fix(core): Parse envelopes that contain an empty attachment

packages/core/src/utils/envelope.ts

@@ -168,7 +168,7 @@ export function parseEnvelope(env: string | Uint8Array): Envelope {
     const itemHeader = readJson<BaseEnvelopeItemHeaders>();
     const binaryLength = typeof itemHeader.length === 'number' ? itemHeader.length : undefined;
 
-    items.push([itemHeader, binaryLength ? readBinary(binaryLength) : readJson()]);
+    items.push([itemHeader, binaryLength !== undefined ? readBinary(binaryLength) : readJson()]);
   }
 
   return [envelopeHeader, items];

packages/core/test/lib/utils/envelope.test.ts

@@ -4,6 +4,7 @@ import type { EventEnvelope } from '../../../src/types/envelope';
 import type { Event } from '../../../src/types/event';
 import {
   addItemToEnvelope,
+  createAttachmentEnvelopeItem,
   createEnvelope,
   forEachEnvelopeItem,
   parseEnvelope,
@@ -90,6 +91,22 @@ describe('envelope', () => {
       after?.();
     });
 
+    it('parses an envelope with an empty attachment', () => {
+      const env = createEnvelope<EventEnvelope>({ event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2', sent_at: '123' }, [
+        [{ type: 'event' }, { event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2' }],
+        createAttachmentEnvelopeItem({ filename: 'empty.txt', data: '' }),
+        createAttachmentEnvelopeItem({ filename: 'foo.txt', data: 'foo' }),
+      ]);
+
+      const [, parsedItems] = parseEnvelope(serializeEnvelope(env));
+
+      expect(parsedItems).toEqual([
+        [{ type: 'event' }, { event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2' }],
+        [{ type: 'attachment', filename: 'empty.txt', length: 0 }, new Uint8Array(0)],
+        [{ type: 'attachment', filename: 'foo.txt', length: 3 }, new TextEncoder().encode('foo')],
+      ]);
+    });
+
     it("doesn't throw when being passed a an envelope that contains a circular item payload", () => {
       const chicken: { egg?: any } = {};
       const egg = { chicken } as unknown as Event;

packages/core/test/lib/utils/tunnel.test.ts

@@ -1,7 +1,7 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { getEnvelopeEndpointWithUrlEncodedAuth } from '../../../src/api';
 import { makeDsn } from '../../../src/utils/dsn';
-import { createEnvelope, serializeEnvelope } from '../../../src/utils/envelope';
+import { createAttachmentEnvelopeItem, createEnvelope, serializeEnvelope } from '../../../src/utils/envelope';
 import { handleTunnelRequest } from '../../../src/utils/tunnel';
 
 const TEST_DSN = 'https://public@dsn.ingest.sentry.io/1337';
@@ -43,6 +43,24 @@ describe('handleTunnelRequest', () => {
     expect(result).toBe(upstreamResponse);
   });
 
+  it('forwards an envelope that contains an empty attachment', async () => {
+    const upstreamResponse = new Response('ok', { status: 200 });
+    fetchMock.mockResolvedValueOnce(upstreamResponse);
+
+    const envelope = createEnvelope({ dsn: TEST_DSN }, [
+      [{ type: 'event' }, { event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2' }],
+      createAttachmentEnvelopeItem({ filename: 'empty.txt', data: '' }),
+    ]);
+
+    const result = await handleTunnelRequest({
+      request: new Request('http://localhost/tunnel', { method: 'POST', body: serializeEnvelope(envelope) }),
+      allowedDsns: [TEST_DSN],
+    });
+
+    expect(fetchMock).toHaveBeenCalledOnce();
+    expect(result).toBe(upstreamResponse);
+  });
+
   it('returns 500 when allowedDsns is empty', async () => {
     const result = await handleTunnelRequest({
       request: makeEnvelopeRequest({ dsn: TEST_DSN }),