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peerconnection.go
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peerconnection.go
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// +build !js
// Package webrtc implements the WebRTC 1.0 as defined in W3C WebRTC specification document.
package webrtc
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"fmt"
mathRand "math/rand"
"strconv"
"strings"
"sync"
"time"
"github.com/pion/logging"
"github.com/pion/rtcp"
"github.com/pion/sdp/v2"
"github.com/pion/webrtc/v3/internal/util"
"github.com/pion/webrtc/v3/pkg/rtcerr"
)
// PeerConnection represents a WebRTC connection that establishes a
// peer-to-peer communications with another PeerConnection instance in a
// browser, or to another endpoint implementing the required protocols.
type PeerConnection struct {
statsID string
mu sync.RWMutex
// ops is an operations queue which will ensure the enqueued actions are
// executed in order. It is used for asynchronously, but serially processing
// remote and local descriptions
ops *operations
configuration Configuration
currentLocalDescription *SessionDescription
pendingLocalDescription *SessionDescription
currentRemoteDescription *SessionDescription
pendingRemoteDescription *SessionDescription
signalingState SignalingState
iceConnectionState ICEConnectionState
connectionState PeerConnectionState
idpLoginURL *string
isClosed *atomicBool
negotiationNeeded bool
lastOffer string
lastAnswer string
// a value containing the last known greater mid value
// we internally generate mids as numbers. Needed since JSEP
// requires that when reusing a media section a new unique mid
// should be defined (see JSEP 3.4.1).
greaterMid int
rtpTransceivers []*RTPTransceiver
onSignalingStateChangeHandler func(SignalingState)
onICEConnectionStateChangeHandler func(ICEConnectionState)
onConnectionStateChangeHandler func(PeerConnectionState)
onTrackHandler func(*Track, *RTPReceiver)
onDataChannelHandler func(*DataChannel)
iceGatherer *ICEGatherer
iceTransport *ICETransport
dtlsTransport *DTLSTransport
sctpTransport *SCTPTransport
// A reference to the associated API state used by this connection
api *API
log logging.LeveledLogger
}
// NewPeerConnection creates a peerconnection with the default
// codecs. See API.NewRTCPeerConnection for details.
func NewPeerConnection(configuration Configuration) (*PeerConnection, error) {
m := MediaEngine{}
m.RegisterDefaultCodecs()
api := NewAPI(WithMediaEngine(m))
return api.NewPeerConnection(configuration)
}
// NewPeerConnection creates a new PeerConnection with the provided configuration against the received API object
func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection, error) {
// https://w3c.github.io/webrtc-pc/#constructor (Step #2)
// Some variables defined explicitly despite their implicit zero values to
// allow better readability to understand what is happening.
pc := &PeerConnection{
statsID: fmt.Sprintf("PeerConnection-%d", time.Now().UnixNano()),
ops: newOperations(),
configuration: Configuration{
ICEServers: []ICEServer{},
ICETransportPolicy: ICETransportPolicyAll,
BundlePolicy: BundlePolicyBalanced,
RTCPMuxPolicy: RTCPMuxPolicyRequire,
Certificates: []Certificate{},
ICECandidatePoolSize: 0,
},
isClosed: &atomicBool{},
negotiationNeeded: false,
lastOffer: "",
lastAnswer: "",
greaterMid: -1,
signalingState: SignalingStateStable,
iceConnectionState: ICEConnectionStateNew,
connectionState: PeerConnectionStateNew,
api: api,
log: api.settingEngine.LoggerFactory.NewLogger("pc"),
}
var err error
if err = pc.initConfiguration(configuration); err != nil {
return nil, err
}
pc.iceGatherer, err = pc.createICEGatherer()
if err != nil {
return nil, err
}
// Create the ice transport
iceTransport := pc.createICETransport()
pc.iceTransport = iceTransport
// Create the DTLS transport
dtlsTransport, err := pc.api.NewDTLSTransport(pc.iceTransport, pc.configuration.Certificates)
if err != nil {
return nil, err
}
pc.dtlsTransport = dtlsTransport
// Create the SCTP transport
pc.sctpTransport = pc.api.NewSCTPTransport(pc.dtlsTransport)
// Wire up the on datachannel handler
pc.sctpTransport.OnDataChannel(func(d *DataChannel) {
pc.mu.RLock()
hdlr := pc.onDataChannelHandler
pc.mu.RUnlock()
if hdlr != nil {
hdlr(d)
}
})
return pc, nil
}
// initConfiguration defines validation of the specified Configuration and
// its assignment to the internal configuration variable. This function differs
// from its SetConfiguration counterpart because most of the checks do not
// include verification statements related to the existing state. Thus the
// function describes only minor verification of some the struct variables.
func (pc *PeerConnection) initConfiguration(configuration Configuration) error {
if configuration.PeerIdentity != "" {
pc.configuration.PeerIdentity = configuration.PeerIdentity
}
// https://www.w3.org/TR/webrtc/#constructor (step #3)
if len(configuration.Certificates) > 0 {
now := time.Now()
for _, x509Cert := range configuration.Certificates {
if !x509Cert.Expires().IsZero() && now.After(x509Cert.Expires()) {
return &rtcerr.InvalidAccessError{Err: ErrCertificateExpired}
}
pc.configuration.Certificates = append(pc.configuration.Certificates, x509Cert)
}
} else {
sk, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return &rtcerr.UnknownError{Err: err}
}
certificate, err := GenerateCertificate(sk)
if err != nil {
return err
}
pc.configuration.Certificates = []Certificate{*certificate}
}
if configuration.BundlePolicy != BundlePolicy(Unknown) {
pc.configuration.BundlePolicy = configuration.BundlePolicy
}
if configuration.RTCPMuxPolicy != RTCPMuxPolicy(Unknown) {
pc.configuration.RTCPMuxPolicy = configuration.RTCPMuxPolicy
}
if configuration.ICECandidatePoolSize != 0 {
pc.configuration.ICECandidatePoolSize = configuration.ICECandidatePoolSize
}
if configuration.ICETransportPolicy != ICETransportPolicy(Unknown) {
pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
}
if configuration.SDPSemantics != SDPSemantics(Unknown) {
pc.configuration.SDPSemantics = configuration.SDPSemantics
}
sanitizedICEServers := configuration.getICEServers()
if len(sanitizedICEServers) > 0 {
for _, server := range sanitizedICEServers {
if err := server.validate(); err != nil {
return err
}
}
pc.configuration.ICEServers = sanitizedICEServers
}
return nil
}
// OnSignalingStateChange sets an event handler which is invoked when the
// peer connection's signaling state changes
func (pc *PeerConnection) OnSignalingStateChange(f func(SignalingState)) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.onSignalingStateChangeHandler = f
}
func (pc *PeerConnection) onSignalingStateChange(newState SignalingState) {
pc.mu.RLock()
hdlr := pc.onSignalingStateChangeHandler
pc.mu.RUnlock()
pc.log.Infof("signaling state changed to %s", newState)
if hdlr != nil {
go hdlr(newState)
}
}
// OnDataChannel sets an event handler which is invoked when a data
// channel message arrives from a remote peer.
func (pc *PeerConnection) OnDataChannel(f func(*DataChannel)) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.onDataChannelHandler = f
}
// OnICECandidate sets an event handler which is invoked when a new ICE
// candidate is found.
// Take note that the handler is gonna be called with a nil pointer when
// gathering is finished.
func (pc *PeerConnection) OnICECandidate(f func(*ICECandidate)) {
pc.iceGatherer.OnLocalCandidate(f)
}
// OnICEGatheringStateChange sets an event handler which is invoked when the
// ICE candidate gathering state has changed.
func (pc *PeerConnection) OnICEGatheringStateChange(f func(ICEGathererState)) {
pc.iceGatherer.OnStateChange(f)
}
// OnTrack sets an event handler which is called when remote track
// arrives from a remote peer.
func (pc *PeerConnection) OnTrack(f func(*Track, *RTPReceiver)) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.onTrackHandler = f
}
func (pc *PeerConnection) onTrack(t *Track, r *RTPReceiver) {
pc.mu.RLock()
hdlr := pc.onTrackHandler
pc.mu.RUnlock()
pc.log.Debugf("got new track: %+v", t)
if hdlr != nil && t != nil {
go hdlr(t, r)
}
}
// OnICEConnectionStateChange sets an event handler which is called
// when an ICE connection state is changed.
func (pc *PeerConnection) OnICEConnectionStateChange(f func(ICEConnectionState)) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.onICEConnectionStateChangeHandler = f
}
func (pc *PeerConnection) onICEConnectionStateChange(cs ICEConnectionState) {
pc.mu.Lock()
pc.iceConnectionState = cs
hdlr := pc.onICEConnectionStateChangeHandler
pc.mu.Unlock()
pc.log.Infof("ICE connection state changed: %s", cs)
if hdlr != nil {
go hdlr(cs)
}
}
// OnConnectionStateChange sets an event handler which is called
// when the PeerConnectionState has changed
func (pc *PeerConnection) OnConnectionStateChange(f func(PeerConnectionState)) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.onConnectionStateChangeHandler = f
}
// SetConfiguration updates the configuration of this PeerConnection object.
func (pc *PeerConnection) SetConfiguration(configuration Configuration) error {
// https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-setconfiguration (step #2)
if pc.isClosed.get() {
return &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #3)
if configuration.PeerIdentity != "" {
if configuration.PeerIdentity != pc.configuration.PeerIdentity {
return &rtcerr.InvalidModificationError{Err: ErrModifyingPeerIdentity}
}
pc.configuration.PeerIdentity = configuration.PeerIdentity
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #4)
if len(configuration.Certificates) > 0 {
if len(configuration.Certificates) != len(pc.configuration.Certificates) {
return &rtcerr.InvalidModificationError{Err: ErrModifyingCertificates}
}
for i, certificate := range configuration.Certificates {
if !pc.configuration.Certificates[i].Equals(certificate) {
return &rtcerr.InvalidModificationError{Err: ErrModifyingCertificates}
}
}
pc.configuration.Certificates = configuration.Certificates
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #5)
if configuration.BundlePolicy != BundlePolicy(Unknown) {
if configuration.BundlePolicy != pc.configuration.BundlePolicy {
return &rtcerr.InvalidModificationError{Err: ErrModifyingBundlePolicy}
}
pc.configuration.BundlePolicy = configuration.BundlePolicy
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #6)
if configuration.RTCPMuxPolicy != RTCPMuxPolicy(Unknown) {
if configuration.RTCPMuxPolicy != pc.configuration.RTCPMuxPolicy {
return &rtcerr.InvalidModificationError{Err: ErrModifyingRTCPMuxPolicy}
}
pc.configuration.RTCPMuxPolicy = configuration.RTCPMuxPolicy
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #7)
if configuration.ICECandidatePoolSize != 0 {
if pc.configuration.ICECandidatePoolSize != configuration.ICECandidatePoolSize &&
pc.LocalDescription() != nil {
return &rtcerr.InvalidModificationError{Err: ErrModifyingICECandidatePoolSize}
}
pc.configuration.ICECandidatePoolSize = configuration.ICECandidatePoolSize
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #8)
if configuration.ICETransportPolicy != ICETransportPolicy(Unknown) {
pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
}
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #11)
if len(configuration.ICEServers) > 0 {
// https://www.w3.org/TR/webrtc/#set-the-configuration (step #11.3)
for _, server := range configuration.ICEServers {
if err := server.validate(); err != nil {
return err
}
}
pc.configuration.ICEServers = configuration.ICEServers
}
return nil
}
// GetConfiguration returns a Configuration object representing the current
// configuration of this PeerConnection object. The returned object is a
// copy and direct mutation on it will not take affect until SetConfiguration
// has been called with Configuration passed as its only argument.
// https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-getconfiguration
func (pc *PeerConnection) GetConfiguration() Configuration {
return pc.configuration
}
func (pc *PeerConnection) getStatsID() string {
pc.mu.RLock()
defer pc.mu.RUnlock()
return pc.statsID
}
// CreateOffer starts the PeerConnection and generates the localDescription
func (pc *PeerConnection) CreateOffer(options *OfferOptions) (SessionDescription, error) {
useIdentity := pc.idpLoginURL != nil
switch {
case useIdentity:
return SessionDescription{}, fmt.Errorf("TODO handle identity provider")
case pc.isClosed.get():
return SessionDescription{}, &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
if options != nil && options.ICERestart {
if err := pc.iceTransport.restart(); err != nil {
return SessionDescription{}, err
}
}
isPlanB := pc.configuration.SDPSemantics == SDPSemanticsPlanB
if pc.currentRemoteDescription != nil {
isPlanB = descriptionIsPlanB(pc.RemoteDescription())
}
// include unmatched local transceivers
if !isPlanB {
// update the greater mid if the remote description provides a greater one
if pc.currentRemoteDescription != nil {
for _, media := range pc.currentRemoteDescription.parsed.MediaDescriptions {
mid := getMidValue(media)
if mid == "" {
continue
}
numericMid, err := strconv.Atoi(mid)
if err != nil {
continue
}
if numericMid > pc.greaterMid {
pc.greaterMid = numericMid
}
}
}
for _, t := range pc.GetTransceivers() {
if t.Mid() != "" {
continue
}
pc.greaterMid++
err := t.setMid(strconv.Itoa(pc.greaterMid))
if err != nil {
return SessionDescription{}, err
}
}
}
var (
d *sdp.SessionDescription
err error
)
if pc.currentRemoteDescription == nil {
d, err = pc.generateUnmatchedSDP(useIdentity)
} else {
d, err = pc.generateMatchedSDP(useIdentity, true /*includeUnmatched */, connectionRoleFromDtlsRole(defaultDtlsRoleOffer))
}
if err != nil {
return SessionDescription{}, err
}
sdpBytes, err := d.Marshal()
if err != nil {
return SessionDescription{}, err
}
desc := SessionDescription{
Type: SDPTypeOffer,
SDP: string(sdpBytes),
parsed: d,
}
pc.lastOffer = desc.SDP
return desc, nil
}
func (pc *PeerConnection) createICEGatherer() (*ICEGatherer, error) {
g, err := pc.api.NewICEGatherer(ICEGatherOptions{
ICEServers: pc.configuration.getICEServers(),
ICEGatherPolicy: pc.configuration.ICETransportPolicy,
})
if err != nil {
return nil, err
}
return g, nil
}
// Update the PeerConnectionState given the state of relevant transports
// https://www.w3.org/TR/webrtc/#rtcpeerconnectionstate-enum
func (pc *PeerConnection) updateConnectionState(iceConnectionState ICEConnectionState, dtlsTransportState DTLSTransportState) {
pc.mu.Lock()
defer pc.mu.Unlock()
connectionState := PeerConnectionStateNew
switch {
// The RTCPeerConnection object's [[IsClosed]] slot is true.
case pc.isClosed.get():
connectionState = PeerConnectionStateClosed
// Any of the RTCIceTransports or RTCDtlsTransports are in a "failed" state.
case iceConnectionState == ICEConnectionStateFailed || dtlsTransportState == DTLSTransportStateFailed:
connectionState = PeerConnectionStateFailed
// Any of the RTCIceTransports or RTCDtlsTransports are in the "disconnected"
// state and none of them are in the "failed" or "connecting" or "checking" state. */
case iceConnectionState == ICEConnectionStateDisconnected:
connectionState = PeerConnectionStateDisconnected
// All RTCIceTransports and RTCDtlsTransports are in the "connected", "completed" or "closed"
// state and at least one of them is in the "connected" or "completed" state.
case iceConnectionState == ICEConnectionStateConnected && dtlsTransportState == DTLSTransportStateConnected:
connectionState = PeerConnectionStateConnected
// Any of the RTCIceTransports or RTCDtlsTransports are in the "connecting" or
// "checking" state and none of them is in the "failed" state.
case iceConnectionState == ICEConnectionStateChecking && dtlsTransportState == DTLSTransportStateConnecting:
connectionState = PeerConnectionStateConnecting
}
if pc.connectionState == connectionState {
return
}
pc.log.Infof("peer connection state changed: %s", connectionState)
pc.connectionState = connectionState
hdlr := pc.onConnectionStateChangeHandler
if hdlr != nil {
go hdlr(connectionState)
}
}
func (pc *PeerConnection) createICETransport() *ICETransport {
t := pc.api.NewICETransport(pc.iceGatherer)
t.OnConnectionStateChange(func(state ICETransportState) {
var cs ICEConnectionState
switch state {
case ICETransportStateNew:
cs = ICEConnectionStateNew
case ICETransportStateChecking:
cs = ICEConnectionStateChecking
case ICETransportStateConnected:
cs = ICEConnectionStateConnected
case ICETransportStateCompleted:
cs = ICEConnectionStateCompleted
case ICETransportStateFailed:
cs = ICEConnectionStateFailed
case ICETransportStateDisconnected:
cs = ICEConnectionStateDisconnected
case ICETransportStateClosed:
cs = ICEConnectionStateClosed
default:
pc.log.Warnf("OnConnectionStateChange: unhandled ICE state: %s", state)
return
}
pc.onICEConnectionStateChange(cs)
pc.updateConnectionState(cs, pc.dtlsTransport.State())
})
return t
}
// CreateAnswer starts the PeerConnection and generates the localDescription
func (pc *PeerConnection) CreateAnswer(options *AnswerOptions) (SessionDescription, error) {
useIdentity := pc.idpLoginURL != nil
switch {
case pc.RemoteDescription() == nil:
return SessionDescription{}, &rtcerr.InvalidStateError{Err: ErrNoRemoteDescription}
case useIdentity:
return SessionDescription{}, fmt.Errorf("TODO handle identity provider")
case pc.isClosed.get():
return SessionDescription{}, &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
connectionRole := connectionRoleFromDtlsRole(pc.api.settingEngine.answeringDTLSRole)
if connectionRole == sdp.ConnectionRole(0) {
connectionRole = connectionRoleFromDtlsRole(defaultDtlsRoleAnswer)
}
d, err := pc.generateMatchedSDP(useIdentity, false /*includeUnmatched */, connectionRole)
if err != nil {
return SessionDescription{}, err
}
sdpBytes, err := d.Marshal()
if err != nil {
return SessionDescription{}, err
}
desc := SessionDescription{
Type: SDPTypeAnswer,
SDP: string(sdpBytes),
parsed: d,
}
pc.lastAnswer = desc.SDP
return desc, nil
}
// 4.4.1.6 Set the SessionDescription
func (pc *PeerConnection) setDescription(sd *SessionDescription, op stateChangeOp) error {
if pc.isClosed.get() {
return &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
nextState, err := func() (SignalingState, error) {
pc.mu.Lock()
defer pc.mu.Unlock()
cur := pc.signalingState
setLocal := stateChangeOpSetLocal
setRemote := stateChangeOpSetRemote
newSDPDoesNotMatchOffer := &rtcerr.InvalidModificationError{Err: fmt.Errorf("new sdp does not match previous offer")}
newSDPDoesNotMatchAnswer := &rtcerr.InvalidModificationError{Err: fmt.Errorf("new sdp does not match previous answer")}
var nextState SignalingState
var err error
switch op {
case setLocal:
switch sd.Type {
// stable->SetLocal(offer)->have-local-offer
case SDPTypeOffer:
if sd.SDP != pc.lastOffer {
return nextState, newSDPDoesNotMatchOffer
}
nextState, err = checkNextSignalingState(cur, SignalingStateHaveLocalOffer, setLocal, sd.Type)
if err == nil {
pc.pendingLocalDescription = sd
}
// have-remote-offer->SetLocal(answer)->stable
// have-local-pranswer->SetLocal(answer)->stable
case SDPTypeAnswer:
if sd.SDP != pc.lastAnswer {
return nextState, newSDPDoesNotMatchAnswer
}
nextState, err = checkNextSignalingState(cur, SignalingStateStable, setLocal, sd.Type)
if err == nil {
pc.currentLocalDescription = sd
pc.currentRemoteDescription = pc.pendingRemoteDescription
pc.pendingRemoteDescription = nil
pc.pendingLocalDescription = nil
}
case SDPTypeRollback:
nextState, err = checkNextSignalingState(cur, SignalingStateStable, setLocal, sd.Type)
if err == nil {
pc.pendingLocalDescription = nil
}
// have-remote-offer->SetLocal(pranswer)->have-local-pranswer
case SDPTypePranswer:
if sd.SDP != pc.lastAnswer {
return nextState, newSDPDoesNotMatchAnswer
}
nextState, err = checkNextSignalingState(cur, SignalingStateHaveLocalPranswer, setLocal, sd.Type)
if err == nil {
pc.pendingLocalDescription = sd
}
default:
return nextState, &rtcerr.OperationError{Err: fmt.Errorf("invalid state change op: %s(%s)", op, sd.Type)}
}
case setRemote:
switch sd.Type {
// stable->SetRemote(offer)->have-remote-offer
case SDPTypeOffer:
nextState, err = checkNextSignalingState(cur, SignalingStateHaveRemoteOffer, setRemote, sd.Type)
if err == nil {
pc.pendingRemoteDescription = sd
}
// have-local-offer->SetRemote(answer)->stable
// have-remote-pranswer->SetRemote(answer)->stable
case SDPTypeAnswer:
nextState, err = checkNextSignalingState(cur, SignalingStateStable, setRemote, sd.Type)
if err == nil {
pc.currentRemoteDescription = sd
pc.currentLocalDescription = pc.pendingLocalDescription
pc.pendingRemoteDescription = nil
pc.pendingLocalDescription = nil
}
case SDPTypeRollback:
nextState, err = checkNextSignalingState(cur, SignalingStateStable, setRemote, sd.Type)
if err == nil {
pc.pendingRemoteDescription = nil
}
// have-local-offer->SetRemote(pranswer)->have-remote-pranswer
case SDPTypePranswer:
nextState, err = checkNextSignalingState(cur, SignalingStateHaveRemotePranswer, setRemote, sd.Type)
if err == nil {
pc.pendingRemoteDescription = sd
}
default:
return nextState, &rtcerr.OperationError{Err: fmt.Errorf("invalid state change op: %s(%s)", op, sd.Type)}
}
default:
return nextState, &rtcerr.OperationError{Err: fmt.Errorf("unhandled state change op: %q", op)}
}
return nextState, nil
}()
if err == nil {
pc.signalingState = nextState
pc.onSignalingStateChange(nextState)
}
return err
}
// SetLocalDescription sets the SessionDescription of the local peer
func (pc *PeerConnection) SetLocalDescription(desc SessionDescription) error {
if pc.isClosed.get() {
return &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
haveLocalDescription := pc.currentLocalDescription != nil
// JSEP 5.4
if desc.SDP == "" {
switch desc.Type {
case SDPTypeAnswer, SDPTypePranswer:
desc.SDP = pc.lastAnswer
case SDPTypeOffer:
desc.SDP = pc.lastOffer
default:
return &rtcerr.InvalidModificationError{
Err: fmt.Errorf("invalid SDP type supplied to SetLocalDescription(): %s", desc.Type),
}
}
}
desc.parsed = &sdp.SessionDescription{}
if err := desc.parsed.Unmarshal([]byte(desc.SDP)); err != nil {
return err
}
if err := pc.setDescription(&desc, stateChangeOpSetLocal); err != nil {
return err
}
currentTransceivers := append([]*RTPTransceiver{}, pc.GetTransceivers()...)
weAnswer := desc.Type == SDPTypeAnswer
remoteDesc := pc.RemoteDescription()
if weAnswer && remoteDesc != nil {
pc.ops.Enqueue(func() {
pc.startRTP(haveLocalDescription, remoteDesc, currentTransceivers)
})
}
if pc.iceGatherer.State() == ICEGathererStateNew {
return pc.iceGatherer.Gather()
}
return nil
}
// LocalDescription returns PendingLocalDescription if it is not null and
// otherwise it returns CurrentLocalDescription. This property is used to
// determine if SetLocalDescription has already been called.
// https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-localdescription
func (pc *PeerConnection) LocalDescription() *SessionDescription {
if pendingLocalDescription := pc.PendingLocalDescription(); pendingLocalDescription != nil {
return pendingLocalDescription
}
return pc.CurrentLocalDescription()
}
// SetRemoteDescription sets the SessionDescription of the remote peer
// nolint: gocyclo
func (pc *PeerConnection) SetRemoteDescription(desc SessionDescription) error {
if pc.isClosed.get() {
return &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
}
isRenegotation := pc.currentRemoteDescription != nil
desc.parsed = &sdp.SessionDescription{}
if err := desc.parsed.Unmarshal([]byte(desc.SDP)); err != nil {
return err
}
if err := pc.setDescription(&desc, stateChangeOpSetRemote); err != nil {
return err
}
var t *RTPTransceiver
localTransceivers := append([]*RTPTransceiver{}, pc.GetTransceivers()...)
detectedPlanB := descriptionIsPlanB(pc.RemoteDescription())
weOffer := desc.Type == SDPTypeAnswer
if !weOffer && !detectedPlanB {
for _, media := range pc.RemoteDescription().parsed.MediaDescriptions {
midValue := getMidValue(media)
if midValue == "" {
return fmt.Errorf("RemoteDescription contained media section without mid value")
}
if media.MediaName.Media == mediaSectionApplication {
continue
}
kind := NewRTPCodecType(media.MediaName.Media)
direction := getPeerDirection(media)
if kind == 0 || direction == RTPTransceiverDirection(Unknown) {
continue
}
t, localTransceivers = findByMid(midValue, localTransceivers)
if t == nil {
t, localTransceivers = satisfyTypeAndDirection(kind, direction, localTransceivers)
}
if t == nil {
receiver, err := pc.api.NewRTPReceiver(kind, pc.dtlsTransport)
if err != nil {
return err
}
t = pc.newRTPTransceiver(receiver, nil, RTPTransceiverDirectionRecvonly, kind)
}
if t.Mid() == "" {
_ = t.setMid(midValue)
}
}
}
remoteUfrag, remotePwd, candidates, err := extractICEDetails(desc.parsed)
if err != nil {
return err
}
if isRenegotation && pc.iceTransport.haveRemoteCredentialsChange(remoteUfrag, remotePwd) {
// An ICE Restart only happens implicitly for a SetRemoteDescription of type offer
if !weOffer {
if err = pc.iceTransport.restart(); err != nil {
return err
}
}
if err = pc.iceTransport.setRemoteCredentials(remoteUfrag, remotePwd); err != nil {
return err
}
}
for _, c := range candidates {
if err = pc.iceTransport.AddRemoteCandidate(c); err != nil {
return err
}
}
currentTransceivers := append([]*RTPTransceiver{}, pc.GetTransceivers()...)
if isRenegotation {
if weOffer {
pc.ops.Enqueue(func() {
pc.startRTP(true, &desc, currentTransceivers)
})
}
return nil
}
remoteIsLite := false
if liteValue, haveRemoteIs := desc.parsed.Attribute(sdp.AttrKeyICELite); haveRemoteIs && liteValue == sdp.AttrKeyICELite {
remoteIsLite = true
}
fingerprint, fingerprintHash, err := extractFingerprint(desc.parsed)
if err != nil {
return err
}
iceRole := ICERoleControlled
// If one of the agents is lite and the other one is not, the lite agent must be the controlling agent.
// If both or neither agents are lite the offering agent is controlling.
// RFC 8445 S6.1.1
if (weOffer && remoteIsLite == pc.api.settingEngine.candidates.ICELite) || (remoteIsLite && !pc.api.settingEngine.candidates.ICELite) {
iceRole = ICERoleControlling
}
// Start the networking in a new routine since it will block until
// the connection is actually established.
pc.ops.Enqueue(func() {
pc.startTransports(iceRole, dtlsRoleFromRemoteSDP(desc.parsed), remoteUfrag, remotePwd, fingerprint, fingerprintHash)
if weOffer {
pc.startRTP(false, &desc, currentTransceivers)
}
})
return nil
}
func (pc *PeerConnection) startReceiver(incoming trackDetails, receiver *RTPReceiver) {
err := receiver.Receive(RTPReceiveParameters{
Encodings: RTPDecodingParameters{
RTPCodingParameters{SSRC: incoming.ssrc},
}})
if err != nil {
pc.log.Warnf("RTPReceiver Receive failed %s", err)
return
}
// set track id and label early so they can be set as new track information
// is received from the SDP.
receiver.Track().mu.Lock()
receiver.Track().id = incoming.id
receiver.Track().label = incoming.label
receiver.Track().mu.Unlock()
go func() {
if err = receiver.Track().determinePayloadType(); err != nil {
pc.log.Warnf("Could not determine PayloadType for SSRC %d", receiver.Track().SSRC())
return
}
pc.mu.RLock()
defer pc.mu.RUnlock()
codec, err := pc.api.mediaEngine.getCodec(receiver.Track().PayloadType())
if err != nil {
pc.log.Warnf("no codec could be found for payloadType %d", receiver.Track().PayloadType())
return
}
receiver.Track().mu.Lock()
receiver.Track().kind = codec.Type
receiver.Track().codec = codec
receiver.Track().mu.Unlock()
if pc.onTrackHandler != nil {
pc.onTrack(receiver.Track(), receiver)
} else {
pc.log.Warnf("OnTrack unset, unable to handle incoming media streams")
}
}()
}
// startRTPReceivers opens knows inbound SRTP streams from the RemoteDescription
func (pc *PeerConnection) startRTPReceivers(incomingTracks map[uint32]trackDetails, currentTransceivers []*RTPTransceiver) {
localTransceivers := append([]*RTPTransceiver{}, currentTransceivers...)
remoteIsPlanB := false
switch pc.configuration.SDPSemantics {
case SDPSemanticsPlanB:
remoteIsPlanB = true
case SDPSemanticsUnifiedPlanWithFallback:
remoteIsPlanB = descriptionIsPlanB(pc.RemoteDescription())
}
// Ensure we haven't already started a transceiver for this ssrc
for ssrc := range incomingTracks {
for i := range localTransceivers {
if t := localTransceivers[i]; (t.Receiver()) == nil || t.Receiver().Track() == nil || t.Receiver().Track().ssrc != ssrc {
continue
}
delete(incomingTracks, ssrc)
}
}
for ssrc, incoming := range incomingTracks {
for i := range localTransceivers {
t := localTransceivers[i]
if t.Mid() != incoming.mid {
continue
}
if (incomingTracks[ssrc].kind != t.kind) ||
(t.Direction() != RTPTransceiverDirectionRecvonly && t.Direction() != RTPTransceiverDirectionSendrecv) ||
(t.Receiver()) == nil ||
(t.Receiver().haveReceived()) {
continue
}
delete(incomingTracks, ssrc)
localTransceivers = append(localTransceivers[:i], localTransceivers[i+1:]...)
pc.startReceiver(incoming, t.Receiver())
break
}
}
if remoteIsPlanB {
for ssrc, incoming := range incomingTracks {
t, err := pc.AddTransceiverFromKind(incoming.kind, RtpTransceiverInit{
Direction: RTPTransceiverDirectionSendrecv,
})
if err != nil {
pc.log.Warnf("Could not add transceiver for remote SSRC %d: %s", ssrc, err)
continue
}
pc.startReceiver(incoming, t.Receiver())
}
}
}
// startRTPSenders starts all outbound RTP streams
func (pc *PeerConnection) startRTPSenders(currentTransceivers []*RTPTransceiver) {
for _, transceiver := range currentTransceivers {
// TODO(sgotti) when in future we'll avoid replacing a transceiver sender just check the transceiver negotiation status
if transceiver.Sender() != nil && transceiver.Sender().isNegotiated() && !transceiver.Sender().hasSent() {
err := transceiver.Sender().Send(RTPSendParameters{
Encodings: RTPEncodingParameters{
RTPCodingParameters{
SSRC: transceiver.Sender().track.SSRC(),
PayloadType: transceiver.Sender().track.PayloadType(),
},
}})
if err != nil {
pc.log.Warnf("Failed to start Sender: %s", err)
}
}
}
}
// Start SCTP subsystem