119 lines
2.8 KiB
Go
119 lines
2.8 KiB
Go
package rtcp
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// Packet represents an RTCP packet, a protocol used for out-of-band statistics and control information for an RTP session
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type Packet interface {
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// DestinationSSRC returns an array of SSRC values that this packet refers to.
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DestinationSSRC() []uint32
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Marshal() ([]byte, error)
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Unmarshal(rawPacket []byte) error
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}
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// Unmarshal takes an entire udp datagram (which may consist of multiple RTCP packets) and
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// returns the unmarshaled packets it contains.
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//
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// If this is a reduced-size RTCP packet a feedback packet (Goodbye, SliceLossIndication, etc)
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// will be returned. Otherwise, the underlying type of the returned packet will be
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// CompoundPacket.
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func Unmarshal(rawData []byte) ([]Packet, error) {
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var packets []Packet
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for len(rawData) != 0 {
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p, processed, err := unmarshal(rawData)
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if err != nil {
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return nil, err
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}
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packets = append(packets, p)
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rawData = rawData[processed:]
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}
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switch len(packets) {
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// Empty packet
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case 0:
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return nil, errInvalidHeader
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// Multiple Packets
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default:
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return packets, nil
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}
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}
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// Marshal takes an array of Packets and serializes them to a single buffer
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func Marshal(packets []Packet) ([]byte, error) {
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out := make([]byte, 0)
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for _, p := range packets {
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data, err := p.Marshal()
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if err != nil {
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return nil, err
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}
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out = append(out, data...)
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}
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return out, nil
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}
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// unmarshal is a factory which pulls the first RTCP packet from a bytestream,
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// and returns it's parsed representation, and the amount of data that was processed.
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func unmarshal(rawData []byte) (packet Packet, bytesprocessed int, err error) {
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var h Header
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err = h.Unmarshal(rawData)
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if err != nil {
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return nil, 0, err
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}
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bytesprocessed = int(h.Length+1) * 4
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if bytesprocessed > len(rawData) {
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return nil, 0, errPacketTooShort
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}
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inPacket := rawData[:bytesprocessed]
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switch h.Type {
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case TypeSenderReport:
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packet = new(SenderReport)
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case TypeReceiverReport:
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packet = new(ReceiverReport)
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case TypeSourceDescription:
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packet = new(SourceDescription)
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case TypeGoodbye:
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packet = new(Goodbye)
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case TypeTransportSpecificFeedback:
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switch h.Count {
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case FormatTLN:
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packet = new(TransportLayerNack)
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case FormatRRR:
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packet = new(RapidResynchronizationRequest)
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case FormatTCC:
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packet = new(TransportLayerCC)
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default:
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packet = new(RawPacket)
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}
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case TypePayloadSpecificFeedback:
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switch h.Count {
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case FormatPLI:
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packet = new(PictureLossIndication)
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case FormatSLI:
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packet = new(SliceLossIndication)
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case FormatREMB:
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packet = new(ReceiverEstimatedMaximumBitrate)
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case FormatFIR:
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packet = new(FullIntraRequest)
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default:
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packet = new(RawPacket)
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}
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case TypeExtendedReport:
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packet = new(ExtendedReport)
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default:
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packet = new(RawPacket)
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}
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err = packet.Unmarshal(inPacket)
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return packet, bytesprocessed, err
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}
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