Use JoinRequest as query param (#712)

* Use JoinRequest as query param

* deps

* split out join request signalling and use it only when client version is >= 3.0.0

* fix semver check

* no gzip

* gzip in wrapper

Author: boks1971

engine.go

@@ -24,6 +24,7 @@ import (
 
 	"github.com/pion/webrtc/v4"
 	"go.uber.org/atomic"
+	"golang.org/x/mod/semver"
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
 
@@ -127,9 +128,10 @@ type RTCEngine struct {
 	engineHandler            engineHandler
 	cbGetLocalParticipantSID func() string
 
-	pclock     sync.Mutex
-	publisher  *PCTransport
-	subscriber *PCTransport
+	pclock                sync.Mutex
+	publisher             *PCTransport
+	pendingPublisherOffer webrtc.SessionDescription
+	subscriber            *PCTransport
 
 	signalling      signalling.Signalling
 	signalHandler   signalling.SignalHandler
@@ -175,9 +177,15 @@ func NewRTCEngine(
 		joinTimeout:              15 * time.Second,
 		reliableMsgSeq:           1,
 	}
-	e.signalling = signalling.NewSignalling(signalling.SignallingParams{
-		Logger: e.log,
-	})
+	if semver.Compare("v"+Version, "v3.0.0") < 0 {
+		e.signalling = signalling.NewSignalling(signalling.SignallingParams{
+			Logger: e.log,
+		})
+	} else {
+		e.signalling = signalling.NewSignallingJoinRequest(signalling.SignallingJoinRequestParams{
+			Logger: e.log,
+		})
+	}
 	e.signalHandler = signalling.NewSignalHandler(signalling.SignalHandlerParams{
 		Logger:    e.log,
 		Processor: e,
@@ -219,14 +227,31 @@ func (e *RTCEngine) JoinContext(
 	e.token.Store(token)
 	e.connParams = connectParams
 
-	if err := e.signalTransport.Join(ctx, url, token, *connectParams); err != nil {
+	var (
+		publisherOffer webrtc.SessionDescription
+		err            error
+	)
+	if e.signalling.PublishInJoin() {
+		e.pclock.Lock()
+		e.createPublisherPCLocked(webrtc.Configuration{})
+
+		publisherOffer, err = e.publisher.GetLocalOffer()
+		if err != nil {
+			e.pclock.Unlock()
+			return false, err
+		}
+		e.pendingPublisherOffer = publisherOffer
+		e.pclock.Unlock()
+	}
+
+	if err = e.signalTransport.Join(ctx, url, token, *connectParams, nil, publisherOffer); err != nil {
 		if verr := e.validate(ctx, url, token, connectParams, ""); verr != nil {
 			return false, verr
 		}
 		return false, err
 	}
 
-	if err := e.waitUntilConnected(); err != nil {
+	if err = e.waitUntilConnected(); err != nil {
 		return false, err
 	}
 
@@ -1183,12 +1208,25 @@ func (e *RTCEngine) OnJoinResponse(res *livekit.JoinResponse) error {
 
 	e.signalTransport.Start()
 
-	// send offer
-	if !res.SubscriberPrimary || res.FastPublish {
+	if e.signalling.PublishInJoin() {
 		if publisher, ok := e.Publisher(); ok {
-			publisher.Negotiate()
-		} else {
-			e.log.Warnw("no publisher peer connection", ErrNoPeerConnection)
+			e.pclock.Lock()
+			pendingPublisherOffer := e.pendingPublisherOffer
+			e.pendingPublisherOffer = webrtc.SessionDescription{}
+			e.pclock.Unlock()
+
+			if pendingPublisherOffer.SDP != "" {
+				publisher.SetLocalOffer(pendingPublisherOffer)
+			}
+		}
+	} else {
+		// send offer
+		if !res.SubscriberPrimary || res.FastPublish {
+			if publisher, ok := e.Publisher(); ok {
+				publisher.Negotiate()
+			} else {
+				e.log.Warnw("no publisher peer connection", ErrNoPeerConnection)
+			}
 		}
 	}
 

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/livekit/mageutil v0.0.0-20250511045019-0f1ff63f7731
 	github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5
 	github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded
-	github.com/livekit/protocol v1.39.4-0.20250806031641-1edabe8e86df
+	github.com/livekit/protocol v1.39.4-0.20250807105828-ccbae8154e54
 	github.com/magefile/mage v1.15.0
 	github.com/pion/dtls/v3 v3.0.6
 	github.com/pion/interceptor v0.1.40
@@ -23,9 +23,11 @@ require (
 	go.uber.org/atomic v1.11.0
 	golang.org/x/crypto v0.40.0
 	golang.org/x/exp v0.0.0-20250718183923-645b1fa84792
-	google.golang.org/protobuf v1.36.6
+	google.golang.org/protobuf v1.36.7
 )
 
+require golang.org/x/mod v0.26.0
+
 require (
 	buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go v1.36.6-20250717185734-6c6e0d3c608e.1 // indirect
 	buf.build/go/protovalidate v0.14.0 // indirect

go.sum

@@ -99,8 +99,8 @@ github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5 h1:aFCwt/rticj5L
 github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5/go.mod h1:7ssWiG+U4xnbvLih9WiZbhQP6zIKMjgXdUtIE1bm/E8=
 github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded h1:ylZPdnlX1RW9Z15SD4mp87vT2D2shsk0hpLJwSPcq3g=
 github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded/go.mod h1:mSNtYzSf6iY9xM3UX42VEI+STHvMgHmrYzEHPcdhB8A=
-github.com/livekit/protocol v1.39.4-0.20250806031641-1edabe8e86df h1:3YB9qvVAPK0SNWDngETtE7UL75xAygZw07DtsYbKSNk=
-github.com/livekit/protocol v1.39.4-0.20250806031641-1edabe8e86df/go.mod h1:YlgUxAegtU8jZ0tVXoIV/4fHeHqqLvS+6JnPKDbpFPU=
+github.com/livekit/protocol v1.39.4-0.20250807105828-ccbae8154e54 h1:Bh4IzI1UUqyxUnAJScR2rT/7V8mJqkzFSoEuMfm/T5k=
+github.com/livekit/protocol v1.39.4-0.20250807105828-ccbae8154e54/go.mod h1:YlgUxAegtU8jZ0tVXoIV/4fHeHqqLvS+6JnPKDbpFPU=
 github.com/livekit/psrpc v0.6.1-0.20250726180611-3915e005e741 h1:KKL1u94l6dF9u4cBwnnfozk27GH1txWy2SlvkfgmzoY=
 github.com/livekit/psrpc v0.6.1-0.20250726180611-3915e005e741/go.mod h1:AuDC5uOoEjQJEc69v4Li3t77Ocz0e0NdjQEuFfO+vfk=
 github.com/magefile/mage v1.15.0 h1:BvGheCMAsG3bWUDbZ8AyXXpCNwU9u5CB6sM+HNb9HYg=
@@ -214,6 +214,8 @@ golang.org/x/exp v0.0.0-20250718183923-645b1fa84792 h1:R9PFI6EUdfVKgwKjZef7QIwGc
 golang.org/x/exp v0.0.0-20250718183923-645b1fa84792/go.mod h1:A+z0yzpGtvnG90cToK5n2tu8UJVP2XUATh+r+sfOOOc=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.26.0 h1:EGMPT//Ezu+ylkCijjPc+f4Aih7sZvaAr+O3EHBxvZg=
+golang.org/x/mod v0.26.0/go.mod h1:/j6NAhSk8iQ723BGAUyoAcn7SlD7s15Dp9Nd/SfeaFQ=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
@@ -260,8 +262,8 @@ google.golang.org/genproto/googleapis/rpc v0.0.0-20250804133106-a7a43d27e69b h1:
 google.golang.org/genproto/googleapis/rpc v0.0.0-20250804133106-a7a43d27e69b/go.mod h1:qQ0YXyHHx3XkvlzUtpXDkS29lDSafHMZBAZDc03LQ3A=
 google.golang.org/grpc v1.74.2 h1:WoosgB65DlWVC9FqI82dGsZhWFNBSLjQ84bjROOpMu4=
 google.golang.org/grpc v1.74.2/go.mod h1:CtQ+BGjaAIXHs/5YS3i473GqwBBa1zGQNevxdeBEXrM=
-google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
-google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
+google.golang.org/protobuf v1.36.7 h1:IgrO7UwFQGJdRNXH/sQux4R1Dj1WAKcLElzeeRaXV2A=
+google.golang.org/protobuf v1.36.7/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

room.go

@@ -138,6 +138,12 @@ func WithDisableRegionDiscovery() ConnectOption {
 	}
 }
 
+func WithMetadata(metadata string) ConnectOption {
+	return func(p *signalling.ConnectParams) {
+		p.Metadata = metadata
+	}
+}
+
 func WithExtraAttributes(attrs map[string]string) ConnectOption {
 	return func(p *signalling.ConnectParams) {
 		if len(attrs) != 0 && p.Attributes == nil {

signalling/interfaces.go

@@ -32,10 +32,14 @@ type Signalling interface {
 	Path() string
 	ValidatePath() string
 
+	PublishInJoin() bool
+
 	ConnectQueryParams(
 		version string,
 		protocol int,
 		connectParams *ConnectParams,
+		addTrackRequests []*livekit.AddTrackRequest,
+		publisherOffer webrtc.SessionDescription,
 		participantSID string,
 	) (string, error)
 	HTTPRequestForValidate(
@@ -70,6 +74,8 @@ type ConnectParams struct {
 
 	RetransmitBufferSize uint16
 
+	Metadata string // See WithMetadata
+
 	Attributes map[string]string // See WithExtraAttributes
 
 	Pacer pacer.Factory
@@ -90,6 +96,8 @@ type SignalTransport interface {
 		url string,
 		token string,
 		connectParams ConnectParams,
+		addTrackRequests []*livekit.AddTrackRequest,
+		publisherOffer webrtc.SessionDescription,
 	) error
 	Reconnect(
 		url string,