refactor: include base64-arraybuffer in the repository

In order to reduce the number of dependencies and the attack surface in
case of supply chain attacks.

.prettierignore

@@ -0,0 +1 @@
+lib/contrib/*

lib/contrib/base64-arraybuffer.ts

@@ -0,0 +1,64 @@
+// imported from https://github.com/socketio/base64-arraybuffer
+const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+
+// Use a lookup table to find the index.
+const lookup = typeof Uint8Array === 'undefined' ? [] : new Uint8Array(256);
+for (let i = 0; i < chars.length; i++) {
+    lookup[chars.charCodeAt(i)] = i;
+}
+
+export const encode = (arraybuffer: ArrayBuffer): string => {
+    let bytes = new Uint8Array(arraybuffer),
+        i,
+        len = bytes.length,
+        base64 = '';
+
+    for (i = 0; i < len; i += 3) {
+        base64 += chars[bytes[i] >> 2];
+        base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
+        base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
+        base64 += chars[bytes[i + 2] & 63];
+    }
+
+    if (len % 3 === 2) {
+        base64 = base64.substring(0, base64.length - 1) + '=';
+    } else if (len % 3 === 1) {
+        base64 = base64.substring(0, base64.length - 2) + '==';
+    }
+
+    return base64;
+};
+
+export const decode = (base64: string): ArrayBuffer => {
+    let bufferLength = base64.length * 0.75,
+        len = base64.length,
+        i,
+        p = 0,
+        encoded1,
+        encoded2,
+        encoded3,
+        encoded4;
+
+    if (base64[base64.length - 1] === '=') {
+        bufferLength--;
+        if (base64[base64.length - 2] === '=') {
+            bufferLength--;
+        }
+    }
+
+    const arraybuffer = new ArrayBuffer(bufferLength),
+        bytes = new Uint8Array(arraybuffer);
+
+    for (i = 0; i < len; i += 4) {
+        encoded1 = lookup[base64.charCodeAt(i)];
+        encoded2 = lookup[base64.charCodeAt(i + 1)];
+        encoded3 = lookup[base64.charCodeAt(i + 2)];
+        encoded4 = lookup[base64.charCodeAt(i + 3)];
+
+        bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
+        bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
+        bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
+    }
+
+    return arraybuffer;
+};

lib/decodePacket.browser.ts

@@ -5,7 +5,7 @@ import {
   BinaryType,
   RawData
 } from "./commons.js";
-import { decode } from "@socket.io/base64-arraybuffer";
+import { decode } from "./contrib/base64-arraybuffer.js";
 
 const withNativeArrayBuffer = typeof ArrayBuffer === "function";
 

package.json

@@ -30,9 +30,6 @@
     "zuul": "3.11.1",
     "zuul-ngrok": "4.0.0"
   },
-  "dependencies": {
-    "@socket.io/base64-arraybuffer": "~1.0.2"
-  },
   "scripts": {
     "compile": "rimraf ./build && tsc && tsc -p tsconfig.esm.json && ./postcompile.sh",
     "test": "npm run format:check && npm run compile && if test \"$BROWSERS\" = \"1\" ; then npm run test:browser; else npm run test:node; fi",