// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package p2p
import (
"errors"
"fmt"
"io"
"net"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/rlp"
)
const (
baseProtocolVersion = 4
baseProtocolLength = uint64(16)
baseProtocolMaxMsgSize = 2 * 1024
pingInterval = 15 * time.Second
)
const (
// devp2p message codes
handshakeMsg = 0x00
discMsg = 0x01
pingMsg = 0x02
pongMsg = 0x03
getPeersMsg = 0x04
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
// Ignore additional fields (for forward compatibility).
Rest []rlp.RawValue `rlp:"tail"`
}
// Peer represents a connected remote node.
type Peer struct {
rw *conn
running map[string]*protoRW
wg 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 {
pipe, _ := net.Pipe()
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
}
// Name returns the node name that the remote node advertised.
func (p *Peer) Name() string {
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
}
// RemoteAddr returns the remote address of the network connection.
func (p *Peer) RemoteAddr() net.Addr {
return p.rw.fd.RemoteAddr()
}
// LocalAddr returns the local address of the network connection.
func (p *Peer) LocalAddr() net.Addr {
return p.rw.fd.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 %x %v", p.rw.id[:8], p.RemoteAddr())
}
func newPeer(conn *conn, protocols []Protocol) *Peer {
protomap := matchProtocols(protocols, conn.caps, conn)
p := &Peer{
rw: conn,
running: protomap,
disc: make(chan DiscReason),
protoErr: make(chan error, len(protomap)+1), // protocols + pingLoop
closed: make(chan struct{}),
}
return p
}
func (p *Peer) run() DiscReason {
var (
writeStart = make(chan struct{}, 1)
writeErr = make(chan error, 1)
readErr = make(chan error, 1)
reason DiscReason
requested bool
)
p.wg.Add(2)
go p.readLoop(readErr)
go p.pingLoop()
// Start all protocol handlers.
writeStart <- struct{}{}
p.startProtocols(writeStart, writeErr)
// Wait for an error or disconnect.
loop:
for {
select {
case err := <-writeErr:
// A write finished. Allow the next write to start if
// there was no error.
if err != nil {
log.Trace(fmt.Sprintf("%v: write error: %v", p, err))
reason = DiscNetworkError
break loop
}
writeStart <- struct{}{}
case err := <-readErr:
if r, ok := err.(DiscReason); ok {
log.Debug(fmt.Sprintf("%v: remote requested disconnect: %v", p, r))
requested = true
reason = r
} else {
log.Trace(fmt.Sprintf("%v: read error: %v", p, err))
reason = DiscNetworkError
}
break loop
case err := <-p.protoErr:
reason = discReasonForError(err)
log.Debug(fmt.Sprintf("%v: protocol error: %v (%v)", p, err, reason))
break loop
case reason = <-p.disc:
log.Debug(fmt.Sprintf("%v: locally requested disconnect: %v", p, reason))
break loop
}
}
close(p.closed)
p.rw.close(reason)
p.wg.Wait()
if requested {
reason = DiscRequested
}
return reason
}
func (p *Peer) pingLoop() {
ping := time.NewTicker(pingInterval)
defer p.wg.Done()
defer ping.Stop()
for {
select {
case <-ping.C:
if err := SendItems(p.rw, pingMsg); err != nil {
p.protoErr <- err
return
}
case <-p.closed:
return
}
}
}
func (p *Peer) readLoop(errc chan<- error) {
defer p.wg.Done()
for {
msg, err := p.rw.ReadMsg()
if err != nil {
errc <- err
return
}
msg.ReceivedAt = time.Now()
if err = p.handle(msg); err != nil {
errc <- err
return
}
}
}
func (p *Peer) handle(msg Msg) error {
switch {
case msg.Code == pingMsg:
msg.Discard()
go SendItems(p.rw, pongMsg)
case msg.Code == discMsg:
var reason [1]DiscReason
// This is the last message. We don't need to discard or
// check errors because, the connection will be closed after it.
rlp.Decode(msg.Payload, &reason)
return reason[0]
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)
}
select {
case proto.in <- msg:
return nil
case <-p.closed:
return io.EOF
}
}
return nil
}
func countMatchingProtocols(protocols []Protocol, caps []Cap) int {
n := 0
for _, cap := range caps {
for _, proto := range protocols {
if proto.Name == cap.Name && proto.Version == cap.Version {
n++
}
}
}
return n
}
// matchProtocols creates structures for matching named subprotocols.
func matchProtocols(protocols []Protocol, caps []Cap, rw MsgReadWriter) map[string]*protoRW {
sort.Sort(capsByNameAndVersion(caps))
offset := baseProtocolLength
result := make(map[string]*protoRW)
outer:
for _, cap := range caps {
for _, proto := range protocols {
if proto.Name == cap.Name && proto.Version == cap.Version {
// If an old protocol version matched, revert it
if old := result[cap.Name]; old != nil {
offset -= old.Length
}
// Assign the new match
result[cap.Name] = &protoRW{Protocol: proto, offset: offset, in: make(chan Msg), w: rw}
offset += proto.Length
continue outer
}
}
}
return result
}
func (p *Peer) startProtocols(writeStart <-chan struct{}, writeErr chan<- error) {
p.wg.Add(len(p.running))
for _, proto := range p.running {
proto := proto
proto.closed = p.closed
proto.wstart = writeStart
proto.werr = writeErr
log.Trace(fmt.Sprintf("%v: Starting protocol %s/%d", p, proto.Name, proto.Version))
go func() {
err := proto.Run(p, proto)
if err == nil {
log.Trace(fmt.Sprintf("%v: Protocol %s/%d returned", p, proto.Name, proto.Version))
err = errors.New("protocol returned")
} else if err != io.EOF {
log.Trace(fmt.Sprintf("%v: Protocol %s/%d error: %v", p, proto.Name, proto.Version, err))
}
p.protoErr <- err
p.wg.Done()
}()
}
}
// getProto finds the protocol responsible for handling
// the given message code.
func (p *Peer) getProto(code uint64) (*protoRW, error) {
for _, proto := range p.running {
if code >= proto.offset && code < proto.offset+proto.Length {
return proto, nil
}
}
return nil, newPeerError(errInvalidMsgCode, "%d", code)
}
type protoRW struct {
Protocol
in chan Msg // receices read messages
closed <-chan struct{} // receives when peer is shutting down
wstart <-chan struct{} // receives when write may start
werr chan<- error // for write results
offset uint64
w MsgWriter
}
func (rw *protoRW) WriteMsg(msg Msg) (err error) {
if msg.Code >= rw.Length {
return newPeerError(errInvalidMsgCode, "not handled")
}
msg.Code += rw.offset
select {
case <-rw.wstart:
err = rw.w.WriteMsg(msg)
// Report write status back to Peer.run. It will initiate
// shutdown if the error is non-nil and unblock the next write
// otherwise. The calling protocol code should exit for errors
// as well but we don't want to rely on that.
rw.werr <- err
case <-rw.closed:
err = fmt.Errorf("shutting down")
}
return err
}
func (rw *protoRW) ReadMsg() (Msg, error) {
select {
case msg := <-rw.in:
msg.Code -= rw.offset
return msg, nil
case <-rw.closed:
return Msg{}, io.EOF
}
}
// PeerInfo represents a short summary of the information known about a connected
// peer. Sub-protocol independent fields are contained and initialized here, with
// protocol specifics delegated to all connected sub-protocols.
type PeerInfo struct {
ID string `json:"id"` // Unique node identifier (also the encryption key)
Name string `json:"name"` // Name of the node, including client type, version, OS, custom data
Caps []string `json:"caps"` // Sum-protocols advertised by this particular peer
Network struct {
LocalAddress string `json:"localAddress"` // Local endpoint of the TCP data connection
RemoteAddress string `json:"remoteAddress"` // Remote endpoint of the TCP data connection
} `json:"network"`
Protocols map[string]interface{} `json:"protocols"` // Sub-protocol specific metadata fields
}
// Info gathers and returns a collection of metadata known about a peer.
func (p *Peer) Info() *PeerInfo {
// Gather the protocol capabilities
var caps []string
for _, cap := range p.Caps() {
caps = append(caps, cap.String())
}
// Assemble the generic peer metadata
info := &PeerInfo{
ID: p.ID().String(),
Name: p.Name(),
Caps: caps,
Protocols: make(map[string]interface{}),
}
info.Network.LocalAddress = p.LocalAddr().String()
info.Network.RemoteAddress = p.RemoteAddr().String()
// Gather all the running protocol infos
for _, proto := range p.running {
protoInfo := interface{}("unknown")
if query := proto.Protocol.PeerInfo; query != nil {
if metadata := query(p.ID()); metadata != nil {
protoInfo = metadata
} else {
protoInfo = "handshake"
}
}
info.Protocols[proto.Name] = protoInfo
}
return info
}
