snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/sfu/interceptor/unhandlesimulcast.go

@@ -0,0 +1,183 @@
+// Copyright 2023 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package interceptor
+
+import (
+	"github.com/pion/interceptor"
+	"github.com/pion/rtp"
+	"github.com/pion/sdp/v3"
+	"github.com/pion/webrtc/v4"
+	"go.uber.org/zap/zapcore"
+
+	"github.com/livekit/livekit-server/pkg/sfu/utils"
+	"github.com/livekit/protocol/logger"
+)
+
+const (
+	simulcastProbeCount = 10
+)
+
+type SimulcastTrackInfo struct {
+	Mid            string
+	StreamID       string
+	RepairSSRC     uint32 // set only when `IsRepairStream: false`, i. e. RTX SSRC for the primary stream
+	IsRepairStream bool
+}
+
+func (s *SimulcastTrackInfo) MarshalLogObject(e zapcore.ObjectEncoder) error {
+	e.AddString("Mid", s.Mid)
+	e.AddString("StreamID", s.StreamID)
+	e.AddUint32("RepairSSRC", s.RepairSSRC)
+	e.AddBool("IsRepairStream", s.IsRepairStream)
+	return nil
+}
+
+// -------------------------------------------------------------------
+
+type UnhandleSimulcastOption func(u *UnhandleSimulcastInterceptor) error
+
+func UnhandleSimulcastTracks(logger logger.Logger, tracks map[uint32]SimulcastTrackInfo) UnhandleSimulcastOption {
+	return func(u *UnhandleSimulcastInterceptor) error {
+		u.logger = logger
+		u.simTracks = tracks
+		return nil
+	}
+}
+
+type UnhandleSimulcastInterceptorFactory struct {
+	opts []UnhandleSimulcastOption
+}
+
+func (f *UnhandleSimulcastInterceptorFactory) NewInterceptor(id string) (interceptor.Interceptor, error) {
+	i := &UnhandleSimulcastInterceptor{simTracks: map[uint32]SimulcastTrackInfo{}}
+	for _, o := range f.opts {
+		if err := o(i); err != nil {
+			return nil, err
+		}
+	}
+	return i, nil
+}
+
+func NewUnhandleSimulcastInterceptorFactory(opts ...UnhandleSimulcastOption) (*UnhandleSimulcastInterceptorFactory, error) {
+	return &UnhandleSimulcastInterceptorFactory{opts: opts}, nil
+}
+
+type unhandleSimulcastRTPReader struct {
+	SimulcastTrackInfo
+	logger    logger.Logger
+	tryTimes  int
+	reader    interceptor.RTPReader
+	midExtID  uint8
+	ridExtID  uint8
+	rsidExtID uint8
+}
+
+func (u *unhandleSimulcastRTPReader) Read(b []byte, a interceptor.Attributes) (int, interceptor.Attributes, error) {
+	n, a, err := u.reader.Read(b, a)
+	if u.tryTimes < 0 || err != nil {
+		return n, a, err
+	}
+
+	header := rtp.Header{}
+	hsize, err := header.Unmarshal(b[:n])
+	if err != nil {
+		return n, a, nil
+	}
+	var mid, rid, rsid string
+	if payload := header.GetExtension(u.midExtID); payload != nil {
+		mid = string(payload)
+	}
+
+	if payload := header.GetExtension(u.ridExtID); payload != nil {
+		rid = string(payload)
+	}
+
+	if payload := header.GetExtension(u.rsidExtID); payload != nil {
+		rid = string(payload)
+	}
+
+	if mid != "" && (rid != "" || rsid != "") {
+		u.logger.Debugw(
+			"unhandle stream found",
+			"mid", mid,
+			"rid", rid,
+			"rsid", rsid,
+			"ssrc", header.SSRC,
+			"simulcastTrackInfo", u.SimulcastTrackInfo,
+		)
+		u.tryTimes = -1
+		return n, a, nil
+	} else {
+		// ignore padding only packet for probe count
+		if !header.Padding || n-header.MarshalSize()-int(b[n-1]) != 0 {
+			u.tryTimes--
+		}
+	}
+
+	if mid == "" {
+		header.SetExtension(u.midExtID, []byte(u.Mid))
+	}
+	if rid == "" && !u.IsRepairStream {
+		header.SetExtension(u.ridExtID, []byte(u.StreamID))
+	}
+	if rsid == "" && u.IsRepairStream {
+		header.SetExtension(u.rsidExtID, []byte(u.StreamID))
+	}
+
+	hsize2 := header.MarshalSize()
+
+	if hsize2-hsize+n > len(b) { // no enough buf to set extension
+		return n, a, nil
+	}
+	copy(b[hsize2:], b[hsize:n])
+	header.MarshalTo(b)
+	u.logger.Debugw(
+		"unhandle stream injecting",
+		"mid", mid,
+		"rid", rid,
+		"rsid", rsid,
+		"ssrc", header.SSRC,
+		"simulcastTrackInfo", u.SimulcastTrackInfo,
+	)
+	return hsize2 - hsize + n, a, nil
+}
+
+type UnhandleSimulcastInterceptor struct {
+	interceptor.NoOp
+	logger    logger.Logger
+	simTracks map[uint32]SimulcastTrackInfo
+}
+
+func (u *UnhandleSimulcastInterceptor) BindRemoteStream(info *interceptor.StreamInfo, reader interceptor.RTPReader) interceptor.RTPReader {
+	if t, ok := u.simTracks[info.SSRC]; ok {
+		midExtensionID := utils.GetHeaderExtensionID(info.RTPHeaderExtensions, webrtc.RTPHeaderExtensionCapability{URI: sdp.SDESMidURI})
+		streamIDExtensionID := utils.GetHeaderExtensionID(info.RTPHeaderExtensions, webrtc.RTPHeaderExtensionCapability{URI: sdp.SDESRTPStreamIDURI})
+		repairStreamIDExtensionID := utils.GetHeaderExtensionID(info.RTPHeaderExtensions, webrtc.RTPHeaderExtensionCapability{URI: sdp.SDESRepairRTPStreamIDURI})
+		if midExtensionID == 0 || streamIDExtensionID == 0 || repairStreamIDExtensionID == 0 {
+			return reader
+		}
+
+		return &unhandleSimulcastRTPReader{
+			SimulcastTrackInfo: t,
+			logger:             u.logger,
+			reader:             reader,
+			tryTimes:           simulcastProbeCount,
+			midExtID:           uint8(midExtensionID),
+			ridExtID:           uint8(streamIDExtensionID),
+			rsidExtID:          uint8(repairStreamIDExtensionID),
+		}
+	}
+	return reader
+}