Function probePort

packages/cli/src/server/portUtils.ts:225–261

* Probe a single port for a HyperFrames config response. * Returns the full config or null if not a HyperFrames server.

(port: number)

 * Returns the full config or null if not a HyperFrames server.
 */
function probePort(port: number): Promise<HyperframesConfigResponse | null> {
  return new Promise<HyperframesConfigResponse | null>((resolveResult) => {
    const req = http.get(
      { hostname: "127.0.0.1", port, path: "/__hyperframes_config", timeout: PROBE_TIMEOUT_MS },
      (res) => {
        if (res.statusCode !== 200) {
          res.resume();
          return resolveResult(null);
        }
        let data = "";
        let bytes = 0;
        res.on("data", (chunk: Buffer | string) => {
          bytes += typeof chunk === "string" ? chunk.length : chunk.byteLength;
          if (bytes > PROBE_MAX_BYTES) {
            req.destroy();
            return resolveResult(null);
          }
          data += chunk;
        });
        res.on("error", () => resolveResult(null));
        res.on("end", () => {
          try {
            const json = JSON.parse(data) as HyperframesConfigResponse;
            resolveResult(json.isHyperframes === true ? json : null);
          } catch {
            resolveResult(null);
          }
        });
      },
    );
    req.on("error", () => resolveResult(null));
    req.on("timeout", () => {
      req.destroy();
      resolveResult(null);
    });
  });
}

/**
 * Scan the default port range for active HyperFrames preview servers.