deadem/src/extractors/MessagePacketRawExtractor.js

JavaScript (Node.js & Browsers) parser for Deadlock (Valve Source 2 Engine) demo/replay files

import { Buffer } from 'node:buffer';

import BitBuffer from '#core/BitBuffer.js';

import MessagePacketRaw from '#data/MessagePacketRaw.js';

class MessagePacketRawExtractor {
    /**
     * @constructor
     * @public
     * @param {Buffer} buffer
     */
    constructor(buffer) {
        this._bitBuffer = new BitBuffer(buffer);
    }

    /**
     * Extracts and returns all message packets (raw) from the buffer.
     *
     * @public
     * @returns {Array<MessagePacketRaw>}
     */
    all() {
        const extracted = [ ];

        const bytes = Math.ceil(this._bitBuffer.getUnreadCount() / BitBuffer.BITS_PER_BYTE);
        const buffer = Buffer.allocUnsafe(bytes);

        let bytesRead = 0;

        while (this._bitBuffer.getUnreadCount() >= BitBuffer.BITS_PER_BYTE) {
            const type = this._bitBuffer.readUVarInt();
            const size = this._bitBuffer.readUVarInt32();

            const payload = this._bitBuffer.readInBuffer(size * BitBuffer.BITS_PER_BYTE, buffer.subarray(bytesRead, bytesRead + size));

            bytesRead += size;

            extracted.push(new MessagePacketRaw(type, size, payload));
        }

        return extracted;
    }

    /**
     * Extracts and returns all message packets from the buffer
     * in a packed (transferable) format, suitable for transmission
     * between threads.
     *
     * @public
     * @returns {MessagePacketRawPacked}
     */
    allPacked() {
        const bytes = Math.ceil(this._bitBuffer.getUnreadCount() / BitBuffer.BITS_PER_BYTE);

        const buffer = Buffer.allocUnsafe(bytes);
        const meta = [ ];

        let pointer = 0;

        while (this._bitBuffer.getUnreadCount() >= BitBuffer.BITS_PER_BYTE) {
            const type = this._bitBuffer.readUVarInt();
            const size = this._bitBuffer.readUVarInt32();

            meta.push(type, pointer, size);

            this._bitBuffer.readInBuffer(size * BitBuffer.BITS_PER_BYTE, buffer.subarray(pointer, pointer + size));

            pointer += size;
        }

        return { buffer, meta };
    }

    /**
     * @public
     */
    reset() {
        this._bitBuffer.reset();
    }
}

/**
 * @typedef {{ meta: Array<number>, buffer: Buffer }} MessagePacketRawPacked
 */

export default MessagePacketRawExtractor;