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464 lines
12 KiB
Go
464 lines
12 KiB
Go
package sctp
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import (
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"errors"
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"fmt"
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"io"
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"math"
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"os"
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"sync"
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"sync/atomic"
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"time"
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"github.com/pion/logging"
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)
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const (
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// ReliabilityTypeReliable is used for reliable transmission
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ReliabilityTypeReliable byte = 0
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// ReliabilityTypeRexmit is used for partial reliability by retransmission count
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ReliabilityTypeRexmit byte = 1
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// ReliabilityTypeTimed is used for partial reliability by retransmission duration
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ReliabilityTypeTimed byte = 2
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)
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// StreamState is an enum for SCTP Stream state field
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// This field identifies the state of stream.
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type StreamState int
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// StreamState enums
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const (
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StreamStateOpen StreamState = iota // Stream object starts with StreamStateOpen
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StreamStateClosing // Outgoing stream is being reset
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StreamStateClosed // Stream has been closed
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)
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func (ss StreamState) String() string {
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switch ss {
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case StreamStateOpen:
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return "open"
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case StreamStateClosing:
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return "closing"
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case StreamStateClosed:
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return "closed"
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}
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return "unknown"
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}
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// SCTP stream errors
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var (
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ErrOutboundPacketTooLarge = errors.New("outbound packet larger than maximum message size")
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ErrStreamClosed = errors.New("stream closed")
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ErrReadDeadlineExceeded = fmt.Errorf("read deadline exceeded: %w", os.ErrDeadlineExceeded)
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)
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// Stream represents an SCTP stream
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type Stream struct {
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association *Association
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lock sync.RWMutex
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streamIdentifier uint16
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defaultPayloadType PayloadProtocolIdentifier
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reassemblyQueue *reassemblyQueue
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sequenceNumber uint16
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readNotifier *sync.Cond
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readErr error
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readTimeoutCancel chan struct{}
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unordered bool
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reliabilityType byte
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reliabilityValue uint32
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bufferedAmount uint64
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bufferedAmountLow uint64
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onBufferedAmountLow func()
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state StreamState
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log logging.LeveledLogger
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name string
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}
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// StreamIdentifier returns the Stream identifier associated to the stream.
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func (s *Stream) StreamIdentifier() uint16 {
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s.lock.RLock()
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defer s.lock.RUnlock()
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return s.streamIdentifier
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}
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// SetDefaultPayloadType sets the default payload type used by Write.
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func (s *Stream) SetDefaultPayloadType(defaultPayloadType PayloadProtocolIdentifier) {
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atomic.StoreUint32((*uint32)(&s.defaultPayloadType), uint32(defaultPayloadType))
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}
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// SetReliabilityParams sets reliability parameters for this stream.
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func (s *Stream) SetReliabilityParams(unordered bool, relType byte, relVal uint32) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.setReliabilityParams(unordered, relType, relVal)
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}
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// setReliabilityParams sets reliability parameters for this stream.
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// The caller should hold the lock.
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func (s *Stream) setReliabilityParams(unordered bool, relType byte, relVal uint32) {
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s.log.Debugf("[%s] reliability params: ordered=%v type=%d value=%d",
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s.name, !unordered, relType, relVal)
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s.unordered = unordered
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s.reliabilityType = relType
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s.reliabilityValue = relVal
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}
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// Read reads a packet of len(p) bytes, dropping the Payload Protocol Identifier.
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// Returns EOF when the stream is reset or an error if the stream is closed
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// otherwise.
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func (s *Stream) Read(p []byte) (int, error) {
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n, _, err := s.ReadSCTP(p)
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return n, err
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}
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// ReadSCTP reads a packet of len(p) bytes and returns the associated Payload
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// Protocol Identifier.
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// Returns EOF when the stream is reset or an error if the stream is closed
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// otherwise.
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func (s *Stream) ReadSCTP(p []byte) (int, PayloadProtocolIdentifier, error) {
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s.lock.Lock()
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defer s.lock.Unlock()
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defer func() {
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// close readTimeoutCancel if the current read timeout routine is no longer effective
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if s.readTimeoutCancel != nil && s.readErr != nil {
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close(s.readTimeoutCancel)
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s.readTimeoutCancel = nil
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}
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}()
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for {
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n, ppi, err := s.reassemblyQueue.read(p)
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if err == nil {
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return n, ppi, nil
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} else if errors.Is(err, io.ErrShortBuffer) {
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return 0, PayloadProtocolIdentifier(0), err
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}
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err = s.readErr
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if err != nil {
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return 0, PayloadProtocolIdentifier(0), err
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}
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s.readNotifier.Wait()
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}
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}
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// SetReadDeadline sets the read deadline in an identical way to net.Conn
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func (s *Stream) SetReadDeadline(deadline time.Time) error {
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s.lock.Lock()
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defer s.lock.Unlock()
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if s.readTimeoutCancel != nil {
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close(s.readTimeoutCancel)
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s.readTimeoutCancel = nil
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}
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if s.readErr != nil {
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if !errors.Is(s.readErr, ErrReadDeadlineExceeded) {
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return nil
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}
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s.readErr = nil
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}
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if !deadline.IsZero() {
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s.readTimeoutCancel = make(chan struct{})
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go func(readTimeoutCancel chan struct{}) {
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t := time.NewTimer(time.Until(deadline))
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select {
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case <-readTimeoutCancel:
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t.Stop()
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return
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case <-t.C:
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s.lock.Lock()
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if s.readErr == nil {
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s.readErr = ErrReadDeadlineExceeded
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}
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s.readTimeoutCancel = nil
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s.lock.Unlock()
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s.readNotifier.Signal()
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}
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}(s.readTimeoutCancel)
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}
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return nil
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}
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func (s *Stream) handleData(pd *chunkPayloadData) {
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s.lock.Lock()
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defer s.lock.Unlock()
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var readable bool
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if s.reassemblyQueue.push(pd) {
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readable = s.reassemblyQueue.isReadable()
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s.log.Debugf("[%s] reassemblyQueue readable=%v", s.name, readable)
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if readable {
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s.log.Debugf("[%s] readNotifier.signal()", s.name)
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s.readNotifier.Signal()
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s.log.Debugf("[%s] readNotifier.signal() done", s.name)
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}
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}
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}
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func (s *Stream) handleForwardTSNForOrdered(ssn uint16) {
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var readable bool
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func() {
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s.lock.Lock()
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defer s.lock.Unlock()
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if s.unordered {
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return // unordered chunks are handled by handleForwardUnordered method
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}
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// Remove all chunks older than or equal to the new TSN from
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// the reassemblyQueue.
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s.reassemblyQueue.forwardTSNForOrdered(ssn)
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readable = s.reassemblyQueue.isReadable()
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}()
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// Notify the reader asynchronously if there's a data chunk to read.
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if readable {
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s.readNotifier.Signal()
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}
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}
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func (s *Stream) handleForwardTSNForUnordered(newCumulativeTSN uint32) {
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var readable bool
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func() {
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s.lock.Lock()
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defer s.lock.Unlock()
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if !s.unordered {
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return // ordered chunks are handled by handleForwardTSNOrdered method
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}
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// Remove all chunks older than or equal to the new TSN from
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// the reassemblyQueue.
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s.reassemblyQueue.forwardTSNForUnordered(newCumulativeTSN)
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readable = s.reassemblyQueue.isReadable()
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}()
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// Notify the reader asynchronously if there's a data chunk to read.
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if readable {
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s.readNotifier.Signal()
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}
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}
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// Write writes len(p) bytes from p with the default Payload Protocol Identifier
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func (s *Stream) Write(p []byte) (n int, err error) {
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ppi := PayloadProtocolIdentifier(atomic.LoadUint32((*uint32)(&s.defaultPayloadType)))
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return s.WriteSCTP(p, ppi)
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}
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// WriteSCTP writes len(p) bytes from p to the DTLS connection
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func (s *Stream) WriteSCTP(p []byte, ppi PayloadProtocolIdentifier) (int, error) {
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maxMessageSize := s.association.MaxMessageSize()
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if len(p) > int(maxMessageSize) {
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return 0, fmt.Errorf("%w: %v", ErrOutboundPacketTooLarge, math.MaxUint16)
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}
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if s.State() != StreamStateOpen {
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return 0, ErrStreamClosed
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}
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chunks := s.packetize(p, ppi)
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n := len(p)
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err := s.association.sendPayloadData(chunks)
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if err != nil {
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return n, ErrStreamClosed
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}
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return n, nil
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}
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func (s *Stream) packetize(raw []byte, ppi PayloadProtocolIdentifier) []*chunkPayloadData {
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s.lock.Lock()
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defer s.lock.Unlock()
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i := uint32(0)
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remaining := uint32(len(raw))
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// From draft-ietf-rtcweb-data-protocol-09, section 6:
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// All Data Channel Establishment Protocol messages MUST be sent using
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// ordered delivery and reliable transmission.
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unordered := ppi != PayloadTypeWebRTCDCEP && s.unordered
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var chunks []*chunkPayloadData
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var head *chunkPayloadData
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for remaining != 0 {
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fragmentSize := min32(s.association.maxPayloadSize, remaining)
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// Copy the userdata since we'll have to store it until acked
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// and the caller may re-use the buffer in the mean time
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userData := make([]byte, fragmentSize)
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copy(userData, raw[i:i+fragmentSize])
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chunk := &chunkPayloadData{
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streamIdentifier: s.streamIdentifier,
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userData: userData,
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unordered: unordered,
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beginningFragment: i == 0,
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endingFragment: remaining-fragmentSize == 0,
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immediateSack: false,
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payloadType: ppi,
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streamSequenceNumber: s.sequenceNumber,
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head: head,
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}
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if head == nil {
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head = chunk
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}
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chunks = append(chunks, chunk)
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remaining -= fragmentSize
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i += fragmentSize
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}
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// RFC 4960 Sec 6.6
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// Note: When transmitting ordered and unordered data, an endpoint does
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// not increment its Stream Sequence Number when transmitting a DATA
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// chunk with U flag set to 1.
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if !unordered {
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s.sequenceNumber++
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}
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s.bufferedAmount += uint64(len(raw))
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s.log.Tracef("[%s] bufferedAmount = %d", s.name, s.bufferedAmount)
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return chunks
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}
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// Close closes the write-direction of the stream.
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// Future calls to Write are not permitted after calling Close.
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func (s *Stream) Close() error {
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if sid, resetOutbound := func() (uint16, bool) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.log.Debugf("[%s] Close: state=%s", s.name, s.state.String())
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if s.state == StreamStateOpen {
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if s.readErr == nil {
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s.state = StreamStateClosing
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} else {
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s.state = StreamStateClosed
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}
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s.log.Debugf("[%s] state change: open => %s", s.name, s.state.String())
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return s.streamIdentifier, true
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}
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return s.streamIdentifier, false
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}(); resetOutbound {
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// Reset the outgoing stream
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// https://tools.ietf.org/html/rfc6525
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return s.association.sendResetRequest(sid)
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}
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return nil
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}
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// BufferedAmount returns the number of bytes of data currently queued to be sent over this stream.
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func (s *Stream) BufferedAmount() uint64 {
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s.lock.RLock()
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defer s.lock.RUnlock()
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return s.bufferedAmount
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}
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// BufferedAmountLowThreshold returns the number of bytes of buffered outgoing data that is
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// considered "low." Defaults to 0.
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func (s *Stream) BufferedAmountLowThreshold() uint64 {
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s.lock.RLock()
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defer s.lock.RUnlock()
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return s.bufferedAmountLow
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}
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// SetBufferedAmountLowThreshold is used to update the threshold.
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// See BufferedAmountLowThreshold().
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func (s *Stream) SetBufferedAmountLowThreshold(th uint64) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.bufferedAmountLow = th
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}
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// OnBufferedAmountLow sets the callback handler which would be called when the number of
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// bytes of outgoing data buffered is lower than the threshold.
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func (s *Stream) OnBufferedAmountLow(f func()) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.onBufferedAmountLow = f
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}
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// This method is called by association's readLoop (go-)routine to notify this stream
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// of the specified amount of outgoing data has been delivered to the peer.
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func (s *Stream) onBufferReleased(nBytesReleased int) {
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if nBytesReleased <= 0 {
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return
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}
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s.lock.Lock()
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fromAmount := s.bufferedAmount
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if s.bufferedAmount < uint64(nBytesReleased) {
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s.bufferedAmount = 0
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s.log.Errorf("[%s] released buffer size %d should be <= %d",
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s.name, nBytesReleased, s.bufferedAmount)
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} else {
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s.bufferedAmount -= uint64(nBytesReleased)
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}
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s.log.Tracef("[%s] bufferedAmount = %d", s.name, s.bufferedAmount)
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if s.onBufferedAmountLow != nil && fromAmount > s.bufferedAmountLow && s.bufferedAmount <= s.bufferedAmountLow {
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f := s.onBufferedAmountLow
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s.lock.Unlock()
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f()
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return
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}
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s.lock.Unlock()
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}
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func (s *Stream) getNumBytesInReassemblyQueue() int {
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// No lock is required as it reads the size with atomic load function.
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return s.reassemblyQueue.getNumBytes()
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}
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func (s *Stream) onInboundStreamReset() {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.log.Debugf("[%s] onInboundStreamReset: state=%s", s.name, s.state.String())
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// No more inbound data to read. Unblock the read with io.EOF.
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// This should cause DCEP layer (datachannel package) to call Close() which
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// will reset outgoing stream also.
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// See RFC 8831 section 6.7:
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// if one side decides to close the data channel, it resets the corresponding
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// outgoing stream. When the peer sees that an incoming stream was
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// reset, it also resets its corresponding outgoing stream. Once this
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// is completed, the data channel is closed.
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s.readErr = io.EOF
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s.readNotifier.Broadcast()
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if s.state == StreamStateClosing {
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s.log.Debugf("[%s] state change: closing => closed", s.name)
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s.state = StreamStateClosed
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}
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}
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// State return the stream state.
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func (s *Stream) State() StreamState {
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s.lock.RLock()
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defer s.lock.RUnlock()
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return s.state
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}
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