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stream.go
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stream.go
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package smux
import (
"bytes"
"io"
"net"
"sync"
"sync/atomic"
"time"
"github.com/pkg/errors"
"container/heap"
)
// Stream implements net.Conn
type Stream struct {
id uint32
niceness uint8
rstflag int32
sess *Session
buffer bytes.Buffer
bufferLock sync.Mutex
frameSize int
chReadEvent chan struct{} // notify a read event
die chan struct{} // flag the stream has closed
dieLock sync.Mutex
readDeadline atomic.Value
writeDeadline atomic.Value
writeTokenBucket int32 // write tokens required for writing to the sessions
writeTokenBucketNotify chan struct{} // used for waiting for tokens
}
// newStream initiates a Stream struct
func newStream(id uint32, niceness uint8, frameSize int, writeTokenBucketSize int32, sess *Session) *Stream {
s := new(Stream)
s.niceness = niceness
s.id = id
s.chReadEvent = make(chan struct{}, 1)
s.frameSize = frameSize
s.sess = sess
s.die = make(chan struct{})
s.writeTokenBucket = writeTokenBucketSize
s.writeTokenBucketNotify = make(chan struct{}, 1)
return s
}
// ID returns the unique stream ID.
func (s *Stream) ID() uint32 {
return s.id
}
// Read implements net.Conn
func (s *Stream) Read(b []byte) (n int, err error) {
if len(b) == 0 {
select {
case <-s.die:
return 0, errors.New(errBrokenPipe)
default:
return 0, nil
}
}
var deadline <-chan time.Time
if d, ok := s.readDeadline.Load().(time.Time); ok && !d.IsZero() {
timer := time.NewTimer(time.Until(d))
defer timer.Stop()
deadline = timer.C
}
READ:
s.bufferLock.Lock()
n, err = s.buffer.Read(b)
s.bufferLock.Unlock()
if n > 0 {
s.sess.queueAcks(s.id, int32(n))
return n, nil
} else if atomic.LoadInt32(&s.rstflag) == 1 {
_ = s.Close()
return 0, io.EOF
}
select {
case <-s.chReadEvent:
goto READ
case <-deadline:
return n, errTimeout
case <-s.die:
return 0, errors.New(errBrokenPipe)
}
}
// Write implements net.Conn
func (s *Stream) Write(b []byte) (n int, err error) {
var deadline <-chan time.Time
if d, ok := s.writeDeadline.Load().(time.Time); ok && !d.IsZero() {
timer := time.NewTimer(time.Until(d))
defer timer.Stop()
deadline = timer.C
}
select {
case <-s.die:
return 0, errors.New(errBrokenPipe)
default:
}
frames := s.split(b, cmdPSH, s.id)
sent := 0
for k := range frames {
for atomic.LoadInt32(&s.writeTokenBucket) <= 0 {
select {
case <-s.writeTokenBucketNotify:
case <-s.die:
return sent, errors.New(errBrokenPipe)
case <-deadline:
return sent, errTimeout
}
}
atomic.AddInt32(&s.writeTokenBucket, -int32(len(frames[k].data)))
req := writeRequest{
niceness: s.niceness,
sequence: atomic.AddUint64(&s.sess.writeSequenceNum, 1),
frame: frames[k],
result: make(chan writeResult, 1),
}
// TODO(jnewman): replace with session.writeFrame(..)?
s.sess.writesLock.Lock()
heap.Push(&s.sess.writes, req)
s.sess.writesLock.Unlock()
select {
case s.sess.writeTicket <- struct{}{}:
case <-s.die:
return sent, errors.New(errBrokenPipe)
case <-deadline:
return sent, errTimeout
}
select {
case result := <-req.result:
sent += result.n
if result.err != nil {
return sent, result.err
}
case <-s.die:
return sent, errors.New(errBrokenPipe)
case <-deadline:
return sent, errTimeout
}
}
return sent, nil
}
// Close implements net.Conn
func (s *Stream) Close() error {
s.dieLock.Lock()
select {
case <-s.die:
s.dieLock.Unlock()
return errors.New(errBrokenPipe)
default:
close(s.die)
s.dieLock.Unlock()
s.sess.streamClosed(s.id)
_, err := s.sess.writeFrame(0, newFrame(cmdFIN, s.id))
return err
}
}
// SetReadDeadline sets the read deadline as defined by
// net.Conn.SetReadDeadline.
// A zero time value disables the deadline.
func (s *Stream) SetReadDeadline(t time.Time) error {
s.readDeadline.Store(t)
return nil
}
// SetWriteDeadline sets the write deadline as defined by
// net.Conn.SetWriteDeadline.
// A zero time value disables the deadline.
func (s *Stream) SetWriteDeadline(t time.Time) error {
s.writeDeadline.Store(t)
return nil
}
// SetDeadline sets both read and write deadlines as defined by
// net.Conn.SetDeadline.
// A zero time value disables the deadlines.
func (s *Stream) SetDeadline(t time.Time) error {
if err := s.SetReadDeadline(t); err != nil {
return err
}
if err := s.SetWriteDeadline(t); err != nil {
return err
}
return nil
}
// session closes the stream
func (s *Stream) sessionClose() {
s.dieLock.Lock()
defer s.dieLock.Unlock()
select {
case <-s.die:
default:
close(s.die)
}
}
// LocalAddr satisfies net.Conn interface
func (s *Stream) LocalAddr() net.Addr {
if ts, ok := s.sess.conn.(interface {
LocalAddr() net.Addr
}); ok {
return ts.LocalAddr()
}
return nil
}
// RemoteAddr satisfies net.Conn interface
func (s *Stream) RemoteAddr() net.Addr {
if ts, ok := s.sess.conn.(interface {
RemoteAddr() net.Addr
}); ok {
return ts.RemoteAddr()
}
return nil
}
// pushBytes a slice into buffer
func (s *Stream) pushBytes(p []byte) {
s.bufferLock.Lock()
s.buffer.Write(p)
s.bufferLock.Unlock()
}
// receiveAck replenishes the token writeTokenBucket so that more writes can proceed
func (s *Stream) receiveAck(numTokens int32) {
if atomic.AddInt32(&s.writeTokenBucket, numTokens) > 0 {
s.notifyBucket()
}
}
// notifyBucket notifies waiting write loops that there are more tokens in the writeTokenBucket
func (s *Stream) notifyBucket() {
select {
case s.writeTokenBucketNotify <- struct{}{}:
default:
}
}
// split large byte buffer into smaller frames, reference only
func (s *Stream) split(bts []byte, cmd byte, sid uint32) []Frame {
frames := make([]Frame, 0, len(bts)/s.frameSize+1)
for len(bts) > s.frameSize {
frame := newFrame(cmd, sid)
frame.data = bts[:s.frameSize]
bts = bts[s.frameSize:]
frames = append(frames, frame)
}
if len(bts) > 0 {
frame := newFrame(cmd, sid)
frame.data = bts
frames = append(frames, frame)
}
return frames
}
// notify read event
func (s *Stream) notifyReadEvent() {
select {
case s.chReadEvent <- struct{}{}:
default:
}
}
// mark this stream has been reset
func (s *Stream) markRST() {
atomic.StoreInt32(&s.rstflag, 1)
}
var errTimeout error = &timeoutError{}
type timeoutError struct{}
func (e *timeoutError) Error() string { return "i/o timeout" }
func (e *timeoutError) Timeout() bool { return true }
func (e *timeoutError) Temporary() bool { return true }