import { isBinary } from "./is-binary.js"; /** * Replaces every Buffer | ArrayBuffer | Blob | File in packet with a numbered placeholder. * * @param {Object} packet - socket.io event packet * @return {Object} with deconstructed packet and list of buffers * @public */ export function deconstructPacket(packet) { const buffers = []; const packetData = packet.data; const pack = packet; pack.data = _deconstructPacket(packetData, buffers); pack.attachments = buffers.length; // number of binary 'attachments' return { packet: pack, buffers: buffers }; } function _deconstructPacket(data, buffers) { if (!data) return data; if (isBinary(data)) { const placeholder = { _placeholder: true, num: buffers.length }; buffers.push(data); return placeholder; } else if (Array.isArray(data)) { const newData = new Array(data.length); for (let i = 0; i < data.length; i++) { newData[i] = _deconstructPacket(data[i], buffers); } return newData; } else if (typeof data === "object" && !(data instanceof Date)) { const newData = {}; for (const key in data) { if (Object.prototype.hasOwnProperty.call(data, key)) { newData[key] = _deconstructPacket(data[key], buffers); } } return newData; } return data; } /** * Reconstructs a binary packet from its placeholder packet and buffers * * @param {Object} packet - event packet with placeholders * @param {Array} buffers - binary buffers to put in placeholder positions * @return {Object} reconstructed packet * @public */ export function reconstructPacket(packet, buffers) { packet.data = _reconstructPacket(packet.data, buffers); delete packet.attachments; // no longer useful return packet; } function _reconstructPacket(data, buffers) { if (!data) return data; if (data && data._placeholder === true) { const isIndexValid = typeof data.num === "number" && data.num >= 0 && data.num < buffers.length; if (isIndexValid) { return buffers[data.num]; // appropriate buffer (should be natural order anyway) } else { throw new Error("illegal attachments"); } } else if (Array.isArray(data)) { for (let i = 0; i < data.length; i++) { data[i] = _reconstructPacket(data[i], buffers); } } else if (typeof data === "object") { for (const key in data) { if (Object.prototype.hasOwnProperty.call(data, key)) { data[key] = _reconstructPacket(data[key], buffers); } } } return data; }