515 lines
14 KiB
Go
515 lines
14 KiB
Go
// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
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// SPDX-License-Identifier: MIT
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//go:build !js
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// +build !js
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package webrtc
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"crypto/tls"
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"crypto/x509"
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"errors"
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"fmt"
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"strings"
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"sync"
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"sync/atomic"
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"time"
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"github.com/pion/dtls/v2"
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"github.com/pion/dtls/v2/pkg/crypto/fingerprint"
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"github.com/pion/interceptor"
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"github.com/pion/logging"
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"github.com/pion/rtcp"
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"github.com/pion/srtp/v2"
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"github.com/pion/webrtc/v3/internal/mux"
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"github.com/pion/webrtc/v3/internal/util"
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"github.com/pion/webrtc/v3/pkg/rtcerr"
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)
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// DTLSTransport allows an application access to information about the DTLS
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// transport over which RTP and RTCP packets are sent and received by
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// RTPSender and RTPReceiver, as well other data such as SCTP packets sent
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// and received by data channels.
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type DTLSTransport struct {
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lock sync.RWMutex
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iceTransport *ICETransport
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certificates []Certificate
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remoteParameters DTLSParameters
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remoteCertificate []byte
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state DTLSTransportState
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srtpProtectionProfile srtp.ProtectionProfile
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onStateChangeHandler func(DTLSTransportState)
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conn *dtls.Conn
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srtpSession, srtcpSession atomic.Value
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srtpEndpoint, srtcpEndpoint *mux.Endpoint
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simulcastStreams []*srtp.ReadStreamSRTP
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srtpReady chan struct{}
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dtlsMatcher mux.MatchFunc
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api *API
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log logging.LeveledLogger
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}
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// NewDTLSTransport creates a new DTLSTransport.
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// This constructor is part of the ORTC API. It is not
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// meant to be used together with the basic WebRTC API.
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func (api *API) NewDTLSTransport(transport *ICETransport, certificates []Certificate) (*DTLSTransport, error) {
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t := &DTLSTransport{
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iceTransport: transport,
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api: api,
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state: DTLSTransportStateNew,
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dtlsMatcher: mux.MatchDTLS,
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srtpReady: make(chan struct{}),
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log: api.settingEngine.LoggerFactory.NewLogger("DTLSTransport"),
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}
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if len(certificates) > 0 {
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now := time.Now()
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for _, x509Cert := range certificates {
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if !x509Cert.Expires().IsZero() && now.After(x509Cert.Expires()) {
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return nil, &rtcerr.InvalidAccessError{Err: ErrCertificateExpired}
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}
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t.certificates = append(t.certificates, x509Cert)
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}
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} else {
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sk, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
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if err != nil {
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return nil, &rtcerr.UnknownError{Err: err}
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}
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certificate, err := GenerateCertificate(sk)
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if err != nil {
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return nil, err
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}
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t.certificates = []Certificate{*certificate}
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}
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return t, nil
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}
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// ICETransport returns the currently-configured *ICETransport or nil
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// if one has not been configured
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func (t *DTLSTransport) ICETransport() *ICETransport {
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t.lock.RLock()
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defer t.lock.RUnlock()
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return t.iceTransport
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}
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// onStateChange requires the caller holds the lock
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func (t *DTLSTransport) onStateChange(state DTLSTransportState) {
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t.state = state
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handler := t.onStateChangeHandler
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if handler != nil {
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handler(state)
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}
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}
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// OnStateChange sets a handler that is fired when the DTLS
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// connection state changes.
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func (t *DTLSTransport) OnStateChange(f func(DTLSTransportState)) {
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t.lock.Lock()
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defer t.lock.Unlock()
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t.onStateChangeHandler = f
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}
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// State returns the current dtls transport state.
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func (t *DTLSTransport) State() DTLSTransportState {
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t.lock.RLock()
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defer t.lock.RUnlock()
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return t.state
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}
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// WriteRTCP sends a user provided RTCP packet to the connected peer. If no peer is connected the
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// packet is discarded.
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func (t *DTLSTransport) WriteRTCP(pkts []rtcp.Packet) (int, error) {
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raw, err := rtcp.Marshal(pkts)
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if err != nil {
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return 0, err
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}
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srtcpSession, err := t.getSRTCPSession()
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if err != nil {
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return 0, err
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}
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writeStream, err := srtcpSession.OpenWriteStream()
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if err != nil {
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// nolint
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return 0, fmt.Errorf("%w: %v", errPeerConnWriteRTCPOpenWriteStream, err)
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}
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return writeStream.Write(raw)
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}
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// GetLocalParameters returns the DTLS parameters of the local DTLSTransport upon construction.
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func (t *DTLSTransport) GetLocalParameters() (DTLSParameters, error) {
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fingerprints := []DTLSFingerprint{}
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for _, c := range t.certificates {
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prints, err := c.GetFingerprints()
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if err != nil {
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return DTLSParameters{}, err
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}
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fingerprints = append(fingerprints, prints...)
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}
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return DTLSParameters{
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Role: DTLSRoleAuto, // always returns the default role
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Fingerprints: fingerprints,
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}, nil
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}
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// GetRemoteCertificate returns the certificate chain in use by the remote side
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// returns an empty list prior to selection of the remote certificate
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func (t *DTLSTransport) GetRemoteCertificate() []byte {
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t.lock.RLock()
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defer t.lock.RUnlock()
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return t.remoteCertificate
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}
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func (t *DTLSTransport) startSRTP() error {
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srtpConfig := &srtp.Config{
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Profile: t.srtpProtectionProfile,
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BufferFactory: t.api.settingEngine.BufferFactory,
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LoggerFactory: t.api.settingEngine.LoggerFactory,
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}
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if t.api.settingEngine.replayProtection.SRTP != nil {
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srtpConfig.RemoteOptions = append(
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srtpConfig.RemoteOptions,
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srtp.SRTPReplayProtection(*t.api.settingEngine.replayProtection.SRTP),
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)
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}
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if t.api.settingEngine.disableSRTPReplayProtection {
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srtpConfig.RemoteOptions = append(
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srtpConfig.RemoteOptions,
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srtp.SRTPNoReplayProtection(),
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)
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}
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if t.api.settingEngine.replayProtection.SRTCP != nil {
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srtpConfig.RemoteOptions = append(
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srtpConfig.RemoteOptions,
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srtp.SRTCPReplayProtection(*t.api.settingEngine.replayProtection.SRTCP),
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)
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}
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if t.api.settingEngine.disableSRTCPReplayProtection {
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srtpConfig.RemoteOptions = append(
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srtpConfig.RemoteOptions,
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srtp.SRTCPNoReplayProtection(),
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)
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}
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connState := t.conn.ConnectionState()
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err := srtpConfig.ExtractSessionKeysFromDTLS(&connState, t.role() == DTLSRoleClient)
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if err != nil {
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// nolint
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return fmt.Errorf("%w: %v", errDtlsKeyExtractionFailed, err)
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}
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srtpSession, err := srtp.NewSessionSRTP(t.srtpEndpoint, srtpConfig)
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if err != nil {
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// nolint
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return fmt.Errorf("%w: %v", errFailedToStartSRTP, err)
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}
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srtcpSession, err := srtp.NewSessionSRTCP(t.srtcpEndpoint, srtpConfig)
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if err != nil {
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// nolint
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return fmt.Errorf("%w: %v", errFailedToStartSRTCP, err)
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}
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t.srtpSession.Store(srtpSession)
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t.srtcpSession.Store(srtcpSession)
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close(t.srtpReady)
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return nil
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}
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func (t *DTLSTransport) getSRTPSession() (*srtp.SessionSRTP, error) {
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if value, ok := t.srtpSession.Load().(*srtp.SessionSRTP); ok {
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return value, nil
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}
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return nil, errDtlsTransportNotStarted
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}
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func (t *DTLSTransport) getSRTCPSession() (*srtp.SessionSRTCP, error) {
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if value, ok := t.srtcpSession.Load().(*srtp.SessionSRTCP); ok {
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return value, nil
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}
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return nil, errDtlsTransportNotStarted
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}
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func (t *DTLSTransport) role() DTLSRole {
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// If remote has an explicit role use the inverse
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switch t.remoteParameters.Role {
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case DTLSRoleClient:
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return DTLSRoleServer
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case DTLSRoleServer:
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return DTLSRoleClient
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default:
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}
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// If SettingEngine has an explicit role
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switch t.api.settingEngine.answeringDTLSRole {
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case DTLSRoleServer:
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return DTLSRoleServer
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case DTLSRoleClient:
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return DTLSRoleClient
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default:
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}
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// Remote was auto and no explicit role was configured via SettingEngine
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if t.iceTransport.Role() == ICERoleControlling {
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return DTLSRoleServer
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}
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return defaultDtlsRoleAnswer
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}
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// Start DTLS transport negotiation with the parameters of the remote DTLS transport
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func (t *DTLSTransport) Start(remoteParameters DTLSParameters) error {
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// Take lock and prepare connection, we must not hold the lock
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// when connecting
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prepareTransport := func() (DTLSRole, *dtls.Config, error) {
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t.lock.Lock()
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defer t.lock.Unlock()
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if err := t.ensureICEConn(); err != nil {
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return DTLSRole(0), nil, err
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}
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if t.state != DTLSTransportStateNew {
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return DTLSRole(0), nil, &rtcerr.InvalidStateError{Err: fmt.Errorf("%w: %s", errInvalidDTLSStart, t.state)}
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}
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t.srtpEndpoint = t.iceTransport.newEndpoint(mux.MatchSRTP)
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t.srtcpEndpoint = t.iceTransport.newEndpoint(mux.MatchSRTCP)
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t.remoteParameters = remoteParameters
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cert := t.certificates[0]
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t.onStateChange(DTLSTransportStateConnecting)
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return t.role(), &dtls.Config{
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Certificates: []tls.Certificate{
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{
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Certificate: [][]byte{cert.x509Cert.Raw},
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PrivateKey: cert.privateKey,
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},
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},
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SRTPProtectionProfiles: func() []dtls.SRTPProtectionProfile {
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if len(t.api.settingEngine.srtpProtectionProfiles) > 0 {
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return t.api.settingEngine.srtpProtectionProfiles
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}
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return defaultSrtpProtectionProfiles()
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}(),
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ClientAuth: dtls.RequireAnyClientCert,
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LoggerFactory: t.api.settingEngine.LoggerFactory,
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InsecureSkipVerify: !t.api.settingEngine.dtls.disableInsecureSkipVerify,
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}, nil
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}
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var dtlsConn *dtls.Conn
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dtlsEndpoint := t.iceTransport.newEndpoint(mux.MatchDTLS)
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role, dtlsConfig, err := prepareTransport()
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if err != nil {
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return err
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}
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if t.api.settingEngine.replayProtection.DTLS != nil {
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dtlsConfig.ReplayProtectionWindow = int(*t.api.settingEngine.replayProtection.DTLS)
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}
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if t.api.settingEngine.dtls.clientAuth != nil {
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dtlsConfig.ClientAuth = *t.api.settingEngine.dtls.clientAuth
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}
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dtlsConfig.FlightInterval = t.api.settingEngine.dtls.retransmissionInterval
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dtlsConfig.InsecureSkipVerifyHello = t.api.settingEngine.dtls.insecureSkipHelloVerify
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dtlsConfig.EllipticCurves = t.api.settingEngine.dtls.ellipticCurves
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dtlsConfig.ConnectContextMaker = t.api.settingEngine.dtls.connectContextMaker
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dtlsConfig.ExtendedMasterSecret = t.api.settingEngine.dtls.extendedMasterSecret
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dtlsConfig.ClientCAs = t.api.settingEngine.dtls.clientCAs
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dtlsConfig.RootCAs = t.api.settingEngine.dtls.rootCAs
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dtlsConfig.KeyLogWriter = t.api.settingEngine.dtls.keyLogWriter
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// Connect as DTLS Client/Server, function is blocking and we
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// must not hold the DTLSTransport lock
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if role == DTLSRoleClient {
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dtlsConn, err = dtls.Client(dtlsEndpoint, dtlsConfig)
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} else {
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dtlsConn, err = dtls.Server(dtlsEndpoint, dtlsConfig)
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}
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// Re-take the lock, nothing beyond here is blocking
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t.lock.Lock()
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defer t.lock.Unlock()
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if err != nil {
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t.onStateChange(DTLSTransportStateFailed)
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return err
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}
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srtpProfile, ok := dtlsConn.SelectedSRTPProtectionProfile()
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if !ok {
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t.onStateChange(DTLSTransportStateFailed)
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return ErrNoSRTPProtectionProfile
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}
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switch srtpProfile {
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case dtls.SRTP_AEAD_AES_128_GCM:
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t.srtpProtectionProfile = srtp.ProtectionProfileAeadAes128Gcm
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case dtls.SRTP_AEAD_AES_256_GCM:
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t.srtpProtectionProfile = srtp.ProtectionProfileAeadAes256Gcm
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case dtls.SRTP_AES128_CM_HMAC_SHA1_80:
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t.srtpProtectionProfile = srtp.ProtectionProfileAes128CmHmacSha1_80
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default:
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t.onStateChange(DTLSTransportStateFailed)
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return ErrNoSRTPProtectionProfile
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}
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// Check the fingerprint if a certificate was exchanged
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remoteCerts := dtlsConn.ConnectionState().PeerCertificates
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if len(remoteCerts) == 0 {
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t.onStateChange(DTLSTransportStateFailed)
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return errNoRemoteCertificate
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}
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t.remoteCertificate = remoteCerts[0]
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if !t.api.settingEngine.disableCertificateFingerprintVerification {
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parsedRemoteCert, err := x509.ParseCertificate(t.remoteCertificate)
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if err != nil {
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if closeErr := dtlsConn.Close(); closeErr != nil {
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t.log.Error(err.Error())
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}
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t.onStateChange(DTLSTransportStateFailed)
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return err
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}
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if err = t.validateFingerPrint(parsedRemoteCert); err != nil {
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if closeErr := dtlsConn.Close(); closeErr != nil {
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t.log.Error(err.Error())
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}
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t.onStateChange(DTLSTransportStateFailed)
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return err
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}
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}
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t.conn = dtlsConn
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t.onStateChange(DTLSTransportStateConnected)
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return t.startSRTP()
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}
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// Stop stops and closes the DTLSTransport object.
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func (t *DTLSTransport) Stop() error {
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t.lock.Lock()
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defer t.lock.Unlock()
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// Try closing everything and collect the errors
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var closeErrs []error
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if srtpSession, err := t.getSRTPSession(); err == nil && srtpSession != nil {
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closeErrs = append(closeErrs, srtpSession.Close())
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}
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if srtcpSession, err := t.getSRTCPSession(); err == nil && srtcpSession != nil {
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closeErrs = append(closeErrs, srtcpSession.Close())
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}
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for i := range t.simulcastStreams {
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closeErrs = append(closeErrs, t.simulcastStreams[i].Close())
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}
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if t.conn != nil {
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// dtls connection may be closed on sctp close.
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if err := t.conn.Close(); err != nil && !errors.Is(err, dtls.ErrConnClosed) {
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closeErrs = append(closeErrs, err)
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}
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}
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t.onStateChange(DTLSTransportStateClosed)
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return util.FlattenErrs(closeErrs)
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}
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func (t *DTLSTransport) validateFingerPrint(remoteCert *x509.Certificate) error {
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for _, fp := range t.remoteParameters.Fingerprints {
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hashAlgo, err := fingerprint.HashFromString(fp.Algorithm)
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if err != nil {
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return err
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}
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remoteValue, err := fingerprint.Fingerprint(remoteCert, hashAlgo)
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if err != nil {
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return err
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}
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if strings.EqualFold(remoteValue, fp.Value) {
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return nil
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}
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}
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return errNoMatchingCertificateFingerprint
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}
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func (t *DTLSTransport) ensureICEConn() error {
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if t.iceTransport == nil {
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return errICEConnectionNotStarted
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}
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return nil
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}
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func (t *DTLSTransport) storeSimulcastStream(s *srtp.ReadStreamSRTP) {
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t.lock.Lock()
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defer t.lock.Unlock()
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t.simulcastStreams = append(t.simulcastStreams, s)
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}
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func (t *DTLSTransport) streamsForSSRC(ssrc SSRC, streamInfo interceptor.StreamInfo) (*srtp.ReadStreamSRTP, interceptor.RTPReader, *srtp.ReadStreamSRTCP, interceptor.RTCPReader, error) {
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srtpSession, err := t.getSRTPSession()
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if err != nil {
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return nil, nil, nil, nil, err
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}
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rtpReadStream, err := srtpSession.OpenReadStream(uint32(ssrc))
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if err != nil {
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return nil, nil, nil, nil, err
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}
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rtpInterceptor := t.api.interceptor.BindRemoteStream(&streamInfo, interceptor.RTPReaderFunc(func(in []byte, a interceptor.Attributes) (n int, attributes interceptor.Attributes, err error) {
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n, err = rtpReadStream.Read(in)
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return n, a, err
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}))
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srtcpSession, err := t.getSRTCPSession()
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if err != nil {
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return nil, nil, nil, nil, err
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}
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rtcpReadStream, err := srtcpSession.OpenReadStream(uint32(ssrc))
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if err != nil {
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return nil, nil, nil, nil, err
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}
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rtcpInterceptor := t.api.interceptor.BindRTCPReader(interceptor.RTCPReaderFunc(func(in []byte, a interceptor.Attributes) (n int, attributes interceptor.Attributes, err error) {
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n, err = rtcpReadStream.Read(in)
|
|
return n, a, err
|
|
}))
|
|
|
|
return rtpReadStream, rtpInterceptor, rtcpReadStream, rtcpInterceptor, nil
|
|
}
|