<?php

class HTMLPurifier_URIFilter_DisableExternal extends HTMLPurifier_URIFilter
{
    public $name = 'DisableExternal';
    protected $ourHostParts = false;
    public function prepare($config) {
        $our_host = $config->getDefinition('URI')->host;
        if ($our_host !== null) $this->ourHostParts = array_reverse(explode('.', $our_host));
    }
    public function filter(&$uri, $config, $context) {
        if (is_null($uri->host)) return true;
        if ($this->ourHostParts === false) return false;
        $host_parts = array_reverse(explode('.', $uri->host));
        foreach ($this->ourHostParts as $i => $x) {
            if (!isset($host_parts[$i])) return false;
            if ($host_parts[$i] != $this->ourHostParts[$i]) return false;
        }
        return true;
    }
}