Request.headers missing or undefined-CodePudding

Hopefully somebody will find this a relatively simple answer, but it is beyond me at the moment. I have a Node.js/Express setup. I am simply trying to retrieve the client IP address upon each request to the site. My code is as follows:

const express = require('express');
const app = express();
const port = 3000;

...

// Start server...
var webServer = app.listen(process.env.PORT || port, function(request, response) { 
  console.log(" Received request for "   new Date()); 

  var _FORWARD_IP = request.headers['x-forwarded-for'];
  console.log('_FORWARD_IP (CLIENT IP ADDRESS): '   _FORWARD_IP);       
});

However this throws the following error:

"TypeError: Cannot read property 'headers' of undefined"

Therefore it seems there are no headers in the 'request' object within the 'app.listen' command. I am unsure how to resolve, this is the initial instance of dealing with something like this. If anybody knows an answer or a workaround it is greatly appreciated. I thank you in advance.

Regards

CodePudding user response：

app.listen() just starts the server, telling it to listen for requests. There is no request at that point in your code.

This sounds like a job for some custom middleware

const port = process.env.PORT || 3000;

// Middleware
app.use((req, res, next) => {
  const _FORWARD_IP = req.get('x-forwarded-for');
  console.log('_FORWARD_IP (CLIENT IP ADDRESS):', _FORWARD_IP);
  next();
});

app.listen(port, () => {
  // This callback executes when the server is ready to accept connections
  console.info(`Express server started on port ${port}`);
});