p2p: fix decoding of disconnect reason

p2p/message.go

@@ -3,9 +3,11 @@ package p2p
 import (
  "bytes"
  "encoding/binary"
+ "errors"
  "io"
  "io/ioutil"
  "math/big"
+ "sync/atomic"
 
  "github.com/ethereum/go-ethereum/ethutil"
  "github.com/ethereum/go-ethereum/rlp"
@@ -153,3 +155,78 @@ func (r *postrack) ReadByte() (byte, error) {
  }
  return b, err
 }
+
+// MsgPipe creates a message pipe. Reads on one end are matched
+// with writes on the other. The pipe is full-duplex, both ends
+// implement MsgReadWriter.
+func MsgPipe() (*MsgPipeRW, *MsgPipeRW) {
+ var (
+ c1, c2 = make(chan Msg), make(chan Msg)
+ closing = make(chan struct{})
+ closed = new(int32)
+ rw1 = &MsgPipeRW{c1, c2, closing, closed}
+ rw2 = &MsgPipeRW{c2, c1, closing, closed}
+ )
+ return rw1, rw2
+}
+
+// ErrPipeClosed is returned from pipe operations after the
+// pipe has been closed.
+var ErrPipeClosed = errors.New("p2p: read or write on closed message pipe")
+
+// MsgPipeRW is an endpoint of a MsgReadWriter pipe.
+type MsgPipeRW struct {
+ w chan<- Msg
+ r <-chan Msg
+ closing chan struct{}
+ closed *int32
+}
+
+// WriteMsg sends a messsage on the pipe.
+// It blocks until the receiver has consumed the message payload.
+func (p *MsgPipeRW) WriteMsg(msg Msg) error {
+ if atomic.LoadInt32(p.closed) == 0 {
+ consumed := make(chan struct{}, 1)
+ msg.Payload = &eofSignal{msg.Payload, int64(msg.Size), consumed}
+ select {
+ case p.w <- msg:
+ if msg.Size > 0 {
+ // wait for payload read or discard
+ <-consumed
+ }
+ return nil
+ case <-p.closing:
+ }
+ }
+ return ErrPipeClosed
+}
+
+// EncodeMsg is a convenient shorthand for sending an RLP-encoded message.
+func (p *MsgPipeRW) EncodeMsg(code uint64, data ...interface{}) error {
+ return p.WriteMsg(NewMsg(code, data...))
+}
+
+// ReadMsg returns a message sent on the other end of the pipe.
+func (p *MsgPipeRW) ReadMsg() (Msg, error) {
+ if atomic.LoadInt32(p.closed) == 0 {
+ select {
+ case msg := <-p.r:
+ return msg, nil
+ case <-p.closing:
+ }
+ }
+ return Msg{}, ErrPipeClosed
+}
+
+// Close unblocks any pending ReadMsg and WriteMsg calls on both ends
+// of the pipe. They will return ErrPipeClosed. Note that Close does
+// not interrupt any reads from a message payload.
+func (p *MsgPipeRW) Close() error {
+ if atomic.AddInt32(p.closed, 1) != 1 {
+ // someone else is already closing
+ atomic.StoreInt32(p.closed, 1) // avoid overflow
+ return nil
+ }
+ close(p.closing)
+ return nil
+}

p2p/message_test.go

@@ -2,8 +2,11 @@ package p2p
 
 import (
  "bytes"
+ "fmt"
  "io/ioutil"
+ "runtime"
  "testing"
+ "time"
 
  "github.com/ethereum/go-ethereum/ethutil"
 )
@@ -68,3 +71,63 @@ func TestDecodeRealMsg(t *testing.T) {
  t.Errorf("incorrect code %d, want %d", msg.Code, 0)
  }
 }
+
+func ExampleMsgPipe() {
+ rw1, rw2 := MsgPipe()
+ go func() {
+ rw1.EncodeMsg(8, []byte{0, 0})
+ rw1.EncodeMsg(5, []byte{1, 1})
+ rw1.Close()
+ }()
+
+ for {
+ msg, err := rw2.ReadMsg()
+ if err != nil {
+ break
+ }
+ var data [1][]byte
+ msg.Decode(&data)
+ fmt.Printf("msg: %d, %x\n", msg.Code, data[0])
+ }
+ // Output:
+ // msg: 8, 0000
+ // msg: 5, 0101
+}
+
+func TestMsgPipeUnblockWrite(t *testing.T) {
+loop:
+ for i := 0; i < 100; i++ {
+ rw1, rw2 := MsgPipe()
+ done := make(chan struct{})
+ go func() {
+ if err := rw1.EncodeMsg(1); err == nil {
+ t.Error("EncodeMsg returned nil error")
+ } else if err != ErrPipeClosed {
+ t.Error("EncodeMsg returned wrong error: got %v, want %v", err, ErrPipeClosed)
+ }
+ close(done)
+ }()
+
+ // this call should ensure that EncodeMsg is waiting to
+ // deliver sometimes. if this isn't done, Close is likely to
+ // be executed before EncodeMsg starts and then we won't test
+ // all the cases.
+ runtime.Gosched()
+
+ rw2.Close()
+ select {
+ case <-done:
+ case <-time.After(200 * time.Millisecond):
+ t.Errorf("write didn't unblock")
+ break loop
+ }
+ }
+}
+
+// This test should panic if concurrent close isn't implemented correctly.
+func TestMsgPipeConcurrentClose(t *testing.T) {
+ rw1, _ := MsgPipe()
+ for i := 0; i < 10; i++ {
+ go rw1.Close()
+ }
+}

p2p/peer.go

@@ -300,7 +300,7 @@ func (p *Peer) dispatch(msg Msg, protoDone chan struct{}) (wait bool, err error)
  proto.in <- msg
  } else {
  wait = true
- pr := &eofSignal{msg.Payload, protoDone}
+ pr := &eofSignal{msg.Payload, int64(msg.Size), protoDone}
  msg.Payload = pr
  proto.in <- msg
  }
@@ -438,18 +438,25 @@ func (rw *proto) ReadMsg() (Msg, error) {
  return msg, nil
 }
 
-// eofSignal wraps a reader with eof signaling.
-// the eof channel is closed when the wrapped reader
-// reaches EOF.
+// 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)
- if err != nil {
+ 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
 }

p2p/peer_error.go

@@ -100,7 +100,16 @@ func (d DiscReason) String() string {
  return discReasonToString[d]
 }
 
+type discRequestedError DiscReason
+
+func (err discRequestedError) Error() string {
+ return fmt.Sprintf("disconnect requested: %v", DiscReason(err))
+}
+
 func discReasonForError(err error) DiscReason {
+ if reason, ok := err.(discRequestedError); ok {
+ return DiscReason(reason)
+ }
  peerError, ok := err.(*peerError)
  if !ok {
  return DiscSubprotocolError

p2p/peer_test.go

@@ -4,6 +4,7 @@ import (
  "bufio"
  "bytes"
  "encoding/hex"
+ "io"
  "io/ioutil"
  "net"
  "reflect"
@@ -237,3 +238,58 @@ func TestNewPeer(t *testing.T) {
  // Should not hang.
  p.Disconnect(DiscAlreadyConnected)
 }
+
+func TestEOFSignal(t *testing.T) {
+ rb := make([]byte, 10)
+
+ // empty reader
+ eof := make(chan struct{}, 1)
+ sig := &eofSignal{new(bytes.Buffer), 0, eof}
+ if n, err := sig.Read(rb); n != 0 || err != io.EOF {
+ t.Errorf("Read returned unexpected values: (%v, %v)", n, err)
+ }
+ select {
+ case <-eof:
+ default:
+ t.Error("EOF chan not signaled")
+ }
+
+ // count before error
+ eof = make(chan struct{}, 1)
+ sig = &eofSignal{bytes.NewBufferString("aaaaaaaa"), 4, eof}
+ if n, err := sig.Read(rb); n != 8 || err != nil {
+ t.Errorf("Read returned unexpected values: (%v, %v)", n, err)
+ }
+ select {
+ case <-eof:
+ default:
+ t.Error("EOF chan not signaled")
+ }
+
+ // error before count
+ eof = make(chan struct{}, 1)
+ sig = &eofSignal{bytes.NewBufferString("aaaa"), 999, eof}
+ if n, err := sig.Read(rb); n != 4 || err != nil {
+ t.Errorf("Read returned unexpected values: (%v, %v)", n, err)
+ }
+ if n, err := sig.Read(rb); n != 0 || err != io.EOF {
+ t.Errorf("Read returned unexpected values: (%v, %v)", n, err)
+ }
+ select {
+ case <-eof:
+ default:
+ t.Error("EOF chan not signaled")
+ }
+
+ // no signal if neither occurs
+ eof = make(chan struct{}, 1)
+ sig = &eofSignal{bytes.NewBufferString("aaaaaaaaaaaaaaaaaaaaa"), 999, eof}
+ if n, err := sig.Read(rb); n != 10 || err != nil {
+ t.Errorf("Read returned unexpected values: (%v, %v)", n, err)
+ }
+ select {
+ case <-eof:
+ t.Error("unexpected EOF signal")
+ default:
+ }
+}

p2p/protocol.go

@@ -154,12 +154,11 @@ func (bp *baseProtocol) handle(rw MsgReadWriter) error {
  return newPeerError(errProtocolBreach, "extra handshake received")
 
  case discMsg:
- var reason DiscReason
+ var reason [1]DiscReason
  if err := msg.Decode(&reason); err != nil {
  return err
  }
- bp.peer.Disconnect(reason)
- return nil
+ return discRequestedError(reason[0])
 
  case pingMsg:
  return bp.rw.EncodeMsg(pongMsg)

p2p/protocol_test.go

@@ -0,0 +1,58 @@
+package p2p
+
+import (
+ "fmt"
+ "testing"
+)
+
+func TestBaseProtocolDisconnect(t *testing.T) {
+ peer := NewPeer(NewSimpleClientIdentity("p1", "", "", "foo"), nil)
+ peer.ourID = NewSimpleClientIdentity("p2", "", "", "bar")
+ peer.pubkeyHook = func(*peerAddr) error { return nil }
+
+ rw1, rw2 := MsgPipe()
+ done := make(chan struct{})
+ go func() {
+ if err := expectMsg(rw2, handshakeMsg); err != nil {
+ t.Error(err)
+ }
+ err := rw2.EncodeMsg(handshakeMsg,
+ baseProtocolVersion,
+ "",
+ []interface{}{},
+ 0,
+ make([]byte, 64),
+ )
+ if err != nil {
+ t.Error(err)
+ }
+ if err := expectMsg(rw2, getPeersMsg); err != nil {
+ t.Error(err)
+ }
+ if err := rw2.EncodeMsg(discMsg, DiscQuitting); err != nil {
+ t.Error(err)
+ }
+ close(done)
+ }()
+
+ if err := runBaseProtocol(peer, rw1); err == nil {
+ t.Errorf("base protocol returned without error")
+ } else if reason, ok := err.(discRequestedError); !ok || reason != DiscQuitting {
+ t.Errorf("base protocol returned wrong error: %v", err)
+ }
+ <-done
+}
+
+func expectMsg(r MsgReader, code uint64) error {
+ msg, err := r.ReadMsg()
+ if err != nil {
+ return err
+ }
+ if err := msg.Discard(); err != nil {
+ return err
+ }
+ if msg.Code != code {
+ return fmt.Errorf("wrong message code: got %d, expected %d", msg.Code, code)
+ }
+ return nil
+}