refactor: import single-file 3rd party modules

This commit allows to:

- provide an ESM version of those modules ([1])
- reduce the attack surface in case of supply chain attacks
- reduce the size of the bundle with tree-shaking

As a downside, we won't receive security updates for those modules
anymore.

[1]: socketio/socket.io-client#1536

.prettierignore

@@ -1 +1,2 @@
 test/support/public/engine.io.min.js
+lib/contrib/*

lib/contrib/has-cors.ts

@@ -0,0 +1,12 @@
+// imported from https://github.com/component/has-cors
+let value = false;
+
+try {
+    value = typeof XMLHttpRequest !== 'undefined' &&
+        'withCredentials' in new XMLHttpRequest();
+} catch (err) {
+    // if XMLHttp support is disabled in IE then it will throw
+    // when trying to create
+}
+
+export const hasCORS = value;

lib/contrib/parseqs.ts

@@ -0,0 +1,38 @@
+// imported from https://github.com/galkn/querystring
+/**
+ * Compiles a querystring
+ * Returns string representation of the object
+ *
+ * @param {Object}
+ * @api private
+ */
+
+export function encode (obj) {
+    let str = '';
+
+    for (let i in obj) {
+        if (obj.hasOwnProperty(i)) {
+            if (str.length) str += '&';
+            str += encodeURIComponent(i) + '=' + encodeURIComponent(obj[i]);
+        }
+    }
+
+    return str;
+}
+
+/**
+ * Parses a simple querystring into an object
+ *
+ * @param {String} qs
+ * @api private
+ */
+
+export function decode (qs) {
+    let qry = {};
+    let pairs = qs.split('&');
+    for (let i = 0, l = pairs.length; i < l; i++) {
+        let pair = pairs[i].split('=');
+        qry[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1]);
+    }
+    return qry;
+}

lib/contrib/parseuri.ts

@@ -0,0 +1,68 @@
+// imported from https://github.com/galkn/parseuri
+/**
+ * Parses an URI
+ *
+ * @author Steven Levithan <stevenlevithan.com> (MIT license)
+ * @api private
+ */
+const re = /^(?:(?![^:@]+:[^:@\/]*@)(http|https|ws|wss):\/\/)?((?:(([^:@]*)(?::([^:@]*))?)?@)?((?:[a-f0-9]{0,4}:){2,7}[a-f0-9]{0,4}|[^:\/?#]*)(?::(\d*))?)(((\/(?:[^?#](?![^?#\/]*\.[^?#\/.]+(?:[?#]|$)))*\/?)?([^?#\/]*))(?:\?([^#]*))?(?:#(.*))?)/;
+
+const parts = [
+    'source', 'protocol', 'authority', 'userInfo', 'user', 'password', 'host', 'port', 'relative', 'path', 'directory', 'file', 'query', 'anchor'
+];
+
+export function parse(str) {
+    const src = str,
+        b = str.indexOf('['),
+        e = str.indexOf(']');
+
+    if (b != -1 && e != -1) {
+        str = str.substring(0, b) + str.substring(b, e).replace(/:/g, ';') + str.substring(e, str.length);
+    }
+
+    let m = re.exec(str || ''),
+        uri = {} as any,
+        i = 14;
+
+    while (i--) {
+        uri[parts[i]] = m[i] || '';
+    }
+
+    if (b != -1 && e != -1) {
+        uri.source = src;
+        uri.host = uri.host.substring(1, uri.host.length - 1).replace(/;/g, ':');
+        uri.authority = uri.authority.replace('[', '').replace(']', '').replace(/;/g, ':');
+        uri.ipv6uri = true;
+    }
+
+    uri.pathNames = pathNames(uri, uri['path']);
+    uri.queryKey = queryKey(uri, uri['query']);
+
+    return uri;
+}
+
+function pathNames(obj, path) {
+    const regx = /\/{2,9}/g,
+        names = path.replace(regx, "/").split("/");
+
+    if (path.substr(0, 1) == '/' || path.length === 0) {
+        names.splice(0, 1);
+    }
+    if (path.substr(path.length - 1, 1) == '/') {
+        names.splice(names.length - 1, 1);
+    }
+
+    return names;
+}
+
+function queryKey(uri, query) {
+    const data = {};
+
+    query.replace(/(?:^|&)([^&=]*)=?([^&]*)/g, function ($0, $1, $2) {
+        if ($1) {
+            data[$1] = $2;
+        }
+    });
+
+    return data;
+}

lib/contrib/yeast.ts

@@ -0,0 +1,62 @@
+// imported from https://github.com/unshiftio/yeast
+'use strict';
+
+const alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_'.split('')
+    , length = 64
+    , map = {};
+let seed = 0
+    , i = 0
+    , prev;
+
+/**
+ * Return a string representing the specified number.
+ *
+ * @param {Number} num The number to convert.
+ * @returns {String} The string representation of the number.
+ * @api public
+ */
+export function encode(num) {
+    let encoded = '';
+
+    do {
+        encoded = alphabet[num % length] + encoded;
+        num = Math.floor(num / length);
+    } while (num > 0);
+
+    return encoded;
+}
+
+/**
+ * Return the integer value specified by the given string.
+ *
+ * @param {String} str The string to convert.
+ * @returns {Number} The integer value represented by the string.
+ * @api public
+ */
+export function decode(str) {
+    let decoded = 0;
+
+    for (i = 0; i < str.length; i++) {
+        decoded = decoded * length + map[str.charAt(i)];
+    }
+
+    return decoded;
+}
+
+/**
+ * Yeast: A tiny growing id generator.
+ *
+ * @returns {String} A unique id.
+ * @api public
+ */
+export function yeast() {
+    const now = encode(+new Date());
+
+    if (now !== prev) return seed = 0, prev = now;
+    return now +'.'+ encode(seed++);
+}
+
+//
+// Map each character to its index.
+//
+for (; i < length; i++) map[alphabet[i]] = i;

lib/index.ts

@@ -6,3 +6,4 @@ export const protocol = Socket.protocol;
 export { Transport } from "./transport.js";
 export { transports } from "./transports/index.js";
 export { installTimerFunctions } from "./util.js";
+export { parse } from "./contrib/parseuri";

lib/socket.ts

@@ -1,7 +1,7 @@
 import { transports } from "./transports/index.js";
 import { installTimerFunctions, byteLength } from "./util.js";
-import parseqs from "parseqs";
-import parseuri from "parseuri";
+import { decode } from "./contrib/parseqs.js";
+import { parse } from "./contrib/parseuri.js";
 import debugModule from "debug"; // debug()
 import { Emitter } from "@socket.io/component-emitter";
 import { protocol } from "engine.io-parser";
@@ -277,13 +277,13 @@ export class Socket extends Emitter<{}, {}, SocketReservedEvents> {
     }
 
     if (uri) {
-      uri = parseuri(uri);
+      uri = parse(uri);
       opts.hostname = uri.host;
       opts.secure = uri.protocol === "https" || uri.protocol === "wss";
       opts.port = uri.port;
       if (uri.query) opts.query = uri.query;
     } else if (opts.host) {
-      opts.hostname = parseuri(opts.host).host;
+      opts.hostname = parse(opts.host).host;
     }
 
     installTimerFunctions(this, opts);
@@ -335,7 +335,7 @@ export class Socket extends Emitter<{}, {}, SocketReservedEvents> {
     this.opts.path = this.opts.path.replace(/\/$/, "") + "/";
 
     if (typeof this.opts.query === "string") {
-      this.opts.query = parseqs.decode(this.opts.query);
+      this.opts.query = decode(this.opts.query);
     }
 
     // set on handshake

lib/transports/polling.ts

@@ -1,7 +1,7 @@
 import { Transport } from "../transport.js";
 import debugModule from "debug"; // debug()
-import yeast from "yeast";
-import parseqs from "parseqs";
+import { yeast } from "../contrib/yeast.js";
+import { encode } from "../contrib/parseqs.js";
 import { encodePayload, decodePayload, RawData } from "engine.io-parser";
 import XMLHttpRequest from "./xmlhttprequest.js";
 import { Emitter } from "@socket.io/component-emitter";
@@ -235,7 +235,7 @@ export class Polling extends Transport {
       port = ":" + this.opts.port;
     }
 
-    const encodedQuery = parseqs.encode(query);
+    const encodedQuery = encode(query);
     const ipv6 = this.opts.hostname.indexOf(":") !== -1;
 
     return (

lib/transports/websocket.ts

@@ -1,6 +1,6 @@
 import { Transport } from "../transport.js";
-import parseqs from "parseqs";
-import yeast from "yeast";
+import { encode } from "../contrib/parseqs.js";
+import { yeast } from "../contrib/yeast.js";
 import { pick } from "../util.js";
 import {
   defaultBinaryType,
@@ -220,7 +220,7 @@ export class WS extends Transport {
       query.b64 = 1;
     }
 
-    const encodedQuery = parseqs.encode(query);
+    const encodedQuery = encode(query);
     const ipv6 = this.opts.hostname.indexOf(":") !== -1;
 
     return (

lib/transports/xmlhttprequest.browser.ts

@@ -1,6 +1,6 @@
 // browser shim for xmlhttprequest module
 
-import hasCORS from "has-cors";
+import { hasCORS } from "../contrib/has-cors.js";
 import globalThis from "../globalThis.js";
 
 export default function(opts) {

lib/xmlhttprequest.ts

@@ -1,6 +1,6 @@
 // browser shim for xmlhttprequest module
 
-import hasCORS from "has-cors";
+import { hasCORS } from "./contrib/has-cors.js";
 import globalThis from "./globalThis.js";
 
 export default function(opts) {

package.json

@@ -42,12 +42,8 @@
     "@socket.io/component-emitter": "~3.0.0",
     "debug": "~4.3.1",
     "engine.io-parser": "~5.0.0",
-    "has-cors": "1.1.0",
-    "parseqs": "0.0.6",
-    "parseuri": "0.0.6",
     "ws": "~8.2.3",
-    "xmlhttprequest-ssl": "~2.0.0",
-    "yeast": "0.1.2"
+    "xmlhttprequest-ssl": "~2.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.12.9",