advanced patterns with PHP 8.1's `filter_var` when validating IP addresses from user input
I've been struggling with this for a few days now and could really use some help. I'm experiencing an unexpected result when using `filter_var()` to validate IP addresses in PHP 8.1. I have a form input where users can enter their IP address, and I am trying to validate it using the FILTER_VALIDATE_IP filter. The question arises when users enter IP addresses in different formats, particularly IPv6 addresses. For example, when I input an IPv6 address like `2001:0db8:85a3:0000:0000:8a2e:0370:7334`, `filter_var()` returns `false`, which is not the behavior I expected. Here’s the code I’m using: ```php $ip = $_POST['user_ip']; if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) { echo 'Valid IPv6 address.'; } else { echo 'Invalid IP address.'; } ``` When I try a simple test with the same address directly in the code, it validates correctly. I’ve also tried removing the `FILTER_FLAG_IPV6` to see if it performs differently, but it still fails to validate. Is there something I might be missing regarding how input from `$_POST` is handled or any specific configurations in PHP 8.1 that could affect this? I've also checked the `allow_url_fopen` setting in my php.ini file, and it’s turned on, so that shouldn't be an scenario. Any ideas on what could be causing this behavior? My development environment is Ubuntu. What am I doing wrong?