mirror of
https://github.com/ossrs/srs.git
synced 2025-03-09 15:49:59 +00:00
144 lines
4 KiB
Go
144 lines
4 KiB
Go
package rtcp
|
|
|
|
import (
|
|
"encoding/binary"
|
|
)
|
|
|
|
// PacketType specifies the type of an RTCP packet
|
|
type PacketType uint8
|
|
|
|
// RTCP packet types registered with IANA. See: https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-4
|
|
const (
|
|
TypeSenderReport PacketType = 200 // RFC 3550, 6.4.1
|
|
TypeReceiverReport PacketType = 201 // RFC 3550, 6.4.2
|
|
TypeSourceDescription PacketType = 202 // RFC 3550, 6.5
|
|
TypeGoodbye PacketType = 203 // RFC 3550, 6.6
|
|
TypeApplicationDefined PacketType = 204 // RFC 3550, 6.7 (unimplemented)
|
|
TypeTransportSpecificFeedback PacketType = 205 // RFC 4585, 6051
|
|
TypePayloadSpecificFeedback PacketType = 206 // RFC 4585, 6.3
|
|
TypeExtendedReport PacketType = 207 // RFC 3611
|
|
|
|
)
|
|
|
|
// Transport and Payload specific feedback messages overload the count field to act as a message type. those are listed here
|
|
const (
|
|
FormatSLI uint8 = 2
|
|
FormatPLI uint8 = 1
|
|
FormatFIR uint8 = 4
|
|
FormatTLN uint8 = 1
|
|
FormatRRR uint8 = 5
|
|
FormatCCFB uint8 = 11
|
|
FormatREMB uint8 = 15
|
|
|
|
// https://tools.ietf.org/html/draft-holmer-rmcat-transport-wide-cc-extensions-01#page-5
|
|
FormatTCC uint8 = 15
|
|
)
|
|
|
|
func (p PacketType) String() string {
|
|
switch p {
|
|
case TypeSenderReport:
|
|
return "SR"
|
|
case TypeReceiverReport:
|
|
return "RR"
|
|
case TypeSourceDescription:
|
|
return "SDES"
|
|
case TypeGoodbye:
|
|
return "BYE"
|
|
case TypeApplicationDefined:
|
|
return "APP"
|
|
case TypeTransportSpecificFeedback:
|
|
return "TSFB"
|
|
case TypePayloadSpecificFeedback:
|
|
return "PSFB"
|
|
case TypeExtendedReport:
|
|
return "XR"
|
|
default:
|
|
return string(p)
|
|
}
|
|
}
|
|
|
|
const rtpVersion = 2
|
|
|
|
// A Header is the common header shared by all RTCP packets
|
|
type Header struct {
|
|
// If the padding bit is set, this individual RTCP packet contains
|
|
// some additional padding octets at the end which are not part of
|
|
// the control information but are included in the length field.
|
|
Padding bool
|
|
// The number of reception reports, sources contained or FMT in this packet (depending on the Type)
|
|
Count uint8
|
|
// The RTCP packet type for this packet
|
|
Type PacketType
|
|
// The length of this RTCP packet in 32-bit words minus one,
|
|
// including the header and any padding.
|
|
Length uint16
|
|
}
|
|
|
|
const (
|
|
headerLength = 4
|
|
versionShift = 6
|
|
versionMask = 0x3
|
|
paddingShift = 5
|
|
paddingMask = 0x1
|
|
countShift = 0
|
|
countMask = 0x1f
|
|
countMax = (1 << 5) - 1
|
|
)
|
|
|
|
// Marshal encodes the Header in binary
|
|
func (h Header) Marshal() ([]byte, error) {
|
|
/*
|
|
* 0 1 2 3
|
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* |V=2|P| RC | PT=SR=200 | length |
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
rawPacket := make([]byte, headerLength)
|
|
|
|
rawPacket[0] |= rtpVersion << versionShift
|
|
|
|
if h.Padding {
|
|
rawPacket[0] |= 1 << paddingShift
|
|
}
|
|
|
|
if h.Count > 31 {
|
|
return nil, errInvalidHeader
|
|
}
|
|
rawPacket[0] |= h.Count << countShift
|
|
|
|
rawPacket[1] = uint8(h.Type)
|
|
|
|
binary.BigEndian.PutUint16(rawPacket[2:], h.Length)
|
|
|
|
return rawPacket, nil
|
|
}
|
|
|
|
// Unmarshal decodes the Header from binary
|
|
func (h *Header) Unmarshal(rawPacket []byte) error {
|
|
if len(rawPacket) < headerLength {
|
|
return errPacketTooShort
|
|
}
|
|
|
|
/*
|
|
* 0 1 2 3
|
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* |V=2|P| RC | PT | length |
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
|
|
version := rawPacket[0] >> versionShift & versionMask
|
|
if version != rtpVersion {
|
|
return errBadVersion
|
|
}
|
|
|
|
h.Padding = (rawPacket[0] >> paddingShift & paddingMask) > 0
|
|
h.Count = rawPacket[0] >> countShift & countMask
|
|
|
|
h.Type = PacketType(rawPacket[1])
|
|
|
|
h.Length = binary.BigEndian.Uint16(rawPacket[2:])
|
|
|
|
return nil
|
|
}
|