<?php
$domString = file_get_contents('google.com'); 
$doc = new DOMDocument(); 
$doc->loadHTML($domString); 
var_dump($doc->getElementsByTagName('input'));

php.net/manual/en/function.file-get-contents.php

php.net/manual/en/domdocument.getelementsbytagnam…

that's one of the simplest ways