app.js

const net = require("net");
const proxyServer = net.createServer();

const constants = require('./proxy/constants').Constants;
const proxyHandler = require('./proxy/proxy.handlers');
const utils = require('./proxy/proxy.utils');
const dirPath = __dirname;

const whiteListDomains = utils.GetWhitelistDomains(dirPath);

// =============================================
// Let's open port and run server.
// =============================================
proxyServer.listen(constants.PROXY_PORT_NUMBER, () => {
  console.log("Server running at http://localhost:" + constants.PROXY_PORT_NUMBER);
  console.log("\n");
});


// =============================================
// For each connection.
// =============================================
proxyServer.on("connection", (clientToProxySocket) => {    
  proxyHandler.RunForEachConnection(clientToProxySocket, whiteListDomains);  
});

// =============================================
// Problems with proxy server.
// =============================================
proxyServer.on("error", exitHandler.bind(null, { 
  exit: true, cleanup: true 
}));


// =============================================
// Close connection.
// =============================================
proxyServer.on("close", () => {
  console.log("Client Disconnected");
});


// =============================================
// Problems with this process.
// =============================================
process.on("uncaughtException", exitHandler.bind(null, { 
  exit: true, cleanup: true }
));


// So the program will not close instantly.
process.stdin.resume(); 

function exitHandler(options, exitCode) {
  
  // Cleaning up.
  if (options.cleanup) { 
    proxyServer.close();
    
    // CLEAN UP HERE!! kill port?
    // console.log("CLEANUP");    
  }
  
  if (exitCode || exitCode === 0) { 
    console.log(exitCode);    
    // console.log("EXITCODE");    
  }
  
  // Exiting... 
  if (options.exit) { 
    process.exit();        
  }
}


// https://stackoverflow.com/questions/14031763/doing-a-cleanup-action-just-before-node-js-exits
// do something when app is closing

process.on("exit", exitHandler.bind(null, { 
  cleanup: true 
}));

// catches ctrl+c event
process.on("SIGINT", exitHandler.bind(null, { 
  exit: true, cleanup: true 
}));

// catches "kill pid" (for example: nodemon restart)
process.on("SIGUSR1", exitHandler.bind(null, { 
  exit: true 
}));

process.on("SIGUSR2", exitHandler.bind(null, { 
  exit: true 
}));