package p2p
import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"net"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
)
// peerAddr is the structure of a peer list element.
// It is also a valid net.Addr.
type peerAddr struct {
IP net.IP
Port uint64
Pubkey []byte // optional
}
func newPeerAddr(addr net.Addr, pubkey []byte) *peerAddr {
n := addr.Network()
if n != "tcp" && n != "tcp4" && n != "tcp6" {
// for testing with non-TCP
return &peerAddr{net.ParseIP("127.0.0.1"), 30303, pubkey}
}
ta := addr.(*net.TCPAddr)
return &peerAddr{ta.IP, uint64(ta.Port), pubkey}
}
func (d peerAddr) Network() string {
if d.IP.To4() != nil {
return "tcp4"
} else {
return "tcp6"
}
}
func (d peerAddr) String() string {
return fmt.Sprintf("%v:%d", d.IP, d.Port)
}
func (d *peerAddr) RlpData() interface{} {
return []interface{}{string(d.IP), d.Port, d.Pubkey}
}
// Peer represents a remote peer.
type Peer struct {
// Peers have all the log methods.
// Use them to display messages related to the peer.
*logger.Logger
infolock sync.Mutex
identity ClientIdentity
caps []Cap
listenAddr *peerAddr // what remote peer is listening on
dialAddr *peerAddr // non-nil if dialing
// The mutex protects the connection
// so only one protocol can write at a time.
writeMu sync.Mutex
conn net.Conn
bufconn *bufio.ReadWriter
// These fields maintain the running protocols.
protocols []Protocol
runBaseProtocol bool // for testing
cryptoHandshake bool // for testing
runlock sync.RWMutex // protects running
running map[string]*proto
protoWG sync.WaitGroup
protoErr chan error
closed chan struct{}
disc chan DiscReason
activity event.TypeMux // for activity events
slot int // index into Server peer list
// These fields are kept so base protocol can access them.
// TODO: this should be one or more interfaces
ourID ClientIdentity // client id of the Server
ourListenAddr *peerAddr // listen addr of Server, nil if not listening
newPeerAddr chan<- *peerAddr // tell server about received peers
otherPeers func() []*Peer // should return the list of all peers
pubkeyHook func(*peerAddr) error // called at end of handshake to validate pubkey
}
// NewPeer returns a peer for testing purposes.
func NewPeer(id ClientIdentity, caps []Cap) *Peer {
conn, _ := net.Pipe()
peer := newPeer(conn, nil, nil)
peer.setHandshakeInfo(id, nil, caps)
close(peer.closed)
return peer
}
func newServerPeer(server *Server, conn net.Conn, dialAddr *peerAddr) *Peer {
p := newPeer(conn, server.Protocols, dialAddr)
p.ourID = server.Identity
p.newPeerAddr = server.peerConnect
p.otherPeers = server.Peers
p.pubkeyHook = server.verifyPeer
p.runBaseProtocol = true
// laddr can be updated concurrently by NAT traversal.
// newServerPeer must be called with the server lock held.
if server.laddr != nil {
p.ourListenAddr = newPeerAddr(server.laddr, server.Identity.Pubkey())
}
return p
}
func newPeer(conn net.Conn, protocols []Protocol, dialAddr *peerAddr) *Peer {
p := &Peer{
Logger: logger.NewLogger("P2P " + conn.RemoteAddr().String()),
conn: conn,
dialAddr: dialAddr,
bufconn: bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn)),
protocols: protocols,
running: make(map[string]*proto),
disc: make(chan DiscReason),
protoErr: make(chan error),
closed: make(chan struct{}),
}
return p
}
// Identity returns the client identity of the remote peer. The
// identity can be nil if the peer has not yet completed the
// handshake.
func (p *Peer) Identity() ClientIdentity {
p.infolock.Lock()
defer p.infolock.Unlock()
return p.identity
}
func (self *Peer) Pubkey() (pubkey []byte) {
self.infolock.Lock()
defer self.infolock.Unlock()
switch {
case self.identity != nil:
pubkey = self.identity.Pubkey()
case self.dialAddr != nil:
pubkey = self.dialAddr.Pubkey
case self.listenAddr != nil:
pubkey = self.listenAddr.Pubkey
}
return
}
// Caps returns the capabilities (supported subprotocols) of the remote peer.
func (p *Peer) Caps() []Cap {
p.infolock.Lock()
defer p.infolock.Unlock()
return p.caps
}
func (p *Peer) setHandshakeInfo(id ClientIdentity, laddr *peerAddr, caps []Cap) {
p.infolock.Lock()
p.identity = id
p.listenAddr = laddr
p.caps = caps
p.infolock.Unlock()
}
// RemoteAddr returns the remote address of the network connection.
func (p *Peer) RemoteAddr() net.Addr {
return p.conn.RemoteAddr()
}
// LocalAddr returns the local address of the network connection.
func (p *Peer) LocalAddr() net.Addr {
return p.conn.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 {
kind := "inbound"
p.infolock.Lock()
if p.dialAddr != nil {
kind = "outbound"
}
p.infolock.Unlock()
return fmt.Sprintf("Peer(%p %v %s)", p, p.conn.RemoteAddr(), kind)
}
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
)
var (
inactivityTimeout = 2 * time.Second
disconnectGracePeriod = 2 * time.Second
)
func (p *Peer) loop() (reason DiscReason, err error) {
defer p.activity.Stop()
defer p.closeProtocols()
defer close(p.closed)
defer p.conn.Close()
var readLoop func(chan<- Msg, chan<- error, <-chan bool)
if p.cryptoHandshake {
if readLoop, err = p.handleCryptoHandshake(); err != nil {
// from here on everything can be encrypted, authenticated
return DiscProtocolError, err // no graceful disconnect
}
} else {
readLoop = p.readLoop
}
// read loop
readMsg := make(chan Msg)
readErr := make(chan error)
readNext := make(chan bool, 1)
protoDone := make(chan struct{}, 1)
go readLoop(readMsg, readErr, readNext)
readNext <- true
if p.runBaseProtocol {
p.startBaseProtocol()
}
loop:
for {
select {
case msg := <-readMsg:
// a new message has arrived.
var wait bool
if wait, err = p.dispatch(msg, protoDone); err != nil {
p.Errorf("msg dispatch error: %v\n", err)
reason = discReasonForError(err)
break loop
}
if !wait {
// Msg has already been read completely, continue with next message.
readNext <- true
}
p.activity.Post(time.Now())
case <-protoDone:
// protocol has consumed the message payload,
// we can continue reading from the socket.
readNext <- true
case err := <-readErr:
// read failed. there is no need to run the
// polite disconnect sequence because the connection
// is probably dead anyway.
// TODO: handle write errors as well
return DiscNetworkError, err
case err = <-p.protoErr:
reason = discReasonForError(err)
break loop
case reason = <-p.disc:
break loop
}
}
// wait for read loop to return.
close(readNext)
<-readErr
// tell the remote end to disconnect
done := make(chan struct{})
go func() {
p.conn.SetDeadline(time.Now().Add(disconnectGracePeriod))
p.writeMsg(NewMsg(discMsg, reason), disconnectGracePeriod)
io.Copy(ioutil.Discard, p.conn)
close(done)
}()
select {
case <-done:
case <-time.After(disconnectGracePeriod):
}
return reason, err
}
func (p *Peer) readLoop(msgc chan<- Msg, errc chan<- error, unblock <-chan bool) {
for _ = range unblock {
p.conn.SetReadDeadline(time.Now().Add(msgReadTimeout))
if msg, err := readMsg(p.bufconn); err != nil {
errc <- err
} else {
msgc <- msg
}
}
close(errc)
}
func (p *Peer) dispatch(msg Msg, protoDone chan struct{}) (wait bool, err error) {
proto, err := p.getProto(msg.Code)
if err != nil {
return false, err
}
if msg.Size <= wholePayloadSize {
// optimization: msg is small enough, read all
// of it and move on to the next message
buf, err := ioutil.ReadAll(msg.Payload)
if err != nil {
return false, err
}
msg.Payload = bytes.NewReader(buf)
proto.in <- msg
} else {
wait = true
pr := &eofSignal{msg.Payload, int64(msg.Size), protoDone}
msg.Payload = pr
proto.in <- msg
}
return wait, nil
}
type readLoop func(chan<- Msg, chan<- error, <-chan bool)
func (p *Peer) handleCryptoHandshake() (loop readLoop, err error) {
// cryptoId is just created for the lifecycle of the handshake
// it is survived by an encrypted readwriter
var initiator bool
var sessionToken []byte
if p.dialAddr != nil { // this should have its own method Outgoing() bool
initiator = true
}
// create crypto layer
// this could in principle run only once but maybe we want to allow
// identity switching
var crypto *cryptoId
if crypto, err = newCryptoId(p.ourID); err != nil {
return
}
// run on peer
// this bit handles the handshake and creates a secure communications channel with
// var rw *secretRW
if sessionToken, _, err = crypto.Run(p.conn, p.Pubkey(), sessionToken, initiator); err != nil {
return
}
loop = func(msg chan<- Msg, err chan<- error, next <-chan bool) {
// this is the readloop :)
}
return
}
func (p *Peer) startBaseProtocol() {
p.runlock.Lock()
defer p.runlock.Unlock()
p.running[""] = p.startProto(0, Protocol{
Length: baseProtocolLength,
Run: runBaseProtocol,
})
}
// 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 {
rw := &proto{
in: make(chan Msg),
offset: offset,
maxcode: impl.Length,
peer: p,
}
p.protoWG.Add(1)
go func() {
err := impl.Run(p, rw)
if err == nil {
p.Infof("protocol %q returned", impl.Name)
err = newPeerError(errMisc, "protocol returned")
} else {
p.Errorf("protocol %q error: %v\n", impl.Name, 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.
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.writeMsg(msg, msgWriteTimeout)
}
// writeMsg writes a message to the connection.
func (p *Peer) writeMsg(msg Msg, timeout time.Duration) error {
p.writeMu.Lock()
defer p.writeMu.Unlock()
p.conn.SetWriteDeadline(time.Now().Add(timeout))
if err := writeMsg(p.bufconn, msg); err != nil {
return newPeerError(errWrite, "%v", err)
}
return p.bufconn.Flush()
}
type proto struct {
name string
in chan Msg
maxcode, offset uint64
peer *Peer
}
func (rw *proto) WriteMsg(msg Msg) error {
if msg.Code >= rw.maxcode {
return newPeerError(errInvalidMsgCode, "not handled")
}
msg.Code += rw.offset
return rw.peer.writeMsg(msg, msgWriteTimeout)
}
func (rw *proto) EncodeMsg(code uint64, data ...interface{}) error {
return rw.WriteMsg(NewMsg(code, data...))
}
func (rw *proto) ReadMsg() (Msg, error) {
msg, ok := <-rw.in
if !ok {
return msg, io.EOF
}
msg.Code -= rw.offset
return msg, nil
}
// eofSignal wraps a reader with eof signaling. the eof channel is
// closed when the wrapped reader returns an error or when count bytes
// have been read.
//
type eofSignal struct {
wrapped io.Reader
count int64
eof chan<- struct{}
}
// note: when using eofSignal to detect whether a message payload
// has been read, Read might not be called for zero sized messages.
func (r *eofSignal) Read(buf []byte) (int, error) {
n, err := r.wrapped.Read(buf)
r.count -= int64(n)
if (err != nil || r.count <= 0) && r.eof != nil {
r.eof <- struct{}{} // tell Peer that msg has been consumed
r.eof = nil
}
return n, err
}
