2015-07-06 17:54:22 -07:00
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// Copyright 2014 The go-ethereum Authors
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2015-07-22 09:48:40 -07:00
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// This file is part of the go-ethereum library.
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2015-07-06 17:54:22 -07:00
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//
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2015-07-23 09:35:11 -07:00
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// The go-ethereum library is free software: you can redistribute it and/or modify
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2015-07-06 17:54:22 -07:00
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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2015-07-06 17:54:22 -07:00
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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2015-07-06 17:54:22 -07:00
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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2015-07-22 09:48:40 -07:00
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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2015-07-06 17:54:22 -07:00
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2014-10-23 08:57:54 -07:00
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package p2p
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import (
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"bytes"
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2014-12-12 02:39:07 -08:00
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"errors"
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2015-01-05 08:10:42 -08:00
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"fmt"
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2014-11-04 04:21:44 -08:00
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"io"
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"io/ioutil"
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2014-12-12 02:39:07 -08:00
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"sync/atomic"
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2015-02-04 18:07:58 -08:00
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"time"
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2014-11-04 04:21:44 -08:00
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2017-09-25 01:08:07 -07:00
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/p2p/discover"
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2014-11-24 10:02:48 -08:00
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"github.com/ethereum/go-ethereum/rlp"
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)
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// Msg defines the structure of a p2p message.
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//
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// Note that a Msg can only be sent once since the Payload reader is
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// consumed during sending. It is not possible to create a Msg and
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// send it any number of times. If you want to reuse an encoded
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// structure, encode the payload into a byte array and create a
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// separate Msg with a bytes.Reader as Payload for each send.
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type Msg struct {
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Code uint64
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Size uint32 // size of the paylod
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Payload io.Reader
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ReceivedAt time.Time
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}
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// Decode parses the RLP content of a message into
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// the given value, which must be a pointer.
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//
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// For the decoding rules, please see package rlp.
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func (msg Msg) Decode(val interface{}) error {
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s := rlp.NewStream(msg.Payload, uint64(msg.Size))
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if err := s.Decode(val); err != nil {
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return newPeerError(errInvalidMsg, "(code %x) (size %d) %v", msg.Code, msg.Size, err)
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}
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return nil
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}
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func (msg Msg) String() string {
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return fmt.Sprintf("msg #%v (%v bytes)", msg.Code, msg.Size)
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}
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// Discard reads any remaining payload data into a black hole.
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func (msg Msg) Discard() error {
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_, err := io.Copy(ioutil.Discard, msg.Payload)
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return err
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}
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2014-11-21 12:48:49 -08:00
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type MsgReader interface {
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ReadMsg() (Msg, error)
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}
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type MsgWriter interface {
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// WriteMsg sends a message. It will block until the message's
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// Payload has been consumed by the other end.
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//
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// Note that messages can be sent only once because their
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// payload reader is drained.
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WriteMsg(Msg) error
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}
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// MsgReadWriter provides reading and writing of encoded messages.
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// Implementations should ensure that ReadMsg and WriteMsg can be
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// called simultaneously from multiple goroutines.
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type MsgReadWriter interface {
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MsgReader
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MsgWriter
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}
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// Send writes an RLP-encoded message with the given code.
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// data should encode as an RLP list.
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func Send(w MsgWriter, msgcode uint64, data interface{}) error {
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size, r, err := rlp.EncodeToReader(data)
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if err != nil {
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return err
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}
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return w.WriteMsg(Msg{Code: msgcode, Size: uint32(size), Payload: r})
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}
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// SendItems writes an RLP with the given code and data elements.
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// For a call such as:
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//
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// SendItems(w, code, e1, e2, e3)
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//
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// the message payload will be an RLP list containing the items:
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//
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// [e1, e2, e3]
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//
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func SendItems(w MsgWriter, msgcode uint64, elems ...interface{}) error {
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return Send(w, msgcode, elems)
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}
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// eofSignal wraps a reader with eof signaling. the eof channel is
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// closed when the wrapped reader returns an error or when count bytes
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// have been read.
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type eofSignal struct {
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wrapped io.Reader
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count uint32 // number of bytes left
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eof chan<- struct{}
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}
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// note: when using eofSignal to detect whether a message payload
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// has been read, Read might not be called for zero sized messages.
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func (r *eofSignal) Read(buf []byte) (int, error) {
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if r.count == 0 {
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if r.eof != nil {
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r.eof <- struct{}{}
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r.eof = nil
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}
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return 0, io.EOF
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}
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max := len(buf)
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if int(r.count) < len(buf) {
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max = int(r.count)
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}
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n, err := r.wrapped.Read(buf[:max])
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r.count -= uint32(n)
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if (err != nil || r.count == 0) && r.eof != nil {
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r.eof <- struct{}{} // tell Peer that msg has been consumed
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r.eof = nil
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}
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return n, err
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}
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2014-12-12 02:39:07 -08:00
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// MsgPipe creates a message pipe. Reads on one end are matched
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// with writes on the other. The pipe is full-duplex, both ends
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// implement MsgReadWriter.
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func MsgPipe() (*MsgPipeRW, *MsgPipeRW) {
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var (
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c1, c2 = make(chan Msg), make(chan Msg)
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closing = make(chan struct{})
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closed = new(int32)
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rw1 = &MsgPipeRW{c1, c2, closing, closed}
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rw2 = &MsgPipeRW{c2, c1, closing, closed}
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)
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return rw1, rw2
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}
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// ErrPipeClosed is returned from pipe operations after the
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// pipe has been closed.
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var ErrPipeClosed = errors.New("p2p: read or write on closed message pipe")
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// MsgPipeRW is an endpoint of a MsgReadWriter pipe.
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type MsgPipeRW struct {
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w chan<- Msg
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r <-chan Msg
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closing chan struct{}
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closed *int32
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}
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// WriteMsg sends a messsage on the pipe.
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// It blocks until the receiver has consumed the message payload.
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func (p *MsgPipeRW) WriteMsg(msg Msg) error {
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if atomic.LoadInt32(p.closed) == 0 {
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consumed := make(chan struct{}, 1)
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msg.Payload = &eofSignal{msg.Payload, msg.Size, consumed}
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select {
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case p.w <- msg:
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if msg.Size > 0 {
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// wait for payload read or discard
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select {
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case <-consumed:
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case <-p.closing:
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}
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}
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return nil
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case <-p.closing:
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}
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}
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return ErrPipeClosed
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}
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// ReadMsg returns a message sent on the other end of the pipe.
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func (p *MsgPipeRW) ReadMsg() (Msg, error) {
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if atomic.LoadInt32(p.closed) == 0 {
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select {
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case msg := <-p.r:
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return msg, nil
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case <-p.closing:
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}
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}
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return Msg{}, ErrPipeClosed
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}
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// Close unblocks any pending ReadMsg and WriteMsg calls on both ends
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// of the pipe. They will return ErrPipeClosed. Close also
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// interrupts any reads from a message payload.
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func (p *MsgPipeRW) Close() error {
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if atomic.AddInt32(p.closed, 1) != 1 {
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// someone else is already closing
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atomic.StoreInt32(p.closed, 1) // avoid overflow
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return nil
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}
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close(p.closing)
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return nil
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}
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// ExpectMsg reads a message from r and verifies that its
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// code and encoded RLP content match the provided values.
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// If content is nil, the payload is discarded and not verified.
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func ExpectMsg(r MsgReader, code uint64, content interface{}) error {
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msg, err := r.ReadMsg()
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if err != nil {
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return err
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}
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if msg.Code != code {
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return fmt.Errorf("message code mismatch: got %d, expected %d", msg.Code, code)
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}
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if content == nil {
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return msg.Discard()
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}
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contentEnc, err := rlp.EncodeToBytes(content)
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if err != nil {
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panic("content encode error: " + err.Error())
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}
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if int(msg.Size) != len(contentEnc) {
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return fmt.Errorf("message size mismatch: got %d, want %d", msg.Size, len(contentEnc))
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}
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actualContent, err := ioutil.ReadAll(msg.Payload)
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if err != nil {
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return err
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}
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if !bytes.Equal(actualContent, contentEnc) {
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return fmt.Errorf("message payload mismatch:\ngot: %x\nwant: %x", actualContent, contentEnc)
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}
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return nil
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}
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// msgEventer wraps a MsgReadWriter and sends events whenever a message is sent
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// or received
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type msgEventer struct {
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MsgReadWriter
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feed *event.Feed
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peerID discover.NodeID
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Protocol string
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}
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// newMsgEventer returns a msgEventer which sends message events to the given
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// feed
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func newMsgEventer(rw MsgReadWriter, feed *event.Feed, peerID discover.NodeID, proto string) *msgEventer {
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return &msgEventer{
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MsgReadWriter: rw,
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feed: feed,
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peerID: peerID,
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Protocol: proto,
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}
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}
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// ReadMsg reads a message from the underlying MsgReadWriter and emits a
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// "message received" event
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func (self *msgEventer) ReadMsg() (Msg, error) {
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msg, err := self.MsgReadWriter.ReadMsg()
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if err != nil {
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return msg, err
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}
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self.feed.Send(&PeerEvent{
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Type: PeerEventTypeMsgRecv,
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Peer: self.peerID,
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Protocol: self.Protocol,
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MsgCode: &msg.Code,
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MsgSize: &msg.Size,
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})
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return msg, nil
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}
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// WriteMsg writes a message to the underlying MsgReadWriter and emits a
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// "message sent" event
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func (self *msgEventer) WriteMsg(msg Msg) error {
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err := self.MsgReadWriter.WriteMsg(msg)
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if err != nil {
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return err
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}
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self.feed.Send(&PeerEvent{
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Type: PeerEventTypeMsgSend,
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Peer: self.peerID,
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Protocol: self.Protocol,
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MsgCode: &msg.Code,
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MsgSize: &msg.Size,
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})
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return nil
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}
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// Close closes the underlying MsgReadWriter if it implements the io.Closer
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// interface
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func (self *msgEventer) Close() error {
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if v, ok := self.MsgReadWriter.(io.Closer); ok {
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return v.Close()
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}
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return nil
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}
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