Function forwardRequest

packages/cli/src/commands/ui-proxy.ts:255–352

(
  req: IncomingMessage,
  res: ServerResponse,
  upstreamHost: string,
  upstreamPort: number,
  upstreamTimeoutMs: number,
)

}

function forwardRequest(
  req: IncomingMessage,
  res: ServerResponse,
  upstreamHost: string,
  upstreamPort: number,
  upstreamTimeoutMs: number,
): void {
  const headers: IncomingHttpHeaders = { ...req.headers };
  delete headers.host;
  for (const name of HOP_BY_HOP_HEADERS) {
    delete headers[name];
  }

  req.setTimeout(DEFAULT_REQUEST_TIMEOUT_MS, () => {
    if (!res.headersSent) {
      try {
        emitProblem(
          res,
          408,
          'urn:ok:error:request-timeout',
          'Proxy request exceeded the per-request deadline.',
          `Slow-loris-class: client did not finish within ${DEFAULT_REQUEST_TIMEOUT_MS / 1000}s.`,
        );
      } catch {}
    } else {
      try {
        res.end();
      } catch {}
    }
    try {
      req.socket?.destroy();
    } catch {}
  });

  const upstreamReq = httpRequest(
    {
      host: upstreamHost,
      port: upstreamPort,
      method: req.method,
      path: req.url,
      headers: { ...headers, host: `${upstreamHost}:${upstreamPort}` },
    },
    (upstreamRes) => {
      const resHeaders = { ...upstreamRes.headers };
      for (const name of HOP_BY_HOP_HEADERS) {
        delete resHeaders[name];
      }
      res.writeHead(upstreamRes.statusCode ?? 502, resHeaders);
      upstreamRes.pipe(res);
      upstreamRes.once('error', () => {
        try {
          res.end();
        } catch {}
      });
    },
  );

  if (upstreamTimeoutMs > 0) {