solve rtp ext parse error

pkg/rtprtcp/rtp_packet.go

@@ -11,6 +11,7 @@ package rtprtcp
 import (
 	"encoding/hex"
 	"fmt"
+
 	"github.com/q191201771/lal/pkg/avc"
 	"github.com/q191201771/lal/pkg/base"
 	"github.com/q191201771/lal/pkg/hevc"
@@ -139,6 +140,7 @@ func ParseRtpHeader(b []byte) (h RtpHeader, err error) {
 		offset += 4
 	}
 
+	// TODO 按照RFC-5285-RTP-Header-Extensions去解析
 	if h.Extension != 0 {
 		if offset+4 > len(b) {
 			return h, base.ErrRtpRtcpShortBuffer
@@ -149,8 +151,13 @@ func ParseRtpHeader(b []byte) (h RtpHeader, err error) {
 		offset += 2
 		extensionLength := bele.BeUint16(b[offset:])
 		offset += 2
-		h.Extensions = b[offset : offset+int(extensionLength)]
 
+		if offset+int(4*extensionLength) > len(b) {
+			return h, base.ErrRtpRtcpShortBuffer
+		}
+
+		offset += int(4 * extensionLength)
+		h.Extensions = b[offset : offset+int(4*extensionLength)]
 	}
 
 	if offset >= len(b) {