351 lines
11 KiB
Go
351 lines
11 KiB
Go
package rtcp
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
)
|
|
|
|
// SDESType is the item type used in the RTCP SDES control packet.
|
|
type SDESType uint8
|
|
|
|
// RTP SDES item types registered with IANA. See: https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-5
|
|
const (
|
|
SDESEnd SDESType = iota // end of SDES list RFC 3550, 6.5
|
|
SDESCNAME // canonical name RFC 3550, 6.5.1
|
|
SDESName // user name RFC 3550, 6.5.2
|
|
SDESEmail // user's electronic mail address RFC 3550, 6.5.3
|
|
SDESPhone // user's phone number RFC 3550, 6.5.4
|
|
SDESLocation // geographic user location RFC 3550, 6.5.5
|
|
SDESTool // name of application or tool RFC 3550, 6.5.6
|
|
SDESNote // notice about the source RFC 3550, 6.5.7
|
|
SDESPrivate // private extensions RFC 3550, 6.5.8 (not implemented)
|
|
)
|
|
|
|
func (s SDESType) String() string {
|
|
switch s {
|
|
case SDESEnd:
|
|
return "END"
|
|
case SDESCNAME:
|
|
return "CNAME"
|
|
case SDESName:
|
|
return "NAME"
|
|
case SDESEmail:
|
|
return "EMAIL"
|
|
case SDESPhone:
|
|
return "PHONE"
|
|
case SDESLocation:
|
|
return "LOC"
|
|
case SDESTool:
|
|
return "TOOL"
|
|
case SDESNote:
|
|
return "NOTE"
|
|
case SDESPrivate:
|
|
return "PRIV"
|
|
default:
|
|
return string(s)
|
|
}
|
|
}
|
|
|
|
const (
|
|
sdesSourceLen = 4
|
|
sdesTypeLen = 1
|
|
sdesTypeOffset = 0
|
|
sdesOctetCountLen = 1
|
|
sdesOctetCountOffset = 1
|
|
sdesMaxOctetCount = (1 << 8) - 1
|
|
sdesTextOffset = 2
|
|
)
|
|
|
|
// A SourceDescription (SDES) packet describes the sources in an RTP stream.
|
|
type SourceDescription struct {
|
|
Chunks []SourceDescriptionChunk
|
|
}
|
|
|
|
// Marshal encodes the SourceDescription in binary
|
|
func (s SourceDescription) 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
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* header |V=2|P| SC | PT=SDES=202 | length |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* chunk | SSRC/CSRC_1 |
|
|
* 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* chunk | SSRC/CSRC_2 |
|
|
* 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
*/
|
|
|
|
rawPacket := make([]byte, s.len())
|
|
packetBody := rawPacket[headerLength:]
|
|
|
|
chunkOffset := 0
|
|
for _, c := range s.Chunks {
|
|
data, err := c.Marshal()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
copy(packetBody[chunkOffset:], data)
|
|
chunkOffset += len(data)
|
|
}
|
|
|
|
if len(s.Chunks) > countMax {
|
|
return nil, errTooManyChunks
|
|
}
|
|
|
|
hData, err := s.Header().Marshal()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
copy(rawPacket, hData)
|
|
|
|
return rawPacket, nil
|
|
}
|
|
|
|
// Unmarshal decodes the SourceDescription from binary
|
|
func (s *SourceDescription) Unmarshal(rawPacket []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
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* header |V=2|P| SC | PT=SDES=202 | length |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* chunk | SSRC/CSRC_1 |
|
|
* 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* chunk | SSRC/CSRC_2 |
|
|
* 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
*/
|
|
|
|
var h Header
|
|
if err := h.Unmarshal(rawPacket); err != nil {
|
|
return err
|
|
}
|
|
|
|
if h.Type != TypeSourceDescription {
|
|
return errWrongType
|
|
}
|
|
|
|
for i := headerLength; i < len(rawPacket); {
|
|
var chunk SourceDescriptionChunk
|
|
if err := chunk.Unmarshal(rawPacket[i:]); err != nil {
|
|
return err
|
|
}
|
|
s.Chunks = append(s.Chunks, chunk)
|
|
|
|
i += chunk.len()
|
|
}
|
|
|
|
if len(s.Chunks) != int(h.Count) {
|
|
return errInvalidHeader
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (s *SourceDescription) len() int {
|
|
chunksLength := 0
|
|
for _, c := range s.Chunks {
|
|
chunksLength += c.len()
|
|
}
|
|
return headerLength + chunksLength
|
|
}
|
|
|
|
// Header returns the Header associated with this packet.
|
|
func (s *SourceDescription) Header() Header {
|
|
return Header{
|
|
Count: uint8(len(s.Chunks)),
|
|
Type: TypeSourceDescription,
|
|
Length: uint16((s.len() / 4) - 1),
|
|
}
|
|
}
|
|
|
|
// A SourceDescriptionChunk contains items describing a single RTP source
|
|
type SourceDescriptionChunk struct {
|
|
// The source (ssrc) or contributing source (csrc) identifier this packet describes
|
|
Source uint32
|
|
Items []SourceDescriptionItem
|
|
}
|
|
|
|
// Marshal encodes the SourceDescriptionChunk in binary
|
|
func (s SourceDescriptionChunk) Marshal() ([]byte, error) {
|
|
/*
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* | SSRC/CSRC_1 |
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
*/
|
|
|
|
rawPacket := make([]byte, sdesSourceLen)
|
|
binary.BigEndian.PutUint32(rawPacket, s.Source)
|
|
|
|
for _, it := range s.Items {
|
|
data, err := it.Marshal()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
rawPacket = append(rawPacket, data...)
|
|
}
|
|
|
|
// The list of items in each chunk MUST be terminated by one or more null octets
|
|
rawPacket = append(rawPacket, uint8(SDESEnd))
|
|
|
|
// additional null octets MUST be included if needed to pad until the next 32-bit boundary
|
|
rawPacket = append(rawPacket, make([]byte, getPadding(len(rawPacket)))...)
|
|
|
|
return rawPacket, nil
|
|
}
|
|
|
|
// Unmarshal decodes the SourceDescriptionChunk from binary
|
|
func (s *SourceDescriptionChunk) Unmarshal(rawPacket []byte) error {
|
|
/*
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
* | SSRC/CSRC_1 |
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | SDES items |
|
|
* | ... |
|
|
* +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|
|
*/
|
|
|
|
if len(rawPacket) < (sdesSourceLen + sdesTypeLen) {
|
|
return errPacketTooShort
|
|
}
|
|
|
|
s.Source = binary.BigEndian.Uint32(rawPacket)
|
|
|
|
for i := 4; i < len(rawPacket); {
|
|
if pktType := SDESType(rawPacket[i]); pktType == SDESEnd {
|
|
return nil
|
|
}
|
|
|
|
var it SourceDescriptionItem
|
|
if err := it.Unmarshal(rawPacket[i:]); err != nil {
|
|
return err
|
|
}
|
|
s.Items = append(s.Items, it)
|
|
i += it.len()
|
|
}
|
|
|
|
return errPacketTooShort
|
|
}
|
|
|
|
func (s SourceDescriptionChunk) len() int {
|
|
len := sdesSourceLen
|
|
for _, it := range s.Items {
|
|
len += it.len()
|
|
}
|
|
len += sdesTypeLen // for terminating null octet
|
|
|
|
// align to 32-bit boundary
|
|
len += getPadding(len)
|
|
|
|
return len
|
|
}
|
|
|
|
// A SourceDescriptionItem is a part of a SourceDescription that describes a stream.
|
|
type SourceDescriptionItem struct {
|
|
// The type identifier for this item. eg, SDESCNAME for canonical name description.
|
|
//
|
|
// Type zero or SDESEnd is interpreted as the end of an item list and cannot be used.
|
|
Type SDESType
|
|
// Text is a unicode text blob associated with the item. Its meaning varies based on the item's Type.
|
|
Text string
|
|
}
|
|
|
|
func (s SourceDescriptionItem) len() int {
|
|
/*
|
|
* 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
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | CNAME=1 | length | user and domain name ...
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
return sdesTypeLen + sdesOctetCountLen + len([]byte(s.Text))
|
|
}
|
|
|
|
// Marshal encodes the SourceDescriptionItem in binary
|
|
func (s SourceDescriptionItem) 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
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | CNAME=1 | length | user and domain name ...
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
|
|
if s.Type == SDESEnd {
|
|
return nil, errSDESMissingType
|
|
}
|
|
|
|
rawPacket := make([]byte, sdesTypeLen+sdesOctetCountLen)
|
|
|
|
rawPacket[sdesTypeOffset] = uint8(s.Type)
|
|
|
|
txtBytes := []byte(s.Text)
|
|
octetCount := len(txtBytes)
|
|
if octetCount > sdesMaxOctetCount {
|
|
return nil, errSDESTextTooLong
|
|
}
|
|
rawPacket[sdesOctetCountOffset] = uint8(octetCount)
|
|
|
|
rawPacket = append(rawPacket, txtBytes...)
|
|
|
|
return rawPacket, nil
|
|
}
|
|
|
|
// Unmarshal decodes the SourceDescriptionItem from binary
|
|
func (s *SourceDescriptionItem) Unmarshal(rawPacket []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
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* | CNAME=1 | length | user and domain name ...
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
|
|
if len(rawPacket) < (sdesTypeLen + sdesOctetCountLen) {
|
|
return errPacketTooShort
|
|
}
|
|
|
|
s.Type = SDESType(rawPacket[sdesTypeOffset])
|
|
|
|
octetCount := int(rawPacket[sdesOctetCountOffset])
|
|
if sdesTextOffset+octetCount > len(rawPacket) {
|
|
return errPacketTooShort
|
|
}
|
|
|
|
txtBytes := rawPacket[sdesTextOffset : sdesTextOffset+octetCount]
|
|
s.Text = string(txtBytes)
|
|
|
|
return nil
|
|
}
|
|
|
|
// DestinationSSRC returns an array of SSRC values that this packet refers to.
|
|
func (s *SourceDescription) DestinationSSRC() []uint32 {
|
|
out := make([]uint32, len(s.Chunks))
|
|
for i, v := range s.Chunks {
|
|
out[i] = v.Source
|
|
}
|
|
return out
|
|
}
|
|
|
|
func (s *SourceDescription) String() string {
|
|
out := "Source Description:\n"
|
|
for _, c := range s.Chunks {
|
|
out += fmt.Sprintf("\t%x: %s\n", c.Source, c.Items)
|
|
}
|
|
return out
|
|
}
|