vendor.github.com.pion.sctp.association.go Maven / Gradle / Ivy
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// SPDX-FileCopyrightText: 2023 The Pion community
// SPDX-License-Identifier: MIT
package sctp
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"math"
"net"
"sync"
"sync/atomic"
"time"
"github.com/pion/logging"
"github.com/pion/randutil"
)
// Use global random generator to properly seed by crypto grade random.
var globalMathRandomGenerator = randutil.NewMathRandomGenerator() // nolint:gochecknoglobals
// Association errors
var (
ErrChunk = errors.New("abort chunk, with following errors")
ErrShutdownNonEstablished = errors.New("shutdown called in non-established state")
ErrAssociationClosedBeforeConn = errors.New("association closed before connecting")
ErrSilentlyDiscard = errors.New("silently discard")
ErrInitNotStoredToSend = errors.New("the init not stored to send")
ErrCookieEchoNotStoredToSend = errors.New("cookieEcho not stored to send")
ErrSCTPPacketSourcePortZero = errors.New("sctp packet must not have a source port of 0")
ErrSCTPPacketDestinationPortZero = errors.New("sctp packet must not have a destination port of 0")
ErrInitChunkBundled = errors.New("init chunk must not be bundled with any other chunk")
ErrInitChunkVerifyTagNotZero = errors.New("init chunk expects a verification tag of 0 on the packet when out-of-the-blue")
ErrHandleInitState = errors.New("todo: handle Init when in state")
ErrInitAckNoCookie = errors.New("no cookie in InitAck")
ErrInflightQueueTSNPop = errors.New("unable to be popped from inflight queue TSN")
ErrTSNRequestNotExist = errors.New("requested non-existent TSN")
ErrResetPacketInStateNotExist = errors.New("sending reset packet in non-established state")
ErrParamterType = errors.New("unexpected parameter type")
ErrPayloadDataStateNotExist = errors.New("sending payload data in non-established state")
ErrChunkTypeUnhandled = errors.New("unhandled chunk type")
ErrHandshakeInitAck = errors.New("handshake failed (INIT ACK)")
ErrHandshakeCookieEcho = errors.New("handshake failed (COOKIE ECHO)")
)
const (
receiveMTU uint32 = 8192 // MTU for inbound packet (from DTLS)
initialMTU uint32 = 1228 // initial MTU for outgoing packets (to DTLS)
initialRecvBufSize uint32 = 1024 * 1024
commonHeaderSize uint32 = 12
dataChunkHeaderSize uint32 = 16
defaultMaxMessageSize uint32 = 65536
)
// association state enums
const (
closed uint32 = iota
cookieWait
cookieEchoed
established
shutdownAckSent
shutdownPending
shutdownReceived
shutdownSent
)
// retransmission timer IDs
const (
timerT1Init int = iota
timerT1Cookie
timerT2Shutdown
timerT3RTX
timerReconfig
)
// ack mode (for testing)
const (
ackModeNormal int = iota
ackModeNoDelay
ackModeAlwaysDelay
)
// ack transmission state
const (
ackStateIdle int = iota // ack timer is off
ackStateImmediate // will send ack immediately
ackStateDelay // ack timer is on (ack is being delayed)
)
// other constants
const (
acceptChSize = 16
)
func getAssociationStateString(a uint32) string {
switch a {
case closed:
return "Closed"
case cookieWait:
return "CookieWait"
case cookieEchoed:
return "CookieEchoed"
case established:
return "Established"
case shutdownPending:
return "ShutdownPending"
case shutdownSent:
return "ShutdownSent"
case shutdownReceived:
return "ShutdownReceived"
case shutdownAckSent:
return "ShutdownAckSent"
default:
return fmt.Sprintf("Invalid association state %d", a)
}
}
// Association represents an SCTP association
// 13.2. Parameters Necessary per Association (i.e., the TCB)
//
// Peer : Tag value to be sent in every packet and is received
// Verification: in the INIT or INIT ACK chunk.
// Tag :
// State : A state variable indicating what state the association
// : is in, i.e., COOKIE-WAIT, COOKIE-ECHOED, ESTABLISHED,
// : SHUTDOWN-PENDING, SHUTDOWN-SENT, SHUTDOWN-RECEIVED,
// : SHUTDOWN-ACK-SENT.
//
// Note: No "CLOSED" state is illustrated since if a
// association is "CLOSED" its TCB SHOULD be removed.
type Association struct {
bytesReceived uint64
bytesSent uint64
lock sync.RWMutex
netConn net.Conn
peerVerificationTag uint32
myVerificationTag uint32
state uint32
myNextTSN uint32 // nextTSN
peerLastTSN uint32 // lastRcvdTSN
minTSN2MeasureRTT uint32 // for RTT measurement
willSendForwardTSN bool
willRetransmitFast bool
willRetransmitReconfig bool
willSendShutdown bool
willSendShutdownAck bool
willSendShutdownComplete bool
willSendAbort bool
willSendAbortCause errorCause
// Reconfig
myNextRSN uint32
reconfigs map[uint32]*chunkReconfig
reconfigRequests map[uint32]*paramOutgoingResetRequest
// Non-RFC internal data
sourcePort uint16
destinationPort uint16
myMaxNumInboundStreams uint16
myMaxNumOutboundStreams uint16
myCookie *paramStateCookie
payloadQueue *payloadQueue
inflightQueue *payloadQueue
pendingQueue *pendingQueue
controlQueue *controlQueue
mtu uint32
maxPayloadSize uint32 // max DATA chunk payload size
srtt atomic.Value // type float64
cumulativeTSNAckPoint uint32
advancedPeerTSNAckPoint uint32
useForwardTSN bool
// Congestion control parameters
maxReceiveBufferSize uint32
maxMessageSize uint32
cwnd uint32 // my congestion window size
rwnd uint32 // calculated peer's receiver windows size
ssthresh uint32 // slow start threshold
partialBytesAcked uint32
inFastRecovery bool
fastRecoverExitPoint uint32
// RTX & Ack timer
rtoMgr *rtoManager
t1Init *rtxTimer
t1Cookie *rtxTimer
t2Shutdown *rtxTimer
t3RTX *rtxTimer
tReconfig *rtxTimer
ackTimer *ackTimer
// Chunks stored for retransmission
storedInit *chunkInit
storedCookieEcho *chunkCookieEcho
streams map[uint16]*Stream
acceptCh chan *Stream
readLoopCloseCh chan struct{}
awakeWriteLoopCh chan struct{}
closeWriteLoopCh chan struct{}
handshakeCompletedCh chan error
closeWriteLoopOnce sync.Once
// local error
silentError error
ackState int
ackMode int // for testing
// stats
stats *associationStats
// per inbound packet context
delayedAckTriggered bool
immediateAckTriggered bool
name string
log logging.LeveledLogger
}
// Config collects the arguments to createAssociation construction into
// a single structure
type Config struct {
NetConn net.Conn
MaxReceiveBufferSize uint32
MaxMessageSize uint32
LoggerFactory logging.LoggerFactory
}
// Server accepts a SCTP stream over a conn
func Server(config Config) (*Association, error) {
a := createAssociation(config)
a.init(false)
select {
case err := <-a.handshakeCompletedCh:
if err != nil {
return nil, err
}
return a, nil
case <-a.readLoopCloseCh:
return nil, ErrAssociationClosedBeforeConn
}
}
// Client opens a SCTP stream over a conn
func Client(config Config) (*Association, error) {
a := createAssociation(config)
a.init(true)
select {
case err := <-a.handshakeCompletedCh:
if err != nil {
return nil, err
}
return a, nil
case <-a.readLoopCloseCh:
return nil, ErrAssociationClosedBeforeConn
}
}
func createAssociation(config Config) *Association {
var maxReceiveBufferSize uint32
if config.MaxReceiveBufferSize == 0 {
maxReceiveBufferSize = initialRecvBufSize
} else {
maxReceiveBufferSize = config.MaxReceiveBufferSize
}
var maxMessageSize uint32
if config.MaxMessageSize == 0 {
maxMessageSize = defaultMaxMessageSize
} else {
maxMessageSize = config.MaxMessageSize
}
tsn := globalMathRandomGenerator.Uint32()
a := &Association{
netConn: config.NetConn,
maxReceiveBufferSize: maxReceiveBufferSize,
maxMessageSize: maxMessageSize,
myMaxNumOutboundStreams: math.MaxUint16,
myMaxNumInboundStreams: math.MaxUint16,
payloadQueue: newPayloadQueue(),
inflightQueue: newPayloadQueue(),
pendingQueue: newPendingQueue(),
controlQueue: newControlQueue(),
mtu: initialMTU,
maxPayloadSize: initialMTU - (commonHeaderSize + dataChunkHeaderSize),
myVerificationTag: globalMathRandomGenerator.Uint32(),
myNextTSN: tsn,
myNextRSN: tsn,
minTSN2MeasureRTT: tsn,
state: closed,
rtoMgr: newRTOManager(),
streams: map[uint16]*Stream{},
reconfigs: map[uint32]*chunkReconfig{},
reconfigRequests: map[uint32]*paramOutgoingResetRequest{},
acceptCh: make(chan *Stream, acceptChSize),
readLoopCloseCh: make(chan struct{}),
awakeWriteLoopCh: make(chan struct{}, 1),
closeWriteLoopCh: make(chan struct{}),
handshakeCompletedCh: make(chan error),
cumulativeTSNAckPoint: tsn - 1,
advancedPeerTSNAckPoint: tsn - 1,
silentError: ErrSilentlyDiscard,
stats: &associationStats{},
log: config.LoggerFactory.NewLogger("sctp"),
}
a.name = fmt.Sprintf("%p", a)
// RFC 4690 Sec 7.2.1
// o The initial cwnd before DATA transmission or after a sufficiently
// long idle period MUST be set to min(4*MTU, max (2*MTU, 4380
// bytes)).
a.setCWND(min32(4*a.MTU(), max32(2*a.MTU(), 4380)))
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d inflight=%d (INI)",
a.name, a.CWND(), a.ssthresh, a.inflightQueue.getNumBytes())
a.srtt.Store(float64(0))
a.t1Init = newRTXTimer(timerT1Init, a, maxInitRetrans)
a.t1Cookie = newRTXTimer(timerT1Cookie, a, maxInitRetrans)
a.t2Shutdown = newRTXTimer(timerT2Shutdown, a, noMaxRetrans) // retransmit forever
a.t3RTX = newRTXTimer(timerT3RTX, a, noMaxRetrans) // retransmit forever
a.tReconfig = newRTXTimer(timerReconfig, a, noMaxRetrans) // retransmit forever
a.ackTimer = newAckTimer(a)
return a
}
func (a *Association) init(isClient bool) {
a.lock.Lock()
defer a.lock.Unlock()
go a.readLoop()
go a.writeLoop()
if isClient {
a.setState(cookieWait)
init := &chunkInit{}
init.initialTSN = a.myNextTSN
init.numOutboundStreams = a.myMaxNumOutboundStreams
init.numInboundStreams = a.myMaxNumInboundStreams
init.initiateTag = a.myVerificationTag
init.advertisedReceiverWindowCredit = a.maxReceiveBufferSize
setSupportedExtensions(&init.chunkInitCommon)
a.storedInit = init
err := a.sendInit()
if err != nil {
a.log.Errorf("[%s] failed to send init: %s", a.name, err.Error())
}
a.t1Init.start(a.rtoMgr.getRTO())
}
}
// caller must hold a.lock
func (a *Association) sendInit() error {
a.log.Debugf("[%s] sending INIT", a.name)
if a.storedInit == nil {
return ErrInitNotStoredToSend
}
outbound := &packet{}
outbound.verificationTag = a.peerVerificationTag
a.sourcePort = 5000 // Spec??
a.destinationPort = 5000 // Spec??
outbound.sourcePort = a.sourcePort
outbound.destinationPort = a.destinationPort
outbound.chunks = []chunk{a.storedInit}
a.controlQueue.push(outbound)
a.awakeWriteLoop()
return nil
}
// caller must hold a.lock
func (a *Association) sendCookieEcho() error {
if a.storedCookieEcho == nil {
return ErrCookieEchoNotStoredToSend
}
a.log.Debugf("[%s] sending COOKIE-ECHO", a.name)
outbound := &packet{}
outbound.verificationTag = a.peerVerificationTag
outbound.sourcePort = a.sourcePort
outbound.destinationPort = a.destinationPort
outbound.chunks = []chunk{a.storedCookieEcho}
a.controlQueue.push(outbound)
a.awakeWriteLoop()
return nil
}
// Shutdown initiates the shutdown sequence. The method blocks until the
// shutdown sequence is completed and the connection is closed, or until the
// passed context is done, in which case the context's error is returned.
func (a *Association) Shutdown(ctx context.Context) error {
a.log.Debugf("[%s] closing association..", a.name)
state := a.getState()
if state != established {
return fmt.Errorf("%w: shutdown %s", ErrShutdownNonEstablished, a.name)
}
// Attempt a graceful shutdown.
a.setState(shutdownPending)
a.lock.Lock()
if a.inflightQueue.size() == 0 {
// No more outstanding, send shutdown.
a.willSendShutdown = true
a.awakeWriteLoop()
a.setState(shutdownSent)
}
a.lock.Unlock()
select {
case <-a.closeWriteLoopCh:
return nil
case <-ctx.Done():
return ctx.Err()
}
}
// Close ends the SCTP Association and cleans up any state
func (a *Association) Close() error {
a.log.Debugf("[%s] closing association..", a.name)
err := a.close()
// Wait for readLoop to end
<-a.readLoopCloseCh
a.log.Debugf("[%s] association closed", a.name)
a.log.Debugf("[%s] stats nDATAs (in) : %d", a.name, a.stats.getNumDATAs())
a.log.Debugf("[%s] stats nSACKs (in) : %d", a.name, a.stats.getNumSACKs())
a.log.Debugf("[%s] stats nT3Timeouts : %d", a.name, a.stats.getNumT3Timeouts())
a.log.Debugf("[%s] stats nAckTimeouts: %d", a.name, a.stats.getNumAckTimeouts())
a.log.Debugf("[%s] stats nFastRetrans: %d", a.name, a.stats.getNumFastRetrans())
return err
}
func (a *Association) close() error {
a.log.Debugf("[%s] closing association..", a.name)
a.setState(closed)
err := a.netConn.Close()
a.closeAllTimers()
// awake writeLoop to exit
a.closeWriteLoopOnce.Do(func() { close(a.closeWriteLoopCh) })
return err
}
// Abort sends the abort packet with user initiated abort and immediately
// closes the connection.
func (a *Association) Abort(reason string) {
a.log.Debugf("[%s] aborting association: %s", a.name, reason)
a.lock.Lock()
a.willSendAbort = true
a.willSendAbortCause = &errorCauseUserInitiatedAbort{
upperLayerAbortReason: []byte(reason),
}
a.lock.Unlock()
a.awakeWriteLoop()
// Wait for readLoop to end
<-a.readLoopCloseCh
}
func (a *Association) closeAllTimers() {
// Close all retransmission & ack timers
a.t1Init.close()
a.t1Cookie.close()
a.t2Shutdown.close()
a.t3RTX.close()
a.tReconfig.close()
a.ackTimer.close()
}
func (a *Association) readLoop() {
var closeErr error
defer func() {
// also stop writeLoop, otherwise writeLoop can be leaked
// if connection is lost when there is no writing packet.
a.closeWriteLoopOnce.Do(func() { close(a.closeWriteLoopCh) })
a.lock.Lock()
for _, s := range a.streams {
a.unregisterStream(s, closeErr)
}
a.lock.Unlock()
close(a.acceptCh)
close(a.readLoopCloseCh)
a.log.Debugf("[%s] association closed", a.name)
a.log.Debugf("[%s] stats nDATAs (in) : %d", a.name, a.stats.getNumDATAs())
a.log.Debugf("[%s] stats nSACKs (in) : %d", a.name, a.stats.getNumSACKs())
a.log.Debugf("[%s] stats nT3Timeouts : %d", a.name, a.stats.getNumT3Timeouts())
a.log.Debugf("[%s] stats nAckTimeouts: %d", a.name, a.stats.getNumAckTimeouts())
a.log.Debugf("[%s] stats nFastRetrans: %d", a.name, a.stats.getNumFastRetrans())
}()
a.log.Debugf("[%s] readLoop entered", a.name)
buffer := make([]byte, receiveMTU)
for {
n, err := a.netConn.Read(buffer)
if err != nil {
closeErr = err
break
}
// Make a buffer sized to what we read, then copy the data we
// read from the underlying transport. We do this because the
// user data is passed to the reassembly queue without
// copying.
inbound := make([]byte, n)
copy(inbound, buffer[:n])
atomic.AddUint64(&a.bytesReceived, uint64(n))
if err = a.handleInbound(inbound); err != nil {
closeErr = err
break
}
}
a.log.Debugf("[%s] readLoop exited %s", a.name, closeErr)
}
func (a *Association) writeLoop() {
a.log.Debugf("[%s] writeLoop entered", a.name)
defer a.log.Debugf("[%s] writeLoop exited", a.name)
loop:
for {
rawPackets, ok := a.gatherOutbound()
for _, raw := range rawPackets {
_, err := a.netConn.Write(raw)
if err != nil {
if !errors.Is(err, io.EOF) {
a.log.Warnf("[%s] failed to write packets on netConn: %v", a.name, err)
}
a.log.Debugf("[%s] writeLoop ended", a.name)
break loop
}
atomic.AddUint64(&a.bytesSent, uint64(len(raw)))
}
if !ok {
if err := a.close(); err != nil {
a.log.Warnf("[%s] failed to close association: %v", a.name, err)
}
return
}
select {
case <-a.awakeWriteLoopCh:
case <-a.closeWriteLoopCh:
break loop
}
}
a.setState(closed)
a.closeAllTimers()
}
func (a *Association) awakeWriteLoop() {
select {
case a.awakeWriteLoopCh <- struct{}{}:
default:
}
}
// unregisterStream un-registers a stream from the association
// The caller should hold the association write lock.
func (a *Association) unregisterStream(s *Stream, err error) {
s.lock.Lock()
defer s.lock.Unlock()
delete(a.streams, s.streamIdentifier)
s.readErr = err
s.readNotifier.Broadcast()
}
// handleInbound parses incoming raw packets
func (a *Association) handleInbound(raw []byte) error {
p := &packet{}
if err := p.unmarshal(raw); err != nil {
a.log.Warnf("[%s] unable to parse SCTP packet %s", a.name, err)
return nil
}
if err := checkPacket(p); err != nil {
a.log.Warnf("[%s] failed validating packet %s", a.name, err)
return nil
}
a.handleChunkStart()
for _, c := range p.chunks {
if err := a.handleChunk(p, c); err != nil {
return err
}
}
a.handleChunkEnd()
return nil
}
// The caller should hold the lock
func (a *Association) gatherDataPacketsToRetransmit(rawPackets [][]byte) [][]byte {
for _, p := range a.getDataPacketsToRetransmit() {
raw, err := p.marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a DATA packet to be retransmitted", a.name)
continue
}
rawPackets = append(rawPackets, raw)
}
return rawPackets
}
// The caller should hold the lock
func (a *Association) gatherOutboundDataAndReconfigPackets(rawPackets [][]byte) [][]byte {
// Pop unsent data chunks from the pending queue to send as much as
// cwnd and rwnd allow.
chunks, sisToReset := a.popPendingDataChunksToSend()
if len(chunks) > 0 {
// Start timer. (noop if already started)
a.log.Tracef("[%s] T3-rtx timer start (pt1)", a.name)
a.t3RTX.start(a.rtoMgr.getRTO())
for _, p := range a.bundleDataChunksIntoPackets(chunks) {
raw, err := p.marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a DATA packet", a.name)
continue
}
rawPackets = append(rawPackets, raw)
}
}
if len(sisToReset) > 0 || a.willRetransmitReconfig {
if a.willRetransmitReconfig {
a.willRetransmitReconfig = false
a.log.Debugf("[%s] retransmit %d RECONFIG chunk(s)", a.name, len(a.reconfigs))
for _, c := range a.reconfigs {
p := a.createPacket([]chunk{c})
raw, err := p.marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a RECONFIG packet to be retransmitted", a.name)
} else {
rawPackets = append(rawPackets, raw)
}
}
}
if len(sisToReset) > 0 {
rsn := a.generateNextRSN()
tsn := a.myNextTSN - 1
c := &chunkReconfig{
paramA: ¶mOutgoingResetRequest{
reconfigRequestSequenceNumber: rsn,
senderLastTSN: tsn,
streamIdentifiers: sisToReset,
},
}
a.reconfigs[rsn] = c // store in the map for retransmission
a.log.Debugf("[%s] sending RECONFIG: rsn=%d tsn=%d streams=%v",
a.name, rsn, a.myNextTSN-1, sisToReset)
p := a.createPacket([]chunk{c})
raw, err := p.marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a RECONFIG packet to be transmitted", a.name)
} else {
rawPackets = append(rawPackets, raw)
}
}
if len(a.reconfigs) > 0 {
a.tReconfig.start(a.rtoMgr.getRTO())
}
}
return rawPackets
}
// The caller should hold the lock
func (a *Association) gatherOutboundFastRetransmissionPackets(rawPackets [][]byte) [][]byte {
if a.willRetransmitFast {
a.willRetransmitFast = false
toFastRetrans := []chunk{}
fastRetransSize := commonHeaderSize
for i := 0; ; i++ {
c, ok := a.inflightQueue.get(a.cumulativeTSNAckPoint + uint32(i) + 1)
if !ok {
break // end of pending data
}
if c.acked || c.abandoned() {
continue
}
if c.nSent > 1 || c.missIndicator < 3 {
continue
}
// RFC 4960 Sec 7.2.4 Fast Retransmit on Gap Reports
// 3) Determine how many of the earliest (i.e., lowest TSN) DATA chunks
// marked for retransmission will fit into a single packet, subject
// to constraint of the path MTU of the destination transport
// address to which the packet is being sent. Call this value K.
// Retransmit those K DATA chunks in a single packet. When a Fast
// Retransmit is being performed, the sender SHOULD ignore the value
// of cwnd and SHOULD NOT delay retransmission for this single
// packet.
dataChunkSize := dataChunkHeaderSize + uint32(len(c.userData))
if a.MTU() < fastRetransSize+dataChunkSize {
break
}
fastRetransSize += dataChunkSize
a.stats.incFastRetrans()
c.nSent++
a.checkPartialReliabilityStatus(c)
toFastRetrans = append(toFastRetrans, c)
a.log.Tracef("[%s] fast-retransmit: tsn=%d sent=%d htna=%d",
a.name, c.tsn, c.nSent, a.fastRecoverExitPoint)
}
if len(toFastRetrans) > 0 {
raw, err := a.createPacket(toFastRetrans).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a DATA packet to be fast-retransmitted", a.name)
} else {
rawPackets = append(rawPackets, raw)
}
}
}
return rawPackets
}
// The caller should hold the lock
func (a *Association) gatherOutboundSackPackets(rawPackets [][]byte) [][]byte {
if a.ackState == ackStateImmediate {
a.ackState = ackStateIdle
sack := a.createSelectiveAckChunk()
a.log.Debugf("[%s] sending SACK: %s", a.name, sack)
raw, err := a.createPacket([]chunk{sack}).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a SACK packet", a.name)
} else {
rawPackets = append(rawPackets, raw)
}
}
return rawPackets
}
// The caller should hold the lock
func (a *Association) gatherOutboundForwardTSNPackets(rawPackets [][]byte) [][]byte {
if a.willSendForwardTSN {
a.willSendForwardTSN = false
if sna32GT(a.advancedPeerTSNAckPoint, a.cumulativeTSNAckPoint) {
fwdtsn := a.createForwardTSN()
raw, err := a.createPacket([]chunk{fwdtsn}).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a Forward TSN packet", a.name)
} else {
rawPackets = append(rawPackets, raw)
}
}
}
return rawPackets
}
func (a *Association) gatherOutboundShutdownPackets(rawPackets [][]byte) ([][]byte, bool) {
ok := true
switch {
case a.willSendShutdown:
a.willSendShutdown = false
shutdown := &chunkShutdown{
cumulativeTSNAck: a.cumulativeTSNAckPoint,
}
raw, err := a.createPacket([]chunk{shutdown}).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a Shutdown packet", a.name)
} else {
a.t2Shutdown.start(a.rtoMgr.getRTO())
rawPackets = append(rawPackets, raw)
}
case a.willSendShutdownAck:
a.willSendShutdownAck = false
shutdownAck := &chunkShutdownAck{}
raw, err := a.createPacket([]chunk{shutdownAck}).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a ShutdownAck packet", a.name)
} else {
a.t2Shutdown.start(a.rtoMgr.getRTO())
rawPackets = append(rawPackets, raw)
}
case a.willSendShutdownComplete:
a.willSendShutdownComplete = false
shutdownComplete := &chunkShutdownComplete{}
raw, err := a.createPacket([]chunk{shutdownComplete}).marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a ShutdownComplete packet", a.name)
} else {
rawPackets = append(rawPackets, raw)
ok = false
}
}
return rawPackets, ok
}
func (a *Association) gatherAbortPacket() ([]byte, error) {
cause := a.willSendAbortCause
a.willSendAbort = false
a.willSendAbortCause = nil
abort := &chunkAbort{}
if cause != nil {
abort.errorCauses = []errorCause{cause}
}
raw, err := a.createPacket([]chunk{abort}).marshal()
return raw, err
}
// gatherOutbound gathers outgoing packets. The returned bool value set to
// false means the association should be closed down after the final send.
func (a *Association) gatherOutbound() ([][]byte, bool) {
a.lock.Lock()
defer a.lock.Unlock()
if a.willSendAbort {
pkt, err := a.gatherAbortPacket()
if err != nil {
a.log.Warnf("[%s] failed to serialize an abort packet", a.name)
return nil, false
}
return [][]byte{pkt}, false
}
rawPackets := [][]byte{}
if a.controlQueue.size() > 0 {
for _, p := range a.controlQueue.popAll() {
raw, err := p.marshal()
if err != nil {
a.log.Warnf("[%s] failed to serialize a control packet", a.name)
continue
}
rawPackets = append(rawPackets, raw)
}
}
state := a.getState()
ok := true
switch state {
case established:
rawPackets = a.gatherDataPacketsToRetransmit(rawPackets)
rawPackets = a.gatherOutboundDataAndReconfigPackets(rawPackets)
rawPackets = a.gatherOutboundFastRetransmissionPackets(rawPackets)
rawPackets = a.gatherOutboundSackPackets(rawPackets)
rawPackets = a.gatherOutboundForwardTSNPackets(rawPackets)
case shutdownPending, shutdownSent, shutdownReceived:
rawPackets = a.gatherDataPacketsToRetransmit(rawPackets)
rawPackets = a.gatherOutboundFastRetransmissionPackets(rawPackets)
rawPackets = a.gatherOutboundSackPackets(rawPackets)
rawPackets, ok = a.gatherOutboundShutdownPackets(rawPackets)
case shutdownAckSent:
rawPackets, ok = a.gatherOutboundShutdownPackets(rawPackets)
}
return rawPackets, ok
}
func checkPacket(p *packet) error {
// All packets must adhere to these rules
// This is the SCTP sender's port number. It can be used by the
// receiver in combination with the source IP address, the SCTP
// destination port, and possibly the destination IP address to
// identify the association to which this packet belongs. The port
// number 0 MUST NOT be used.
if p.sourcePort == 0 {
return ErrSCTPPacketSourcePortZero
}
// This is the SCTP port number to which this packet is destined.
// The receiving host will use this port number to de-multiplex the
// SCTP packet to the correct receiving endpoint/application. The
// port number 0 MUST NOT be used.
if p.destinationPort == 0 {
return ErrSCTPPacketDestinationPortZero
}
// Check values on the packet that are specific to a particular chunk type
for _, c := range p.chunks {
switch c.(type) { // nolint:gocritic
case *chunkInit:
// An INIT or INIT ACK chunk MUST NOT be bundled with any other chunk.
// They MUST be the only chunks present in the SCTP packets that carry
// them.
if len(p.chunks) != 1 {
return ErrInitChunkBundled
}
// A packet containing an INIT chunk MUST have a zero Verification
// Tag.
if p.verificationTag != 0 {
return ErrInitChunkVerifyTagNotZero
}
}
}
return nil
}
func min16(a, b uint16) uint16 {
if a < b {
return a
}
return b
}
func max32(a, b uint32) uint32 {
if a > b {
return a
}
return b
}
func min32(a, b uint32) uint32 {
if a < b {
return a
}
return b
}
// setState atomically sets the state of the Association.
// The caller should hold the lock.
func (a *Association) setState(newState uint32) {
oldState := atomic.SwapUint32(&a.state, newState)
if newState != oldState {
a.log.Debugf("[%s] state change: '%s' => '%s'",
a.name,
getAssociationStateString(oldState),
getAssociationStateString(newState))
}
}
// getState atomically returns the state of the Association.
func (a *Association) getState() uint32 {
return atomic.LoadUint32(&a.state)
}
// BytesSent returns the number of bytes sent
func (a *Association) BytesSent() uint64 {
return atomic.LoadUint64(&a.bytesSent)
}
// BytesReceived returns the number of bytes received
func (a *Association) BytesReceived() uint64 {
return atomic.LoadUint64(&a.bytesReceived)
}
// MTU returns the association's current MTU
func (a *Association) MTU() uint32 {
return atomic.LoadUint32(&a.mtu)
}
// CWND returns the association's current congestion window (cwnd)
func (a *Association) CWND() uint32 {
return atomic.LoadUint32(&a.cwnd)
}
func (a *Association) setCWND(cwnd uint32) {
atomic.StoreUint32(&a.cwnd, cwnd)
}
// RWND returns the association's current receiver window (rwnd)
func (a *Association) RWND() uint32 {
return atomic.LoadUint32(&a.rwnd)
}
func (a *Association) setRWND(rwnd uint32) {
atomic.StoreUint32(&a.rwnd, rwnd)
}
// SRTT returns the latest smoothed round-trip time (srrt)
func (a *Association) SRTT() float64 {
return a.srtt.Load().(float64) //nolint:forcetypeassert
}
func setSupportedExtensions(init *chunkInitCommon) {
// nolint:godox
// TODO RFC5061 https://tools.ietf.org/html/rfc6525#section-5.2
// An implementation supporting this (Supported Extensions Parameter)
// extension MUST list the ASCONF, the ASCONF-ACK, and the AUTH chunks
// in its INIT and INIT-ACK parameters.
init.params = append(init.params, ¶mSupportedExtensions{
ChunkTypes: []chunkType{ctReconfig, ctForwardTSN},
})
}
// The caller should hold the lock.
func (a *Association) handleInit(p *packet, i *chunkInit) ([]*packet, error) {
state := a.getState()
a.log.Debugf("[%s] chunkInit received in state '%s'", a.name, getAssociationStateString(state))
// https://tools.ietf.org/html/rfc4960#section-5.2.1
// Upon receipt of an INIT in the COOKIE-WAIT state, an endpoint MUST
// respond with an INIT ACK using the same parameters it sent in its
// original INIT chunk (including its Initiate Tag, unchanged). When
// responding, the endpoint MUST send the INIT ACK back to the same
// address that the original INIT (sent by this endpoint) was sent.
if state != closed && state != cookieWait && state != cookieEchoed {
// 5.2.2. Unexpected INIT in States Other than CLOSED, COOKIE-ECHOED,
// COOKIE-WAIT, and SHUTDOWN-ACK-SENT
return nil, fmt.Errorf("%w: %s", ErrHandleInitState, getAssociationStateString(state))
}
// Should we be setting any of these permanently until we've ACKed further?
a.myMaxNumInboundStreams = min16(i.numInboundStreams, a.myMaxNumInboundStreams)
a.myMaxNumOutboundStreams = min16(i.numOutboundStreams, a.myMaxNumOutboundStreams)
a.peerVerificationTag = i.initiateTag
a.sourcePort = p.destinationPort
a.destinationPort = p.sourcePort
// 13.2 This is the last TSN received in sequence. This value
// is set initially by taking the peer's initial TSN,
// received in the INIT or INIT ACK chunk, and
// subtracting one from it.
a.peerLastTSN = i.initialTSN - 1
for _, param := range i.params {
switch v := param.(type) { // nolint:gocritic
case *paramSupportedExtensions:
for _, t := range v.ChunkTypes {
if t == ctForwardTSN {
a.log.Debugf("[%s] use ForwardTSN (on init)", a.name)
a.useForwardTSN = true
}
}
}
}
if !a.useForwardTSN {
a.log.Warnf("[%s] not using ForwardTSN (on init)", a.name)
}
outbound := &packet{}
outbound.verificationTag = a.peerVerificationTag
outbound.sourcePort = a.sourcePort
outbound.destinationPort = a.destinationPort
initAck := &chunkInitAck{}
initAck.initialTSN = a.myNextTSN
initAck.numOutboundStreams = a.myMaxNumOutboundStreams
initAck.numInboundStreams = a.myMaxNumInboundStreams
initAck.initiateTag = a.myVerificationTag
initAck.advertisedReceiverWindowCredit = a.maxReceiveBufferSize
if a.myCookie == nil {
var err error
if a.myCookie, err = newRandomStateCookie(); err != nil {
return nil, err
}
}
initAck.params = []param{a.myCookie}
setSupportedExtensions(&initAck.chunkInitCommon)
outbound.chunks = []chunk{initAck}
return pack(outbound), nil
}
// The caller should hold the lock.
func (a *Association) handleInitAck(p *packet, i *chunkInitAck) error {
state := a.getState()
a.log.Debugf("[%s] chunkInitAck received in state '%s'", a.name, getAssociationStateString(state))
if state != cookieWait {
// RFC 4960
// 5.2.3. Unexpected INIT ACK
// If an INIT ACK is received by an endpoint in any state other than the
// COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk.
// An unexpected INIT ACK usually indicates the processing of an old or
// duplicated INIT chunk.
return nil
}
a.myMaxNumInboundStreams = min16(i.numInboundStreams, a.myMaxNumInboundStreams)
a.myMaxNumOutboundStreams = min16(i.numOutboundStreams, a.myMaxNumOutboundStreams)
a.peerVerificationTag = i.initiateTag
a.peerLastTSN = i.initialTSN - 1
if a.sourcePort != p.destinationPort ||
a.destinationPort != p.sourcePort {
a.log.Warnf("[%s] handleInitAck: port mismatch", a.name)
return nil
}
a.setRWND(i.advertisedReceiverWindowCredit)
a.log.Debugf("[%s] initial rwnd=%d", a.name, a.RWND())
// RFC 4690 Sec 7.2.1
// o The initial value of ssthresh MAY be arbitrarily high (for
// example, implementations MAY use the size of the receiver
// advertised window).
a.ssthresh = a.RWND()
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d inflight=%d (INI)",
a.name, a.CWND(), a.ssthresh, a.inflightQueue.getNumBytes())
a.t1Init.stop()
a.storedInit = nil
var cookieParam *paramStateCookie
for _, param := range i.params {
switch v := param.(type) {
case *paramStateCookie:
cookieParam = v
case *paramSupportedExtensions:
for _, t := range v.ChunkTypes {
if t == ctForwardTSN {
a.log.Debugf("[%s] use ForwardTSN (on initAck)", a.name)
a.useForwardTSN = true
}
}
}
}
if !a.useForwardTSN {
a.log.Warnf("[%s] not using ForwardTSN (on initAck)", a.name)
}
if cookieParam == nil {
return ErrInitAckNoCookie
}
a.storedCookieEcho = &chunkCookieEcho{}
a.storedCookieEcho.cookie = cookieParam.cookie
err := a.sendCookieEcho()
if err != nil {
a.log.Errorf("[%s] failed to send init: %s", a.name, err.Error())
}
a.t1Cookie.start(a.rtoMgr.getRTO())
a.setState(cookieEchoed)
return nil
}
// The caller should hold the lock.
func (a *Association) handleHeartbeat(c *chunkHeartbeat) []*packet {
a.log.Tracef("[%s] chunkHeartbeat", a.name)
hbi, ok := c.params[0].(*paramHeartbeatInfo)
if !ok {
a.log.Warnf("[%s] failed to handle Heartbeat, no ParamHeartbeatInfo", a.name)
}
return pack(&packet{
verificationTag: a.peerVerificationTag,
sourcePort: a.sourcePort,
destinationPort: a.destinationPort,
chunks: []chunk{&chunkHeartbeatAck{
params: []param{
¶mHeartbeatInfo{
heartbeatInformation: hbi.heartbeatInformation,
},
},
}},
})
}
// The caller should hold the lock.
func (a *Association) handleCookieEcho(c *chunkCookieEcho) []*packet {
state := a.getState()
a.log.Debugf("[%s] COOKIE-ECHO received in state '%s'", a.name, getAssociationStateString(state))
if a.myCookie == nil {
a.log.Debugf("[%s] COOKIE-ECHO received before initialization", a.name)
return nil
}
switch state {
default:
return nil
case established:
if !bytes.Equal(a.myCookie.cookie, c.cookie) {
return nil
}
case closed, cookieWait, cookieEchoed:
if !bytes.Equal(a.myCookie.cookie, c.cookie) {
return nil
}
a.t1Init.stop()
a.storedInit = nil
a.t1Cookie.stop()
a.storedCookieEcho = nil
a.setState(established)
a.handshakeCompletedCh <- nil
}
p := &packet{
verificationTag: a.peerVerificationTag,
sourcePort: a.sourcePort,
destinationPort: a.destinationPort,
chunks: []chunk{&chunkCookieAck{}},
}
return pack(p)
}
// The caller should hold the lock.
func (a *Association) handleCookieAck() {
state := a.getState()
a.log.Debugf("[%s] COOKIE-ACK received in state '%s'", a.name, getAssociationStateString(state))
if state != cookieEchoed {
// RFC 4960
// 5.2.5. Handle Duplicate COOKIE-ACK.
// At any state other than COOKIE-ECHOED, an endpoint should silently
// discard a received COOKIE ACK chunk.
return
}
a.t1Cookie.stop()
a.storedCookieEcho = nil
a.setState(established)
a.handshakeCompletedCh <- nil
}
// The caller should hold the lock.
func (a *Association) handleData(d *chunkPayloadData) []*packet {
a.log.Tracef("[%s] DATA: tsn=%d immediateSack=%v len=%d",
a.name, d.tsn, d.immediateSack, len(d.userData))
a.stats.incDATAs()
canPush := a.payloadQueue.canPush(d, a.peerLastTSN)
if canPush {
s := a.getOrCreateStream(d.streamIdentifier, true, PayloadTypeUnknown)
if s == nil {
// silentely discard the data. (sender will retry on T3-rtx timeout)
// see pion/sctp#30
a.log.Debugf("discard %d", d.streamSequenceNumber)
return nil
}
if a.getMyReceiverWindowCredit() > 0 {
// Pass the new chunk to stream level as soon as it arrives
a.payloadQueue.push(d, a.peerLastTSN)
s.handleData(d)
} else {
// Receive buffer is full
lastTSN, ok := a.payloadQueue.getLastTSNReceived()
if ok && sna32LT(d.tsn, lastTSN) {
a.log.Debugf("[%s] receive buffer full, but accepted as this is a missing chunk with tsn=%d ssn=%d", a.name, d.tsn, d.streamSequenceNumber)
a.payloadQueue.push(d, a.peerLastTSN)
s.handleData(d)
} else {
a.log.Debugf("[%s] receive buffer full. dropping DATA with tsn=%d ssn=%d", a.name, d.tsn, d.streamSequenceNumber)
}
}
}
return a.handlePeerLastTSNAndAcknowledgement(d.immediateSack)
}
// A common routine for handleData and handleForwardTSN routines
// The caller should hold the lock.
func (a *Association) handlePeerLastTSNAndAcknowledgement(sackImmediately bool) []*packet {
var reply []*packet
// Try to advance peerLastTSN
// From RFC 3758 Sec 3.6:
// .. and then MUST further advance its cumulative TSN point locally
// if possible
// Meaning, if peerLastTSN+1 points to a chunk that is received,
// advance peerLastTSN until peerLastTSN+1 points to unreceived chunk.
for {
if _, popOk := a.payloadQueue.pop(a.peerLastTSN + 1); !popOk {
break
}
a.peerLastTSN++
for _, rstReq := range a.reconfigRequests {
resp := a.resetStreamsIfAny(rstReq)
if resp != nil {
a.log.Debugf("[%s] RESET RESPONSE: %+v", a.name, resp)
reply = append(reply, resp)
}
}
}
hasPacketLoss := (a.payloadQueue.size() > 0)
if hasPacketLoss {
a.log.Tracef("[%s] packetloss: %s", a.name, a.payloadQueue.getGapAckBlocksString(a.peerLastTSN))
}
if (a.ackState != ackStateImmediate && !sackImmediately && !hasPacketLoss && a.ackMode == ackModeNormal) || a.ackMode == ackModeAlwaysDelay {
if a.ackState == ackStateIdle {
a.delayedAckTriggered = true
} else {
a.immediateAckTriggered = true
}
} else {
a.immediateAckTriggered = true
}
return reply
}
// The caller should hold the lock.
func (a *Association) getMyReceiverWindowCredit() uint32 {
var bytesQueued uint32
for _, s := range a.streams {
bytesQueued += uint32(s.getNumBytesInReassemblyQueue())
}
if bytesQueued >= a.maxReceiveBufferSize {
return 0
}
return a.maxReceiveBufferSize - bytesQueued
}
// OpenStream opens a stream
func (a *Association) OpenStream(streamIdentifier uint16, defaultPayloadType PayloadProtocolIdentifier) (*Stream, error) {
a.lock.Lock()
defer a.lock.Unlock()
return a.getOrCreateStream(streamIdentifier, false, defaultPayloadType), nil
}
// AcceptStream accepts a stream
func (a *Association) AcceptStream() (*Stream, error) {
s, ok := <-a.acceptCh
if !ok {
return nil, io.EOF // no more incoming streams
}
return s, nil
}
// createStream creates a stream. The caller should hold the lock and check no stream exists for this id.
func (a *Association) createStream(streamIdentifier uint16, accept bool) *Stream {
s := &Stream{
association: a,
streamIdentifier: streamIdentifier,
reassemblyQueue: newReassemblyQueue(streamIdentifier),
log: a.log,
name: fmt.Sprintf("%d:%s", streamIdentifier, a.name),
}
s.readNotifier = sync.NewCond(&s.lock)
if accept {
select {
case a.acceptCh <- s:
a.streams[streamIdentifier] = s
a.log.Debugf("[%s] accepted a new stream (streamIdentifier: %d)",
a.name, streamIdentifier)
default:
a.log.Debugf("[%s] dropped a new stream (acceptCh size: %d)",
a.name, len(a.acceptCh))
return nil
}
} else {
a.streams[streamIdentifier] = s
}
return s
}
// getOrCreateStream gets or creates a stream. The caller should hold the lock.
func (a *Association) getOrCreateStream(streamIdentifier uint16, accept bool, defaultPayloadType PayloadProtocolIdentifier) *Stream {
if s, ok := a.streams[streamIdentifier]; ok {
s.SetDefaultPayloadType(defaultPayloadType)
return s
}
s := a.createStream(streamIdentifier, accept)
if s != nil {
s.SetDefaultPayloadType(defaultPayloadType)
}
return s
}
// The caller should hold the lock.
func (a *Association) processSelectiveAck(d *chunkSelectiveAck) (map[uint16]int, uint32, error) { // nolint:gocognit
bytesAckedPerStream := map[uint16]int{}
// New ack point, so pop all ACKed packets from inflightQueue
// We add 1 because the "currentAckPoint" has already been popped from the inflight queue
// For the first SACK we take care of this by setting the ackpoint to cumAck - 1
for i := a.cumulativeTSNAckPoint + 1; sna32LTE(i, d.cumulativeTSNAck); i++ {
c, ok := a.inflightQueue.pop(i)
if !ok {
return nil, 0, fmt.Errorf("%w: %v", ErrInflightQueueTSNPop, i)
}
if !c.acked {
// RFC 4096 sec 6.3.2. Retransmission Timer Rules
// R3) Whenever a SACK is received that acknowledges the DATA chunk
// with the earliest outstanding TSN for that address, restart the
// T3-rtx timer for that address with its current RTO (if there is
// still outstanding data on that address).
if i == a.cumulativeTSNAckPoint+1 {
// T3 timer needs to be reset. Stop it for now.
a.t3RTX.stop()
}
nBytesAcked := len(c.userData)
// Sum the number of bytes acknowledged per stream
if amount, ok := bytesAckedPerStream[c.streamIdentifier]; ok {
bytesAckedPerStream[c.streamIdentifier] = amount + nBytesAcked
} else {
bytesAckedPerStream[c.streamIdentifier] = nBytesAcked
}
// RFC 4960 sec 6.3.1. RTO Calculation
// C4) When data is in flight and when allowed by rule C5 below, a new
// RTT measurement MUST be made each round trip. Furthermore, new
// RTT measurements SHOULD be made no more than once per round trip
// for a given destination transport address.
// C5) Karn's algorithm: RTT measurements MUST NOT be made using
// packets that were retransmitted (and thus for which it is
// ambiguous whether the reply was for the first instance of the
// chunk or for a later instance)
if c.nSent == 1 && sna32GTE(c.tsn, a.minTSN2MeasureRTT) {
a.minTSN2MeasureRTT = a.myNextTSN
rtt := time.Since(c.since).Seconds() * 1000.0
srtt := a.rtoMgr.setNewRTT(rtt)
a.srtt.Store(srtt)
a.log.Tracef("[%s] SACK: measured-rtt=%f srtt=%f new-rto=%f",
a.name, rtt, srtt, a.rtoMgr.getRTO())
}
}
if a.inFastRecovery && c.tsn == a.fastRecoverExitPoint {
a.log.Debugf("[%s] exit fast-recovery", a.name)
a.inFastRecovery = false
}
}
htna := d.cumulativeTSNAck
// Mark selectively acknowledged chunks as "acked"
for _, g := range d.gapAckBlocks {
for i := g.start; i <= g.end; i++ {
tsn := d.cumulativeTSNAck + uint32(i)
c, ok := a.inflightQueue.get(tsn)
if !ok {
return nil, 0, fmt.Errorf("%w: %v", ErrTSNRequestNotExist, tsn)
}
if !c.acked {
nBytesAcked := a.inflightQueue.markAsAcked(tsn)
// Sum the number of bytes acknowledged per stream
if amount, ok := bytesAckedPerStream[c.streamIdentifier]; ok {
bytesAckedPerStream[c.streamIdentifier] = amount + nBytesAcked
} else {
bytesAckedPerStream[c.streamIdentifier] = nBytesAcked
}
a.log.Tracef("[%s] tsn=%d has been sacked", a.name, c.tsn)
if c.nSent == 1 {
a.minTSN2MeasureRTT = a.myNextTSN
rtt := time.Since(c.since).Seconds() * 1000.0
srtt := a.rtoMgr.setNewRTT(rtt)
a.srtt.Store(srtt)
a.log.Tracef("[%s] SACK: measured-rtt=%f srtt=%f new-rto=%f",
a.name, rtt, srtt, a.rtoMgr.getRTO())
}
if sna32LT(htna, tsn) {
htna = tsn
}
}
}
}
return bytesAckedPerStream, htna, nil
}
// The caller should hold the lock.
func (a *Association) onCumulativeTSNAckPointAdvanced(totalBytesAcked int) {
// RFC 4096, sec 6.3.2. Retransmission Timer Rules
// R2) Whenever all outstanding data sent to an address have been
// acknowledged, turn off the T3-rtx timer of that address.
if a.inflightQueue.size() == 0 {
a.log.Tracef("[%s] SACK: no more packet in-flight (pending=%d)", a.name, a.pendingQueue.size())
a.t3RTX.stop()
} else {
a.log.Tracef("[%s] T3-rtx timer start (pt2)", a.name)
a.t3RTX.start(a.rtoMgr.getRTO())
}
// Update congestion control parameters
if a.CWND() <= a.ssthresh {
// RFC 4096, sec 7.2.1. Slow-Start
// o When cwnd is less than or equal to ssthresh, an SCTP endpoint MUST
// use the slow-start algorithm to increase cwnd only if the current
// congestion window is being fully utilized, an incoming SACK
// advances the Cumulative TSN Ack Point, and the data sender is not
// in Fast Recovery. Only when these three conditions are met can
// the cwnd be increased; otherwise, the cwnd MUST not be increased.
// If these conditions are met, then cwnd MUST be increased by, at
// most, the lesser of 1) the total size of the previously
// outstanding DATA chunk(s) acknowledged, and 2) the destination's
// path MTU.
if !a.inFastRecovery &&
a.pendingQueue.size() > 0 {
a.setCWND(a.CWND() + min32(uint32(totalBytesAcked), a.CWND()))
// a.cwnd += min32(uint32(totalBytesAcked), a.MTU()) // SCTP way (slow)
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d acked=%d (SS)",
a.name, a.CWND(), a.ssthresh, totalBytesAcked)
} else {
a.log.Tracef("[%s] cwnd did not grow: cwnd=%d ssthresh=%d acked=%d FR=%v pending=%d",
a.name, a.CWND(), a.ssthresh, totalBytesAcked, a.inFastRecovery, a.pendingQueue.size())
}
} else {
// RFC 4096, sec 7.2.2. Congestion Avoidance
// o Whenever cwnd is greater than ssthresh, upon each SACK arrival
// that advances the Cumulative TSN Ack Point, increase
// partial_bytes_acked by the total number of bytes of all new chunks
// acknowledged in that SACK including chunks acknowledged by the new
// Cumulative TSN Ack and by Gap Ack Blocks.
a.partialBytesAcked += uint32(totalBytesAcked)
// o When partial_bytes_acked is equal to or greater than cwnd and
// before the arrival of the SACK the sender had cwnd or more bytes
// of data outstanding (i.e., before arrival of the SACK, flight size
// was greater than or equal to cwnd), increase cwnd by MTU, and
// reset partial_bytes_acked to (partial_bytes_acked - cwnd).
if a.partialBytesAcked >= a.CWND() && a.pendingQueue.size() > 0 {
a.partialBytesAcked -= a.CWND()
a.setCWND(a.CWND() + a.MTU())
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d acked=%d (CA)",
a.name, a.CWND(), a.ssthresh, totalBytesAcked)
}
}
}
// The caller should hold the lock.
func (a *Association) processFastRetransmission(cumTSNAckPoint, htna uint32, cumTSNAckPointAdvanced bool) error {
// HTNA algorithm - RFC 4960 Sec 7.2.4
// Increment missIndicator of each chunks that the SACK reported missing
// when either of the following is met:
// a) Not in fast-recovery
// miss indications are incremented only for missing TSNs prior to the
// highest TSN newly acknowledged in the SACK.
// b) In fast-recovery AND the Cumulative TSN Ack Point advanced
// the miss indications are incremented for all TSNs reported missing
// in the SACK.
if !a.inFastRecovery || (a.inFastRecovery && cumTSNAckPointAdvanced) {
var maxTSN uint32
if !a.inFastRecovery {
// a) increment only for missing TSNs prior to the HTNA
maxTSN = htna
} else {
// b) increment for all TSNs reported missing
maxTSN = cumTSNAckPoint + uint32(a.inflightQueue.size()) + 1
}
for tsn := cumTSNAckPoint + 1; sna32LT(tsn, maxTSN); tsn++ {
c, ok := a.inflightQueue.get(tsn)
if !ok {
return fmt.Errorf("%w: %v", ErrTSNRequestNotExist, tsn)
}
if !c.acked && !c.abandoned() && c.missIndicator < 3 {
c.missIndicator++
if c.missIndicator == 3 {
if !a.inFastRecovery {
// 2) If not in Fast Recovery, adjust the ssthresh and cwnd of the
// destination address(es) to which the missing DATA chunks were
// last sent, according to the formula described in Section 7.2.3.
a.inFastRecovery = true
a.fastRecoverExitPoint = htna
a.ssthresh = max32(a.CWND()/2, 4*a.MTU())
a.setCWND(a.ssthresh)
a.partialBytesAcked = 0
a.willRetransmitFast = true
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d inflight=%d (FR)",
a.name, a.CWND(), a.ssthresh, a.inflightQueue.getNumBytes())
}
}
}
}
}
if a.inFastRecovery && cumTSNAckPointAdvanced {
a.willRetransmitFast = true
}
return nil
}
// The caller should hold the lock.
func (a *Association) handleSack(d *chunkSelectiveAck) error {
a.log.Tracef("[%s] SACK: cumTSN=%d a_rwnd=%d", a.name, d.cumulativeTSNAck, d.advertisedReceiverWindowCredit)
state := a.getState()
if state != established && state != shutdownPending && state != shutdownReceived {
return nil
}
a.stats.incSACKs()
if sna32GT(a.cumulativeTSNAckPoint, d.cumulativeTSNAck) {
// RFC 4960 sec 6.2.1. Processing a Received SACK
// D)
// i) If Cumulative TSN Ack is less than the Cumulative TSN Ack
// Point, then drop the SACK. Since Cumulative TSN Ack is
// monotonically increasing, a SACK whose Cumulative TSN Ack is
// less than the Cumulative TSN Ack Point indicates an out-of-
// order SACK.
a.log.Debugf("[%s] SACK Cumulative ACK %v is older than ACK point %v",
a.name,
d.cumulativeTSNAck,
a.cumulativeTSNAckPoint)
return nil
}
// Process selective ack
bytesAckedPerStream, htna, err := a.processSelectiveAck(d)
if err != nil {
return err
}
var totalBytesAcked int
for _, nBytesAcked := range bytesAckedPerStream {
totalBytesAcked += nBytesAcked
}
cumTSNAckPointAdvanced := false
if sna32LT(a.cumulativeTSNAckPoint, d.cumulativeTSNAck) {
a.log.Tracef("[%s] SACK: cumTSN advanced: %d -> %d",
a.name,
a.cumulativeTSNAckPoint,
d.cumulativeTSNAck)
a.cumulativeTSNAckPoint = d.cumulativeTSNAck
cumTSNAckPointAdvanced = true
a.onCumulativeTSNAckPointAdvanced(totalBytesAcked)
}
for si, nBytesAcked := range bytesAckedPerStream {
if s, ok := a.streams[si]; ok {
a.lock.Unlock()
s.onBufferReleased(nBytesAcked)
a.lock.Lock()
}
}
// New rwnd value
// RFC 4960 sec 6.2.1. Processing a Received SACK
// D)
// ii) Set rwnd equal to the newly received a_rwnd minus the number
// of bytes still outstanding after processing the Cumulative
// TSN Ack and the Gap Ack Blocks.
// bytes acked were already subtracted by markAsAcked() method
bytesOutstanding := uint32(a.inflightQueue.getNumBytes())
if bytesOutstanding >= d.advertisedReceiverWindowCredit {
a.setRWND(0)
} else {
a.setRWND(d.advertisedReceiverWindowCredit - bytesOutstanding)
}
err = a.processFastRetransmission(d.cumulativeTSNAck, htna, cumTSNAckPointAdvanced)
if err != nil {
return err
}
if a.useForwardTSN {
// RFC 3758 Sec 3.5 C1
if sna32LT(a.advancedPeerTSNAckPoint, a.cumulativeTSNAckPoint) {
a.advancedPeerTSNAckPoint = a.cumulativeTSNAckPoint
}
// RFC 3758 Sec 3.5 C2
for i := a.advancedPeerTSNAckPoint + 1; ; i++ {
c, ok := a.inflightQueue.get(i)
if !ok {
break
}
if !c.abandoned() {
break
}
a.advancedPeerTSNAckPoint = i
}
// RFC 3758 Sec 3.5 C3
if sna32GT(a.advancedPeerTSNAckPoint, a.cumulativeTSNAckPoint) {
a.willSendForwardTSN = true
}
a.awakeWriteLoop()
}
a.postprocessSack(state, cumTSNAckPointAdvanced)
return nil
}
// The caller must hold the lock. This method was only added because the
// linter was complaining about the "cognitive complexity" of handleSack.
func (a *Association) postprocessSack(state uint32, shouldAwakeWriteLoop bool) {
switch {
case a.inflightQueue.size() > 0:
// Start timer. (noop if already started)
a.log.Tracef("[%s] T3-rtx timer start (pt3)", a.name)
a.t3RTX.start(a.rtoMgr.getRTO())
case state == shutdownPending:
// No more outstanding, send shutdown.
shouldAwakeWriteLoop = true
a.willSendShutdown = true
a.setState(shutdownSent)
case state == shutdownReceived:
// No more outstanding, send shutdown ack.
shouldAwakeWriteLoop = true
a.willSendShutdownAck = true
a.setState(shutdownAckSent)
}
if shouldAwakeWriteLoop {
a.awakeWriteLoop()
}
}
// The caller should hold the lock.
func (a *Association) handleShutdown(_ *chunkShutdown) {
state := a.getState()
switch state {
case established:
if a.inflightQueue.size() > 0 {
a.setState(shutdownReceived)
} else {
// No more outstanding, send shutdown ack.
a.willSendShutdownAck = true
a.setState(shutdownAckSent)
a.awakeWriteLoop()
}
// a.cumulativeTSNAckPoint = c.cumulativeTSNAck
case shutdownSent:
a.willSendShutdownAck = true
a.setState(shutdownAckSent)
a.awakeWriteLoop()
}
}
// The caller should hold the lock.
func (a *Association) handleShutdownAck(_ *chunkShutdownAck) {
state := a.getState()
if state == shutdownSent || state == shutdownAckSent {
a.t2Shutdown.stop()
a.willSendShutdownComplete = true
a.awakeWriteLoop()
}
}
func (a *Association) handleShutdownComplete(_ *chunkShutdownComplete) error {
state := a.getState()
if state == shutdownAckSent {
a.t2Shutdown.stop()
return a.close()
}
return nil
}
func (a *Association) handleAbort(c *chunkAbort) error {
var errStr string
for _, e := range c.errorCauses {
errStr += fmt.Sprintf("(%s)", e)
}
_ = a.close()
return fmt.Errorf("[%s] %w: %s", a.name, ErrChunk, errStr)
}
// createForwardTSN generates ForwardTSN chunk.
// This method will be be called if useForwardTSN is set to false.
// The caller should hold the lock.
func (a *Association) createForwardTSN() *chunkForwardTSN {
// RFC 3758 Sec 3.5 C4
streamMap := map[uint16]uint16{} // to report only once per SI
for i := a.cumulativeTSNAckPoint + 1; sna32LTE(i, a.advancedPeerTSNAckPoint); i++ {
c, ok := a.inflightQueue.get(i)
if !ok {
break
}
ssn, ok := streamMap[c.streamIdentifier]
if !ok {
streamMap[c.streamIdentifier] = c.streamSequenceNumber
} else if sna16LT(ssn, c.streamSequenceNumber) {
// to report only once with greatest SSN
streamMap[c.streamIdentifier] = c.streamSequenceNumber
}
}
fwdtsn := &chunkForwardTSN{
newCumulativeTSN: a.advancedPeerTSNAckPoint,
streams: []chunkForwardTSNStream{},
}
var streamStr string
for si, ssn := range streamMap {
streamStr += fmt.Sprintf("(si=%d ssn=%d)", si, ssn)
fwdtsn.streams = append(fwdtsn.streams, chunkForwardTSNStream{
identifier: si,
sequence: ssn,
})
}
a.log.Tracef("[%s] building fwdtsn: newCumulativeTSN=%d cumTSN=%d - %s", a.name, fwdtsn.newCumulativeTSN, a.cumulativeTSNAckPoint, streamStr)
return fwdtsn
}
// createPacket wraps chunks in a packet.
// The caller should hold the read lock.
func (a *Association) createPacket(cs []chunk) *packet {
return &packet{
verificationTag: a.peerVerificationTag,
sourcePort: a.sourcePort,
destinationPort: a.destinationPort,
chunks: cs,
}
}
// The caller should hold the lock.
func (a *Association) handleReconfig(c *chunkReconfig) ([]*packet, error) {
a.log.Tracef("[%s] handleReconfig", a.name)
pp := make([]*packet, 0)
p, err := a.handleReconfigParam(c.paramA)
if err != nil {
return nil, err
}
if p != nil {
pp = append(pp, p)
}
if c.paramB != nil {
p, err = a.handleReconfigParam(c.paramB)
if err != nil {
return nil, err
}
if p != nil {
pp = append(pp, p)
}
}
return pp, nil
}
// The caller should hold the lock.
func (a *Association) handleForwardTSN(c *chunkForwardTSN) []*packet {
a.log.Tracef("[%s] FwdTSN: %s", a.name, c.String())
if !a.useForwardTSN {
a.log.Warn("[%s] received FwdTSN but not enabled")
// Return an error chunk
cerr := &chunkError{
errorCauses: []errorCause{&errorCauseUnrecognizedChunkType{}},
}
outbound := &packet{}
outbound.verificationTag = a.peerVerificationTag
outbound.sourcePort = a.sourcePort
outbound.destinationPort = a.destinationPort
outbound.chunks = []chunk{cerr}
return []*packet{outbound}
}
// From RFC 3758 Sec 3.6:
// Note, if the "New Cumulative TSN" value carried in the arrived
// FORWARD TSN chunk is found to be behind or at the current cumulative
// TSN point, the data receiver MUST treat this FORWARD TSN as out-of-
// date and MUST NOT update its Cumulative TSN. The receiver SHOULD
// send a SACK to its peer (the sender of the FORWARD TSN) since such a
// duplicate may indicate the previous SACK was lost in the network.
a.log.Tracef("[%s] should send ack? newCumTSN=%d peerLastTSN=%d",
a.name, c.newCumulativeTSN, a.peerLastTSN)
if sna32LTE(c.newCumulativeTSN, a.peerLastTSN) {
a.log.Tracef("[%s] sending ack on Forward TSN", a.name)
a.ackState = ackStateImmediate
a.ackTimer.stop()
a.awakeWriteLoop()
return nil
}
// From RFC 3758 Sec 3.6:
// the receiver MUST perform the same TSN handling, including duplicate
// detection, gap detection, SACK generation, cumulative TSN
// advancement, etc. as defined in RFC 2960 [2]---with the following
// exceptions and additions.
// When a FORWARD TSN chunk arrives, the data receiver MUST first update
// its cumulative TSN point to the value carried in the FORWARD TSN
// chunk,
// Advance peerLastTSN
for sna32LT(a.peerLastTSN, c.newCumulativeTSN) {
a.payloadQueue.pop(a.peerLastTSN + 1) // may not exist
a.peerLastTSN++
}
// Report new peerLastTSN value and abandoned largest SSN value to
// corresponding streams so that the abandoned chunks can be removed
// from the reassemblyQueue.
for _, forwarded := range c.streams {
if s, ok := a.streams[forwarded.identifier]; ok {
s.handleForwardTSNForOrdered(forwarded.sequence)
}
}
// TSN may be forewared for unordered chunks. ForwardTSN chunk does not
// report which stream identifier it skipped for unordered chunks.
// Therefore, we need to broadcast this event to all existing streams for
// unordered chunks.
// See https://github.com/pion/sctp/issues/106
for _, s := range a.streams {
s.handleForwardTSNForUnordered(c.newCumulativeTSN)
}
return a.handlePeerLastTSNAndAcknowledgement(false)
}
func (a *Association) sendResetRequest(streamIdentifier uint16) error {
a.lock.Lock()
defer a.lock.Unlock()
state := a.getState()
if state != established {
return fmt.Errorf("%w: state=%s", ErrResetPacketInStateNotExist,
getAssociationStateString(state))
}
// Create DATA chunk which only contains valid stream identifier with
// nil userData and use it as a EOS from the stream.
c := &chunkPayloadData{
streamIdentifier: streamIdentifier,
beginningFragment: true,
endingFragment: true,
userData: nil,
}
a.pendingQueue.push(c)
a.awakeWriteLoop()
return nil
}
// The caller should hold the lock.
func (a *Association) handleReconfigParam(raw param) (*packet, error) {
switch p := raw.(type) {
case *paramOutgoingResetRequest:
a.log.Tracef("[%s] handleReconfigParam (OutgoingResetRequest)", a.name)
a.reconfigRequests[p.reconfigRequestSequenceNumber] = p
resp := a.resetStreamsIfAny(p)
if resp != nil {
return resp, nil
}
return nil, nil //nolint:nilnil
case *paramReconfigResponse:
a.log.Tracef("[%s] handleReconfigParam (ReconfigResponse)", a.name)
delete(a.reconfigs, p.reconfigResponseSequenceNumber)
if len(a.reconfigs) == 0 {
a.tReconfig.stop()
}
return nil, nil //nolint:nilnil
default:
return nil, fmt.Errorf("%w: %t", ErrParamterType, p)
}
}
// The caller should hold the lock.
func (a *Association) resetStreamsIfAny(p *paramOutgoingResetRequest) *packet {
result := reconfigResultSuccessPerformed
if sna32LTE(p.senderLastTSN, a.peerLastTSN) {
a.log.Debugf("[%s] resetStream(): senderLastTSN=%d <= peerLastTSN=%d",
a.name, p.senderLastTSN, a.peerLastTSN)
for _, id := range p.streamIdentifiers {
s, ok := a.streams[id]
if !ok {
continue
}
a.lock.Unlock()
s.onInboundStreamReset()
a.lock.Lock()
a.log.Debugf("[%s] deleting stream %d", a.name, id)
delete(a.streams, s.streamIdentifier)
}
delete(a.reconfigRequests, p.reconfigRequestSequenceNumber)
} else {
a.log.Debugf("[%s] resetStream(): senderLastTSN=%d > peerLastTSN=%d",
a.name, p.senderLastTSN, a.peerLastTSN)
result = reconfigResultInProgress
}
return a.createPacket([]chunk{&chunkReconfig{
paramA: ¶mReconfigResponse{
reconfigResponseSequenceNumber: p.reconfigRequestSequenceNumber,
result: result,
},
}})
}
// Move the chunk peeked with a.pendingQueue.peek() to the inflightQueue.
// The caller should hold the lock.
func (a *Association) movePendingDataChunkToInflightQueue(c *chunkPayloadData) {
if err := a.pendingQueue.pop(c); err != nil {
a.log.Errorf("[%s] failed to pop from pending queue: %s", a.name, err.Error())
}
// Mark all fragements are in-flight now
if c.endingFragment {
c.setAllInflight()
}
// Assign TSN
c.tsn = a.generateNextTSN()
c.since = time.Now() // use to calculate RTT and also for maxPacketLifeTime
c.nSent = 1 // being sent for the first time
a.checkPartialReliabilityStatus(c)
a.log.Tracef("[%s] sending ppi=%d tsn=%d ssn=%d sent=%d len=%d (%v,%v)",
a.name, c.payloadType, c.tsn, c.streamSequenceNumber, c.nSent, len(c.userData), c.beginningFragment, c.endingFragment)
a.inflightQueue.pushNoCheck(c)
}
// popPendingDataChunksToSend pops chunks from the pending queues as many as
// the cwnd and rwnd allows to send.
// The caller should hold the lock.
func (a *Association) popPendingDataChunksToSend() ([]*chunkPayloadData, []uint16) {
chunks := []*chunkPayloadData{}
var sisToReset []uint16 // stream identifieres to reset
if a.pendingQueue.size() > 0 {
// RFC 4960 sec 6.1. Transmission of DATA Chunks
// A) At any given time, the data sender MUST NOT transmit new data to
// any destination transport address if its peer's rwnd indicates
// that the peer has no buffer space (i.e., rwnd is 0; see Section
// 6.2.1). However, regardless of the value of rwnd (including if it
// is 0), the data sender can always have one DATA chunk in flight to
// the receiver if allowed by cwnd (see rule B, below).
for {
c := a.pendingQueue.peek()
if c == nil {
break // no more pending data
}
dataLen := uint32(len(c.userData))
if dataLen == 0 {
sisToReset = append(sisToReset, c.streamIdentifier)
err := a.pendingQueue.pop(c)
if err != nil {
a.log.Errorf("failed to pop from pending queue: %s", err.Error())
}
continue
}
if uint32(a.inflightQueue.getNumBytes())+dataLen > a.CWND() {
break // would exceeds cwnd
}
if dataLen > a.rwnd {
break // no more rwnd
}
a.setRWND(a.RWND() - dataLen)
a.movePendingDataChunkToInflightQueue(c)
chunks = append(chunks, c)
}
// the data sender can always have one DATA chunk in flight to the receiver
if len(chunks) == 0 && a.inflightQueue.size() == 0 {
// Send zero window probe
c := a.pendingQueue.peek()
if c != nil {
a.movePendingDataChunkToInflightQueue(c)
chunks = append(chunks, c)
}
}
}
return chunks, sisToReset
}
// bundleDataChunksIntoPackets packs DATA chunks into packets. It tries to bundle
// DATA chunks into a packet so long as the resulting packet size does not exceed
// the path MTU.
// The caller should hold the lock.
func (a *Association) bundleDataChunksIntoPackets(chunks []*chunkPayloadData) []*packet {
packets := []*packet{}
chunksToSend := []chunk{}
bytesInPacket := int(commonHeaderSize)
for _, c := range chunks {
// RFC 4960 sec 6.1. Transmission of DATA Chunks
// Multiple DATA chunks committed for transmission MAY be bundled in a
// single packet. Furthermore, DATA chunks being retransmitted MAY be
// bundled with new DATA chunks, as long as the resulting packet size
// does not exceed the path MTU.
if bytesInPacket+len(c.userData) > int(a.MTU()) {
packets = append(packets, a.createPacket(chunksToSend))
chunksToSend = []chunk{}
bytesInPacket = int(commonHeaderSize)
}
chunksToSend = append(chunksToSend, c)
bytesInPacket += int(dataChunkHeaderSize) + len(c.userData)
}
if len(chunksToSend) > 0 {
packets = append(packets, a.createPacket(chunksToSend))
}
return packets
}
// sendPayloadData sends the data chunks.
func (a *Association) sendPayloadData(chunks []*chunkPayloadData) error {
a.lock.Lock()
defer a.lock.Unlock()
state := a.getState()
if state != established {
return fmt.Errorf("%w: state=%s", ErrPayloadDataStateNotExist,
getAssociationStateString(state))
}
// Push the chunks into the pending queue first.
for _, c := range chunks {
a.pendingQueue.push(c)
}
a.awakeWriteLoop()
return nil
}
// The caller should hold the lock.
func (a *Association) checkPartialReliabilityStatus(c *chunkPayloadData) {
if !a.useForwardTSN {
return
}
// draft-ietf-rtcweb-data-protocol-09.txt section 6
// 6. Procedures
// All Data Channel Establishment Protocol messages MUST be sent using
// ordered delivery and reliable transmission.
//
if c.payloadType == PayloadTypeWebRTCDCEP {
return
}
// PR-SCTP
if s, ok := a.streams[c.streamIdentifier]; ok {
s.lock.RLock()
if s.reliabilityType == ReliabilityTypeRexmit {
if c.nSent >= s.reliabilityValue {
c.setAbandoned(true)
a.log.Tracef("[%s] marked as abandoned: tsn=%d ppi=%d (remix: %d)", a.name, c.tsn, c.payloadType, c.nSent)
}
} else if s.reliabilityType == ReliabilityTypeTimed {
elapsed := int64(time.Since(c.since).Seconds() * 1000)
if elapsed >= int64(s.reliabilityValue) {
c.setAbandoned(true)
a.log.Tracef("[%s] marked as abandoned: tsn=%d ppi=%d (timed: %d)", a.name, c.tsn, c.payloadType, elapsed)
}
}
s.lock.RUnlock()
} else {
a.log.Errorf("[%s] stream %d not found)", a.name, c.streamIdentifier)
}
}
// getDataPacketsToRetransmit is called when T3-rtx is timed out and retransmit outstanding data chunks
// that are not acked or abandoned yet.
// The caller should hold the lock.
func (a *Association) getDataPacketsToRetransmit() []*packet {
awnd := min32(a.CWND(), a.RWND())
chunks := []*chunkPayloadData{}
var bytesToSend int
var done bool
for i := 0; !done; i++ {
c, ok := a.inflightQueue.get(a.cumulativeTSNAckPoint + uint32(i) + 1)
if !ok {
break // end of pending data
}
if !c.retransmit {
continue
}
if i == 0 && int(a.RWND()) < len(c.userData) {
// Send it as a zero window probe
done = true
} else if bytesToSend+len(c.userData) > int(awnd) {
break
}
// reset the retransmit flag not to retransmit again before the next
// t3-rtx timer fires
c.retransmit = false
bytesToSend += len(c.userData)
c.nSent++
a.checkPartialReliabilityStatus(c)
a.log.Tracef("[%s] retransmitting tsn=%d ssn=%d sent=%d", a.name, c.tsn, c.streamSequenceNumber, c.nSent)
chunks = append(chunks, c)
}
return a.bundleDataChunksIntoPackets(chunks)
}
// generateNextTSN returns the myNextTSN and increases it. The caller should hold the lock.
// The caller should hold the lock.
func (a *Association) generateNextTSN() uint32 {
tsn := a.myNextTSN
a.myNextTSN++
return tsn
}
// generateNextRSN returns the myNextRSN and increases it. The caller should hold the lock.
// The caller should hold the lock.
func (a *Association) generateNextRSN() uint32 {
rsn := a.myNextRSN
a.myNextRSN++
return rsn
}
func (a *Association) createSelectiveAckChunk() *chunkSelectiveAck {
sack := &chunkSelectiveAck{}
sack.cumulativeTSNAck = a.peerLastTSN
sack.advertisedReceiverWindowCredit = a.getMyReceiverWindowCredit()
sack.duplicateTSN = a.payloadQueue.popDuplicates()
sack.gapAckBlocks = a.payloadQueue.getGapAckBlocks(a.peerLastTSN)
return sack
}
func pack(p *packet) []*packet {
return []*packet{p}
}
func (a *Association) handleChunkStart() {
a.lock.Lock()
defer a.lock.Unlock()
a.delayedAckTriggered = false
a.immediateAckTriggered = false
}
func (a *Association) handleChunkEnd() {
a.lock.Lock()
defer a.lock.Unlock()
if a.immediateAckTriggered {
a.ackState = ackStateImmediate
a.ackTimer.stop()
a.awakeWriteLoop()
} else if a.delayedAckTriggered {
// Will send delayed ack in the next ack timeout
a.ackState = ackStateDelay
a.ackTimer.start()
}
}
func (a *Association) handleChunk(p *packet, c chunk) error {
a.lock.Lock()
defer a.lock.Unlock()
var packets []*packet
var err error
if _, err = c.check(); err != nil {
a.log.Errorf("[ %s ] failed validating chunk: %s ", a.name, err)
return nil
}
isAbort := false
switch c := c.(type) {
case *chunkInit:
packets, err = a.handleInit(p, c)
case *chunkInitAck:
err = a.handleInitAck(p, c)
case *chunkAbort:
isAbort = true
err = a.handleAbort(c)
case *chunkError:
var errStr string
for _, e := range c.errorCauses {
errStr += fmt.Sprintf("(%s)", e)
}
a.log.Debugf("[%s] Error chunk, with following errors: %s", a.name, errStr)
case *chunkHeartbeat:
packets = a.handleHeartbeat(c)
case *chunkCookieEcho:
packets = a.handleCookieEcho(c)
case *chunkCookieAck:
a.handleCookieAck()
case *chunkPayloadData:
packets = a.handleData(c)
case *chunkSelectiveAck:
err = a.handleSack(c)
case *chunkReconfig:
packets, err = a.handleReconfig(c)
case *chunkForwardTSN:
packets = a.handleForwardTSN(c)
case *chunkShutdown:
a.handleShutdown(c)
case *chunkShutdownAck:
a.handleShutdownAck(c)
case *chunkShutdownComplete:
err = a.handleShutdownComplete(c)
default:
err = ErrChunkTypeUnhandled
}
// Log and return, the only condition that is fatal is a ABORT chunk
if err != nil {
if isAbort {
return err
}
a.log.Errorf("Failed to handle chunk: %v", err)
return nil
}
if len(packets) > 0 {
a.controlQueue.pushAll(packets)
a.awakeWriteLoop()
}
return nil
}
func (a *Association) onRetransmissionTimeout(id int, nRtos uint) {
a.lock.Lock()
defer a.lock.Unlock()
if id == timerT1Init {
err := a.sendInit()
if err != nil {
a.log.Debugf("[%s] failed to retransmit init (nRtos=%d): %v", a.name, nRtos, err)
}
return
}
if id == timerT1Cookie {
err := a.sendCookieEcho()
if err != nil {
a.log.Debugf("[%s] failed to retransmit cookie-echo (nRtos=%d): %v", a.name, nRtos, err)
}
return
}
if id == timerT2Shutdown {
a.log.Debugf("[%s] retransmission of shutdown timeout (nRtos=%d): %v", a.name, nRtos)
state := a.getState()
switch state {
case shutdownSent:
a.willSendShutdown = true
a.awakeWriteLoop()
case shutdownAckSent:
a.willSendShutdownAck = true
a.awakeWriteLoop()
}
}
if id == timerT3RTX {
a.stats.incT3Timeouts()
// RFC 4960 sec 6.3.3
// E1) For the destination address for which the timer expires, adjust
// its ssthresh with rules defined in Section 7.2.3 and set the
// cwnd <- MTU.
// RFC 4960 sec 7.2.3
// When the T3-rtx timer expires on an address, SCTP should perform slow
// start by:
// ssthresh = max(cwnd/2, 4*MTU)
// cwnd = 1*MTU
a.ssthresh = max32(a.CWND()/2, 4*a.MTU())
a.setCWND(a.MTU())
a.log.Tracef("[%s] updated cwnd=%d ssthresh=%d inflight=%d (RTO)",
a.name, a.CWND(), a.ssthresh, a.inflightQueue.getNumBytes())
// RFC 3758 sec 3.5
// A5) Any time the T3-rtx timer expires, on any destination, the sender
// SHOULD try to advance the "Advanced.Peer.Ack.Point" by following
// the procedures outlined in C2 - C5.
if a.useForwardTSN {
// RFC 3758 Sec 3.5 C2
for i := a.advancedPeerTSNAckPoint + 1; ; i++ {
c, ok := a.inflightQueue.get(i)
if !ok {
break
}
if !c.abandoned() {
break
}
a.advancedPeerTSNAckPoint = i
}
// RFC 3758 Sec 3.5 C3
if sna32GT(a.advancedPeerTSNAckPoint, a.cumulativeTSNAckPoint) {
a.willSendForwardTSN = true
}
}
a.log.Debugf("[%s] T3-rtx timed out: nRtos=%d cwnd=%d ssthresh=%d", a.name, nRtos, a.CWND(), a.ssthresh)
/*
a.log.Debugf(" - advancedPeerTSNAckPoint=%d", a.advancedPeerTSNAckPoint)
a.log.Debugf(" - cumulativeTSNAckPoint=%d", a.cumulativeTSNAckPoint)
a.inflightQueue.updateSortedKeys()
for i, tsn := range a.inflightQueue.sorted {
if c, ok := a.inflightQueue.get(tsn); ok {
a.log.Debugf(" - [%d] tsn=%d acked=%v abandoned=%v (%v,%v) len=%d",
i, c.tsn, c.acked, c.abandoned(), c.beginningFragment, c.endingFragment, len(c.userData))
}
}
*/
a.inflightQueue.markAllToRetrasmit()
a.awakeWriteLoop()
return
}
if id == timerReconfig {
a.willRetransmitReconfig = true
a.awakeWriteLoop()
}
}
func (a *Association) onRetransmissionFailure(id int) {
a.lock.Lock()
defer a.lock.Unlock()
if id == timerT1Init {
a.log.Errorf("[%s] retransmission failure: T1-init", a.name)
a.handshakeCompletedCh <- ErrHandshakeInitAck
return
}
if id == timerT1Cookie {
a.log.Errorf("[%s] retransmission failure: T1-cookie", a.name)
a.handshakeCompletedCh <- ErrHandshakeCookieEcho
return
}
if id == timerT2Shutdown {
a.log.Errorf("[%s] retransmission failure: T2-shutdown", a.name)
return
}
if id == timerT3RTX {
// T3-rtx timer will not fail by design
// Justifications:
// * ICE would fail if the connectivity is lost
// * WebRTC spec is not clear how this incident should be reported to ULP
a.log.Errorf("[%s] retransmission failure: T3-rtx (DATA)", a.name)
return
}
}
func (a *Association) onAckTimeout() {
a.lock.Lock()
defer a.lock.Unlock()
a.log.Tracef("[%s] ack timed out (ackState: %d)", a.name, a.ackState)
a.stats.incAckTimeouts()
a.ackState = ackStateImmediate
a.awakeWriteLoop()
}
// bufferedAmount returns total amount (in bytes) of currently buffered user data.
// This is used only by testing.
func (a *Association) bufferedAmount() int {
a.lock.RLock()
defer a.lock.RUnlock()
return a.pendingQueue.getNumBytes() + a.inflightQueue.getNumBytes()
}
// MaxMessageSize returns the maximum message size you can send.
func (a *Association) MaxMessageSize() uint32 {
return atomic.LoadUint32(&a.maxMessageSize)
}
// SetMaxMessageSize sets the maximum message size you can send.
func (a *Association) SetMaxMessageSize(maxMsgSize uint32) {
atomic.StoreUint32(&a.maxMessageSize, maxMsgSize)
}