YTSFlix_Go/vendor/github.com/anacrolix/torrent/connection.go

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2018-11-04 14:58:15 +00:00
package torrent
import (
"bufio"
"bytes"
"fmt"
"io"
"math"
"math/rand"
"net"
"strconv"
"strings"
"sync"
"time"
"github.com/anacrolix/dht"
"github.com/anacrolix/log"
"github.com/anacrolix/missinggo"
"github.com/anacrolix/missinggo/bitmap"
"github.com/anacrolix/missinggo/iter"
"github.com/anacrolix/missinggo/prioritybitmap"
"github.com/pkg/errors"
"github.com/anacrolix/torrent/bencode"
"github.com/anacrolix/torrent/mse"
pp "github.com/anacrolix/torrent/peer_protocol"
)
type peerSource string
const (
peerSourceTracker = "Tr"
peerSourceIncoming = "I"
peerSourceDHTGetPeers = "Hg" // Peers we found by searching a DHT.
peerSourceDHTAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
peerSourcePEX = "X"
)
// Maintains the state of a connection with a peer.
type connection struct {
// First to ensure 64-bit alignment for atomics. See #262.
stats ConnStats
t *Torrent
// The actual Conn, used for closing, and setting socket options.
conn net.Conn
outgoing bool
// The Reader and Writer for this Conn, with hooks installed for stats,
// limiting, deadlines etc.
w io.Writer
r io.Reader
// True if the connection is operating over MSE obfuscation.
headerEncrypted bool
cryptoMethod mse.CryptoMethod
Discovery peerSource
closed missinggo.Event
// Set true after we've added our ConnStats generated during handshake to
// other ConnStat instances as determined when the *Torrent became known.
reconciledHandshakeStats bool
lastMessageReceived time.Time
completedHandshake time.Time
lastUsefulChunkReceived time.Time
lastChunkSent time.Time
// Stuff controlled by the local peer.
Interested bool
lastBecameInterested time.Time
priorInterest time.Duration
lastStartedExpectingToReceiveChunks time.Time
cumulativeExpectedToReceiveChunks time.Duration
chunksReceivedWhileExpecting int64
Choked bool
requests map[request]struct{}
requestsLowWater int
// Chunks that we might reasonably expect to receive from the peer. Due to
// latency, buffering, and implementation differences, we may receive
// chunks that are no longer in the set of requests actually want.
validReceiveChunks map[request]struct{}
// Indexed by metadata piece, set to true if posted and pending a
// response.
metadataRequests []bool
sentHaves bitmap.Bitmap
// Stuff controlled by the remote peer.
PeerID PeerID
PeerInterested bool
PeerChoked bool
PeerRequests map[request]struct{}
PeerExtensionBytes pp.PeerExtensionBits
// The pieces the peer has claimed to have.
peerPieces bitmap.Bitmap
// The peer has everything. This can occur due to a special message, when
// we may not even know the number of pieces in the torrent yet.
peerSentHaveAll bool
// The highest possible number of pieces the torrent could have based on
// communication with the peer. Generally only useful until we have the
// torrent info.
peerMinPieces pieceIndex
// Pieces we've accepted chunks for from the peer.
peerTouchedPieces map[pieceIndex]struct{}
peerAllowedFast bitmap.Bitmap
PeerMaxRequests int // Maximum pending requests the peer allows.
PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
PeerClientName string
pieceInclination []int
pieceRequestOrder prioritybitmap.PriorityBitmap
writeBuffer *bytes.Buffer
uploadTimer *time.Timer
writerCond sync.Cond
}
func (cn *connection) updateExpectingChunks() {
if cn.expectingChunks() {
if cn.lastStartedExpectingToReceiveChunks.IsZero() {
cn.lastStartedExpectingToReceiveChunks = time.Now()
}
} else {
if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
cn.lastStartedExpectingToReceiveChunks = time.Time{}
}
}
}
func (cn *connection) expectingChunks() bool {
return cn.Interested && !cn.PeerChoked
}
// Returns true if the connection is over IPv6.
func (cn *connection) ipv6() bool {
ip := missinggo.AddrIP(cn.remoteAddr())
if ip.To4() != nil {
return false
}
return len(ip) == net.IPv6len
}
// Returns true the dialer has the lower client peer ID. TODO: Find the
// specification for this.
func (cn *connection) isPreferredDirection() bool {
return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
}
// Returns whether the left connection should be preferred over the right one,
// considering only their networking properties. If ok is false, we can't
// decide.
func (l *connection) hasPreferredNetworkOver(r *connection) (left, ok bool) {
var ml multiLess
ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
ml.NextBool(!l.utp(), !r.utp())
ml.NextBool(l.ipv6(), r.ipv6())
return ml.FinalOk()
}
func (cn *connection) cumInterest() time.Duration {
ret := cn.priorInterest
if cn.Interested {
ret += time.Since(cn.lastBecameInterested)
}
return ret
}
func (cn *connection) peerHasAllPieces() (all bool, known bool) {
if cn.peerSentHaveAll {
return true, true
}
if !cn.t.haveInfo() {
return false, false
}
return bitmap.Flip(cn.peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
}
func (cn *connection) mu() sync.Locker {
return cn.t.cl.locker()
}
func (cn *connection) remoteAddr() net.Addr {
return cn.conn.RemoteAddr()
}
func (cn *connection) localAddr() net.Addr {
return cn.conn.LocalAddr()
}
func (cn *connection) supportsExtension(ext pp.ExtensionName) bool {
_, ok := cn.PeerExtensionIDs[ext]
return ok
}
// The best guess at number of pieces in the torrent for this peer.
func (cn *connection) bestPeerNumPieces() pieceIndex {
if cn.t.haveInfo() {
return cn.t.numPieces()
}
return cn.peerMinPieces
}
func (cn *connection) completedString() string {
have := pieceIndex(cn.peerPieces.Len())
if cn.peerSentHaveAll {
have = cn.bestPeerNumPieces()
}
return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
}
// Correct the PeerPieces slice length. Return false if the existing slice is
// invalid, such as by receiving badly sized BITFIELD, or invalid HAVE
// messages.
func (cn *connection) setNumPieces(num pieceIndex) error {
cn.peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
cn.peerPiecesChanged()
return nil
}
func eventAgeString(t time.Time) string {
if t.IsZero() {
return "never"
}
return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
}
func (cn *connection) connectionFlags() (ret string) {
c := func(b byte) {
ret += string([]byte{b})
}
if cn.cryptoMethod == mse.CryptoMethodRC4 {
c('E')
} else if cn.headerEncrypted {
c('e')
}
ret += string(cn.Discovery)
if cn.utp() {
c('U')
}
return
}
func (cn *connection) utp() bool {
return isUtpNetwork(cn.remoteAddr().Network())
}
// Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
func (cn *connection) statusFlags() (ret string) {
c := func(b byte) {
ret += string([]byte{b})
}
if cn.Interested {
c('i')
}
if cn.Choked {
c('c')
}
c('-')
ret += cn.connectionFlags()
c('-')
if cn.PeerInterested {
c('i')
}
if cn.PeerChoked {
c('c')
}
return
}
// func (cn *connection) String() string {
// var buf bytes.Buffer
// cn.WriteStatus(&buf, nil)
// return buf.String()
// }
func (cn *connection) downloadRate() float64 {
return float64(cn.stats.BytesReadUsefulData.Int64()) / cn.cumInterest().Seconds()
}
func (cn *connection) WriteStatus(w io.Writer, t *Torrent) {
// \t isn't preserved in <pre> blocks?
fmt.Fprintf(w, "%+-55q %s %s-%s\n", cn.PeerID, cn.PeerExtensionBytes, cn.localAddr(), cn.remoteAddr())
fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
eventAgeString(cn.lastMessageReceived),
eventAgeString(cn.completedHandshake),
eventAgeString(cn.lastHelpful()),
cn.cumInterest(),
cn.totalExpectingTime(),
)
fmt.Fprintf(w,
" %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
cn.completedString(),
len(cn.peerTouchedPieces),
&cn.stats.ChunksReadUseful,
&cn.stats.ChunksRead,
&cn.stats.ChunksWritten,
cn.requestsLowWater,
cn.numLocalRequests(),
cn.nominalMaxRequests(),
len(cn.PeerRequests),
cn.statusFlags(),
cn.downloadRate()/(1<<10),
)
fmt.Fprintf(w, " next pieces: %v%s\n",
iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
func() string {
if cn.shouldRequestWithoutBias() {
return " (fastest)"
} else {
return ""
}
}())
}
func (cn *connection) Close() {
if !cn.closed.Set() {
return
}
cn.tickleWriter()
cn.discardPieceInclination()
cn.pieceRequestOrder.Clear()
if cn.conn != nil {
go cn.conn.Close()
}
}
func (cn *connection) PeerHasPiece(piece pieceIndex) bool {
return cn.peerSentHaveAll || cn.peerPieces.Contains(bitmap.BitIndex(piece))
}
// Writes a message into the write buffer.
func (cn *connection) Post(msg pp.Message) {
torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
// We don't need to track bytes here because a connection.w Writer wrapper
// takes care of that (although there's some delay between us recording
// the message, and the connection writer flushing it out.).
cn.writeBuffer.Write(msg.MustMarshalBinary())
// Last I checked only Piece messages affect stats, and we don't post
// those.
cn.wroteMsg(&msg)
cn.tickleWriter()
}
func (cn *connection) requestMetadataPiece(index int) {
eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
if eID == 0 {
return
}
if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
return
}
cn.Post(pp.Message{
Type: pp.Extended,
ExtendedID: eID,
ExtendedPayload: func() []byte {
b, err := bencode.Marshal(map[string]int{
"msg_type": pp.RequestMetadataExtensionMsgType,
"piece": index,
})
if err != nil {
panic(err)
}
return b
}(),
})
for index >= len(cn.metadataRequests) {
cn.metadataRequests = append(cn.metadataRequests, false)
}
cn.metadataRequests[index] = true
}
func (cn *connection) requestedMetadataPiece(index int) bool {
return index < len(cn.metadataRequests) && cn.metadataRequests[index]
}
// The actual value to use as the maximum outbound requests.
func (cn *connection) nominalMaxRequests() (ret int) {
if cn.t.requestStrategy == 3 {
expectingTime := int64(cn.totalExpectingTime())
if expectingTime == 0 {
expectingTime = math.MaxInt64
} else {
expectingTime *= 2
}
return int(clamp(
1,
int64(cn.PeerMaxRequests),
max(
// It makes sense to always pipeline at least one connection,
// since latency must be non-zero.
2,
// Request only as many as we expect to receive in the
// dupliateRequestTimeout window. We are trying to avoid having to
// duplicate requests.
cn.chunksReceivedWhileExpecting*int64(cn.t.duplicateRequestTimeout)/expectingTime,
),
))
}
return int(clamp(
1,
int64(cn.PeerMaxRequests),
max(64,
cn.stats.ChunksReadUseful.Int64()-(cn.stats.ChunksRead.Int64()-cn.stats.ChunksReadUseful.Int64()))))
}
func (cn *connection) totalExpectingTime() (ret time.Duration) {
ret = cn.cumulativeExpectedToReceiveChunks
if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
}
return
}
func (cn *connection) onPeerSentCancel(r request) {
if _, ok := cn.PeerRequests[r]; !ok {
torrent.Add("unexpected cancels received", 1)
return
}
if cn.fastEnabled() {
cn.reject(r)
} else {
delete(cn.PeerRequests, r)
}
}
func (cn *connection) Choke(msg messageWriter) (more bool) {
if cn.Choked {
return true
}
cn.Choked = true
more = msg(pp.Message{
Type: pp.Choke,
})
if cn.fastEnabled() {
for r := range cn.PeerRequests {
// TODO: Don't reject pieces in allowed fast set.
cn.reject(r)
}
} else {
cn.PeerRequests = nil
}
return
}
func (cn *connection) Unchoke(msg func(pp.Message) bool) bool {
if !cn.Choked {
return true
}
cn.Choked = false
return msg(pp.Message{
Type: pp.Unchoke,
})
}
func (cn *connection) SetInterested(interested bool, msg func(pp.Message) bool) bool {
if cn.Interested == interested {
return true
}
cn.Interested = interested
if interested {
cn.lastBecameInterested = time.Now()
} else if !cn.lastBecameInterested.IsZero() {
cn.priorInterest += time.Since(cn.lastBecameInterested)
}
cn.updateExpectingChunks()
// log.Printf("%p: setting interest: %v", cn, interested)
return msg(pp.Message{
Type: func() pp.MessageType {
if interested {
return pp.Interested
} else {
return pp.NotInterested
}
}(),
})
}
// The function takes a message to be sent, and returns true if more messages
// are okay.
type messageWriter func(pp.Message) bool
// Proxies the messageWriter's response.
func (cn *connection) request(r request, mw messageWriter) bool {
if _, ok := cn.requests[r]; ok {
panic("chunk already requested")
}
if !cn.PeerHasPiece(pieceIndex(r.Index)) {
panic("requesting piece peer doesn't have")
}
if _, ok := cn.t.conns[cn]; !ok {
panic("requesting but not in active conns")
}
if cn.closed.IsSet() {
panic("requesting when connection is closed")
}
if cn.PeerChoked {
if cn.peerAllowedFast.Get(int(r.Index)) {
torrent.Add("allowed fast requests sent", 1)
} else {
panic("requesting while choked and not allowed fast")
}
}
if cn.t.hashingPiece(pieceIndex(r.Index)) {
panic("piece is being hashed")
}
if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
panic("piece is queued for hash")
}
if cn.requests == nil {
cn.requests = make(map[request]struct{})
}
cn.requests[r] = struct{}{}
if cn.validReceiveChunks == nil {
cn.validReceiveChunks = make(map[request]struct{})
}
cn.validReceiveChunks[r] = struct{}{}
cn.t.pendingRequests[r]++
cn.t.lastRequested[r] = time.AfterFunc(cn.t.duplicateRequestTimeout, func() {
torrent.Add("duplicate request timeouts", 1)
cn.mu().Lock()
defer cn.mu().Unlock()
delete(cn.t.lastRequested, r)
for cn := range cn.t.conns {
if cn.PeerHasPiece(pieceIndex(r.Index)) {
cn.updateRequests()
}
}
})
cn.updateExpectingChunks()
return mw(pp.Message{
Type: pp.Request,
Index: r.Index,
Begin: r.Begin,
Length: r.Length,
})
}
func (cn *connection) fillWriteBuffer(msg func(pp.Message) bool) {
if !cn.t.networkingEnabled {
if !cn.SetInterested(false, msg) {
return
}
if len(cn.requests) != 0 {
for r := range cn.requests {
cn.deleteRequest(r)
// log.Printf("%p: cancelling request: %v", cn, r)
if !msg(makeCancelMessage(r)) {
return
}
}
}
}
if len(cn.requests) <= cn.requestsLowWater {
filledBuffer := false
cn.iterPendingPieces(func(pieceIndex pieceIndex) bool {
cn.iterPendingRequests(pieceIndex, func(r request) bool {
if !cn.SetInterested(true, msg) {
filledBuffer = true
return false
}
if len(cn.requests) >= cn.nominalMaxRequests() {
return false
}
// Choking is looked at here because our interest is dependent
// on whether we'd make requests in its absence.
if cn.PeerChoked {
if !cn.peerAllowedFast.Get(bitmap.BitIndex(r.Index)) {
return false
}
}
if _, ok := cn.requests[r]; ok {
return true
}
filledBuffer = !cn.request(r, msg)
return !filledBuffer
})
return !filledBuffer
})
if filledBuffer {
// If we didn't completely top up the requests, we shouldn't mark
// the low water, since we'll want to top up the requests as soon
// as we have more write buffer space.
return
}
cn.requestsLowWater = len(cn.requests) / 2
}
cn.upload(msg)
}
// Routine that writes to the peer. Some of what to write is buffered by
// activity elsewhere in the Client, and some is determined locally when the
// connection is writable.
func (cn *connection) writer(keepAliveTimeout time.Duration) {
var (
lastWrite time.Time = time.Now()
keepAliveTimer *time.Timer
)
keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
cn.mu().Lock()
defer cn.mu().Unlock()
if time.Since(lastWrite) >= keepAliveTimeout {
cn.tickleWriter()
}
keepAliveTimer.Reset(keepAliveTimeout)
})
cn.mu().Lock()
defer cn.mu().Unlock()
defer cn.Close()
defer keepAliveTimer.Stop()
frontBuf := new(bytes.Buffer)
for {
if cn.closed.IsSet() {
return
}
if cn.writeBuffer.Len() == 0 {
cn.fillWriteBuffer(func(msg pp.Message) bool {
cn.wroteMsg(&msg)
cn.writeBuffer.Write(msg.MustMarshalBinary())
torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
return cn.writeBuffer.Len() < 1<<16 // 64KiB
})
}
if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout {
cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
postedKeepalives.Add(1)
}
if cn.writeBuffer.Len() == 0 {
// TODO: Minimize wakeups....
cn.writerCond.Wait()
continue
}
// Flip the buffers.
frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
cn.mu().Unlock()
n, err := cn.w.Write(frontBuf.Bytes())
cn.mu().Lock()
if n != 0 {
lastWrite = time.Now()
keepAliveTimer.Reset(keepAliveTimeout)
}
if err != nil {
return
}
if n != frontBuf.Len() {
panic("short write")
}
frontBuf.Reset()
}
}
func (cn *connection) Have(piece pieceIndex) {
if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
return
}
cn.Post(pp.Message{
Type: pp.Have,
Index: pp.Integer(piece),
})
cn.sentHaves.Add(bitmap.BitIndex(piece))
}
func (cn *connection) PostBitfield() {
if cn.sentHaves.Len() != 0 {
panic("bitfield must be first have-related message sent")
}
if !cn.t.haveAnyPieces() {
return
}
cn.Post(pp.Message{
Type: pp.Bitfield,
Bitfield: cn.t.bitfield(),
})
cn.sentHaves = cn.t.completedPieces.Copy()
}
func (cn *connection) updateRequests() {
// log.Print("update requests")
cn.tickleWriter()
}
// Emits the indices in the Bitmaps bms in order, never repeating any index.
// skip is mutated during execution, and its initial values will never be
// emitted.
func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
return func(cb iter.Callback) {
for _, bm := range bms {
if !iter.All(func(i interface{}) bool {
skip.Add(i.(int))
return cb(i)
}, bitmap.Sub(bm, *skip).Iter) {
return
}
}
}
}
func (cn *connection) iterUnbiasedPieceRequestOrder(f func(piece pieceIndex) bool) bool {
now, readahead := cn.t.readerPiecePriorities()
var skip bitmap.Bitmap
if !cn.peerSentHaveAll {
// Pieces to skip include pieces the peer doesn't have.
skip = bitmap.Flip(cn.peerPieces, 0, bitmap.BitIndex(cn.t.numPieces()))
}
// And pieces that we already have.
skip.Union(cn.t.completedPieces)
skip.Union(cn.t.piecesQueuedForHash)
// Return an iterator over the different priority classes, minus the skip
// pieces.
return iter.All(
func(_piece interface{}) bool {
i := _piece.(bitmap.BitIndex)
if cn.t.hashingPiece(pieceIndex(i)) {
return true
}
return f(pieceIndex(i))
},
iterBitmapsDistinct(&skip, now, readahead),
func(cb iter.Callback) {
cn.t.pendingPieces.IterTyped(func(piece int) bool {
if skip.Contains(piece) {
return true
}
more := cb(piece)
skip.Add(piece)
return more
})
},
)
}
// The connection should download highest priority pieces first, without any
// inclination toward avoiding wastage. Generally we might do this if there's
// a single connection, or this is the fastest connection, and we have active
// readers that signal an ordering preference. It's conceivable that the best
// connection should do this, since it's least likely to waste our time if
// assigned to the highest priority pieces, and assigning more than one this
// role would cause significant wasted bandwidth.
func (cn *connection) shouldRequestWithoutBias() bool {
if cn.t.requestStrategy != 2 {
return false
}
if len(cn.t.readers) == 0 {
return false
}
if len(cn.t.conns) == 1 {
return true
}
if cn == cn.t.fastestConn {
return true
}
return false
}
func (cn *connection) iterPendingPieces(f func(pieceIndex) bool) bool {
if !cn.t.haveInfo() {
return false
}
if cn.t.requestStrategy == 3 {
return cn.iterUnbiasedPieceRequestOrder(f)
}
if cn.shouldRequestWithoutBias() {
return cn.iterUnbiasedPieceRequestOrder(f)
} else {
return cn.pieceRequestOrder.IterTyped(func(i int) bool {
return f(pieceIndex(i))
})
}
}
func (cn *connection) iterPendingPiecesUntyped(f iter.Callback) {
cn.iterPendingPieces(func(i pieceIndex) bool { return f(i) })
}
func (cn *connection) iterPendingRequests(piece pieceIndex, f func(request) bool) bool {
return iterUndirtiedChunks(piece, cn.t, func(cs chunkSpec) bool {
r := request{pp.Integer(piece), cs}
if cn.t.requestStrategy == 3 {
if _, ok := cn.t.lastRequested[r]; ok {
// This piece has been requested on another connection, and
// the duplicate request timer is still running.
return true
}
}
return f(r)
})
}
func iterUndirtiedChunks(piece pieceIndex, t *Torrent, f func(chunkSpec) bool) bool {
p := &t.pieces[piece]
if t.requestStrategy == 3 {
for i := pp.Integer(0); i < p.numChunks(); i++ {
if !p.dirtyChunks.Get(bitmap.BitIndex(i)) {
if !f(t.chunkIndexSpec(i, piece)) {
return false
}
}
}
return true
}
chunkIndices := t.pieces[piece].undirtiedChunkIndices().ToSortedSlice()
// TODO: Use "math/rand".Shuffle >= Go 1.10
return iter.ForPerm(len(chunkIndices), func(i int) bool {
return f(t.chunkIndexSpec(pp.Integer(chunkIndices[i]), piece))
})
}
// check callers updaterequests
func (cn *connection) stopRequestingPiece(piece pieceIndex) bool {
return cn.pieceRequestOrder.Remove(bitmap.BitIndex(piece))
}
// This is distinct from Torrent piece priority, which is the user's
// preference. Connection piece priority is specific to a connection and is
// used to pseudorandomly avoid connections always requesting the same pieces
// and thus wasting effort.
func (cn *connection) updatePiecePriority(piece pieceIndex) bool {
tpp := cn.t.piecePriority(piece)
if !cn.PeerHasPiece(piece) {
tpp = PiecePriorityNone
}
if tpp == PiecePriorityNone {
return cn.stopRequestingPiece(piece)
}
prio := cn.getPieceInclination()[piece]
switch cn.t.requestStrategy {
case 1:
switch tpp {
case PiecePriorityNormal:
case PiecePriorityReadahead:
prio -= int(cn.t.numPieces())
case PiecePriorityNext, PiecePriorityNow:
prio -= 2 * int(cn.t.numPieces())
default:
panic(tpp)
}
prio += int(piece / 3)
default:
}
return cn.pieceRequestOrder.Set(bitmap.BitIndex(piece), prio) || cn.shouldRequestWithoutBias()
}
func (cn *connection) getPieceInclination() []int {
if cn.pieceInclination == nil {
cn.pieceInclination = cn.t.getConnPieceInclination()
}
return cn.pieceInclination
}
func (cn *connection) discardPieceInclination() {
if cn.pieceInclination == nil {
return
}
cn.t.putPieceInclination(cn.pieceInclination)
cn.pieceInclination = nil
}
func (cn *connection) peerPiecesChanged() {
if cn.t.haveInfo() {
prioritiesChanged := false
for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
if cn.updatePiecePriority(i) {
prioritiesChanged = true
}
}
if prioritiesChanged {
cn.updateRequests()
}
}
}
func (cn *connection) raisePeerMinPieces(newMin pieceIndex) {
if newMin > cn.peerMinPieces {
cn.peerMinPieces = newMin
}
}
func (cn *connection) peerSentHave(piece pieceIndex) error {
if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
return errors.New("invalid piece")
}
if cn.PeerHasPiece(piece) {
return nil
}
cn.raisePeerMinPieces(piece + 1)
cn.peerPieces.Set(bitmap.BitIndex(piece), true)
if cn.updatePiecePriority(piece) {
cn.updateRequests()
}
return nil
}
func (cn *connection) peerSentBitfield(bf []bool) error {
cn.peerSentHaveAll = false
if len(bf)%8 != 0 {
panic("expected bitfield length divisible by 8")
}
// We know that the last byte means that at most the last 7 bits are
// wasted.
cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
// Ignore known excess pieces.
bf = bf[:cn.t.numPieces()]
}
for i, have := range bf {
if have {
cn.raisePeerMinPieces(pieceIndex(i) + 1)
}
cn.peerPieces.Set(i, have)
}
cn.peerPiecesChanged()
return nil
}
func (cn *connection) onPeerSentHaveAll() error {
cn.peerSentHaveAll = true
cn.peerPieces.Clear()
cn.peerPiecesChanged()
return nil
}
func (cn *connection) peerSentHaveNone() error {
cn.peerPieces.Clear()
cn.peerSentHaveAll = false
cn.peerPiecesChanged()
return nil
}
func (c *connection) requestPendingMetadata() {
if c.t.haveInfo() {
return
}
if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
// Peer doesn't support this.
return
}
// Request metadata pieces that we don't have in a random order.
var pending []int
for index := 0; index < c.t.metadataPieceCount(); index++ {
if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
pending = append(pending, index)
}
}
for _, i := range rand.Perm(len(pending)) {
c.requestMetadataPiece(pending[i])
}
}
func (cn *connection) wroteMsg(msg *pp.Message) {
torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
}
func (cn *connection) readMsg(msg *pp.Message) {
cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
}
// After handshake, we know what Torrent and Client stats to include for a
// connection.
func (cn *connection) postHandshakeStats(f func(*ConnStats)) {
t := cn.t
f(&t.stats)
f(&t.cl.stats)
}
// All ConnStats that include this connection. Some objects are not known
// until the handshake is complete, after which it's expected to reconcile the
// differences.
func (cn *connection) allStats(f func(*ConnStats)) {
f(&cn.stats)
if cn.reconciledHandshakeStats {
cn.postHandshakeStats(f)
}
}
func (cn *connection) wroteBytes(n int64) {
cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
}
func (cn *connection) readBytes(n int64) {
cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
}
// Returns whether the connection could be useful to us. We're seeding and
// they want data, we don't have metainfo and they can provide it, etc.
func (c *connection) useful() bool {
t := c.t
if c.closed.IsSet() {
return false
}
if !t.haveInfo() {
return c.supportsExtension("ut_metadata")
}
if t.seeding() && c.PeerInterested {
return true
}
if c.peerHasWantedPieces() {
return true
}
return false
}
func (c *connection) lastHelpful() (ret time.Time) {
ret = c.lastUsefulChunkReceived
if c.t.seeding() && c.lastChunkSent.After(ret) {
ret = c.lastChunkSent
}
return
}
func (c *connection) fastEnabled() bool {
return c.PeerExtensionBytes.SupportsFast() && c.t.cl.extensionBytes.SupportsFast()
}
func (c *connection) reject(r request) {
if !c.fastEnabled() {
panic("fast not enabled")
}
c.Post(r.ToMsg(pp.Reject))
delete(c.PeerRequests, r)
}
func (c *connection) onReadRequest(r request) error {
requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
torrent.Add("bad requests received", 1)
return errors.New("bad request")
}
if _, ok := c.PeerRequests[r]; ok {
torrent.Add("duplicate requests received", 1)
return nil
}
if c.Choked {
torrent.Add("requests received while choking", 1)
if c.fastEnabled() {
torrent.Add("requests rejected while choking", 1)
c.reject(r)
}
return nil
}
if len(c.PeerRequests) >= maxRequests {
torrent.Add("requests received while queue full", 1)
if c.fastEnabled() {
c.reject(r)
}
// BEP 6 says we may close here if we choose.
return nil
}
if !c.t.havePiece(pieceIndex(r.Index)) {
// This isn't necessarily them screwing up. We can drop pieces
// from our storage, and can't communicate this to peers
// except by reconnecting.
requestsReceivedForMissingPieces.Add(1)
return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
}
if c.PeerRequests == nil {
c.PeerRequests = make(map[request]struct{}, maxRequests)
}
c.PeerRequests[r] = struct{}{}
c.tickleWriter()
return nil
}
// Processes incoming bittorrent messages. The client lock is held upon entry
// and exit. Returning will end the connection.
func (c *connection) mainReadLoop() (err error) {
defer func() {
if err != nil {
torrent.Add("connection.mainReadLoop returned with error", 1)
} else {
torrent.Add("connection.mainReadLoop returned with no error", 1)
}
}()
t := c.t
cl := t.cl
decoder := pp.Decoder{
R: bufio.NewReaderSize(c.r, 1<<17),
MaxLength: 256 * 1024,
Pool: t.chunkPool,
}
for {
var msg pp.Message
func() {
cl.unlock()
defer cl.lock()
err = decoder.Decode(&msg)
}()
if t.closed.IsSet() || c.closed.IsSet() || err == io.EOF {
return nil
}
if err != nil {
return err
}
c.readMsg(&msg)
c.lastMessageReceived = time.Now()
if msg.Keepalive {
receivedKeepalives.Add(1)
continue
}
messageTypesReceived.Add(msg.Type.String(), 1)
if msg.Type.FastExtension() && !c.fastEnabled() {
return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
}
switch msg.Type {
case pp.Choke:
c.PeerChoked = true
c.deleteAllRequests()
// We can then reset our interest.
c.updateRequests()
c.updateExpectingChunks()
case pp.Reject:
c.deleteRequest(newRequestFromMessage(&msg))
delete(c.validReceiveChunks, newRequestFromMessage(&msg))
case pp.Unchoke:
c.PeerChoked = false
c.tickleWriter()
c.updateExpectingChunks()
case pp.Interested:
c.PeerInterested = true
c.tickleWriter()
case pp.NotInterested:
c.PeerInterested = false
// We don't clear their requests since it isn't clear in the spec.
// We'll probably choke them for this, which will clear them if
// appropriate, and is clearly specified.
case pp.Have:
err = c.peerSentHave(pieceIndex(msg.Index))
case pp.Request:
r := newRequestFromMessage(&msg)
err = c.onReadRequest(r)
case pp.Cancel:
req := newRequestFromMessage(&msg)
c.onPeerSentCancel(req)
case pp.Bitfield:
err = c.peerSentBitfield(msg.Bitfield)
case pp.HaveAll:
err = c.onPeerSentHaveAll()
case pp.HaveNone:
err = c.peerSentHaveNone()
case pp.Piece:
err = c.receiveChunk(&msg)
if len(msg.Piece) == int(t.chunkSize) {
t.chunkPool.Put(&msg.Piece)
}
if err != nil {
err = fmt.Errorf("receiving chunk: %s", err)
}
case pp.Extended:
err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
case pp.Port:
pingAddr, err := net.ResolveUDPAddr("", c.remoteAddr().String())
if err != nil {
panic(err)
}
if msg.Port != 0 {
pingAddr.Port = int(msg.Port)
}
cl.eachDhtServer(func(s *dht.Server) {
go s.Ping(pingAddr, nil)
})
case pp.AllowedFast:
torrent.Add("allowed fasts received", 1)
log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c, debugLogValue).Log(c.t.logger)
c.peerAllowedFast.Add(int(msg.Index))
c.updateRequests()
case pp.Suggest:
torrent.Add("suggests received", 1)
log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index, debugLogValue).Log(c.t.logger)
c.updateRequests()
default:
err = fmt.Errorf("received unknown message type: %#v", msg.Type)
}
if err != nil {
return err
}
}
}
func (c *connection) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
defer func() {
// TODO: Should we still do this?
if err != nil {
// These clients use their own extension IDs for outgoing message
// types, which is incorrect.
if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
err = nil
}
}
}()
t := c.t
cl := t.cl
switch id {
case pp.HandshakeExtendedID:
var d pp.ExtendedHandshakeMessage
if err := bencode.Unmarshal(payload, &d); err != nil {
log.Printf("error parsing extended handshake message %q: %s", payload, err)
return errors.Wrap(err, "unmarshalling extended handshake payload")
}
if d.Reqq != 0 {
c.PeerMaxRequests = d.Reqq
}
c.PeerClientName = d.V
if c.PeerExtensionIDs == nil {
c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
}
for name, id := range d.M {
if _, ok := c.PeerExtensionIDs[name]; !ok {
torrent.Add(fmt.Sprintf("peers supporting extension %q", name), 1)
}
c.PeerExtensionIDs[name] = id
}
if d.MetadataSize != 0 {
if err = t.setMetadataSize(d.MetadataSize); err != nil {
return errors.Wrapf(err, "setting metadata size to %d", d.MetadataSize)
}
}
if _, ok := c.PeerExtensionIDs[pp.ExtensionNameMetadata]; ok {
c.requestPendingMetadata()
}
return nil
case metadataExtendedId:
err := cl.gotMetadataExtensionMsg(payload, t, c)
if err != nil {
return fmt.Errorf("error handling metadata extension message: %s", err)
}
return nil
case pexExtendedId:
if cl.config.DisablePEX {
// TODO: Maybe close the connection. Check that we're not
// advertising that we support PEX if it's disabled.
return nil
}
var pexMsg pp.PexMsg
err := bencode.Unmarshal(payload, &pexMsg)
if err != nil {
return fmt.Errorf("error unmarshalling PEX message: %s", err)
}
torrent.Add("pex added6 peers received", int64(len(pexMsg.Added6)))
var peers Peers
peers.AppendFromPex(pexMsg.Added6, pexMsg.Added6Flags)
peers.AppendFromPex(pexMsg.Added, pexMsg.AddedFlags)
t.addPeers(peers)
return nil
default:
return fmt.Errorf("unexpected extended message ID: %v", id)
}
}
// Set both the Reader and Writer for the connection from a single ReadWriter.
func (cn *connection) setRW(rw io.ReadWriter) {
cn.r = rw
cn.w = rw
}
// Returns the Reader and Writer as a combined ReadWriter.
func (cn *connection) rw() io.ReadWriter {
return struct {
io.Reader
io.Writer
}{cn.r, cn.w}
}
// Handle a received chunk from a peer.
func (c *connection) receiveChunk(msg *pp.Message) error {
t := c.t
cl := t.cl
torrent.Add("chunks received", 1)
req := newRequestFromMessage(msg)
if c.PeerChoked {
torrent.Add("chunks received while choked", 1)
}
if _, ok := c.validReceiveChunks[req]; !ok {
torrent.Add("chunks received unexpected", 1)
return errors.New("received unexpected chunk")
}
delete(c.validReceiveChunks, req)
if c.PeerChoked && c.peerAllowedFast.Get(int(req.Index)) {
torrent.Add("chunks received due to allowed fast", 1)
}
// Request has been satisfied.
if c.deleteRequest(req) {
if c.expectingChunks() {
c.chunksReceivedWhileExpecting++
}
} else {
torrent.Add("chunks received unwanted", 1)
}
// Do we actually want this chunk?
if t.haveChunk(req) {
torrent.Add("chunks received wasted", 1)
c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
return nil
}
piece := &t.pieces[req.Index]
c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
c.lastUsefulChunkReceived = time.Now()
// if t.fastestConn != c {
// log.Printf("setting fastest connection %p", c)
// }
t.fastestConn = c
// Need to record that it hasn't been written yet, before we attempt to do
// anything with it.
piece.incrementPendingWrites()
// Record that we have the chunk, so we aren't trying to download it while
// waiting for it to be written to storage.
piece.unpendChunkIndex(chunkIndex(req.chunkSpec, t.chunkSize))
// Cancel pending requests for this chunk.
for c := range t.conns {
c.postCancel(req)
}
err := func() error {
cl.unlock()
defer cl.lock()
// Write the chunk out. Note that the upper bound on chunk writing
// concurrency will be the number of connections. We write inline with
// receiving the chunk (with this lock dance), because we want to
// handle errors synchronously and I haven't thought of a nice way to
// defer any concurrency to the storage and have that notify the
// client of errors. TODO: Do that instead.
return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
}()
piece.decrementPendingWrites()
if err != nil {
log.Printf("%s (%s): error writing chunk %v: %s", t, t.infoHash, req, err)
t.pendRequest(req)
t.updatePieceCompletion(pieceIndex(msg.Index))
return nil
}
// It's important that the piece is potentially queued before we check if
// the piece is still wanted, because if it is queued, it won't be wanted.
if t.pieceAllDirty(pieceIndex(req.Index)) {
t.queuePieceCheck(pieceIndex(req.Index))
t.pendAllChunkSpecs(pieceIndex(req.Index))
}
c.onDirtiedPiece(pieceIndex(req.Index))
cl.event.Broadcast()
t.publishPieceChange(pieceIndex(req.Index))
return nil
}
func (c *connection) onDirtiedPiece(piece pieceIndex) {
if c.peerTouchedPieces == nil {
c.peerTouchedPieces = make(map[pieceIndex]struct{})
}
c.peerTouchedPieces[piece] = struct{}{}
ds := &c.t.pieces[piece].dirtiers
if *ds == nil {
*ds = make(map[*connection]struct{})
}
(*ds)[c] = struct{}{}
}
func (c *connection) uploadAllowed() bool {
if c.t.cl.config.NoUpload {
return false
}
if c.t.seeding() {
return true
}
if !c.peerHasWantedPieces() {
return false
}
// Don't upload more than 100 KiB more than we download.
if c.stats.BytesWrittenData.Int64() >= c.stats.BytesReadData.Int64()+100<<10 {
return false
}
return true
}
func (c *connection) setRetryUploadTimer(delay time.Duration) {
if c.uploadTimer == nil {
c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
} else {
c.uploadTimer.Reset(delay)
}
}
// Also handles choking and unchoking of the remote peer.
func (c *connection) upload(msg func(pp.Message) bool) bool {
// Breaking or completing this loop means we don't want to upload to the
// peer anymore, and we choke them.
another:
for c.uploadAllowed() {
// We want to upload to the peer.
if !c.Unchoke(msg) {
return false
}
for r := range c.PeerRequests {
res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
if !res.OK() {
panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
}
delay := res.Delay()
if delay > 0 {
res.Cancel()
c.setRetryUploadTimer(delay)
// Hard to say what to return here.
return true
}
more, err := c.sendChunk(r, msg)
if err != nil {
i := pieceIndex(r.Index)
if c.t.pieceComplete(i) {
c.t.updatePieceCompletion(i)
if !c.t.pieceComplete(i) {
// We had the piece, but not anymore.
break another
}
}
log.Str("error sending chunk to peer").AddValues(c, r, err).Log(c.t.logger)
// If we failed to send a chunk, choke the peer to ensure they
// flush all their requests. We've probably dropped a piece,
// but there's no way to communicate this to the peer. If they
// ask for it again, we'll kick them to allow us to send them
// an updated bitfield.
break another
}
delete(c.PeerRequests, r)
if !more {
return false
}
goto another
}
return true
}
return c.Choke(msg)
}
func (cn *connection) Drop() {
cn.t.dropConnection(cn)
}
func (cn *connection) netGoodPiecesDirtied() int64 {
return cn.stats.PiecesDirtiedGood.Int64() - cn.stats.PiecesDirtiedBad.Int64()
}
func (c *connection) peerHasWantedPieces() bool {
return !c.pieceRequestOrder.IsEmpty()
}
func (c *connection) numLocalRequests() int {
return len(c.requests)
}
func (c *connection) deleteRequest(r request) bool {
if _, ok := c.requests[r]; !ok {
return false
}
delete(c.requests, r)
c.updateExpectingChunks()
if t, ok := c.t.lastRequested[r]; ok {
t.Stop()
delete(c.t.lastRequested, r)
}
pr := c.t.pendingRequests
pr[r]--
n := pr[r]
if n == 0 {
delete(pr, r)
}
if n < 0 {
panic(n)
}
c.updateRequests()
for _c := range c.t.conns {
if !_c.Interested && _c != c && c.PeerHasPiece(pieceIndex(r.Index)) {
_c.updateRequests()
}
}
return true
}
func (c *connection) deleteAllRequests() {
for r := range c.requests {
c.deleteRequest(r)
}
if len(c.requests) != 0 {
panic(len(c.requests))
}
// for c := range c.t.conns {
// c.tickleWriter()
// }
}
func (c *connection) tickleWriter() {
c.writerCond.Broadcast()
}
func (c *connection) postCancel(r request) bool {
if !c.deleteRequest(r) {
return false
}
c.Post(makeCancelMessage(r))
return true
}
func (c *connection) sendChunk(r request, msg func(pp.Message) bool) (more bool, err error) {
// Count the chunk being sent, even if it isn't.
b := make([]byte, r.Length)
p := c.t.info.Piece(int(r.Index))
n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
if n != len(b) {
if err == nil {
panic("expected error")
}
return
} else if err == io.EOF {
err = nil
}
more = msg(pp.Message{
Type: pp.Piece,
Index: r.Index,
Begin: r.Begin,
Piece: b,
})
c.lastChunkSent = time.Now()
return
}
func (c *connection) setTorrent(t *Torrent) {
if c.t != nil {
panic("connection already associated with a torrent")
}
c.t = t
t.reconcileHandshakeStats(c)
}
func (c *connection) peerPriority() peerPriority {
return bep40PriorityIgnoreError(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
}
func (c *connection) remoteIp() net.IP {
return missinggo.AddrIP(c.remoteAddr())
}
func (c *connection) remoteIpPort() ipPort {
return ipPort{missinggo.AddrIP(c.remoteAddr()), uint16(missinggo.AddrPort(c.remoteAddr()))}
}