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