294 lines
6.8 KiB
Go
294 lines
6.8 KiB
Go
package p2p
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import (
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"net"
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"sort"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/p2p/discover"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const (
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baseProtocolVersion = 3
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baseProtocolLength = uint64(16)
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baseProtocolMaxMsgSize = 10 * 1024 * 1024
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disconnectGracePeriod = 2 * time.Second
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)
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const (
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// devp2p message codes
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handshakeMsg = 0x00
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discMsg = 0x01
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pingMsg = 0x02
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pongMsg = 0x03
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getPeersMsg = 0x04
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peersMsg = 0x05
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)
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// Peer represents a connected remote node.
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type Peer struct {
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// Peers have all the log methods.
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// Use them to display messages related to the peer.
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*logger.Logger
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rw *conn
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running map[string]*protoRW
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protoWG sync.WaitGroup
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protoErr chan error
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closed chan struct{}
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disc chan DiscReason
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}
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// NewPeer returns a peer for testing purposes.
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func NewPeer(id discover.NodeID, name string, caps []Cap) *Peer {
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pipe, _ := net.Pipe()
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conn := newConn(pipe, &protoHandshake{ID: id, Name: name, Caps: caps})
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peer := newPeer(conn, nil)
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close(peer.closed) // ensures Disconnect doesn't block
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return peer
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}
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// ID returns the node's public key.
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func (p *Peer) ID() discover.NodeID {
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return p.rw.ID
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}
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// Name returns the node name that the remote node advertised.
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func (p *Peer) Name() string {
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return p.rw.Name
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}
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// Caps returns the capabilities (supported subprotocols) of the remote peer.
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func (p *Peer) Caps() []Cap {
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// TODO: maybe return copy
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return p.rw.Caps
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}
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// RemoteAddr returns the remote address of the network connection.
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func (p *Peer) RemoteAddr() net.Addr {
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return p.rw.RemoteAddr()
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}
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// LocalAddr returns the local address of the network connection.
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func (p *Peer) LocalAddr() net.Addr {
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return p.rw.LocalAddr()
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}
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// Disconnect terminates the peer connection with the given reason.
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// It returns immediately and does not wait until the connection is closed.
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func (p *Peer) Disconnect(reason DiscReason) {
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select {
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case p.disc <- reason:
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case <-p.closed:
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}
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}
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// String implements fmt.Stringer.
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func (p *Peer) String() string {
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return fmt.Sprintf("Peer %.8x %v", p.rw.ID[:], p.RemoteAddr())
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}
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func newPeer(conn *conn, protocols []Protocol) *Peer {
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logtag := fmt.Sprintf("Peer %.8x %v", conn.ID[:], conn.RemoteAddr())
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p := &Peer{
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Logger: logger.NewLogger(logtag),
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rw: conn,
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running: matchProtocols(protocols, conn.Caps, conn),
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disc: make(chan DiscReason),
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protoErr: make(chan error),
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closed: make(chan struct{}),
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}
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return p
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}
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func (p *Peer) run() DiscReason {
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var readErr = make(chan error, 1)
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defer p.closeProtocols()
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defer close(p.closed)
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p.startProtocols()
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go func() { readErr <- p.readLoop() }()
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// Wait for an error or disconnect.
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var reason DiscReason
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select {
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case err := <-readErr:
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// We rely on protocols to abort if there is a write error. It
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// might be more robust to handle them here as well.
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p.DebugDetailf("Read error: %v\n", err)
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p.rw.Close()
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return DiscNetworkError
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case err := <-p.protoErr:
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reason = discReasonForError(err)
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case reason = <-p.disc:
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}
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p.politeDisconnect(reason)
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// Wait for readLoop. It will end because conn is now closed.
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<-readErr
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p.Debugf("Disconnected: %v\n", reason)
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return reason
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}
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func (p *Peer) politeDisconnect(reason DiscReason) {
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done := make(chan struct{})
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go func() {
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EncodeMsg(p.rw, discMsg, uint(reason))
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// Wait for the other side to close the connection.
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// Discard any data that they send until then.
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io.Copy(ioutil.Discard, p.rw)
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close(done)
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}()
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select {
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case <-done:
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case <-time.After(disconnectGracePeriod):
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}
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p.rw.Close()
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}
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func (p *Peer) readLoop() error {
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for {
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msg, err := p.rw.ReadMsg()
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if err != nil {
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return err
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}
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if err = p.handle(msg); err != nil {
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return err
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}
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}
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return nil
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}
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func (p *Peer) handle(msg Msg) error {
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switch {
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case msg.Code == pingMsg:
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msg.Discard()
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go EncodeMsg(p.rw, pongMsg)
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case msg.Code == discMsg:
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var reason DiscReason
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// no need to discard or for error checking, we'll close the
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// connection after this.
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rlp.Decode(msg.Payload, &reason)
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p.Disconnect(DiscRequested)
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return discRequestedError(reason)
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case msg.Code < baseProtocolLength:
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// ignore other base protocol messages
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return msg.Discard()
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default:
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// it's a subprotocol message
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proto, err := p.getProto(msg.Code)
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if err != nil {
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return fmt.Errorf("msg code out of range: %v", msg.Code)
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}
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proto.in <- msg
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}
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return nil
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}
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// matchProtocols creates structures for matching named subprotocols.
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func matchProtocols(protocols []Protocol, caps []Cap, rw MsgReadWriter) map[string]*protoRW {
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sort.Sort(capsByName(caps))
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offset := baseProtocolLength
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result := make(map[string]*protoRW)
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outer:
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for _, cap := range caps {
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for _, proto := range protocols {
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if proto.Name == cap.Name && proto.Version == cap.Version && result[cap.Name] == nil {
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result[cap.Name] = &protoRW{Protocol: proto, offset: offset, in: make(chan Msg), w: rw}
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offset += proto.Length
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continue outer
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}
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}
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}
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return result
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}
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func (p *Peer) startProtocols() {
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for _, proto := range p.running {
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proto := proto
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p.DebugDetailf("Starting protocol %s/%d\n", proto.Name, proto.Version)
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p.protoWG.Add(1)
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go func() {
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err := proto.Run(p, proto)
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if err == nil {
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p.DebugDetailf("Protocol %s/%d returned\n", proto.Name, proto.Version)
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err = errors.New("protocol returned")
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} else {
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p.DebugDetailf("Protocol %s/%d error: %v\n", proto.Name, proto.Version, err)
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}
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select {
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case p.protoErr <- err:
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case <-p.closed:
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}
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p.protoWG.Done()
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}()
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}
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}
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// getProto finds the protocol responsible for handling
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// the given message code.
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func (p *Peer) getProto(code uint64) (*protoRW, error) {
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for _, proto := range p.running {
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if code >= proto.offset && code < proto.offset+proto.Length {
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return proto, nil
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}
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}
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return nil, newPeerError(errInvalidMsgCode, "%d", code)
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}
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func (p *Peer) closeProtocols() {
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for _, p := range p.running {
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close(p.in)
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}
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p.protoWG.Wait()
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}
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// writeProtoMsg sends the given message on behalf of the given named protocol.
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// this exists because of Server.Broadcast.
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func (p *Peer) writeProtoMsg(protoName string, msg Msg) error {
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proto, ok := p.running[protoName]
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if !ok {
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return fmt.Errorf("protocol %s not handled by peer", protoName)
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}
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if msg.Code >= proto.Length {
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return newPeerError(errInvalidMsgCode, "code %x is out of range for protocol %q", msg.Code, protoName)
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}
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msg.Code += proto.offset
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return p.rw.WriteMsg(msg)
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}
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type protoRW struct {
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Protocol
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in chan Msg
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offset uint64
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w MsgWriter
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}
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func (rw *protoRW) WriteMsg(msg Msg) error {
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if msg.Code >= rw.Length {
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return newPeerError(errInvalidMsgCode, "not handled")
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}
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msg.Code += rw.offset
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return rw.w.WriteMsg(msg)
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}
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func (rw *protoRW) ReadMsg() (Msg, error) {
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msg, ok := <-rw.in
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if !ok {
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return msg, io.EOF
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}
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msg.Code -= rw.offset
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return msg, nil
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}
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