fix: support encoding of special characters in path params for gen2 funcs

Author: IzaakGough

src/cloud_events.ts

@@ -65,7 +65,10 @@ export function getBinaryCloudEventContext(
       const attributeName = name.substring(
         'ce-'.length,
       ) as keyof CloudEvent<unknown>;
-      context[attributeName] = req.header(name);
+      const val = req.header(name);
+      context[attributeName] = val
+        ? Buffer.from(val, 'binary').toString('utf-8')
+        : val;
     }
   }
   return context;

test/cloud_events.ts

@@ -0,0 +1,113 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import * as assert from 'assert';
+import {Request} from 'express';
+import {getBinaryCloudEventContext} from '../src/cloud_events';
+
+// Simulates what Node.js HTTP parsing produces when UTF-8-encoded bytes arrive
+// in a header and are decoded as Latin-1 (binary). This is what req.header()
+// returns in practice when non-ASCII Unicode is sent in CloudEvent extension
+// attributes by services like Firestore.
+function asNodeHttpHeader(s: string): string {
+  return Buffer.from(s, 'utf-8').toString('binary');
+}
+
+function makeMockRequest(headers: Record<string, string>): Request {
+  const lowercased = Object.fromEntries(
+    Object.entries(headers).map(([k, v]) => [k.toLowerCase(), v]),
+  );
+  return {
+    headers: lowercased,
+    header: (name: string) => lowercased[name.toLowerCase()],
+  } as unknown as Request;
+}
+
+describe('getBinaryCloudEventContext', () => {
+  describe('binary-encoded UTF-8 extension attributes (Firestore path params)', () => {
+    const cases = [
+      {
+        name: 'latin script with diacritics',
+        input: 'Helvétios',
+        expected: 'Helvétios',
+      },
+      {
+        name: 'CJK text',
+        input: asNodeHttpHeader('中文'),
+        expected: '中文',
+      },
+      {
+        name: 'emoji',
+        input: asNodeHttpHeader('😀'),
+        expected: '😀',
+      },
+      {
+        name: 'Hindi text',
+        input: asNodeHttpHeader('हिन्दी'),
+        expected: 'हिन्दी',
+      },
+      {
+        name: 'Arabic text',
+        input: asNodeHttpHeader('اَلْعَرَبِيَّةُ'),
+        expected: 'اَلْعَرَبِيَّةُ',
+      },
+    ];
+
+    for (const {name, input, expected} of cases) {
+      it(`decodes ${name}`, () => {
+        const req = makeMockRequest({
+          'ce-specversion': '1.0',
+          'ce-type': 'google.cloud.firestore.document.v1.created',
+          'ce-source': '//firestore.googleapis.com/projects/my-project',
+          'ce-id': 'test-id',
+          'ce-document': input,
+        });
+        const context = getBinaryCloudEventContext(req);
+        assert.strictEqual(context['document' as keyof typeof context], expected);
+      });
+    }
+
+    it('decodes mojibake embedded in a longer path', () => {
+      const req = makeMockRequest({
+        'ce-specversion': '1.0',
+        'ce-type': 'google.cloud.firestore.document.v1.created',
+        'ce-source': '//firestore.googleapis.com/projects/my-project',
+        'ce-id': 'test-id',
+        'ce-document': asNodeHttpHeader('users/Helvétios/posts/café'),
+      });
+      const context = getBinaryCloudEventContext(req);
+      assert.strictEqual(
+        context['document' as keyof typeof context],
+        'users/Helvétios/posts/café',
+      );
+    });
+  });
+
+  describe('ASCII extension attributes', () => {
+    it('passes through ASCII values without modification', () => {
+      const req = makeMockRequest({
+        'ce-specversion': '1.0',
+        'ce-type': 'google.cloud.firestore.document.v1.created',
+        'ce-source': '//firestore.googleapis.com/projects/my-project',
+        'ce-id': 'test-id',
+        'ce-document': 'users/hello-world',
+      });
+      const context = getBinaryCloudEventContext(req);
+      assert.strictEqual(
+        context['document' as keyof typeof context],
+        'users/hello-world',
+      );
+    });
+  });
+});