HTTP Sniffer – listening to the HTTP conversation

The events emitted by the HTTPServer object can be used for additional purposes beyond the immediate task of delivering a web application. The following code demonstrates a useful module that listens to all the HTTP Server events. It could be a useful debugging tool, which also demonstrates how HTTP server objects operate.

Node.js's HTTP Server object is an EventEmitter and the HTTP Sniffer simply listens to every server event, printing out information pertinent to each event.

Create a file named httpsniffer.js containing the following code:

var util = require('util');
var url  = require('url');

exports.sniffOn = function(server) {
  server.on('request', (req, res) => {
    util.log('e_request');
    util.log(reqToString(req));
  });
  server.on('close', errno => { util.log('e_close errno='+ errno);  });
  server.on('checkContinue', (req, res) => {
    util.log('e_checkContinue');
    util.log(reqToString(req));
    res.writeContinue...