bun-src/test/regression/issue/26915.test.ts

import assert from "node:assert";
import { once } from "node:events";
import http2 from "node:http2";
import { test } from "node:test";

// Regression test for https://github.com/oven-sh/bun/issues/26915
// setLocalWindowSize() must send a connection-level WINDOW_UPDATE frame.
// Without this, the peer's connection-level window stays at the default
// 65,535 bytes and streams stall when receiving larger payloads.

function startServer(payloadSize: number): Promise<{ port: number; server: http2.Http2Server }> {
  const payload = Buffer.alloc(payloadSize, "x");
  return new Promise(resolve => {
    const server = http2.createServer();
    server.on("stream", stream => {
      stream.respond({ ":status": 200 });
      stream.end(payload);
    });
    server.listen(0, () => {
      const addr = server.address();
      if (addr && typeof addr === "object") {
        resolve({ port: addr.port, server });
      }
    });
  });
}

function doRequest(client: http2.ClientHttp2Session): Promise<Buffer> {
  return new Promise((resolve, reject) => {
    const req = client.request({ ":path": "/" });
    const chunks: Buffer[] = [];
    req.on("data", (chunk: Buffer) => chunks.push(chunk));
    req.on("end", () => resolve(Buffer.concat(chunks)));
    req.on("error", reject);
    req.end();
  });
}

function closeClient(client: http2.ClientHttp2Session): Promise<void> {
  return new Promise(resolve => client.close(resolve));
}

function closeServer(server: http2.Http2Server): Promise<void> {
  return new Promise(resolve => server.close(() => resolve()));
}

test("http2 client setLocalWindowSize sends connection-level WINDOW_UPDATE", async () => {
  const payloadSize = 256 * 1024; // 256 KB - well above the 65535 default
  const { port, server } = await startServer(payloadSize);

  try {
    const client = http2.connect(`http://127.0.0.1:${port}`, {
      settings: { initialWindowSize: 10 * 1024 * 1024 },
    });

    // setLocalWindowSize requires the session handle to be ready
    await once(client, "connect");
    client.setLocalWindowSize(10 * 1024 * 1024);

    const result = await doRequest(client);
    assert.strictEqual(result.length, payloadSize);

    await closeClient(client);
  } finally {
    await closeServer(server);
  }
});

test("http2 client initialWindowSize setting allows large stream payloads", async () => {
  const payloadSize = 1024 * 1024; // 1 MB
  const { port, server } = await startServer(payloadSize);

  try {
    const client = http2.connect(`http://127.0.0.1:${port}`, {
      settings: { initialWindowSize: 10 * 1024 * 1024 },
    });

    const result = await doRequest(client);
    assert.strictEqual(result.length, payloadSize);

    await closeClient(client);
  } finally {
    await closeServer(server);
  }
});