Add cache layer for attachment streaming

ts/test-node/util/ValidatingPassThrough_test.ts

@@ -0,0 +1,72 @@
+// Copyright 2024 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import { randomBytes } from 'node:crypto';
+import { Readable } from 'node:stream';
+import { pipeline, finished } from 'node:stream/promises';
+import {
+  inferChunkSize,
+  DigestingWritable,
+} from '@signalapp/libsignal-client/dist/incremental_mac';
+
+import { ValidatingPassThrough } from '../../util/ValidatingPassThrough';
+
+// Use uneven chunk size to trigger buffering
+const CHUNK_SIZE = 13579;
+
+function toChunkedReadable(buffer: Buffer): Readable {
+  const chunked = new Array<Buffer>();
+  for (let i = 0; i < buffer.byteLength; i += CHUNK_SIZE) {
+    chunked.push(buffer.subarray(i, i + CHUNK_SIZE));
+  }
+
+  return Readable.from(chunked);
+}
+
+describe('ValidatingPassThrough', () => {
+  it('should emit whole source stream', async () => {
+    const source = randomBytes(10 * 1024 * 1024);
+    const key = randomBytes(32);
+
+    const chunkSize = inferChunkSize(source.byteLength);
+    const writable = new DigestingWritable(key, chunkSize);
+    await pipeline(Readable.from(source), writable);
+
+    const digest = writable.getFinalDigest();
+    const validator = new ValidatingPassThrough(key, chunkSize, digest);
+
+    const received = new Array<Buffer>();
+    validator.on('data', chunk => received.push(chunk));
+
+    await Promise.all([
+      pipeline(toChunkedReadable(source), validator),
+      finished(validator),
+    ]);
+
+    const actual = Buffer.concat(received);
+    assert.isTrue(actual.equals(source));
+  });
+
+  it('should emit error on digest mismatch', async () => {
+    const source = randomBytes(10 * 1024 * 1024);
+    const key = randomBytes(32);
+
+    const chunkSize = inferChunkSize(source.byteLength);
+    const writable = new DigestingWritable(key, chunkSize);
+    await pipeline(Readable.from(source), writable);
+
+    const digest = writable.getFinalDigest();
+    const wrongKey = randomBytes(32);
+    const validator = new ValidatingPassThrough(wrongKey, chunkSize, digest);
+
+    validator.on('data', () => {
+      throw new Error('Should not be called');
+    });
+
+    await assert.isRejected(
+      pipeline(toChunkedReadable(source), validator),
+      'Corrupted input data'
+    );
+  });
+});