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Copy pathchunk_payload_data.go
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Copy pathchunk_payload_data.go
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319 lines (268 loc) · 9.22 KB
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// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package sctp
import (
"encoding/binary"
"errors"
"fmt"
"time"
)
/*
chunkPayloadData represents an SCTP Chunk of type DATA
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0 | Reserved|U|B|E| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TSN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Identifier S | Stream Sequence Number n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Protocol Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| User Data (seq n of Stream S) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An unfragmented user message shall have both the B and E bits set to
'1'. Setting both B and E bits to '0' indicates a middle fragment of
a multi-fragment user message, as summarized in the following table:
B E Description
============================================================
| 1 0 | First piece of a fragmented user message |
+----------------------------------------------------------+
| 0 0 | Middle piece of a fragmented user message |
+----------------------------------------------------------+
| 0 1 | Last piece of a fragmented user message |
+----------------------------------------------------------+
| 1 1 | Unfragmented message |
============================================================
| Table 1: Fragment Description Flags |
============================================================
*/
type chunkPayloadData struct {
chunkHeader
unordered bool
beginningFragment bool
endingFragment bool
immediateSack bool
tsn uint32
streamIdentifier uint16
streamSequenceNumber uint16
messageIdentifier uint32
fragmentSequenceNumber uint32
payloadType PayloadProtocolIdentifier
userData []byte
iData bool
// Whether this data chunk was acknowledged (received by peer)
acked bool
missIndicator uint32
// Partial-reliability parameters used only by sender
since time.Time
nSent uint32 // number of transmission made for this chunk
_abandoned bool
_allInflight bool // valid only with the first fragment
// Retransmission flag set when T1-RTX timeout occurred and this
// chunk is still in the inflight queue
retransmit bool
head *chunkPayloadData // link to the head of the fragment
rackPrev *chunkPayloadData
rackNext *chunkPayloadData
rackInList bool
}
func (p *chunkPayloadData) StreamIdentifier() uint16 {
return p.streamIdentifier
}
func (p *chunkPayloadData) UserDataLen() int {
return len(p.userData)
}
func (p *chunkPayloadData) IsStreamReset() bool {
return p.userData == nil
}
func (p *chunkPayloadData) chunkPayloadData() *chunkPayloadData {
return p
}
const (
payloadDataEndingFragmentBitmask = 1
payloadDataBeginingFragmentBitmask = 2
payloadDataUnorderedBitmask = 4
payloadDataImmediateSACK = 8
payloadDataHeaderSize = 12
iDataHeaderSize = 16
)
// PayloadProtocolIdentifier is an enum for DataChannel payload types.
type PayloadProtocolIdentifier uint32
// PayloadProtocolIdentifier enums
// https://www.iana.org/assignments/sctp-parameters/sctp-parameters.xhtml#sctp-parameters-25
const (
PayloadTypeUnknown PayloadProtocolIdentifier = 0
PayloadTypeWebRTCDCEP PayloadProtocolIdentifier = 50
PayloadTypeWebRTCString PayloadProtocolIdentifier = 51
PayloadTypeWebRTCBinary PayloadProtocolIdentifier = 53
PayloadTypeWebRTCStringEmpty PayloadProtocolIdentifier = 56
PayloadTypeWebRTCBinaryEmpty PayloadProtocolIdentifier = 57
)
// Data chunk errors.
var (
ErrChunkPayloadSmall = errors.New("packet is smaller than the header size")
)
func (p PayloadProtocolIdentifier) String() string {
switch p {
case PayloadTypeWebRTCDCEP:
return "WebRTC DCEP"
case PayloadTypeWebRTCString:
return "WebRTC String"
case PayloadTypeWebRTCBinary:
return "WebRTC Binary"
case PayloadTypeWebRTCStringEmpty:
return "WebRTC String (Empty)"
case PayloadTypeWebRTCBinaryEmpty:
return "WebRTC Binary (Empty)"
default:
return fmt.Sprintf("Unknown Payload Protocol Identifier: %d", p)
}
}
func (p *chunkPayloadData) unmarshal(raw []byte) error {
if err := p.chunkHeader.unmarshal(raw); err != nil {
return err
}
p.immediateSack = p.flags&payloadDataImmediateSACK != 0
p.unordered = p.flags&payloadDataUnorderedBitmask != 0
p.beginningFragment = p.flags&payloadDataBeginingFragmentBitmask != 0
p.endingFragment = p.flags&payloadDataEndingFragmentBitmask != 0
switch p.typ {
case ctPayloadData:
if len(p.raw) < payloadDataHeaderSize {
return ErrChunkPayloadSmall
}
p.tsn = binary.BigEndian.Uint32(p.raw[0:])
p.streamIdentifier = binary.BigEndian.Uint16(p.raw[4:])
p.streamSequenceNumber = binary.BigEndian.Uint16(p.raw[6:])
p.payloadType = PayloadProtocolIdentifier(binary.BigEndian.Uint32(p.raw[8:]))
p.userData = p.raw[payloadDataHeaderSize:]
p.iData = false
case ctIData:
if len(p.raw) < iDataHeaderSize {
return ErrChunkPayloadSmall
}
p.tsn = binary.BigEndian.Uint32(p.raw[0:])
p.streamIdentifier = binary.BigEndian.Uint16(p.raw[4:])
p.messageIdentifier = binary.BigEndian.Uint32(p.raw[8:])
if p.beginningFragment {
p.payloadType = PayloadProtocolIdentifier(binary.BigEndian.Uint32(p.raw[12:]))
p.fragmentSequenceNumber = 0
} else {
p.fragmentSequenceNumber = binary.BigEndian.Uint32(p.raw[12:])
p.payloadType = PayloadTypeUnknown
}
p.streamSequenceNumber = uint16(p.messageIdentifier) //nolint:gosec // lower 16 bits for API exposure
p.userData = p.raw[iDataHeaderSize:]
p.iData = true
default:
return fmt.Errorf("%w: unsupported payload data chunk type %d", ErrChunkTypeUnhandled, p.typ)
}
return nil
}
func (p *chunkPayloadData) marshal() ([]byte, error) { //nolint:cyclop
if p.isIData() { //nolint:nestif
payRaw := make([]byte, iDataHeaderSize+len(p.userData))
binary.BigEndian.PutUint32(payRaw[0:], p.tsn)
binary.BigEndian.PutUint16(payRaw[4:], p.streamIdentifier)
binary.BigEndian.PutUint16(payRaw[6:], 0)
binary.BigEndian.PutUint32(payRaw[8:], p.messageIdentifier)
if p.beginningFragment {
binary.BigEndian.PutUint32(payRaw[12:], uint32(p.payloadType))
} else {
binary.BigEndian.PutUint32(payRaw[12:], p.fragmentSequenceNumber)
}
copy(payRaw[iDataHeaderSize:], p.userData)
flags := uint8(0)
if p.endingFragment {
flags = 1
}
if p.beginningFragment {
flags |= 1 << 1
}
if p.unordered {
flags |= 1 << 2
}
if p.immediateSack {
flags |= 1 << 3
}
p.chunkHeader.flags = flags
p.chunkHeader.typ = ctIData
p.chunkHeader.raw = payRaw
return p.chunkHeader.marshal()
}
payRaw := make([]byte, payloadDataHeaderSize+len(p.userData))
binary.BigEndian.PutUint32(payRaw[0:], p.tsn)
binary.BigEndian.PutUint16(payRaw[4:], p.streamIdentifier)
binary.BigEndian.PutUint16(payRaw[6:], p.streamSequenceNumber)
binary.BigEndian.PutUint32(payRaw[8:], uint32(p.payloadType))
copy(payRaw[payloadDataHeaderSize:], p.userData)
flags := uint8(0)
if p.endingFragment {
flags = 1
}
if p.beginningFragment {
flags |= 1 << 1
}
if p.unordered {
flags |= 1 << 2
}
if p.immediateSack {
flags |= 1 << 3
}
p.chunkHeader.flags = flags
p.chunkHeader.typ = ctPayloadData
p.chunkHeader.raw = payRaw
return p.chunkHeader.marshal()
}
func (p *chunkPayloadData) check() (abort bool, err error) {
return false, nil
}
// String makes chunkPayloadData printable.
func (p *chunkPayloadData) String() string {
if p.isIData() {
return fmt.Sprintf("%s\ntsn=%d mid=%d fsn=%d", p.chunkHeader, p.tsn, p.messageIdentifier, p.fragmentSequenceNumber)
}
return fmt.Sprintf("%s\n%d", p.chunkHeader, p.tsn)
}
func (p *chunkPayloadData) abandoned() bool {
if p.head != nil {
return p.head._abandoned && p.head._allInflight
}
return p._abandoned && p._allInflight
}
func (p *chunkPayloadData) setAbandoned(abandoned bool) {
if p.head != nil {
p.head._abandoned = abandoned
return
}
p._abandoned = abandoned
}
func (p *chunkPayloadData) setAllInflight() {
if p.endingFragment {
if p.head != nil {
p.head._allInflight = true
} else {
p._allInflight = true
}
}
}
func (p *chunkPayloadData) isFragmented() bool {
return p.head != nil || !p.beginningFragment || !p.endingFragment
}
func (p *chunkPayloadData) isIData() bool {
return p.iData || p.typ == ctIData
}
func (p *chunkPayloadData) chunkSize() int {
if p.isIData() {
return chunkHeaderSize + iDataHeaderSize + len(p.userData)
}
return chunkHeaderSize + payloadDataHeaderSize + len(p.userData)
}
func (p *chunkPayloadData) chunkSizeInPacket() int {
chunkSize := p.chunkSize()
return chunkSize + getPadding(chunkSize)
}