I need to check if a form field is a valid URL (it can be done through HTML5, but not every browser has it yet), and I can't find a good URL checker function. It's strange, because with email-checking, there are lots of already-done functions.
I've seen (I just discovered it) the filter_var() function, but as I read, there are some issues with urls.
I can find some regular expressions, but they don't seem very exhaustive.
Do you know any good url checker function?
It's because URL format can be so versatile :
Http// is optionnal
www is optionnal
.com, .net, .us, etc so many possible pattern
.html, /, .php, or nothing are possible ends
Rather than using a pre-made function, I'd recommend you to build your own function depending on how most of your users send URL, with which ending etc ...
My two cents.
Let's go a little advanced:
<?php
function validate_url($url) {
return (bool)preg_match("
/^ # Start at the beginning of the text
(?:ftp|https?|feed):\/\/ # Look for ftp, http, https or feed schemes
(?: # Userinfo (optional) which is typically
(?:(?:[\w\.\-\+!$&'\(\)*\+,;=]|%[0-9a-f]{2})+:)* # a username or a username and password
(?:[\w\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})+@ # combination
)?
(?:
(?:[a-z0-9\-\.]|%[0-9a-f]{2})+ # A domain name or a IPv4 address
|(?:\[(?:[0-9a-f]{0,4}:)*(?:[0-9a-f]{0,4})\]) # or a well formed IPv6 address
)
(?::[0-9]+)? # Server port number (optional)
(?:[\/|\?]
(?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2}) # The path and query (optional)
*)?
$/xi", $url);
}
?>
Mainly from valid_url function in Drupal.
Example use:
validate_url($url); // this will return TRUE if the URL is correct. Protocol should exist in $url
Or try a different aproach.
Why not check with file_get_contents($url) ? This way you will also know if the URL works, or not.
I guess you could use something like fread(fopen($url,'r'),100); so it can not be injected with some huge file. Checking for things like localhost, is still something you might want to do.
