Storm Dragon
60 lines
1.1 KiB
Go
60 lines
1.1 KiB
Go
package codecs
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import (
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"errors"
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)
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var errTruncated = errors.New("truncated packet")
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// Flags holds parsed RTP header flags.
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type Flags struct {
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Seqno uint16
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Pid uint16
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Marker bool
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}
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// PacketFlags extracts basic RTP header flags from a raw packet buffer.
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func PacketFlags(codec string, buf []byte) (Flags, error) {
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if len(buf) < 4 {
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return Flags{}, errTruncated
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}
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var flags Flags
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flags.Seqno = (uint16(buf[2]) << 8) | uint16(buf[3])
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flags.Marker = (buf[1] & 0x80) != 0
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return flags, nil
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}
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// RewritePacket rewrites the sequence number and marker bit in a raw RTP packet.
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func RewritePacket(codec string, data []byte, setMarker bool, seqno uint16, delta uint16) error {
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if len(data) < 12 {
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return errTruncated
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}
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if setMarker {
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data[1] |= 0x80
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}
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data[2] = uint8(seqno >> 8)
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data[3] = uint8(seqno)
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if delta == 0 {
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return nil
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}
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offset := 12
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offset += int(data[0]&0x0F) * 4
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if len(data) <= offset {
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return errTruncated
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}
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if (data[0] & 0x10) != 0 {
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length := uint16(data[offset+2])<<8 | uint16(data[offset+3])
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offset += 4 + int(length)*4
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if len(data) < offset+4 {
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return errTruncated
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}
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}
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return nil
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}
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