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|
package rtp
import (
"encoding/binary"
"fmt"
"io"
)
const (
headerExtensionProfileOneByte = 0xBEDE
headerExtensionProfileTwoByte = 0x1000
headerExtensionIDReserved = 0xF
)
// HeaderExtension represents an RTP extension header.
type HeaderExtension interface {
Set(id uint8, payload []byte) error
GetIDs() []uint8
Get(id uint8) []byte
Del(id uint8) error
Unmarshal(buf []byte) (int, error)
Marshal() ([]byte, error)
MarshalTo(buf []byte) (int, error)
MarshalSize() int
}
// OneByteHeaderExtension is an RFC8285 one-byte header extension.
type OneByteHeaderExtension struct {
payload []byte
}
// Set sets the extension payload for the specified ID.
func (e *OneByteHeaderExtension) Set(id uint8, buf []byte) error {
if id < 1 || id > 14 {
return fmt.Errorf("%w actual(%d)", errRFC8285OneByteHeaderIDRange, id)
}
if len(buf) > 16 {
return fmt.Errorf("%w actual(%d)", errRFC8285OneByteHeaderSize, len(buf))
}
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n] >> 4
len := int(e.payload[n]&^0xF0 + 1)
n++
if extid == id {
e.payload = append(e.payload[:n+1], append(buf, e.payload[n+1+len:]...)...)
return nil
}
n += len
}
e.payload = append(e.payload, (id<<4 | uint8(len(buf)-1)))
e.payload = append(e.payload, buf...)
binary.BigEndian.PutUint16(e.payload[2:4], binary.BigEndian.Uint16(e.payload[2:4])+1)
return nil
}
// GetIDs returns the available IDs.
func (e *OneByteHeaderExtension) GetIDs() []uint8 {
ids := make([]uint8, 0, binary.BigEndian.Uint16(e.payload[2:4]))
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n] >> 4
len := int(e.payload[n]&^0xF0 + 1)
n++
if extid == headerExtensionIDReserved {
break
}
ids = append(ids, extid)
n += len
}
return ids
}
// Get returns the payload of the extension with the given ID.
func (e *OneByteHeaderExtension) Get(id uint8) []byte {
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n] >> 4
len := int(e.payload[n]&^0xF0 + 1)
n++
if extid == id {
return e.payload[n : n+len]
}
n += len
}
return nil
}
// Del deletes the extension with the specified ID.
func (e *OneByteHeaderExtension) Del(id uint8) error {
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n] >> 4
len := int(e.payload[n]&^0xF0 + 1)
if extid == id {
e.payload = append(e.payload[:n], e.payload[n+1+len:]...)
return nil
}
n += len + 1
}
return errHeaderExtensionNotFound
}
// Unmarshal parses the extension payload.
func (e *OneByteHeaderExtension) Unmarshal(buf []byte) (int, error) {
profile := binary.BigEndian.Uint16(buf[0:2])
if profile != headerExtensionProfileOneByte {
return 0, fmt.Errorf("%w actual(%x)", errHeaderExtensionNotFound, buf[0:2])
}
e.payload = buf
return len(buf), nil
}
// Marshal returns the extension payload.
func (e OneByteHeaderExtension) Marshal() ([]byte, error) {
return e.payload, nil
}
// MarshalTo writes the extension payload to the given buffer.
func (e OneByteHeaderExtension) MarshalTo(buf []byte) (int, error) {
size := e.MarshalSize()
if size > len(buf) {
return 0, io.ErrShortBuffer
}
return copy(buf, e.payload), nil
}
// MarshalSize returns the size of the extension payload.
func (e OneByteHeaderExtension) MarshalSize() int {
return len(e.payload)
}
// TwoByteHeaderExtension is an RFC8285 two-byte header extension.
type TwoByteHeaderExtension struct {
payload []byte
}
// Set sets the extension payload for the specified ID.
func (e *TwoByteHeaderExtension) Set(id uint8, buf []byte) error {
if id < 1 || id > 255 {
return fmt.Errorf("%w actual(%d)", errRFC8285TwoByteHeaderIDRange, id)
}
if len(buf) > 255 {
return fmt.Errorf("%w actual(%d)", errRFC8285TwoByteHeaderSize, len(buf))
}
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n]
n++
len := int(e.payload[n])
n++
if extid == id {
e.payload = append(e.payload[:n+2], append(buf, e.payload[n+2+len:]...)...)
return nil
}
n += len
}
e.payload = append(e.payload, id, uint8(len(buf)))
e.payload = append(e.payload, buf...)
binary.BigEndian.PutUint16(e.payload[2:4], binary.BigEndian.Uint16(e.payload[2:4])+1)
return nil
}
// GetIDs returns the available IDs.
func (e *TwoByteHeaderExtension) GetIDs() []uint8 {
ids := make([]uint8, 0, binary.BigEndian.Uint16(e.payload[2:4]))
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n]
n++
len := int(e.payload[n])
n++
ids = append(ids, extid)
n += len
}
return ids
}
// Get returns the payload of the extension with the given ID.
func (e *TwoByteHeaderExtension) Get(id uint8) []byte {
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n]
n++
len := int(e.payload[n])
n++
if extid == id {
return e.payload[n : n+len]
}
n += len
}
return nil
}
// Del deletes the extension with the specified ID.
func (e *TwoByteHeaderExtension) Del(id uint8) error {
for n := 4; n < len(e.payload); {
if e.payload[n] == 0x00 { // padding
n++
continue
}
extid := e.payload[n]
len := int(e.payload[n+1])
if extid == id {
e.payload = append(e.payload[:n], e.payload[n+2+len:]...)
return nil
}
n += len + 2
}
return errHeaderExtensionNotFound
}
// Unmarshal parses the extension payload.
func (e *TwoByteHeaderExtension) Unmarshal(buf []byte) (int, error) {
profile := binary.BigEndian.Uint16(buf[0:2])
if profile != headerExtensionProfileTwoByte {
return 0, fmt.Errorf("%w actual(%x)", errHeaderExtensionNotFound, buf[0:2])
}
e.payload = buf
return len(buf), nil
}
// Marshal returns the extension payload.
func (e TwoByteHeaderExtension) Marshal() ([]byte, error) {
return e.payload, nil
}
// MarshalTo marshals the extension to the given buffer.
func (e TwoByteHeaderExtension) MarshalTo(buf []byte) (int, error) {
size := e.MarshalSize()
if size > len(buf) {
return 0, io.ErrShortBuffer
}
return copy(buf, e.payload), nil
}
// MarshalSize returns the size of the extension payload.
func (e TwoByteHeaderExtension) MarshalSize() int {
return len(e.payload)
}
// RawExtension represents an RFC3550 header extension.
type RawExtension struct {
payload []byte
}
// Set sets the extension payload for the specified ID.
func (e *RawExtension) Set(id uint8, payload []byte) error {
if id != 0 {
return fmt.Errorf("%w actual(%d)", errRFC3550HeaderIDRange, id)
}
e.payload = payload
return nil
}
// GetIDs returns the available IDs.
func (e *RawExtension) GetIDs() []uint8 {
return []uint8{0}
}
// Get returns the payload of the extension with the given ID.
func (e *RawExtension) Get(id uint8) []byte {
if id == 0 {
return e.payload
}
return nil
}
// Del deletes the extension with the specified ID.
func (e *RawExtension) Del(id uint8) error {
if id == 0 {
e.payload = nil
return nil
}
return fmt.Errorf("%w actual(%d)", errRFC3550HeaderIDRange, id)
}
// Unmarshal parses the extension from the given buffer.
func (e *RawExtension) Unmarshal(buf []byte) (int, error) {
profile := binary.BigEndian.Uint16(buf[0:2])
if profile == headerExtensionProfileOneByte || profile == headerExtensionProfileTwoByte {
return 0, fmt.Errorf("%w actual(%x)", errHeaderExtensionNotFound, buf[0:2])
}
e.payload = buf
return len(buf), nil
}
// Marshal returns the raw extension payload.
func (e RawExtension) Marshal() ([]byte, error) {
return e.payload, nil
}
// MarshalTo marshals the extension to the given buffer.
func (e RawExtension) MarshalTo(buf []byte) (int, error) {
size := e.MarshalSize()
if size > len(buf) {
return 0, io.ErrShortBuffer
}
return copy(buf, e.payload), nil
}
// MarshalSize returns the size of the extension when marshaled.
func (e RawExtension) MarshalSize() int {
return len(e.payload)
}
|
