How do I get the domain originating the request in express.js?

I'm using express.js and i need to know the domain which is originating the call. This is the simple code

app.get(
    '/verify_license_key.json',
    function( req, res ) {
    	// do something

How do i get the domain from the req or the res object? I mean i need to know if the api was called by somesite.com or someothersite.com. I tried doing a console.dir of both req and res but i got no idea from there, also read the documentation but it gave me no help.

You have to retrieve it from the HOST header.

var host = req.get('host');

It is optional with HTTP 1.0, but required by 1.1. And, the app can always impose a requirement of its own.

---

If this is for supporting cross-origin requests, you would instead use the Origin header.

var origin = req.get('origin');

Note that some cross-origin requests require validation through a "preflight" request:

req.options('/route', function (req, res) {
    var origin = req.get('origin');
    // ...
});

---

If you're looking for the client's IP, you can retrieve that with:

var userIP = req.socket.remoteAddress;

• message.socket.
• socket.remoteAddress

Note that, if your server is behind a proxy, this will likely give you the proxy's IP. Whether you can get the user's IP depends on what info the proxy passes along. But, it'll typically be in the headers as well.

Instead of:

var host = req.get('host');
var origin = req.get('origin');

you can also use:

var host = req.headers.host;
var origin = req.headers.origin;

In Express 4.x you can use req.hostname, which returns the domain name, without port. i.e.:

// Host: "example.com:3000"
req.hostname
// => "example.com"

See: http://expressjs.com/en/4x/api.html#req.hostname

req.get('host') is now deprecated, using it will give Undefined.

Use,

    req.header('Origin');
    req.header('Host');
    // this method can be used to access other request headers like, 'Referer', 'User-Agent' etc.