From bfb7db2d91e647e3c0c08c3dfab6be8090644f1b Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Thu, 4 Jul 2024 12:42:25 +0530
Subject: [PATCH] RTP packet validity check. (#2833)

Adding some checks before packet is forwarded to check for anomalies.
Will remove after a round of debug.
---
 pkg/sfu/buffer/buffer.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/pkg/sfu/buffer/buffer.go b/pkg/sfu/buffer/buffer.go
index 829ee1794..2236056bd 100644
--- a/pkg/sfu/buffer/buffer.go
+++ b/pkg/sfu/buffer/buffer.go
@@ -17,6 +17,7 @@ package buffer
 import (
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"io"
 	"strings"
 	"sync"
@@ -680,6 +681,29 @@ func (b *Buffer) patchExtPacket(ep *ExtPacket, buf []byte) *ExtPacket {
 		b.logger.Warnw("unexpected marshal size", nil, "max", n, "need", payloadEnd)
 		return nil
 	}
+	// TODO-REMOVE-AFTER-DEBUG START
+	if payloadEnd != n {
+		b.logger.Warnw("unexpected marshal size", nil, "max", n, "need", payloadEnd)
+	}
+	// check a few fields for validity
+	checkVersion := (buf[0] & 0xc0) >> 6
+	checkPayloadType := buf[1] & 0x7f
+	checkSequenceNumber := binary.BigEndian.Uint16(buf[2:])
+	checkSSRC := binary.BigEndian.Uint32(buf[8:])
+	if checkVersion != pkt.Version || checkPayloadType != pkt.PayloadType || checkSequenceNumber != pkt.SequenceNumber || checkSSRC != pkt.SSRC {
+		b.logger.Warnw(
+			"rtp packet mismatch", nil,
+			"version", fmt.Sprintf("%d != %d", checkVersion, pkt.Version),
+			"payloadType", fmt.Sprintf("%d != %d", checkPayloadType, pkt.PayloadType),
+			"sequenceNumber", fmt.Sprintf("%d != %d", checkSequenceNumber, pkt.SequenceNumber),
+			"SSRC", fmt.Sprintf("%d != %d", checkSSRC, pkt.SSRC),
+			"bytes", buf[0:16],
+			"len", n,
+			"headerSize", payloadStart,
+			"payloadSize", payloadEnd-payloadStart,
+		)
+	}
+	// TODO-REMOVE-AFTER-DEBUG END
 	pkt.Payload = buf[payloadStart:payloadEnd]
 	ep.Packet = &pkt