server.js

var net = require('net');
var fs = require('fs');
var path = require('path');
var config = require('./config');
var startStopDaemon = require('start-stop-daemon');

startStopDaemon({logFile: config.logfile, errFile: config.error_logfile}, function() {
  var policypath = path.resolve(__dirname, config.policyfile);
  var policy = fs.readFileSync(policypath);

  var command = '<policy-file-request/>';
  var commandLength = command.length;

  var connectionCount = 0;

  var server = net.createServer(function (socket) {

      socket.openedAt = new Date();
      socket.connectionId = ++connectionCount;
      socket.connectionRemoteAddress = socket.remoteAddress; // remember remote ip

      logForConnection(socket, 'connected');

      socket.setTimeout(config.timeout, function () {
          logForConnection(socket, 'timeout');
          socket.destroy();
      });

      socket.on('data', function (data) {
          var message = 'received ';
          if (config.log_request_data) {
              message += escape(data.toString()) + ' - ';
          }

          message += data.toString().length + ' bytes - '
          if (data.toString().slice(0, commandLength) === command) {
              socket.end(policy);
              message += 'OK';
          } else {
              socket.end();
              message += 'BAD';
          }
          socket.destroy();
          logForConnection(socket, message);
      });

      socket.on('close', function () {
          logForConnection(socket, 'closed (handled in ' + (new Date() - socket.openedAt) + 'ms)');
      });

      socket.on('error', function (e) {
          logForConnection(socket, 'error receiving data: ' + e);
          socket.destroy();
      });
  });
  server.on('error', function (e) {
      if (e.code == 'EADDRINUSE') {
          log("server error, address already in use: " + e);
      } else {
          log("server error: " + e);
      }
  });
  server.on('close', function () {
      log("socket policy server closing after handling " + connectionCount + " connections");
  });

  log('socket policy server binding to port ' + config.port + ' on ' + config.host + ' with policy file ' + policypath);
  server.listen(config.port, config.host, function () {
    log("successfully bound!");
  });

  function logForConnection(socket, message) {
      log(socket.connectionId + ' - ' + socket.connectionRemoteAddress + ' - ' + message);
  }

  function log(message) {
      if (!config.logging) {
        return;
      }
      var t = (new Date()).toISOString();
      console.log(t + ' - ' + message);
  }

  function escape(message) {
      return message.replace(/\n/g, '\\n').replace(/\r/g, '\\r').replace(/\x07\x1b\f\t\v/g, '?');
  }
});