fix(utils): manally conver from b64 to b64url to avoid web polyfill i…

…ssues

jest.config.mjs

@@ -2,7 +2,7 @@ export default {
   preset: 'ts-jest',
   clearMocks: true,
   moduleFileExtensions: ['ts', 'js', 'mjs'],
-  testMatch: ['**/src/**/*.test.ts'],
+  testMatch: ['**/tests/unit/**.test.ts'],
   collectCoverage: true,
   collectCoverageFrom: ['src/**/*.ts'],
   testEnvironment: 'node',

src/utils/base64.ts

@@ -16,12 +16,39 @@
  */
 import { createHash } from 'crypto';
 
+// safely encodes and decodes base64url strings to and from buffers
+const BASE64_CHAR_62 = '+';
+const BASE64_CHAR_63 = '/';
+const BASE64URL_CHAR_62 = '-';
+const BASE64URL_CHAR_63 = '_';
+const BASE64_PADDING = '=';
+
+function base64urlToBase64(str: string): string {
+  const padLength = str.length % 4;
+  if (padLength) {
+    str += BASE64_PADDING.repeat(4 - padLength);
+  }
+
+  return str
+    .replaceAll(BASE64URL_CHAR_62, BASE64_CHAR_62)
+    .replaceAll(BASE64URL_CHAR_63, BASE64_CHAR_63);
+}
+
+function base64urlFromBase64(str) {
+  return str
+    .replaceAll(BASE64_CHAR_62, BASE64URL_CHAR_62)
+    .replaceAll(BASE64_CHAR_63, BASE64URL_CHAR_63)
+    .replaceAll(BASE64_PADDING, '');
+}
+
 export function fromB64Url(input: string): Buffer {
-  return Buffer.from(input, 'base64');
+  const b64Str = base64urlToBase64(input);
+  return Buffer.from(b64Str, 'base64');
 }
 
 export function toB64Url(buffer: Buffer): string {
-  return buffer.toString('base64url');
+  const b64Str = buffer.toString('base64');
+  return base64urlFromBase64(b64Str);
 }
 
 export function sha256B64Url(input: Buffer): string {

tests/unit/b64.test.ts

@@ -0,0 +1,15 @@
+import { fromB64Url, toB64Url } from '../../src/utils/base64';
+
+describe('b64utils', () => {
+  it('should properly convert a buffer to base64url string', async () => {
+    const input = Buffer.from('hello+_world_+', 'base64');
+    const expected = input.toString('base64url');
+    expect(toB64Url(input)).toEqual(expected);
+  });
+
+  it('should properly convert a base64 string to a buffer', async () => {
+    const b64url = Buffer.from('hello+_world_+').toString('base64url');
+    const expected = Buffer.from(b64url, 'base64url');
+    expect(fromB64Url(b64url)).toEqual(expected);
+  });
+});