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peerreader.go
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peerreader.go
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package peerreader
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"time"
"github.com/cenkalti/rain/internal/bufferpool"
"github.com/cenkalti/rain/internal/logger"
"github.com/cenkalti/rain/internal/peerprotocol"
"github.com/cenkalti/rain/internal/piece"
)
const (
// maxBlockSize is the max size of block data that we accept from peers.
maxBlockSize = 32 * 1024
// time to wait for a message. peer must send keep-alive messages to keep connection alive.
readTimeout = 2 * time.Minute
)
var blockPool = bufferpool.New(piece.BlockSize)
type PeerReader struct {
conn net.Conn
buf *bufio.Reader
log logger.Logger
pieceTimeout time.Duration
messages chan interface{}
stopC chan struct{}
doneC chan struct{}
}
func New(conn net.Conn, l logger.Logger, pieceTimeout time.Duration, bufferSize int) *PeerReader {
return &PeerReader{
conn: conn,
buf: bufio.NewReaderSize(conn, bufferSize),
log: l,
pieceTimeout: pieceTimeout,
messages: make(chan interface{}),
stopC: make(chan struct{}),
doneC: make(chan struct{}),
}
}
func (p *PeerReader) Messages() <-chan interface{} {
return p.messages
}
func (p *PeerReader) Stop() {
close(p.stopC)
}
func (p *PeerReader) Done() chan struct{} {
return p.doneC
}
func (p *PeerReader) Run() {
defer close(p.doneC)
var err error
defer func() {
if err == nil {
return
} else if err == io.EOF { // peer closed the connection
return
} else if err == io.ErrUnexpectedEOF {
return
} else if _, ok := err.(*net.OpError); ok {
return
}
select {
case <-p.stopC: // don't log error if peer is stopped
default:
p.log.Error(err)
}
}()
first := true
for {
err = p.conn.SetReadDeadline(time.Now().Add(readTimeout))
if err != nil {
return
}
var length uint32
// p.log.Debug("Reading message...")
err = binary.Read(p.buf, binary.BigEndian, &length)
if err != nil {
return
}
// p.log.Debugf("Received message of length: %d", length)
if length == 0 { // keep-alive message
p.log.Debug("Received message of type \"keep alive\"")
continue
}
var id peerprotocol.MessageID
err = binary.Read(p.buf, binary.BigEndian, &id)
if err != nil {
return
}
length--
// p.log.Debugf("Received message of type: %q", id)
var msg interface{}
switch id {
case peerprotocol.Choke:
msg = peerprotocol.ChokeMessage{}
case peerprotocol.Unchoke:
msg = peerprotocol.UnchokeMessage{}
case peerprotocol.Interested:
msg = peerprotocol.InterestedMessage{}
case peerprotocol.NotInterested:
msg = peerprotocol.NotInterestedMessage{}
case peerprotocol.Have:
var hm peerprotocol.HaveMessage
err = binary.Read(p.buf, binary.BigEndian, &hm)
if err != nil {
return
}
msg = hm
case peerprotocol.Bitfield:
if !first {
err = errors.New("bitfield can only be sent after handshake")
return
}
var bm peerprotocol.BitfieldMessage
bm.Data = make([]byte, length)
_, err = io.ReadFull(p.buf, bm.Data)
if err != nil {
return
}
msg = bm
case peerprotocol.Request:
var rm peerprotocol.RequestMessage
err = binary.Read(p.buf, binary.BigEndian, &rm)
if err != nil {
return
}
// p.log.Debugf("Received Request: %+v", rm)
if rm.Length > maxBlockSize {
err = fmt.Errorf("received a request with block size larger than allowed (%d > %d)", rm.Length, maxBlockSize)
return
}
msg = rm
case peerprotocol.Reject:
var rm peerprotocol.RejectMessage
err = binary.Read(p.buf, binary.BigEndian, &rm)
if err != nil {
return
}
p.log.Debugf("Received Reject: %+v", rm)
msg = rm
case peerprotocol.Cancel:
var cm peerprotocol.CancelMessage
err = binary.Read(p.buf, binary.BigEndian, &cm)
if err != nil {
return
}
if cm.Length > maxBlockSize {
err = errors.New("received a cancel with block size larger than allowed")
return
}
msg = cm
case peerprotocol.Piece:
var pm peerprotocol.PieceMessage
err = binary.Read(p.buf, binary.BigEndian, &pm)
if err != nil {
return
}
var m int
buf := blockPool.Get(int(length - 8))
for {
err = p.conn.SetReadDeadline(time.Now().Add(p.pieceTimeout))
if err != nil {
return
}
n, rerr := io.ReadFull(p.buf, buf.Data[m:])
if rerr != nil {
if nerr, ok := rerr.(net.Error); ok && nerr.Timeout() {
// Peer didn't send the full block in allowed time.
if n == 0 {
// Disconnect if no bytes received.
return
}
// Some bytes received, peer appears to be slow, keep receiving the rest.
m += n
continue
}
return
}
// Received full block.
break
}
msg = Piece{PieceMessage: pm, Buffer: buf}
case peerprotocol.HaveAll:
if !first {
err = errors.New("have_all can only be sent after handshake")
return
}
msg = peerprotocol.HaveAllMessage{}
case peerprotocol.HaveNone:
if !first {
err = errors.New("have_none can only be sent after handshake")
return
}
msg = peerprotocol.HaveNoneMessage{}
case peerprotocol.AllowedFast:
var am peerprotocol.AllowedFastMessage
err = binary.Read(p.buf, binary.BigEndian, &am)
if err != nil {
return
}
msg = am
case peerprotocol.Extension:
buf := make([]byte, length)
_, err = io.ReadFull(p.buf, buf)
if err != nil {
return
}
var em peerprotocol.ExtensionMessage
err = em.UnmarshalBinary(buf)
if err != nil {
return
}
msg = em.Payload
default:
p.log.Debugf("unhandled message type: %s", id)
p.log.Debugln("Discarding", length, "bytes...")
_, err = io.CopyN(ioutil.Discard, p.buf, int64(length))
if err != nil {
return
}
continue
}
if msg == nil {
panic("msg unset")
}
// Only message types defined in BEP 3 are counted.
if id < 9 {
first = false
}
select {
case p.messages <- msg:
case <-p.stopC:
return
}
}
}