p2p: new dialer, peer management without locks

The most visible change is event-based dialing, which should be an
improvement over the timer-based system that we have at the moment.
The dialer gets a chance to compute new tasks whenever peers change or
dials complete. This is better than checking peers on a timer because
dials happen faster. The dialer can now make more precise decisions
about whom to dial based on the peer set and we can test those
decisions without actually opening any sockets.

Peer management is easier to test because the tests can inject
connections at checkpoints (after enc handshake, after protocol
handshake).

Most of the handshake stuff is now part of the RLPx code. It could be
exported or move to its own package because it is no longer entangled
with Server logic.

p2p/peer.go

@@ -33,9 +33,17 @@ const (
 	peersMsg     = 0x05
 )
 
+// protoHandshake is the RLP structure of the protocol handshake.
+type protoHandshake struct {
+	Version    uint64
+	Name       string
+	Caps       []Cap
+	ListenPort uint64
+	ID         discover.NodeID
+}
+
 // Peer represents a connected remote node.
 type Peer struct {
-	conn    net.Conn
 	rw      *conn
 	running map[string]*protoRW
 
@@ -48,37 +56,36 @@ type Peer struct {
 // NewPeer returns a peer for testing purposes.
 func NewPeer(id discover.NodeID, name string, caps []Cap) *Peer {
 	pipe, _ := net.Pipe()
-	msgpipe, _ := MsgPipe()
-	conn := &conn{msgpipe, &protoHandshake{ID: id, Name: name, Caps: caps}}
-	peer := newPeer(pipe, conn, nil)
+	conn := &conn{fd: pipe, transport: nil, id: id, caps: caps, name: name}
+	peer := newPeer(conn, nil)
 	close(peer.closed) // ensures Disconnect doesn't block
 	return peer
 }
 
 // ID returns the node's public key.
 func (p *Peer) ID() discover.NodeID {
-	return p.rw.ID
+	return p.rw.id
 }
 
 // Name returns the node name that the remote node advertised.
 func (p *Peer) Name() string {
-	return p.rw.Name
+	return p.rw.name
 }
 
 // Caps returns the capabilities (supported subprotocols) of the remote peer.
 func (p *Peer) Caps() []Cap {
 	// TODO: maybe return copy
-	return p.rw.Caps
+	return p.rw.caps
 }
 
 // RemoteAddr returns the remote address of the network connection.
 func (p *Peer) RemoteAddr() net.Addr {
-	return p.conn.RemoteAddr()
+	return p.rw.fd.RemoteAddr()
 }
 
 // LocalAddr returns the local address of the network connection.
 func (p *Peer) LocalAddr() net.Addr {
-	return p.conn.LocalAddr()
+	return p.rw.fd.LocalAddr()
 }
 
 // Disconnect terminates the peer connection with the given reason.
@@ -92,13 +99,12 @@ func (p *Peer) Disconnect(reason DiscReason) {
 
 // String implements fmt.Stringer.
 func (p *Peer) String() string {
-	return fmt.Sprintf("Peer %.8x %v", p.rw.ID[:], p.RemoteAddr())
+	return fmt.Sprintf("Peer %x %v", p.rw.id[:8], p.RemoteAddr())
 }
 
-func newPeer(fd net.Conn, conn *conn, protocols []Protocol) *Peer {
-	protomap := matchProtocols(protocols, conn.Caps, conn)
+func newPeer(conn *conn, protocols []Protocol) *Peer {
+	protomap := matchProtocols(protocols, conn.caps, conn)
 	p := &Peer{
-		conn:     fd,
 		rw:       conn,
 		running:  protomap,
 		disc:     make(chan DiscReason),
@@ -117,7 +123,10 @@ func (p *Peer) run() DiscReason {
 	p.startProtocols()
 
 	// Wait for an error or disconnect.
-	var reason DiscReason
+	var (
+		reason    DiscReason
+		requested bool
+	)
 	select {
 	case err := <-readErr:
 		if r, ok := err.(DiscReason); ok {
@@ -131,23 +140,19 @@ func (p *Peer) run() DiscReason {
 	case err := <-p.protoErr:
 		reason = discReasonForError(err)
 	case reason = <-p.disc:
-		p.politeDisconnect(reason)
+		requested = true
+	}
+	close(p.closed)
+	p.rw.close(reason)
+	p.wg.Wait()
+
+	if requested {
 		reason = DiscRequested
 	}
-
-	close(p.closed)
-	p.wg.Wait()
 	glog.V(logger.Debug).Infof("%v: Disconnected: %v\n", p, reason)
 	return reason
 }
 
-func (p *Peer) politeDisconnect(reason DiscReason) {
-	if reason != DiscNetworkError {
-		SendItems(p.rw, discMsg, uint(reason))
-	}
-	p.conn.Close()
-}
-
 func (p *Peer) pingLoop() {
 	ping := time.NewTicker(pingInterval)
 	defer p.wg.Done()
@@ -254,7 +259,7 @@ func (p *Peer) startProtocols() {
 				glog.V(logger.Detail).Infof("%v: Protocol %s/%d returned\n", p, proto.Name, proto.Version)
 				err = errors.New("protocol returned")
 			} else if err != io.EOF {
-				glog.V(logger.Detail).Infof("%v: Protocol %s/%d error: \n", p, proto.Name, proto.Version, err)
+				glog.V(logger.Detail).Infof("%v: Protocol %s/%d error: %v\n", p, proto.Name, proto.Version, err)
 			}
 			p.protoErr <- err
 			p.wg.Done()