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170 lines
4.0 KiB
Go
170 lines
4.0 KiB
Go
package multiplex
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import (
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"errors"
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"net"
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"time"
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//"log"
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"math"
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prand "math/rand"
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"sync"
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"sync/atomic"
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)
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var ErrBrokenStream = errors.New("broken stream")
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type Stream struct {
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id uint32
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session *Session
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// Explanations of the following 4 fields can be found in frameSorter.go
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nextRecvSeq uint32
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rev int
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sh sorterHeap
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wrapMode bool
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// New frames are received through newFrameCh by frameSorter
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newFrameCh chan *Frame
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sortedBuf *bufferedPipe
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// atomic
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nextSendSeq uint32
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writingM sync.RWMutex
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// close(die) is used to notify different goroutines that this stream is closing
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closed uint32
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}
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func makeStream(id uint32, sesh *Session) *Stream {
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stream := &Stream{
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id: id,
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session: sesh,
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sh: []*frameNode{},
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newFrameCh: make(chan *Frame, 1024),
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sortedBuf: NewBufferedPipe(),
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}
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go stream.recvNewFrame()
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return stream
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}
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func (s *Stream) isClosed() bool { return atomic.LoadUint32(&s.closed) == 1 }
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func (s *Stream) Read(buf []byte) (n int, err error) {
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if len(buf) == 0 {
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if s.isClosed() {
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return 0, ErrBrokenStream
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} else {
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return 0, nil
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}
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}
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if s.isClosed() {
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if s.sortedBuf.Len() == 0 {
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return 0, ErrBrokenStream
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} else {
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return s.sortedBuf.Read(buf)
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}
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} else {
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return s.sortedBuf.Read(buf)
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}
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}
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func (s *Stream) Write(in []byte) (n int, err error) {
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// RWMutex used here isn't really for RW.
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// we use it to exploit the fact that RLock doesn't create contention.
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// The use of RWMutex is so that the stream will not actively close
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// in the middle of the execution of Write. This may cause the closing frame
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// to be sent before the data frame and cause loss of packet.
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s.writingM.RLock()
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if s.isClosed() {
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s.writingM.RUnlock()
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return 0, ErrBrokenStream
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}
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f := &Frame{
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StreamID: s.id,
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Seq: atomic.AddUint32(&s.nextSendSeq, 1) - 1,
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Closing: 0,
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Payload: in,
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}
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tlsRecord, err := s.session.obfs(f)
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if err != nil {
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s.writingM.RUnlock()
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return 0, err
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}
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n, err = s.session.sb.send(tlsRecord)
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s.writingM.RUnlock()
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return
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}
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// the necessary steps to mark the stream as closed and to release resources
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func (s *Stream) _close() {
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atomic.StoreUint32(&s.closed, 1)
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s.newFrameCh <- nil // this will trigger frameSorter to return
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s.sortedBuf.Close()
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}
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// only close locally. Used when the stream close is notified by the remote
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func (s *Stream) passiveClose() {
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s._close()
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s.session.delStream(s.id)
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//log.Printf("%v passive closing\n", stream.id)
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}
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// active close. Close locally and tell the remote that this stream is being closed
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func (s *Stream) Close() error {
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s.writingM.Lock()
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if s.isClosed() {
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s.writingM.Unlock()
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return errors.New("Already Closed")
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}
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// Notify remote that this stream is closed
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prand.Seed(int64(s.id))
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padLen := int(math.Floor(prand.Float64()*200 + 300))
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pad := make([]byte, padLen)
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prand.Read(pad)
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f := &Frame{
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StreamID: s.id,
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Seq: atomic.AddUint32(&s.nextSendSeq, 1) - 1,
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Closing: 1,
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Payload: pad,
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}
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tlsRecord, _ := s.session.obfs(f)
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s.session.sb.send(tlsRecord)
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s._close()
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s.session.delStream(s.id)
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//log.Printf("%v actively closed\n", stream.id)
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s.writingM.Unlock()
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return nil
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}
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// Same as passiveClose() but no call to session.delStream.
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// This is called in session.Close() to avoid mutex deadlock
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// We don't notify the remote because session.Close() is always
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// called when the session is passively closed
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func (s *Stream) closeNoDelMap() {
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s._close()
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}
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// the following functions are purely for implementing net.Conn interface.
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// they are not used
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var errNotImplemented = errors.New("Not implemented")
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func (s *Stream) LocalAddr() net.Addr { return s.session.addrs.Load().([]net.Addr)[0] }
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func (s *Stream) RemoteAddr() net.Addr { return s.session.addrs.Load().([]net.Addr)[1] }
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// TODO: implement the following
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func (s *Stream) SetDeadline(t time.Time) error { return errNotImplemented }
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func (s *Stream) SetReadDeadline(t time.Time) error { return errNotImplemented }
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func (s *Stream) SetWriteDeadline(t time.Time) error { return errNotImplemented }
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