@gr2m/http-interceptor

Intercept and mock outgoing http/https requests

Install

npm install @gr2m/http-interceptor

Usage

import httpInterceptor from "@gr2m/http-interceptor";

httpInterceptor.start();
httpInterceptor.on("connect", (socket, options, bypass) => {
  // call bypass() to continue the unintercepted request
  if (options.host === "db.example.com") return bypass();
});

httpInterceptor.on("request", (request, response) => {
  response.end("Hello World!");
});

API

httpInterceptor is a singleton API.

httpInterceptor.start()

Hooks into the request life cycle and emits connect events for each request that connects to a server as well as request events for all intercepted requests.

httpInterceptor.stop()

Stops intercepting. No connect or request events will be emitted.

httpInterceptor.addListener(event, listener)

connect event

The listener callback is called with 3 arguments

• socket: the intercepted net or TLS socket
• options: socket options: {port, /* host, localAddress, localPort, family, allowHalfOpen */}
• bypass: a function to call to continue the unintercepted connection

request event

The listener callback is called with 2 arguments

• request: Http.IncomingMessage
• response: Http.ServerResponse

It's the same arguments as e.g. http.createServer(listener) receives.

httpInterceptor.removeListener(event, listener)

Remove an event listener.

httpInterceptor.removeAllListeners(event)

Removes all event listeners for the given event. Or when called without the event argument, remove all listeners for all events.

See also

• @gr2m/net-interceptor - Intercept outgoing network TCP/TLS connections
• @gr2m/http-recorder - Library agnostic in-process recording of http(s) requests and responses

How it works

@gr2m/http-interceptor is using @gr2m/net-interceptor to intercept TCP/TLS connections, and to permit to bypass the interception.

@gr2m/http-interceptor also hooks into http.ClientRequest.prototype.onSocket which is called in the http.ClientRequest constructor. Each time http.ClientRequest is instantiated with a socket, we check if the socket is intercepted and if so, emit the request event with a request/response pair for mocking.

Contributing

See CONTRIBUTING.md

Credits

@gr2m/http-interceptor is built upon code and concepts from moll/node-mitm by Andri Möll. Monday Calendar supported that engineering work.

Gregor Martynus removed all http(s)-related code and made its focus on intercepting connections that use the lower-level net and tls modules.

License

LGPL