vendor.github.com.pion.rtcp.rfc8888.go Maven / Gradle / Ivy
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// SPDX-FileCopyrightText: 2023 The Pion community
// SPDX-License-Identifier: MIT
package rtcp
import (
"encoding/binary"
"errors"
"fmt"
"math"
)
// https://www.rfc-editor.org/rfc/rfc8888.html#name-rtcp-congestion-control-fee
// 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| FMT=11 | PT = 205 | length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of RTCP packet sender |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of 1st RTP Stream |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | begin_seq | num_reports |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |R|ECN| Arrival time offset | ... .
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// . .
// . .
// . .
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of nth RTP Stream |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | begin_seq | num_reports |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |R|ECN| Arrival time offset | ... |
// . .
// . .
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Report Timestamp (32 bits) |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
var (
errReportBlockLength = errors.New("feedback report blocks must be at least 8 bytes")
errIncorrectNumReports = errors.New("feedback report block contains less reports than num_reports")
errMetricBlockLength = errors.New("feedback report metric blocks must be exactly 2 bytes")
)
// ECN represents the two ECN bits
type ECN uint8
const (
//nolint:misspell
// ECNNonECT signals Non ECN-Capable Transport, Non-ECT
ECNNonECT ECN = iota // 00
//nolint:misspell
// ECNECT1 signals ECN Capable Transport, ECT(0)
ECNECT1 // 01
//nolint:misspell
// ECNECT0 signals ECN Capable Transport, ECT(1)
ECNECT0 // 10
// ECNCE signals ECN Congestion Encountered, CE
ECNCE // 11
)
const (
reportTimestampLength = 4
reportBlockOffset = 8
)
// CCFeedbackReport is a Congestion Control Feedback Report as defined in
// https://www.rfc-editor.org/rfc/rfc8888.html#name-rtcp-congestion-control-fee
type CCFeedbackReport struct {
// SSRC of sender
SenderSSRC uint32
// Report Blocks
ReportBlocks []CCFeedbackReportBlock
// Basetime
ReportTimestamp uint32
}
// DestinationSSRC returns an array of SSRC values that this packet refers to.
func (b CCFeedbackReport) DestinationSSRC() []uint32 {
ssrcs := make([]uint32, len(b.ReportBlocks))
for i, block := range b.ReportBlocks {
ssrcs[i] = block.MediaSSRC
}
return ssrcs
}
// Len returns the length of the report in bytes
func (b *CCFeedbackReport) Len() int {
n := 0
for _, block := range b.ReportBlocks {
n += block.len()
}
return reportBlockOffset + n + reportTimestampLength
}
// Header returns the Header associated with this packet.
func (b *CCFeedbackReport) Header() Header {
return Header{
Padding: false,
Count: FormatCCFB,
Type: TypeTransportSpecificFeedback,
Length: uint16(b.Len()/4 - 1),
}
}
// Marshal encodes the Congestion Control Feedback Report in binary
func (b CCFeedbackReport) Marshal() ([]byte, error) {
header := b.Header()
headerBuf, err := header.Marshal()
if err != nil {
return nil, err
}
length := 4 * (header.Length + 1)
buf := make([]byte, length)
copy(buf[:headerLength], headerBuf)
binary.BigEndian.PutUint32(buf[headerLength:], b.SenderSSRC)
offset := reportBlockOffset
for _, block := range b.ReportBlocks {
b, err := block.marshal()
if err != nil {
return nil, err
}
copy(buf[offset:], b)
offset += block.len()
}
binary.BigEndian.PutUint32(buf[offset:], b.ReportTimestamp)
return buf, nil
}
func (b CCFeedbackReport) String() string {
out := fmt.Sprintf("CCFB:\n\tHeader %v\n", b.Header())
out += fmt.Sprintf("CCFB:\n\tSender SSRC %d\n", b.SenderSSRC)
out += fmt.Sprintf("\tReport Timestamp %d\n", b.ReportTimestamp)
out += "\tFeedback Reports \n"
for _, report := range b.ReportBlocks {
out += fmt.Sprintf("%v ", report)
}
out += "\n"
return out
}
// Unmarshal decodes the Congestion Control Feedback Report from binary
func (b *CCFeedbackReport) Unmarshal(rawPacket []byte) error {
if len(rawPacket) < headerLength+ssrcLength+reportTimestampLength {
return errPacketTooShort
}
var h Header
if err := h.Unmarshal(rawPacket); err != nil {
return err
}
if h.Type != TypeTransportSpecificFeedback {
return errWrongType
}
b.SenderSSRC = binary.BigEndian.Uint32(rawPacket[headerLength:])
reportTimestampOffset := len(rawPacket) - reportTimestampLength
b.ReportTimestamp = binary.BigEndian.Uint32(rawPacket[reportTimestampOffset:])
offset := reportBlockOffset
b.ReportBlocks = []CCFeedbackReportBlock{}
for offset < reportTimestampOffset {
var block CCFeedbackReportBlock
if err := block.unmarshal(rawPacket[offset:]); err != nil {
return err
}
b.ReportBlocks = append(b.ReportBlocks, block)
offset += block.len()
}
return nil
}
const (
ssrcOffset = 0
beginSequenceOffset = 4
numReportsOffset = 6
reportsOffset = 8
maxMetricBlocks = 16384
)
// CCFeedbackReportBlock is a Feedback Report Block
type CCFeedbackReportBlock struct {
// SSRC of the RTP stream on which this block is reporting
MediaSSRC uint32
BeginSequence uint16
MetricBlocks []CCFeedbackMetricBlock
}
// len returns the length of the report block in bytes
func (b *CCFeedbackReportBlock) len() int {
n := len(b.MetricBlocks)
if n%2 != 0 {
n++
}
return reportsOffset + 2*n
}
func (b CCFeedbackReportBlock) String() string {
out := fmt.Sprintf("\tReport Block Media SSRC %d\n", b.MediaSSRC)
out += fmt.Sprintf("\tReport Begin Sequence Nr %d\n", b.BeginSequence)
out += fmt.Sprintf("\tReport length %d\n\t", len(b.MetricBlocks))
for i, block := range b.MetricBlocks {
out += fmt.Sprintf("{nr: %d, rx: %v, ts: %v} ", b.BeginSequence+uint16(i), block.Received, block.ArrivalTimeOffset)
}
out += "\n"
return out
}
// marshal encodes the Congestion Control Feedback Report Block in binary
func (b CCFeedbackReportBlock) marshal() ([]byte, error) {
if len(b.MetricBlocks) > maxMetricBlocks {
return nil, errTooManyReports
}
buf := make([]byte, b.len())
binary.BigEndian.PutUint32(buf[ssrcOffset:], b.MediaSSRC)
binary.BigEndian.PutUint16(buf[beginSequenceOffset:], b.BeginSequence)
length := uint16(len(b.MetricBlocks))
if length > 0 {
length--
}
binary.BigEndian.PutUint16(buf[numReportsOffset:], length)
for i, block := range b.MetricBlocks {
b, err := block.marshal()
if err != nil {
return nil, err
}
copy(buf[reportsOffset+i*2:], b)
}
return buf, nil
}
// Unmarshal decodes the Congestion Control Feedback Report Block from binary
func (b *CCFeedbackReportBlock) unmarshal(rawPacket []byte) error {
if len(rawPacket) < reportsOffset {
return errReportBlockLength
}
b.MediaSSRC = binary.BigEndian.Uint32(rawPacket[:beginSequenceOffset])
b.BeginSequence = binary.BigEndian.Uint16(rawPacket[beginSequenceOffset:numReportsOffset])
numReportsField := binary.BigEndian.Uint16(rawPacket[numReportsOffset:])
if numReportsField == 0 {
return nil
}
if int(b.BeginSequence)+int(numReportsField) > math.MaxUint16 {
return errIncorrectNumReports
}
endSequence := b.BeginSequence + numReportsField
numReports := int(endSequence - b.BeginSequence + 1)
if len(rawPacket) < reportsOffset+numReports*2 {
return errIncorrectNumReports
}
b.MetricBlocks = make([]CCFeedbackMetricBlock, numReports)
for i := int(0); i < numReports; i++ {
var mb CCFeedbackMetricBlock
offset := reportsOffset + 2*i
if err := mb.unmarshal(rawPacket[offset : offset+2]); err != nil {
return err
}
b.MetricBlocks[i] = mb
}
return nil
}
const (
metricBlockLength = 2
)
// CCFeedbackMetricBlock is a Feedback Metric Block
type CCFeedbackMetricBlock struct {
Received bool
ECN ECN
// Offset in 1/1024 seconds before Report Timestamp
ArrivalTimeOffset uint16
}
// Marshal encodes the Congestion Control Feedback Metric Block in binary
func (b CCFeedbackMetricBlock) marshal() ([]byte, error) {
buf := make([]byte, 2)
r := uint16(0)
if b.Received {
r = 1
}
dst, err := setNBitsOfUint16(0, 1, 0, r)
if err != nil {
return nil, err
}
dst, err = setNBitsOfUint16(dst, 2, 1, uint16(b.ECN))
if err != nil {
return nil, err
}
dst, err = setNBitsOfUint16(dst, 13, 3, b.ArrivalTimeOffset)
if err != nil {
return nil, err
}
binary.BigEndian.PutUint16(buf, dst)
return buf, nil
}
// Unmarshal decodes the Congestion Control Feedback Metric Block from binary
func (b *CCFeedbackMetricBlock) unmarshal(rawPacket []byte) error {
if len(rawPacket) != metricBlockLength {
return errMetricBlockLength
}
b.Received = rawPacket[0]&0x80 != 0
if !b.Received {
b.ECN = ECNNonECT
b.ArrivalTimeOffset = 0
return nil
}
b.ECN = ECN(rawPacket[0] >> 5 & 0x03)
b.ArrivalTimeOffset = binary.BigEndian.Uint16(rawPacket) & 0x1FFF
return nil
}
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