@bengreenier/krtp/dist/Packet.js

Node implementation of rdp protocol. RFC 3550

"use strict";
/*
 * +===============================================
 * | Author:        Parham Alvani (parham.alvani@gmail.com)
 * |
 * | Creation Date: 01-06-2017
 * |
 * | File Name:     packet.ts
 * +===============================================
 */
/**
 */
Object.defineProperty(exports, "__esModule", { value: true });
class Packet {
    constructor(payload, sequenceNumber, ssrc, timestamp = 0, payloadType = 95) {
        this.csrc = [];
        this.payload = payload;
        this.sequenceNumber = sequenceNumber;
        this.ssrc = ssrc;
        this.timestamp = timestamp;
        this.payloadType = payloadType;
    }
    addCSRC(csrc) {
        /* TODO: csrc must be a 32 bit integer */
        this.csrc.push(csrc);
    }
    serialize() {
        const buff = Buffer.alloc(12 + 4 * this.csrc.length + this.payload.length);
        /* buff[0] = (V << 6 | P << 5 | X << 4 | CC) */
        buff[0] = (2 << 6) | (0 << 5) | (0 << 4) | this.csrc.length;
        /* buff[1] = (M << 7 | PT) */
        buff[1] = (0 << 7) | this.payloadType;
        /* buff[2, 3] = SN */
        buff.writeUInt16BE(this.sequenceNumber, 2);
        /* buff[4, 5, 6, 7] = TS */
        buff.writeUInt32BE(this.timestamp, 4);
        /* buff[8, 9, 10, 11] = SSRC */
        buff.writeUInt32BE(this.ssrc, 8);
        /* CSRC section */
        for (let i = 0; i < this.csrc.length; i++) {
            buff.writeUInt32BE(this.csrc[i], 12 + i * 4);
        }
        this.payload.copy(buff, 12 + this.csrc.length * 4, 0);
        return buff;
    }
    static deserialize(buff) {
        const csrc = [];
        /* buff[0] = (V << 6 | P << 5 | X << 4 | CC) */
        if ((buff[0] & 0xc0) >> 6 !== 2) {
            throw new Error(`Invalid RTP packet ${buff[0] & 0xc0}`);
        }
        const cc = buff[0] & 0x1f;
        /* buff[1] = (M << 7 | PT) */
        const payloadType = buff[1] & 0x7f;
        /* buff[2, 3] = SN */
        const sequenceNumber = buff.readUInt16BE(2);
        /* buff[4, 5, 6, 7] = TS */
        const timestamp = buff.readUInt32BE(4);
        /* buff[8, 9, 10, 11] = SSRC */
        const ssrc = buff.readUInt32BE(8);
        /* CSRC section */
        for (let i = 0; i < cc; i++) {
            csrc.push(buff.readUInt32BE(12 + i * 4));
        }
        const payload = Buffer.from(buff.slice(12 + csrc.length * 4));
        const packet = new Packet(payload, sequenceNumber, ssrc, timestamp, payloadType);
        for (const s of csrc) {
            packet.addCSRC(s);
        }
        return packet;
    }
}
exports.Packet = Packet;