func (r *req) receiver(ep mangos.Endpoint) {
	rq := r.sock.RecvChannel()
	cq := r.sock.CloseChannel()

	for {
		m := ep.RecvMsg()
		if m == nil {
			break
		}

		if len(m.Body) < 4 {
			m.Free()
			continue
		}
		m.Header = append(m.Header, m.Body[:4]...)
		m.Body = m.Body[4:]

		select {
		case rq <- m:
		case <-cq:
			m.Free()
			break
		}
	}
}

func (r *rep) receiver(ep mangos.Endpoint) {
	for {

		m := ep.RecvMsg()
		if m == nil {
			return
		}

		v := ep.GetID()
		m.Header = append(m.Header,
			byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
		// Move backtrace from body to header.
		for {
			if len(m.Body) < 4 {
				m.Free() // ErrGarbled
				return
			}
			m.Header = append(m.Header, m.Body[:4]...)
			m.Body = m.Body[4:]
			// Check for high order bit set (0x80000000, big endian)
			if m.Header[len(m.Header)-4]&0x80 != 0 {
				break
			}
		}

		select {
		case r.sock.RecvChannel() <- m:
		case <-r.sock.CloseChannel():
			m.Free()
			return
		}
	}
}

func (s *sub) receiver(ep mangos.Endpoint) {
	for {
		var matched = false

		m := ep.RecvMsg()
		if m == nil {
			return
		}

		s.Lock()
		for _, sub := range s.subs {
			if bytes.HasPrefix(m.Body, sub) {
				// Matched, send it up.  Best effort.
				matched = true
				break
			}
		}
		s.Unlock()

		if !matched {
			m.Free()
			continue
		}

		select {
		case s.sock.RecvChannel() <- m:
		case <-s.sock.CloseChannel():
			m.Free()
			return
		default: // no room, drop it
			m.Free()
		}
	}
}

func (x *surveyor) AddEndpoint(ep mangos.Endpoint) {
	peer := &surveyorP{ep: ep, x: x, q: make(chan *mangos.Message, 1)}
	x.Lock()
	x.peers[ep.GetID()] = peer
	go peer.receiver()
	go peer.sender()
	x.Unlock()
}

func (x *star) RemoveEndpoint(ep mangos.Endpoint) {
	x.Lock()
	if peer := x.eps[ep.GetID()]; peer != nil {
		delete(x.eps, ep.GetID())
		close(peer.q)
	}
	x.Unlock()
}

func (x *bus) RemoveEndpoint(ep mangos.Endpoint) {
	x.Lock()
	if peer := x.peers[ep.GetID()]; peer != nil {
		close(peer.q)
		delete(x.peers, ep.GetID())
	}
	x.Unlock()
}

func (r *req) AddEndpoint(ep mangos.Endpoint) {
	r.Lock()
	r.eps[ep.GetID()] = ep
	r.Unlock()
	r.senders.Add()
	go r.receiver(ep)
	go r.sender(ep)
}

func (x *surveyor) RemoveEndpoint(ep mangos.Endpoint) {
	x.Lock()
	defer x.Unlock()
	peer := x.peers[ep.GetID()]
	if peer == nil {
		return
	}
	delete(x.peers, ep.GetID())
}

func (x *push) AddEndpoint(ep mangos.Endpoint) {
	pe := &pushEp{ep: ep, cq: make(chan struct{})}
	x.Lock()
	x.eps[ep.GetID()] = pe
	x.Unlock()
	x.w.Add()
	go x.sender(pe)
	go mangos.NullRecv(ep)
}

func (p *pub) RemoveEndpoint(ep mangos.Endpoint) {
	id := ep.GetID()
	p.Lock()
	pe := p.eps[id]
	delete(p.eps, id)
	p.Unlock()
	if pe != nil {
		close(pe.q)
	}
}

func (x *push) RemoveEndpoint(ep mangos.Endpoint) {
	id := ep.GetID()
	x.Lock()
	pe := x.eps[id]
	delete(x.eps, id)
	x.Unlock()
	if pe != nil {
		close(pe.cq)
	}
}

func (r *rep) AddEndpoint(ep mangos.Endpoint) {
	pe := &repEp{ep: ep, r: r, q: make(chan *mangos.Message, 2)}
	pe.w.Init()
	r.Lock()
	r.eps[ep.GetID()] = pe
	r.Unlock()
	pe.w.Add()
	go r.receiver(ep)
	go pe.sender()
}

func (r *req) RemoveEndpoint(ep mangos.Endpoint) {
	id := ep.GetID()
	r.Lock()
	pe := r.eps[id]
	delete(r.eps, id)
	r.Unlock()
	if pe != nil {
		close(pe.cq)
	}
}

func (x *push) receiver(ep mangos.Endpoint) {
	// In order for us to detect a dropped connection, we need to poll
	// on the socket.  We don't care about the results and discard them,
	// but this allows the disconnect to be noticed.  Note that we will
	// be blocked in this call forever, until the connection is dropped.
	for {
		if m := ep.RecvMsg(); m == nil {
			break
		}
	}
}

func (x *surveyor) RemoveEndpoint(ep mangos.Endpoint) {
	id := ep.GetID()

	x.Lock()
	peer := x.peers[id]
	delete(x.peers, id)
	x.Unlock()

	if peer != nil {
		close(peer.q)
	}
}

func (x *star) AddEndpoint(ep mangos.Endpoint) {
	depth := 16
	if i, err := x.sock.GetOption(mangos.OptionWriteQLen); err == nil {
		depth = i.(int)
	}
	pe := &starEp{ep: ep, x: x, q: make(chan *mangos.Message, depth)}
	x.Lock()
	x.eps[ep.GetID()] = pe
	x.Unlock()
	x.senders.Add()
	go pe.sender()
	go pe.receiver()
}

func (x *resp) AddEndpoint(ep mangos.Endpoint) {
	x.init.Do(func() {
		x.w.Add()
		go x.sender()
	})
	peer := &respPeer{ep: ep, x: x, q: make(chan *mangos.Message, 1)}

	x.Lock()
	x.peers[ep.GetID()] = peer
	x.Unlock()

	go x.receiver(ep)
	go peer.sender()
}

func (x *pair) AddEndpoint(ep mangos.Endpoint) {
	x.Lock()
	if x.peer != nil {
		x.Unlock()
		ep.Close()
		return
	}
	x.peer = ep
	x.Unlock()

	x.senders.Add()
	go x.receiver(ep)
	go x.sender(ep)
}

func (x *resp) AddEndpoint(ep mangos.Endpoint) {
	x.Lock()
	if x.peer != nil {
		x.Unlock()
		ep.Close()
		return
	}
	peer := &respPeer{ep: ep, x: x, q: make(chan *mangos.Message, 1)}
	x.peer = peer
	x.Unlock()

	x.senders.Add()
	go peer.receiver()
	go peer.sender()
}

func (r *req) AddEndpoint(ep mangos.Endpoint) {

	r.init.Do(func() {
		r.w.Add()
		go r.resender()
	})

	pe := &reqEp{cq: make(chan struct{}), ep: ep}
	r.Lock()
	r.eps[ep.GetID()] = pe
	r.Unlock()
	go r.receiver(ep)
	r.w.Add()
	go r.sender(pe)
}