package p2p
import (
"fmt"
"io"
"io/ioutil"
"net"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/rlp"
)
const (
// maximum amount of time allowed for reading a message
msgReadTimeout = 5 * time.Second
// maximum amount of time allowed for writing a message
msgWriteTimeout = 5 * time.Second
// messages smaller than this many bytes will be read at
// once before passing them to a protocol.
wholePayloadSize = 64 * 1024
disconnectGracePeriod = 2 * time.Second
)
const (
baseProtocolVersion = 2
baseProtocolLength = uint64(16)
baseProtocolMaxMsgSize = 10 * 1024 * 1024
)
const (
// devp2p message codes
handshakeMsg = 0x00
discMsg = 0x01
pingMsg = 0x02
pongMsg = 0x03
getPeersMsg = 0x04
peersMsg = 0x05
)
// handshake is the RLP structure of the protocol handshake.
type handshake struct {
Version uint64
Name string
Caps []Cap
ListenPort uint64
NodeID discover.NodeID
}
// Peer represents a connected remote node.
type Peer struct {
// Peers have all the log methods.
// Use them to display messages related to the peer.
*logger.Logger
infoMu sync.Mutex
name string
caps []Cap
ourID, remoteID *discover.NodeID
ourName string
rw *frameRW
// These fields maintain the running protocols.
protocols []Protocol
runlock sync.RWMutex // protects running
running map[string]*proto
protocolHandshakeEnabled bool
protoWG sync.WaitGroup
protoErr chan error
closed chan struct{}
disc chan DiscReason
}
// NewPeer returns a peer for testing purposes.
func NewPeer(id discover.NodeID, name string, caps []Cap) *Peer {
conn, _ := net.Pipe()
peer := newPeer(conn, nil, "", nil, &id)
peer.setHandshakeInfo(name, caps)
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.remoteID
}
// Name returns the node name that the remote node advertised.
func (p *Peer) Name() string {
// this needs a lock because the information is part of the
// protocol handshake.
p.infoMu.Lock()
name := p.name
p.infoMu.Unlock()
return name
}
// Caps returns the capabilities (supported subprotocols) of the remote peer.
func (p *Peer) Caps() []Cap {
// this needs a lock because the information is part of the
// protocol handshake.
p.infoMu.Lock()
caps := p.caps
p.infoMu.Unlock()
return caps
}
// RemoteAddr returns the remote address of the network connection.
func (p *Peer) RemoteAddr() net.Addr {
return p.rw.RemoteAddr()
}
// LocalAddr returns the local address of the network connection.
func (p *Peer) LocalAddr() net.Addr {
return p.rw.LocalAddr()
}
// Disconnect terminates the peer connection with the given reason.
// It returns immediately and does not wait until the connection is closed.
func (p *Peer) Disconnect(reason DiscReason) {
select {
case p.disc <- reason:
case <-p.closed:
}
}
// String implements fmt.Stringer.
func (p *Peer) String() string {
return fmt.Sprintf("Peer %.8x %v", p.remoteID, p.RemoteAddr())
}
func newPeer(conn net.Conn, protocols []Protocol, ourName string, ourID, remoteID *discover.NodeID) *Peer {
logtag := fmt.Sprintf("Peer %.8x %v", remoteID, conn.RemoteAddr())
return &Peer{
Logger: logger.NewLogger(logtag),
rw: newFrameRW(conn, msgWriteTimeout),
ourID: ourID,
ourName: ourName,
remoteID: remoteID,
protocols: protocols,
running: make(map[string]*proto),
disc: make(chan DiscReason),
protoErr: make(chan error),
closed: make(chan struct{}),
}
}
func (p *Peer) setHandshakeInfo(name string, caps []Cap) {
p.infoMu.Lock()
p.name = name
p.caps = caps
p.infoMu.Unlock()
}
func (p *Peer) run() DiscReason {
var readErr = make(chan error, 1)
defer p.closeProtocols()
defer close(p.closed)
defer p.rw.Close()
// start the read loop
go func() { readErr <- p.readLoop() }()
if p.protocolHandshakeEnabled {
if err := writeProtocolHandshake(p.rw, p.ourName, *p.ourID, p.protocols); err != nil {
p.DebugDetailf("Protocol handshake error: %v\n", err)
return DiscProtocolError
}
}
// wait for an error or disconnect
var reason DiscReason
select {
case err := <-readErr:
// We rely on protocols to abort if there is a write error. It
// might be more robust to handle them here as well.
p.DebugDetailf("Read error: %v\n", err)
reason = DiscNetworkError
case err := <-p.protoErr:
reason = discReasonForError(err)
case reason = <-p.disc:
}
if reason != DiscNetworkError {
p.politeDisconnect(reason)
}
p.Debugf("Disconnected: %v\n", reason)
return reason
}
func (p *Peer) politeDisconnect(reason DiscReason) {
done := make(chan struct{})
go func() {
// send reason
EncodeMsg(p.rw, discMsg, uint(reason))
// discard any data that might arrive
io.Copy(ioutil.Discard, p.rw)
close(done)
}()
select {
case <-done:
case <-time.After(disconnectGracePeriod):
}
}
func (p *Peer) readLoop() error {
if p.protocolHandshakeEnabled {
if err := readProtocolHandshake(p, p.rw); err != nil {
return err
}
}
for {
msg, err := p.rw.ReadMsg()
if err != nil {
return err
}
if err = p.handle(msg); err != nil {
return err
}
}
return nil
}
func (p *Peer) handle(msg Msg) error {
switch {
case msg.Code == pingMsg:
msg.Discard()
go EncodeMsg(p.rw, pongMsg)
case msg.Code == discMsg:
var reason DiscReason
// no need to discard or for error checking, we'll close the
// connection after this.
rlp.Decode(msg.Payload, &reason)
p.Disconnect(DiscRequested)
return discRequestedError(reason)
case msg.Code < baseProtocolLength:
// ignore other base protocol messages
return msg.Discard()
default:
// it's a subprotocol message
proto, err := p.getProto(msg.Code)
if err != nil {
return fmt.Errorf("msg code out of range: %v", msg.Code)
}
proto.in <- msg
}
return nil
}
func readProtocolHandshake(p *Peer, rw MsgReadWriter) error {
// read and handle remote handshake
msg, err := rw.ReadMsg()
if err != nil {
return err
}
if msg.Code != handshakeMsg {
return newPeerError(errProtocolBreach, "expected handshake, got %x", msg.Code)
}
if msg.Size > baseProtocolMaxMsgSize {
return newPeerError(errMisc, "message too big")
}
var hs handshake
if err := msg.Decode(&hs); err != nil {
return err
}
// validate handshake info
if hs.Version != baseProtocolVersion {
return newPeerError(errP2PVersionMismatch, "required version %d, received %d\n",
baseProtocolVersion, hs.Version)
}
if hs.NodeID == *p.remoteID {
return newPeerError(errPubkeyForbidden, "node ID mismatch")
}
// TODO: remove Caps with empty name
p.setHandshakeInfo(hs.Name, hs.Caps)
p.startSubprotocols(hs.Caps)
return nil
}
func writeProtocolHandshake(w MsgWriter, name string, id discover.NodeID, ps []Protocol) error {
var caps []interface{}
for _, proto := range ps {
caps = append(caps, proto.cap())
}
return EncodeMsg(w, handshakeMsg, baseProtocolVersion, name, caps, 0, id)
}
// startProtocols starts matching named subprotocols.
func (p *Peer) startSubprotocols(caps []Cap) {
sort.Sort(capsByName(caps))
p.runlock.Lock()
defer p.runlock.Unlock()
offset := baseProtocolLength
outer:
for _, cap := range caps {
for _, proto := range p.protocols {
if proto.Name == cap.Name &&
proto.Version == cap.Version &&
p.running[cap.Name] == nil {
p.running[cap.Name] = p.startProto(offset, proto)
offset += proto.Length
continue outer
}
}
}
}
func (p *Peer) startProto(offset uint64, impl Protocol) *proto {
p.DebugDetailf("Starting protocol %s/%d\n", impl.Name, impl.Version)
rw := &proto{
name: impl.Name,
in: make(chan Msg),
offset: offset,
maxcode: impl.Length,
w: p.rw,
}
p.protoWG.Add(1)
go func() {
err := impl.Run(p, rw)
if err == nil {
p.DebugDetailf("Protocol %s/%d returned\n", impl.Name, impl.Version)
err = newPeerError(errMisc, "protocol returned")
} else {
p.DebugDetailf("Protocol %s/%d error: %v\n", impl.Name, impl.Version, err)
}
select {
case p.protoErr <- err:
case <-p.closed:
}
p.protoWG.Done()
}()
return rw
}
// getProto finds the protocol responsible for handling
// the given message code.
func (p *Peer) getProto(code uint64) (*proto, error) {
p.runlock.RLock()
defer p.runlock.RUnlock()
for _, proto := range p.running {
if code >= proto.offset && code < proto.offset+proto.maxcode {
return proto, nil
}
}
return nil, newPeerError(errInvalidMsgCode, "%d", code)
}
func (p *Peer) closeProtocols() {
p.runlock.RLock()
for _, p := range p.running {
close(p.in)
}
p.runlock.RUnlock()
p.protoWG.Wait()
}
// writeProtoMsg sends the given message on behalf of the given named protocol.
// this exists because of Server.Broadcast.
func (p *Peer) writeProtoMsg(protoName string, msg Msg) error {
p.runlock.RLock()
proto, ok := p.running[protoName]
p.runlock.RUnlock()
if !ok {
return fmt.Errorf("protocol %s not handled by peer", protoName)
}
if msg.Code >= proto.maxcode {
return newPeerError(errInvalidMsgCode, "code %x is out of range for protocol %q", msg.Code, protoName)
}
msg.Code += proto.offset
return p.rw.WriteMsg(msg)
}
type proto struct {
name string
in chan Msg
maxcode, offset uint64
w MsgWriter
}
func (rw *proto) WriteMsg(msg Msg) error {
if msg.Code >= rw.maxcode {
return newPeerError(errInvalidMsgCode, "not handled")
}
msg.Code += rw.offset
return rw.w.WriteMsg(msg)
}
func (rw *proto) ReadMsg() (Msg, error) {
msg, ok := <-rw.in
if !ok {
return msg, io.EOF
}
msg.Code -= rw.offset
return msg, nil
}
