Check if URL entered is from a certain domain - php

Question

I have a field where a user can enter a URL. I need to check if that URL is from a certain domain, in this case google.com.
I've tried this, however, it doesn't work for all cases (which I list below):
if(strstr(parse_url($link, PHP_URL_HOST), 'google.com') { // continue }
http://www.google.com/blah - works
https://www.google.com/blah - works
google.com/blah - doesn't work
www.google.com/blah - doesn't work
Is there a way to do this without regex? If not, how would it be done?
Thanks.

Answer 1

parse_url requires a valid URL and google.com/blah isn't valid (as of PHP 5.3.3) -- so it won't work. As a work around, you can append the http if doesn't exist already, and then check the domain.
Use the following function:
function checkRootDomain($url)
{
if (!preg_match("~^(?:f|ht)tps?://~i", $url)) {
$url = "http://" . $url;
}
$domain = implode('.', array_slice(explode('.', parse_url($url, PHP_URL_HOST)), -2));
if ($domain == 'google.com') {
return True;
} else {
return False;
}
}
Test cases:
var_dump(checkRootDomain('http://www.google.com/blah'));
var_dump(checkRootDomain('https://www.google.com/blah '));
var_dump(checkRootDomain('google.com/blah'));
var_dump(checkRootDomain('www.google.com/blah '));
Result:
bool(true)
bool(true)
bool(true)
bool(true)
It is a modified version of my own answer here.
Hope this helps!

Answer 2

This was an issue in php prior to version 5.4.7: http://php.net/manual/en/function.parse-url.php
Version 5.4.7 Fixed host recognition when scheme is omitted and a leading component separator is present.
<?php
$url = '//www.example.com/path?googleguy=googley';
// Prior to 5.4.7 this would show the path as "//www.example.com/path"
var_dump(parse_url($url));
?>
Your options are to upgrade to php >=5.4.7, or to detect a missing http: and add it if it is missing.

Answer 3

parse_url() requires a valid URL. If it doesn't have the scheme (ie the http:// bit) then it's not a valid URL.
You can add a scheme very easily, though. Just check whether the string contains a colon (:), and if not, add http:// to the front of it:
if(strpos($link, ':')===false) {$link = "http://".$link;}
Now your parse_url() call should work a bit better.