makeHttpError: Ensure response headers have lowercase names

ts/test-electron/textsecure/WebAPI_test.ts

@@ -0,0 +1,40 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { makeKeysLowercase } from '../../textsecure/WebAPI';
+
+describe('WebAPI', () => {
+  describe('makeKeysLowercase', () => {
+    it('handles empty object', () => {
+      const expected = Object.create(null);
+      const actual = makeKeysLowercase({});
+      assert.deepEqual(expected, actual);
+    });
+    it('handles one key', () => {
+      const expected = Object.create(null);
+      expected.low = 4;
+
+      const actual = makeKeysLowercase({
+        LOW: 4,
+      });
+
+      assert.deepEqual(expected, actual);
+    });
+    it('handles lots of keys', () => {
+      const expected = Object.create(null);
+      expected.one = 'one more';
+      expected.two = 'two more';
+      expected.three = 'three';
+
+      const actual = makeKeysLowercase({
+        One: 'one more',
+        TWO: 'two more',
+        ThreE: 'three',
+      });
+
+      assert.deepEqual(expected, actual);
+    });
+  });
+});

ts/textsecure/WebAPI.ts

@@ -638,12 +638,25 @@ function makeHTTPError(
 ) {
   return new HTTPError(message, {
     code: providedCode,
-    headers,
+    headers: makeKeysLowercase(headers),
     response,
     stack,
   });
 }
 
+export function makeKeysLowercase<V>(
+  headers: Record<string, V>
+): Record<string, V> {
+  const keys = Object.keys(headers);
+  const lowerCase: Record<string, V> = Object.create(null);
+
+  keys.forEach(key => {
+    lowerCase[key.toLowerCase()] = headers[key];
+  });
+
+  return lowerCase;
+}
+
 const URL_CALLS = {
   accountExistence: 'v1/accounts/account',
   attachmentUploadForm: 'v4/attachments/form/upload',