312 lines
9.7 KiB
JavaScript
312 lines
9.7 KiB
JavaScript
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import { Emitter } from "@socket.io/component-emitter";
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import { deconstructPacket, reconstructPacket } from "./binary.js";
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import { isBinary, hasBinary } from "./is-binary.js";
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/**
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* These strings must not be used as event names, as they have a special meaning.
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*/
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const RESERVED_EVENTS = [
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"connect",
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"connect_error",
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"disconnect",
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"disconnecting",
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"newListener",
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"removeListener", // used by the Node.js EventEmitter
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];
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/**
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* Protocol version.
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*
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* @public
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*/
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export const protocol = 5;
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export var PacketType;
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(function (PacketType) {
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PacketType[PacketType["CONNECT"] = 0] = "CONNECT";
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PacketType[PacketType["DISCONNECT"] = 1] = "DISCONNECT";
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PacketType[PacketType["EVENT"] = 2] = "EVENT";
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PacketType[PacketType["ACK"] = 3] = "ACK";
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PacketType[PacketType["CONNECT_ERROR"] = 4] = "CONNECT_ERROR";
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PacketType[PacketType["BINARY_EVENT"] = 5] = "BINARY_EVENT";
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PacketType[PacketType["BINARY_ACK"] = 6] = "BINARY_ACK";
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})(PacketType || (PacketType = {}));
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/**
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* A socket.io Encoder instance
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*/
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export class Encoder {
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/**
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* Encoder constructor
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*
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* @param {function} replacer - custom replacer to pass down to JSON.parse
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*/
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constructor(replacer) {
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this.replacer = replacer;
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}
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/**
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* Encode a packet as a single string if non-binary, or as a
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* buffer sequence, depending on packet type.
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*
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* @param {Object} obj - packet object
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*/
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encode(obj) {
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if (obj.type === PacketType.EVENT || obj.type === PacketType.ACK) {
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if (hasBinary(obj)) {
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return this.encodeAsBinary({
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type: obj.type === PacketType.EVENT
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? PacketType.BINARY_EVENT
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: PacketType.BINARY_ACK,
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nsp: obj.nsp,
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data: obj.data,
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id: obj.id,
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});
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}
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}
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return [this.encodeAsString(obj)];
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}
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/**
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* Encode packet as string.
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*/
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encodeAsString(obj) {
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// first is type
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let str = "" + obj.type;
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// attachments if we have them
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if (obj.type === PacketType.BINARY_EVENT ||
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obj.type === PacketType.BINARY_ACK) {
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str += obj.attachments + "-";
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}
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// if we have a namespace other than `/`
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// we append it followed by a comma `,`
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if (obj.nsp && "/" !== obj.nsp) {
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str += obj.nsp + ",";
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}
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// immediately followed by the id
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if (null != obj.id) {
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str += obj.id;
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}
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// json data
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if (null != obj.data) {
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str += JSON.stringify(obj.data, this.replacer);
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}
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return str;
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}
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/**
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* Encode packet as 'buffer sequence' by removing blobs, and
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* deconstructing packet into object with placeholders and
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* a list of buffers.
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*/
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encodeAsBinary(obj) {
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const deconstruction = deconstructPacket(obj);
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const pack = this.encodeAsString(deconstruction.packet);
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const buffers = deconstruction.buffers;
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buffers.unshift(pack); // add packet info to beginning of data list
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return buffers; // write all the buffers
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}
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}
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// see https://stackoverflow.com/questions/8511281/check-if-a-value-is-an-object-in-javascript
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function isObject(value) {
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return Object.prototype.toString.call(value) === "[object Object]";
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}
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/**
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* A socket.io Decoder instance
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*
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* @return {Object} decoder
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*/
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export class Decoder extends Emitter {
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/**
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* Decoder constructor
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*
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* @param {function} reviver - custom reviver to pass down to JSON.stringify
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*/
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constructor(reviver) {
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super();
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this.reviver = reviver;
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}
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/**
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* Decodes an encoded packet string into packet JSON.
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*
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* @param {String} obj - encoded packet
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*/
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add(obj) {
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let packet;
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if (typeof obj === "string") {
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if (this.reconstructor) {
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throw new Error("got plaintext data when reconstructing a packet");
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}
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packet = this.decodeString(obj);
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const isBinaryEvent = packet.type === PacketType.BINARY_EVENT;
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if (isBinaryEvent || packet.type === PacketType.BINARY_ACK) {
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packet.type = isBinaryEvent ? PacketType.EVENT : PacketType.ACK;
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// binary packet's json
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this.reconstructor = new BinaryReconstructor(packet);
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// no attachments, labeled binary but no binary data to follow
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if (packet.attachments === 0) {
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super.emitReserved("decoded", packet);
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}
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}
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else {
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// non-binary full packet
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super.emitReserved("decoded", packet);
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}
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}
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else if (isBinary(obj) || obj.base64) {
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// raw binary data
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if (!this.reconstructor) {
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throw new Error("got binary data when not reconstructing a packet");
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}
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else {
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packet = this.reconstructor.takeBinaryData(obj);
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if (packet) {
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// received final buffer
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this.reconstructor = null;
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super.emitReserved("decoded", packet);
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}
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}
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}
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else {
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throw new Error("Unknown type: " + obj);
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}
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}
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/**
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* Decode a packet String (JSON data)
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*
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* @param {String} str
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* @return {Object} packet
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*/
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decodeString(str) {
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let i = 0;
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// look up type
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const p = {
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type: Number(str.charAt(0)),
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};
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if (PacketType[p.type] === undefined) {
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throw new Error("unknown packet type " + p.type);
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}
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// look up attachments if type binary
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if (p.type === PacketType.BINARY_EVENT ||
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p.type === PacketType.BINARY_ACK) {
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const start = i + 1;
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while (str.charAt(++i) !== "-" && i != str.length) { }
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const buf = str.substring(start, i);
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if (buf != Number(buf) || str.charAt(i) !== "-") {
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throw new Error("Illegal attachments");
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}
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p.attachments = Number(buf);
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}
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// look up namespace (if any)
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if ("/" === str.charAt(i + 1)) {
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const start = i + 1;
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while (++i) {
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const c = str.charAt(i);
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if ("," === c)
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break;
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if (i === str.length)
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break;
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}
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p.nsp = str.substring(start, i);
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}
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else {
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p.nsp = "/";
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}
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// look up id
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const next = str.charAt(i + 1);
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if ("" !== next && Number(next) == next) {
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const start = i + 1;
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while (++i) {
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const c = str.charAt(i);
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if (null == c || Number(c) != c) {
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--i;
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break;
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}
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if (i === str.length)
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break;
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}
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p.id = Number(str.substring(start, i + 1));
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}
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// look up json data
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if (str.charAt(++i)) {
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const payload = this.tryParse(str.substr(i));
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if (Decoder.isPayloadValid(p.type, payload)) {
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p.data = payload;
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}
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else {
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throw new Error("invalid payload");
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}
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}
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return p;
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}
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tryParse(str) {
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try {
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return JSON.parse(str, this.reviver);
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}
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catch (e) {
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return false;
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}
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}
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static isPayloadValid(type, payload) {
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switch (type) {
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case PacketType.CONNECT:
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return isObject(payload);
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case PacketType.DISCONNECT:
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return payload === undefined;
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case PacketType.CONNECT_ERROR:
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return typeof payload === "string" || isObject(payload);
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case PacketType.EVENT:
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case PacketType.BINARY_EVENT:
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return (Array.isArray(payload) &&
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(typeof payload[0] === "number" ||
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(typeof payload[0] === "string" &&
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RESERVED_EVENTS.indexOf(payload[0]) === -1)));
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case PacketType.ACK:
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case PacketType.BINARY_ACK:
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return Array.isArray(payload);
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}
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}
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/**
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* Deallocates a parser's resources
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*/
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destroy() {
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if (this.reconstructor) {
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this.reconstructor.finishedReconstruction();
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this.reconstructor = null;
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}
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}
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}
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/**
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* A manager of a binary event's 'buffer sequence'. Should
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* be constructed whenever a packet of type BINARY_EVENT is
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* decoded.
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*
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* @param {Object} packet
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* @return {BinaryReconstructor} initialized reconstructor
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*/
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class BinaryReconstructor {
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constructor(packet) {
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this.packet = packet;
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this.buffers = [];
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this.reconPack = packet;
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}
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/**
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* Method to be called when binary data received from connection
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* after a BINARY_EVENT packet.
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*
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* @param {Buffer | ArrayBuffer} binData - the raw binary data received
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* @return {null | Object} returns null if more binary data is expected or
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* a reconstructed packet object if all buffers have been received.
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*/
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takeBinaryData(binData) {
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this.buffers.push(binData);
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if (this.buffers.length === this.reconPack.attachments) {
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// done with buffer list
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const packet = reconstructPacket(this.reconPack, this.buffers);
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this.finishedReconstruction();
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return packet;
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}
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return null;
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}
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/**
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* Cleans up binary packet reconstruction variables.
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*/
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finishedReconstruction() {
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this.reconPack = null;
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this.buffers = [];
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}
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}
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