9feec51e2d
This commit introduces a network simulation framework which can be used to run simulated networks of devp2p nodes. The intention is to use this for testing protocols, performing benchmarks and visualising emergent network behaviour.
340 lines
9.0 KiB
Go
340 lines
9.0 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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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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// 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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// 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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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package p2p
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"net"
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"sync"
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"sync/atomic"
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"time"
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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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"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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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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// netWrapper wraps a MsgReadWriter with locks around
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// ReadMsg/WriteMsg and applies read/write deadlines.
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type netWrapper struct {
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rmu, wmu sync.Mutex
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rtimeout, wtimeout time.Duration
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conn net.Conn
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wrapped MsgReadWriter
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}
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func (rw *netWrapper) ReadMsg() (Msg, error) {
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rw.rmu.Lock()
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defer rw.rmu.Unlock()
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rw.conn.SetReadDeadline(time.Now().Add(rw.rtimeout))
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return rw.wrapped.ReadMsg()
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}
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func (rw *netWrapper) WriteMsg(msg Msg) error {
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rw.wmu.Lock()
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defer rw.wmu.Unlock()
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rw.conn.SetWriteDeadline(time.Now().Add(rw.wtimeout))
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return rw.wrapped.WriteMsg(msg)
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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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// 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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} else {
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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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}
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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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