.RemotePeer())
		c.Close()
		return
	} else {
		bwc := ids.Host.GetBandwidthReporter()
		s = mstream.WrapStream(s, ID, bwc)

		// ok give the response to our handler.
		if err := protocol.WriteHeader(s, ID); err != nil {
			log.Debugf("error writing stream header for %s", ID)
			log.Event(context.TODO(), "IdentifyOpenFailed", c.RemotePeer())
			s.Close()
			c.Close()
			return
		}
		ids.ResponseHandler(s)
	}

	ids.currmu.Lock()
	ch, found := ids.currid[c]
	delete(ids.currid, c)
	ids.currmu.Unlock()

	if !found {
		log.Debugf("IdentifyConn failed to find channel (programmer error) for %s", c)
		return
	}

	close(ch) // release everyone waiting.
}

func (ids *IDService) consumeMessage(mes *pb.Identify, c inet.Conn) {
	p := c.RemotePeer()

	// mes.Protocols

	// mes.ObservedAddr
	ids.consumeObservedAddress(mes.GetObservedAddr(), c)

	// mes.ListenAddrs
	laddrs := mes.GetListenAddrs()
	lmaddrs := make([]ma.Multiaddr, 0, len(laddrs))
	for _, addr := range laddrs {
		maddr, err := ma.NewMultiaddrBytes(addr)
		if err != nil {
			log.Debugf("%s failed to parse multiaddr from %s %s", ID,
				p, c.RemoteMultiaddr())
			continue
		}
		lmaddrs = append(lmaddrs, maddr)
	}

	// update our peerstore with the addresses. here, we SET the addresses, clearing old ones.
	// We are receiving from the peer itself. this is current address ground truth.
	ids.Host.Peerstore().SetAddrs(p, lmaddrs, peer.ConnectedAddrTTL)
	log.Debugf("%s received listen addrs for %s: %s", c.LocalPeer(), c.RemotePeer(), lmaddrs)

	// get protocol versions
	pv := mes.GetProtocolVersion()
	av := mes.GetAgentVersion()

	// version check. if we shouldn't talk, bail.
	// TODO: at this point, we've already exchanged information.
	// move this into a first handshake before the connection can open streams.
	if !protocolVersionsAreCompatible(pv, LibP2PVersion) {
		logProtocolMismatchDisconnect(c, pv, av)
		c.Close()
		return
	}

	ids.Host.Peerstore().Put(p, "ProtocolVersion", pv)
	ids.Host.Peerstore().Put(p, "AgentVersion", av)
}

func (ids *IDService) populateMessage(mes *pb.Identify, c inet.Conn) {

	// set protocols this node is currently handling
	protos := ids.Host.Mux().Protocols()
	mes.Protocols = make([]string, len(protos))
	for i, p := range protos {
		mes.Protocols[i] = string(p)
	}

	// observed address so other side is informed of their
	// "public" address, at least in relation to us.
	mes.ObservedAddr = c.RemoteMultiaddr().Bytes()

	// set listen addrs, get our latest addrs from Host.
	laddrs := ids.Host.Addrs()
	mes.ListenAddrs = make([][]byte, len(laddrs))
	for i, addr := range laddrs {
		mes.ListenAddrs[i] = addr.Bytes()
	}
	log.Debugf("%s sent listen addrs to %s: %s", c.LocalPeer(), c.RemotePeer(), laddrs)

	// set protocol versions
	pv := LibP2PVersion
	av := ClientVersion
	mes.ProtocolVersion = &pv
	mes.AgentVersion = &av
}

func logProtocolMismatchDisconnect(c inet.Conn, protocol, agent string) {
	lm := make(lgbl.DeferredMap)
	lm["remotePeer"] = func() interface{} { return c.RemotePeer().Pretty() }
	lm["remoteAddr"] = func() interface{} { return c.RemoteMultiaddr().String() }
	lm["protocolVersion"] = protocol
	lm["agentVersion"] = agent
	log.Event(context.TODO(), "IdentifyProtocolMismatch", lm)
	log.Debug("IdentifyProtocolMismatch %s %s %s (disconnected)", c.RemotePeer(), protocol, agent)
}