webrtc/settingengine.go

// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

//go:build !js
// +build !js

package webrtc

import (
	"context"
	"crypto/x509"
	"io"
	"net"
	"time"

	"github.com/pion/dtls/v3"
	dtlsElliptic "github.com/pion/dtls/v3/pkg/crypto/elliptic"
	"github.com/pion/dtls/v3/pkg/protocol/handshake"
	"github.com/pion/ice/v4"
	"github.com/pion/logging"
	"github.com/pion/stun/v3"
	"github.com/pion/transport/v3"
	"github.com/pion/transport/v3/packetio"
	"golang.org/x/net/proxy"
)

// SettingEngine allows influencing behavior in ways that are not
// supported by the WebRTC API. This allows us to support additional
// use-cases without deviating from the WebRTC API elsewhere.
type SettingEngine struct {
	ephemeralUDP struct {
		PortMin uint16
		PortMax uint16
	}
	detach struct {
		DataChannels bool
	}
	timeout struct {
		ICEDisconnectedTimeout    *time.Duration
		ICEFailedTimeout          *time.Duration
		ICEKeepaliveInterval      *time.Duration
		ICEHostAcceptanceMinWait  *time.Duration
		ICESrflxAcceptanceMinWait *time.Duration
		ICEPrflxAcceptanceMinWait *time.Duration
		ICERelayAcceptanceMinWait *time.Duration
		ICESTUNGatherTimeout      *time.Duration
	}
	candidates struct {
		ICELite                  bool
		ICENetworkTypes          []NetworkType
		InterfaceFilter          func(string) (keep bool)
		IPFilter                 func(net.IP) (keep bool)
		NAT1To1IPs               []string
		NAT1To1IPCandidateType   ICECandidateType
		MulticastDNSMode         ice.MulticastDNSMode
		MulticastDNSHostName     string
		UsernameFragment         string
		Password                 string
		IncludeLoopbackCandidate bool
	}
	replayProtection struct {
		DTLS  *uint
		SRTP  *uint
		SRTCP *uint
	}
	dtls struct {
		insecureSkipHelloVerify       bool
		disableInsecureSkipVerify     bool
		retransmissionInterval        time.Duration
		ellipticCurves                []dtlsElliptic.Curve
		connectContextMaker           func() (context.Context, func())
		extendedMasterSecret          dtls.ExtendedMasterSecretType
		clientAuth                    *dtls.ClientAuthType
		clientCAs                     *x509.CertPool
		rootCAs                       *x509.CertPool
		keyLogWriter                  io.Writer
		customCipherSuites            func() []dtls.CipherSuite
		clientHelloMessageHook        func(handshake.MessageClientHello) handshake.Message
		serverHelloMessageHook        func(handshake.MessageServerHello) handshake.Message
		certificateRequestMessageHook func(handshake.MessageCertificateRequest) handshake.Message
	}
	sctp struct {
		maxReceiveBufferSize uint32
		enableZeroChecksum   bool
		rtoMax               time.Duration
		maxMessageSize       uint32
		minCwnd              uint32
		fastRtxWnd           uint32
		cwndCAStep           uint32
	}
	sdpMediaLevelFingerprints                 bool
	answeringDTLSRole                         DTLSRole
	disableCertificateFingerprintVerification bool
	disableSRTPReplayProtection               bool
	disableSRTCPReplayProtection              bool
	net                                       transport.Net
	BufferFactory                             func(packetType packetio.BufferPacketType, ssrc uint32) io.ReadWriteCloser
	LoggerFactory                             logging.LoggerFactory
	iceTCPMux                                 ice.TCPMux
	iceUDPMux                                 ice.UDPMux
	iceProxyDialer                            proxy.Dialer
	iceDisableActiveTCP                       bool
	iceBindingRequestHandler                  func(m *stun.Message, local, remote ice.Candidate, pair *ice.CandidatePair) bool //nolint:lll
	disableMediaEngineCopy                    bool
	disableMediaEngineMultipleCodecs          bool
	srtpProtectionProfiles                    []dtls.SRTPProtectionProfile
	receiveMTU                                uint
	iceMaxBindingRequests                     *uint16
	fireOnTrackBeforeFirstRTP                 bool
	disableCloseByDTLS                        bool
	dataChannelBlockWrite                     bool
	handleUndeclaredSSRCWithoutAnswer         bool
}

func (e *SettingEngine) getSCTPMaxMessageSize() uint32 {
	if e.sctp.maxMessageSize != 0 {
		return e.sctp.maxMessageSize
	}

	return defaultMaxSCTPMessageSize
}

// getReceiveMTU returns the configured MTU. If SettingEngine's MTU is configured to 0 it returns the default.
func (e *SettingEngine) getReceiveMTU() uint {
	if e.receiveMTU != 0 {
		return e.receiveMTU
	}

	return receiveMTU
}

// DetachDataChannels enables detaching data channels. When enabled
// data channels have to be detached in the OnOpen callback using the
// DataChannel.Detach method.
func (e *SettingEngine) DetachDataChannels() {
	e.detach.DataChannels = true
}

// EnableDataChannelBlockWrite allows data channels to block on write,
// it only works if DetachDataChannels is enabled.
func (e *SettingEngine) EnableDataChannelBlockWrite(nonblockWrite bool) {
	e.dataChannelBlockWrite = nonblockWrite
}

// SetSRTPProtectionProfiles allows the user to override the default SRTP Protection Profiles
// The default srtp protection profiles are provided by the function `defaultSrtpProtectionProfiles`.
func (e *SettingEngine) SetSRTPProtectionProfiles(profiles ...dtls.SRTPProtectionProfile) {
	e.srtpProtectionProfiles = profiles
}

// SetICETimeouts sets the behavior around ICE Timeouts
//
// disconnectedTimeout:
//
//	Duration without network activity before an Agent is considered disconnected. Default is 5 Seconds
//
// failedTimeout:
//
//	Duration without network activity before an Agent is considered failed after disconnected. Default is 25 Seconds
//
// keepAliveInterval:
//
//	How often the ICE Agent sends extra traffic if there is no activity, if media is flowing no traffic will be sent.
//
// Default is 2 seconds.
func (e *SettingEngine) SetICETimeouts(disconnectedTimeout, failedTimeout, keepAliveInterval time.Duration) {
	e.timeout.ICEDisconnectedTimeout = &disconnectedTimeout
	e.timeout.ICEFailedTimeout = &failedTimeout
	e.timeout.ICEKeepaliveInterval = &keepAliveInterval
}

// SetHostAcceptanceMinWait sets the ICEHostAcceptanceMinWait.
func (e *SettingEngine) SetHostAcceptanceMinWait(t time.Duration) {
	e.timeout.ICEHostAcceptanceMinWait = &t
}

// SetSrflxAcceptanceMinWait sets the ICESrflxAcceptanceMinWait.
func (e *SettingEngine) SetSrflxAcceptanceMinWait(t time.Duration) {
	e.timeout.ICESrflxAcceptanceMinWait = &t
}

// SetPrflxAcceptanceMinWait sets the ICEPrflxAcceptanceMinWait.
func (e *SettingEngine) SetPrflxAcceptanceMinWait(t time.Duration) {
	e.timeout.ICEPrflxAcceptanceMinWait = &t
}

// SetRelayAcceptanceMinWait sets the ICERelayAcceptanceMinWait.
func (e *SettingEngine) SetRelayAcceptanceMinWait(t time.Duration) {
	e.timeout.ICERelayAcceptanceMinWait = &t
}

// SetSTUNGatherTimeout sets the ICESTUNGatherTimeout.
func (e *SettingEngine) SetSTUNGatherTimeout(t time.Duration) {
	e.timeout.ICESTUNGatherTimeout = &t
}

// SetEphemeralUDPPortRange limits the pool of ephemeral ports that
// ICE UDP connections can allocate from. This affects both host candidates,
// and the local address of server reflexive candidates.
//
// When portMin and portMax are left to the 0 default value, pion/ice candidate
// gatherer replaces them and uses 1 for portMin and 65535 for portMax.
func (e *SettingEngine) SetEphemeralUDPPortRange(portMin, portMax uint16) error {
	if portMax < portMin {
		return ice.ErrPort
	}

	e.ephemeralUDP.PortMin = portMin
	e.ephemeralUDP.PortMax = portMax

	return nil
}

// SetLite configures whether or not the ice agent should be a lite agent.
func (e *SettingEngine) SetLite(lite bool) {
	e.candidates.ICELite = lite
}

// SetNetworkTypes configures what types of candidate networks are supported
// during local and server reflexive gathering.
func (e *SettingEngine) SetNetworkTypes(candidateTypes []NetworkType) {
	e.candidates.ICENetworkTypes = candidateTypes
}

// SetInterfaceFilter sets the filtering functions when gathering ICE candidates
// This can be used to exclude certain network interfaces from ICE. Which may be
// useful if you know a certain interface will never succeed, or if you wish to reduce
// the amount of information you wish to expose to the remote peer.
func (e *SettingEngine) SetInterfaceFilter(filter func(string) (keep bool)) {
	e.candidates.InterfaceFilter = filter
}

// SetIPFilter sets the filtering functions when gathering ICE candidates
// This can be used to exclude certain ip from ICE. Which may be
// useful if you know a certain ip will never succeed, or if you wish to reduce
// the amount of information you wish to expose to the remote peer.
func (e *SettingEngine) SetIPFilter(filter func(net.IP) (keep bool)) {
	e.candidates.IPFilter = filter
}

// SetNAT1To1IPs sets a list of external IP addresses of 1:1 (D)NAT
// and a candidate type for which the external IP address is used.
// This is useful when you host a server using Pion on an AWS EC2 instance
// which has a private address, behind a 1:1 DNAT with a public IP (e.g.
// Elastic IP). In this case, you can give the public IP address so that
// Pion will use the public IP address in its candidate instead of the private
// IP address. The second argument, candidateType, is used to tell Pion which
// type of candidate should use the given public IP address.
// Two types of candidates are supported:
//
// ICECandidateTypeHost:
//
//	The public IP address will be used for the host candidate in the SDP.
//
// ICECandidateTypeSrflx:
//
//	A server reflexive candidate with the given public IP address will be added to the SDP.
//
// Please note that if you choose ICECandidateTypeHost, then the private IP address
// won't be advertised with the peer. Also, this option cannot be used along with mDNS.
//
// If you choose ICECandidateTypeSrflx, it simply adds a server reflexive candidate
// with the public IP. The host candidate is still available along with mDNS
// capabilities unaffected. Also, you cannot give STUN server URL at the same time.
// It will result in an error otherwise.
func (e *SettingEngine) SetNAT1To1IPs(ips []string, candidateType ICECandidateType) {
	e.candidates.NAT1To1IPs = ips
	e.candidates.NAT1To1IPCandidateType = candidateType
}

// SetIncludeLoopbackCandidate enable pion to gather loopback candidates, it is useful
// for some VM have public IP mapped to loopback interface.
func (e *SettingEngine) SetIncludeLoopbackCandidate(include bool) {
	e.candidates.IncludeLoopbackCandidate = include
}

// SetAnsweringDTLSRole sets the DTLS role that is selected when offering
// The DTLS role controls if the WebRTC Client as a client or server. This
// may be useful when interacting with non-compliant clients or debugging issues.
//
// DTLSRoleActive:
//
//	Act as DTLS Client, send the ClientHello and starts the handshake
//
// DTLSRolePassive:
//
//	Act as DTLS Server, wait for ClientHello
func (e *SettingEngine) SetAnsweringDTLSRole(role DTLSRole) error {
	if role != DTLSRoleClient && role != DTLSRoleServer {
		return errSettingEngineSetAnsweringDTLSRole
	}

	e.answeringDTLSRole = role

	return nil
}

// SetNet sets the Net instance that is passed to pion/ice
//
// Net is an network interface layer for Pion, allowing users to replace
// Pions network stack with a custom implementation.
func (e *SettingEngine) SetNet(net transport.Net) {
	e.net = net
}

// SetICEMulticastDNSMode controls if pion/ice queries and generates mDNS ICE Candidates.
func (e *SettingEngine) SetICEMulticastDNSMode(multicastDNSMode ice.MulticastDNSMode) {
	e.candidates.MulticastDNSMode = multicastDNSMode
}

// SetMulticastDNSHostName sets a static HostName to be used by pion/ice instead of generating one on startup
//
// This should only be used for a single PeerConnection.
// Having multiple PeerConnections with the same HostName will cause undefined behavior.
func (e *SettingEngine) SetMulticastDNSHostName(hostName string) {
	e.candidates.MulticastDNSHostName = hostName
}

// SetICECredentials sets a staic uFrag/uPwd to be used by pion/ice
//
// This is useful if you want to do signalless WebRTC session,
// or having a reproducible environment with static credentials.
func (e *SettingEngine) SetICECredentials(usernameFragment, password string) {
	e.candidates.UsernameFragment = usernameFragment
	e.candidates.Password = password
}

// DisableCertificateFingerprintVerification disables fingerprint verification after DTLS Handshake has finished.
func (e *SettingEngine) DisableCertificateFingerprintVerification(isDisabled bool) {
	e.disableCertificateFingerprintVerification = isDisabled
}

// SetDTLSReplayProtectionWindow sets a replay attack protection window size of DTLS connection.
func (e *SettingEngine) SetDTLSReplayProtectionWindow(n uint) {
	e.replayProtection.DTLS = &n
}

// SetSRTPReplayProtectionWindow sets a replay attack protection window size of SRTP session.
func (e *SettingEngine) SetSRTPReplayProtectionWindow(n uint) {
	e.disableSRTPReplayProtection = false
	e.replayProtection.SRTP = &n
}

// SetSRTCPReplayProtectionWindow sets a replay attack protection window size of SRTCP session.
func (e *SettingEngine) SetSRTCPReplayProtectionWindow(n uint) {
	e.disableSRTCPReplayProtection = false
	e.replayProtection.SRTCP = &n
}

// DisableSRTPReplayProtection disables SRTP replay protection.
func (e *SettingEngine) DisableSRTPReplayProtection(isDisabled bool) {
	e.disableSRTPReplayProtection = isDisabled
}

// DisableSRTCPReplayProtection disables SRTCP replay protection.
func (e *SettingEngine) DisableSRTCPReplayProtection(isDisabled bool) {
	e.disableSRTCPReplayProtection = isDisabled
}

// SetSDPMediaLevelFingerprints configures the logic for DTLS Fingerprint insertion
// If true, fingerprints will be inserted in the sdp at the fingerprint
// level, instead of the session level. This helps with compatibility with
// some webrtc implementations.
func (e *SettingEngine) SetSDPMediaLevelFingerprints(sdpMediaLevelFingerprints bool) {
	e.sdpMediaLevelFingerprints = sdpMediaLevelFingerprints
}

// SetICETCPMux enables ICE-TCP when set to a non-nil value. Make sure that
// NetworkTypeTCP4 or NetworkTypeTCP6 is enabled as well.
func (e *SettingEngine) SetICETCPMux(tcpMux ice.TCPMux) {
	e.iceTCPMux = tcpMux
}

// SetICEUDPMux allows ICE traffic to come through a single UDP port, drastically
// simplifying deployments where ports will need to be opened/forwarded.
// UDPMux should be started prior to creating PeerConnections.
func (e *SettingEngine) SetICEUDPMux(udpMux ice.UDPMux) {
	e.iceUDPMux = udpMux
}

// SetICEProxyDialer sets the proxy dialer interface based on golang.org/x/net/proxy.
func (e *SettingEngine) SetICEProxyDialer(d proxy.Dialer) {
	e.iceProxyDialer = d
}

// SetICEMaxBindingRequests sets the maximum amount of binding requests
// that can be sent on a candidate before it is considered invalid.
func (e *SettingEngine) SetICEMaxBindingRequests(d uint16) {
	e.iceMaxBindingRequests = &d
}

// DisableActiveTCP disables using active TCP for ICE. Active TCP is enabled by default.
func (e *SettingEngine) DisableActiveTCP(isDisabled bool) {
	e.iceDisableActiveTCP = isDisabled
}

// DisableMediaEngineCopy stops the MediaEngine from being copied. This allows a user to modify
// the MediaEngine after the PeerConnection has been constructed. This is useful if you wish to
// modify codecs after signaling. Make sure not to share MediaEngines between PeerConnections.
func (e *SettingEngine) DisableMediaEngineCopy(isDisabled bool) {
	e.disableMediaEngineCopy = isDisabled
}

// DisableMediaEngineMultipleCodecs disables the MediaEngine negotiating different codecs.
// With the default value multiple media sections in the SDP can each negotiate different
// codecs. This is the new default behvior, because it makes Pion more spec compliant.
// The value of this setting will get copied to every copy of the MediaEngine generated
// for new PeerConnections (assuming DisableMediaEngineCopy is set to false).
// Note: this setting is targeted to be removed in release 4.2.0 (or later).
func (e *SettingEngine) DisableMediaEngineMultipleCodecs(isDisabled bool) {
	e.disableMediaEngineMultipleCodecs = isDisabled
}

// SetReceiveMTU sets the size of read buffer that copies incoming packets. This is optional.
// Leave this 0 for the default receiveMTU.
func (e *SettingEngine) SetReceiveMTU(receiveMTU uint) {
	e.receiveMTU = receiveMTU
}

// SetDTLSRetransmissionInterval sets the retranmission interval for DTLS.
func (e *SettingEngine) SetDTLSRetransmissionInterval(interval time.Duration) {
	e.dtls.retransmissionInterval = interval
}

// SetDTLSInsecureSkipHelloVerify sets the skip HelloVerify flag for DTLS.
// If true and when acting as DTLS server, will allow client to skip hello verify phase and
// receive ServerHello after initial ClientHello. This will mean faster connect times,
// but will have lower DoS attack resistance.
func (e *SettingEngine) SetDTLSInsecureSkipHelloVerify(skip bool) {
	e.dtls.insecureSkipHelloVerify = skip
}

// SetDTLSDisableInsecureSkipVerify sets the disable skip insecure verify flag for DTLS.
// This controls whether a client verifies the server's certificate chain and host name.
func (e *SettingEngine) SetDTLSDisableInsecureSkipVerify(disable bool) {
	e.dtls.disableInsecureSkipVerify = disable
}

// SetDTLSEllipticCurves sets the elliptic curves for DTLS.
func (e *SettingEngine) SetDTLSEllipticCurves(ellipticCurves ...dtlsElliptic.Curve) {
	e.dtls.ellipticCurves = ellipticCurves
}

// SetDTLSConnectContextMaker sets the context used during the DTLS Handshake.
// It can be used to extend or reduce the timeout on the DTLS Handshake.
// If nil, the default dtls.ConnectContextMaker is used. It can be implemented as following.
//
//	func ConnectContextMaker() (context.Context, func()) {
//		return context.WithTimeout(context.Background(), 30*time.Second)
//	}
func (e *SettingEngine) SetDTLSConnectContextMaker(connectContextMaker func() (context.Context, func())) {
	e.dtls.connectContextMaker = connectContextMaker
}

// SetDTLSExtendedMasterSecret sets the extended master secret type for DTLS.
func (e *SettingEngine) SetDTLSExtendedMasterSecret(extendedMasterSecret dtls.ExtendedMasterSecretType) {
	e.dtls.extendedMasterSecret = extendedMasterSecret
}

// SetDTLSClientAuth sets the client auth type for DTLS.
func (e *SettingEngine) SetDTLSClientAuth(clientAuth dtls.ClientAuthType) {
	e.dtls.clientAuth = &clientAuth
}

// SetDTLSClientCAs sets the client CA certificate pool for DTLS certificate verification.
func (e *SettingEngine) SetDTLSClientCAs(clientCAs *x509.CertPool) {
	e.dtls.clientCAs = clientCAs
}

// SetDTLSRootCAs sets the root CA certificate pool for DTLS certificate verification.
func (e *SettingEngine) SetDTLSRootCAs(rootCAs *x509.CertPool) {
	e.dtls.rootCAs = rootCAs
}

// SetDTLSKeyLogWriter sets the destination of the TLS key material for debugging.
// Logging key material compromises security and should only be use for debugging.
func (e *SettingEngine) SetDTLSKeyLogWriter(writer io.Writer) {
	e.dtls.keyLogWriter = writer
}

// SetSCTPMaxReceiveBufferSize sets the maximum receive buffer size.
// Leave this 0 for the default maxReceiveBufferSize.
func (e *SettingEngine) SetSCTPMaxReceiveBufferSize(maxReceiveBufferSize uint32) {
	e.sctp.maxReceiveBufferSize = maxReceiveBufferSize
}

// EnableSCTPZeroChecksum controls the zero checksum feature in SCTP.
// This removes the need to checksum every incoming/outgoing packet and will reduce
// latency and CPU usage. This feature is not backwards compatible so is disabled by default.
func (e *SettingEngine) EnableSCTPZeroChecksum(isEnabled bool) {
	e.sctp.enableZeroChecksum = isEnabled
}

// SetSCTPMaxMessageSize sets the largest message we are willing to accept.
// Leave this 0 for the default max message size.
func (e *SettingEngine) SetSCTPMaxMessageSize(maxMessageSize uint32) {
	e.sctp.maxMessageSize = maxMessageSize
}

// SetDTLSCustomerCipherSuites allows the user to specify a list of DTLS CipherSuites.
// This allow usage of Ciphers that are reserved for private usage.
func (e *SettingEngine) SetDTLSCustomerCipherSuites(customCipherSuites func() []dtls.CipherSuite) {
	e.dtls.customCipherSuites = customCipherSuites
}

// SetDTLSClientHelloMessageHook if not nil, is called when a DTLS Client Hello message is sent
// from a client. The returned handshake message replaces the original message.
func (e *SettingEngine) SetDTLSClientHelloMessageHook(hook func(handshake.MessageClientHello) handshake.Message) {
	e.dtls.clientHelloMessageHook = hook
}

// SetDTLSServerHelloMessageHook if not nil, is called when a DTLS Server Hello message is sent
// from a client. The returned handshake message replaces the original message.
func (e *SettingEngine) SetDTLSServerHelloMessageHook(hook func(handshake.MessageServerHello) handshake.Message) {
	e.dtls.serverHelloMessageHook = hook
}

// SetDTLSCertificateRequestMessageHook if not nil, is called when a DTLS Certificate Request message is sent
// from a client. The returned handshake message replaces the original message.
func (e *SettingEngine) SetDTLSCertificateRequestMessageHook(
	hook func(handshake.MessageCertificateRequest) handshake.Message,
) {
	e.dtls.certificateRequestMessageHook = hook
}

// SetSCTPRTOMax sets the maximum retransmission timeout.
// Leave this 0 for the default timeout.
func (e *SettingEngine) SetSCTPRTOMax(rtoMax time.Duration) {
	e.sctp.rtoMax = rtoMax
}

// SetSCTPMinCwnd sets the minimum congestion window size. The congestion window
// will not be smaller than this value during congestion control.
func (e *SettingEngine) SetSCTPMinCwnd(minCwnd uint32) {
	e.sctp.minCwnd = minCwnd
}

// SetSCTPFastRtxWnd sets the fast retransmission window size.
func (e *SettingEngine) SetSCTPFastRtxWnd(fastRtxWnd uint32) {
	e.sctp.fastRtxWnd = fastRtxWnd
}

// SetSCTPCwndCAStep sets congestion window adjustment step size during congestion avoidance.
func (e *SettingEngine) SetSCTPCwndCAStep(cwndCAStep uint32) {
	e.sctp.cwndCAStep = cwndCAStep
}

// SetICEBindingRequestHandler sets a callback that is fired on a STUN BindingRequest
// This allows users to do things like
// - Log incoming Binding Requests for debugging
// - Implement draft-thatcher-ice-renomination
// - Implement custom CandidatePair switching logic.
func (e *SettingEngine) SetICEBindingRequestHandler(
	bindingRequestHandler func(m *stun.Message, local, remote ice.Candidate, pair *ice.CandidatePair) bool,
) {
	e.iceBindingRequestHandler = bindingRequestHandler
}

// SetFireOnTrackBeforeFirstRTP sets if firing the OnTrack event should happen
// before any RTP packets are received. Setting this to true will
// have the Track's Codec and PayloadTypes be initially set to their
// zero values in the OnTrack handler.
// Note: This does not yet affect simulcast tracks.
func (e *SettingEngine) SetFireOnTrackBeforeFirstRTP(fireOnTrackBeforeFirstRTP bool) {
	e.fireOnTrackBeforeFirstRTP = fireOnTrackBeforeFirstRTP
}

// DisableCloseByDTLS sets if the connection should be closed when dtls transport is closed.
// Setting this to true will keep the connection open when dtls transport is closed
// and relies on the ice failed state to detect the connection is interrupted.
func (e *SettingEngine) DisableCloseByDTLS(isEnabled bool) {
	e.disableCloseByDTLS = isEnabled
}

// SetHandleUndeclaredSSRCWithoutAnswer controls if an SDP answer is required for
// processing early media of non-simulcast tracks.
func (e *SettingEngine) SetHandleUndeclaredSSRCWithoutAnswer(handleUndeclaredSSRCWithoutAnswer bool) {
	e.handleUndeclaredSSRCWithoutAnswer = handleUndeclaredSSRCWithoutAnswer
}