60 lines
1.6 KiB
Go
60 lines
1.6 KiB
Go
package extension
|
|
|
|
import "encoding/binary"
|
|
|
|
const (
|
|
useSRTPHeaderSize = 6
|
|
)
|
|
|
|
// UseSRTP allows a Client/Server to negotiate what SRTPProtectionProfiles
|
|
// they both support
|
|
//
|
|
// https://tools.ietf.org/html/rfc8422
|
|
type UseSRTP struct {
|
|
ProtectionProfiles []SRTPProtectionProfile
|
|
}
|
|
|
|
// TypeValue returns the extension TypeValue
|
|
func (u UseSRTP) TypeValue() TypeValue {
|
|
return UseSRTPTypeValue
|
|
}
|
|
|
|
// Marshal encodes the extension
|
|
func (u *UseSRTP) Marshal() ([]byte, error) {
|
|
out := make([]byte, useSRTPHeaderSize)
|
|
|
|
binary.BigEndian.PutUint16(out, uint16(u.TypeValue()))
|
|
binary.BigEndian.PutUint16(out[2:], uint16(2+(len(u.ProtectionProfiles)*2)+ /* MKI Length */ 1))
|
|
binary.BigEndian.PutUint16(out[4:], uint16(len(u.ProtectionProfiles)*2))
|
|
|
|
for _, v := range u.ProtectionProfiles {
|
|
out = append(out, []byte{0x00, 0x00}...)
|
|
binary.BigEndian.PutUint16(out[len(out)-2:], uint16(v))
|
|
}
|
|
|
|
out = append(out, 0x00) /* MKI Length */
|
|
return out, nil
|
|
}
|
|
|
|
// Unmarshal populates the extension from encoded data
|
|
func (u *UseSRTP) Unmarshal(data []byte) error {
|
|
if len(data) <= useSRTPHeaderSize {
|
|
return errBufferTooSmall
|
|
} else if TypeValue(binary.BigEndian.Uint16(data)) != u.TypeValue() {
|
|
return errInvalidExtensionType
|
|
}
|
|
|
|
profileCount := int(binary.BigEndian.Uint16(data[4:]) / 2)
|
|
if supportedGroupsHeaderSize+(profileCount*2) > len(data) {
|
|
return errLengthMismatch
|
|
}
|
|
|
|
for i := 0; i < profileCount; i++ {
|
|
supportedProfile := SRTPProtectionProfile(binary.BigEndian.Uint16(data[(useSRTPHeaderSize + (i * 2)):]))
|
|
if _, ok := srtpProtectionProfiles()[supportedProfile]; ok {
|
|
u.ProtectionProfiles = append(u.ProtectionProfiles, supportedProfile)
|
|
}
|
|
}
|
|
return nil
|
|
}
|