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

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.example or someothersite.example. 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.

Solution

You have to retrieve it from the HOST header.

const 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.

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

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

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

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

const userIP = req.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.