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133 lines
2.6 KiB
Go
133 lines
2.6 KiB
Go
/*
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RFC 3550. RTP: A Transport Protocol for Real-Time Applications
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*/
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package icspacketparser
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import (
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"encoding/binary"
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"fmt"
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"gitlab.com/cinnamon/voiceagent/icserror"
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"gitlab.com/cinnamon/voiceagent/icsnet"
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)
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type RTP struct {
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Version int
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PayloadType PayloadType
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Seq uint16
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Timestamp uint32
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SSID uint32
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PayloadLen int
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Payload []byte
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SrcAddr *icsnet.IcsNetAddr
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DstAddr *icsnet.IcsNetAddr
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}
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type RTPHeader struct {
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v byte //2bits
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m byte //1
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pt byte //7
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seq []byte //16
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ts []byte //4
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ssrc []byte //4
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}
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type PayloadType int
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const RTPHeaderLen = 12
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const (
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PCMU = 0
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PCMA = 8
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G729 = 18
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)
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func NewRTP() RTP {
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rtp := RTP{}
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return rtp
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}
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func (r *RTP) RTPParser(data []byte) *icserror.IcsError {
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datalen := len(data)
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if datalen <= RTPHeaderLen {
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return icserror.ICSERRRTPNo
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}
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//fmt.Println(data)
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r.PayloadLen = datalen - RTPHeaderLen
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//fmt.Println("Payload Len:", r.PayloadLen)
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header := RTPHeader{}
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//RTP version 2bit
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header.v = data[0] >> 6
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r.Version = int(header.v)
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if r.Version != 2 {
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return icserror.ICSERRRTPNo
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}
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//fmt.Println("Version", r.Version)
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//mark 1bit
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header.m = data[1] >> 7
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//fmt.Println("Mark", header.m)
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//payload type 7bit
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ptint := data[1]
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ptint = ptint << 1
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header.pt = ptint >> 1
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r.PayloadType = PayloadType(header.pt)
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//fmt.Println("PayloadType:", r.PayloadType)
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if r.PayloadType == 18 { //g729
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if datalen != 32 {
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return icserror.ICSERRRTPNo
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}
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}
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header.seq = make([]byte, 2)
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copy(header.seq, data[2:4])
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r.Seq = binary.BigEndian.Uint16(header.seq[0:])
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//fmt.Println("SEQ:", r.Seq)
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header.ts = make([]byte, 4)
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copy(header.ts, data[4:8])
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r.Timestamp = binary.BigEndian.Uint32(header.ts[0:])
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//fmt.Println("Timestamp:", r.Timestamp)
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header.ssrc = make([]byte, 4)
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copy(header.ssrc, data[8:12])
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r.SSID = binary.BigEndian.Uint32(header.ssrc[0:])
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//fmt.Println("SSID:", r.SSID)
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r.Payload = make([]byte, r.PayloadLen)
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copy(r.Payload, data[12:])
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//fmt.Println("Payload data:", r.Payload)
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return nil
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}
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//implm interface Packeter
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func (r *RTP) GetPacketData(addr []*icsnet.IcsNetAddr, packet []byte) *icserror.IcsError {
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r.SrcAddr = addr[0]
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r.DstAddr = addr[1]
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//fmt.Println("RTP GetPacketData()", r.SrcAddr, r.DstAddr)
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if err := r.RTPParser(packet); err != nil {
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//err.Print()
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return err
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}
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return nil
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}
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func (r RTP) GetPayloadType() PayloadType {
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return r.PayloadType
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}
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func (r RTP) GetPayloadLen() int {
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return r.PayloadLen
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}
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func (r RTP) String() string {
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return fmt.Sprintf("ssrc: %d, seq: %d, ts: %d, pt: %d, payload len: %d", r.SSID, r.Seq, r.Timestamp, r.PayloadType, r.PayloadLen)
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}
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