CODEWITHSUNDEEP
javascriptnode.jsip-addresshostnamehosts
Abhilash Kant
Abhilash Kant

Reputation: 368

How to resolve hostname to an ip address in node js

I need to resolve hostname defined in hosts file to its corresponding IP address.

For example my host file look like this - "/etc/hosts"

127.0.0.1    ggns2dss81 localhost.localdomain localhost
::1     localhost6.localdomain6 localhost6
192.168.253.8    abcdserver
192.168.253.20   testwsserver

Now in my node.js, i can read content of this file, but i need to fetch for given hostname.

hostname = "testwsserver"
hostIP = getIP(hostname);
console.log(hostIP); // This should print 192.168.253.20

PS - npm pkg or any third party package cannot be installed on machine.

Help is much appreciated!!

Upvotes: 20

Views: 42969

Answers (3)

Lonnie Best
Lonnie Best

Reputation: 11454

Here's an example using standard modules, promises, and async/await:

import { default as dns } from 'dns';

async function getIP(hostname)
{
    let obj = await dns.promises.lookup(hostname).catch((error)=>
    {
        console.error(error);
    });
    return obj?.address;
}

async function main()
{
    let hostname = "stackoverflow.com";
    let hostIP = await getIP(hostname);
    console.log(`IP Address of ${hostname}:`, hostIP);
}
main();

You'd save this to a file ending with the extension mjs instead of js, so that node will know we're using the ES6 module's import statement instead of the commonJS require statement.

Upvotes: 2

Ben Winding
Ben Winding

Reputation: 11827

Just to build on Krzysztof Safjanowski's answer,

you can also use the builtin promisify utility to convert it to a promise rather than a callback.

const util = require('util');
const dns = require('dns');
const lookup = util.promisify(dns.lookup);

try {
  result = await lookup('google.com')
  console.log(result)
} catch (error) {
  console.error(error)
}

Upvotes: 8

Krzysztof Safjanowski
Krzysztof Safjanowski

Reputation: 7438

How about NodeJS documentation - DNS – have you checked it?

const dns = require('dns')

dns.lookup('testwsserver', function(err, result) {
  console.log(result)
})

Upvotes: 48

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