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https://github.com/ezyang/htmlpurifier.git
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8c9dbe142d
- Genericized flush-definition-cache script git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1333 48356398-32a2-884e-a903-53898d9a118a
263 lines
11 KiB
PHP
263 lines
11 KiB
PHP
<?php
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require_once 'HTMLPurifier/AttrDef.php';
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require_once 'HTMLPurifier/URIParser.php';
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require_once 'HTMLPurifier/URIScheme.php';
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require_once 'HTMLPurifier/URISchemeRegistry.php';
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require_once 'HTMLPurifier/AttrDef/URI/Host.php';
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require_once 'HTMLPurifier/PercentEncoder.php';
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HTMLPurifier_ConfigSchema::define(
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'URI', 'DefaultScheme', 'http', 'string',
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'Defines through what scheme the output will be served, in order to '.
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'select the proper object validator when no scheme information is present.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'Host', null, 'string/null',
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'Defines the domain name of the server, so we can determine whether or '.
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'an absolute URI is from your website or not. Not strictly necessary, '.
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'as users should be using relative URIs to reference resources on your '.
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'website. It will, however, let you use absolute URIs to link to '.
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'subdomains of the domain you post here: i.e. example.com will allow '.
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'sub.example.com. However, higher up domains will still be excluded: '.
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'if you set %URI.Host to sub.example.com, example.com will be blocked. '.
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'This directive has been available since 1.2.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'DisableExternal', false, 'bool',
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'Disables links to external websites. This is a highly effective '.
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'anti-spam and anti-pagerank-leech measure, but comes at a hefty price: no'.
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'links or images outside of your domain will be allowed. Non-linkified '.
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'URIs will still be preserved. If you want to be able to link to '.
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'subdomains or use absolute URIs, specify %URI.Host for your website. '.
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'This directive has been available since 1.2.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'DisableExternalResources', false, 'bool',
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'Disables the embedding of external resources, preventing users from '.
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'embedding things like images from other hosts. This prevents '.
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'access tracking (good for email viewers), bandwidth leeching, '.
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'cross-site request forging, goatse.cx posting, and '.
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'other nasties, but also results in '.
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'a loss of end-user functionality (they can\'t directly post a pic '.
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'they posted from Flickr anymore). Use it if you don\'t have a '.
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'robust user-content moderation team. This directive has been '.
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'available since 1.3.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'DisableResources', false, 'bool',
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'Disables embedding resources, essentially meaning no pictures. You can '.
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'still link to them though. See %URI.DisableExternalResources for why '.
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'this might be a good idea. This directive has been available since 1.3.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'Munge', null, 'string/null',
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'Munges all browsable (usually http, https and ftp) URI\'s into some URL '.
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'redirection service. Pass this directive a URI, with %s inserted where '.
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'the url-encoded original URI should be inserted (sample: '.
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'<code>http://www.google.com/url?q=%s</code>). '.
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'This prevents PageRank leaks, while being as transparent as possible '.
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'to users (you may also want to add some client side JavaScript to '.
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'override the text in the statusbar). Warning: many security experts '.
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'believe that this form of protection does not deter spam-bots. '.
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'You can also use this directive to redirect users to a splash page '.
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'telling them they are leaving your website. '.
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'This directive has been available since 1.3.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'HostBlacklist', array(), 'list',
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'List of strings that are forbidden in the host of any URI. Use it to '.
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'kill domain names of spam, etc. Note that it will catch anything in '.
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'the domain, so <tt>moo.com</tt> will catch <tt>moo.com.example.com</tt>. '.
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'This directive has been available since 1.3.0.'
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);
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HTMLPurifier_ConfigSchema::define(
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'URI', 'Disable', false, 'bool',
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'Disables all URIs in all forms. Not sure why you\'d want to do that '.
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'(after all, the Internet\'s founded on the notion of a hyperlink). '.
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'This directive has been available since 1.3.0.'
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);
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HTMLPurifier_ConfigSchema::defineAlias('Attr', 'DisableURI', 'URI', 'Disable');
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/**
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* Validates a URI as defined by RFC 3986.
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* @note Scheme-specific mechanics deferred to HTMLPurifier_URIScheme
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*/
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class HTMLPurifier_AttrDef_URI extends HTMLPurifier_AttrDef
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{
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var $host, $parser;
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var $embeds_resource;
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/**
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* @param $embeds_resource_resource Does the URI here result in an extra HTTP request?
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*/
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function HTMLPurifier_AttrDef_URI($embeds_resource = false) {
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$this->host = new HTMLPurifier_AttrDef_URI_Host();
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$this->parser = new HTMLPurifier_URIParser();
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$this->embeds_resource = (bool) $embeds_resource;
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}
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function validate($uri, $config, &$context) {
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static $PercentEncoder = null;
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if ($PercentEncoder === null) $PercentEncoder = new HTMLPurifier_PercentEncoder();
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if ($config->get('URI', 'Disable')) return false;
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// initial operations
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$uri = $this->parseCDATA($uri);
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$uri = $PercentEncoder->normalize($uri);
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// parse the URI
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$parsed_uri = $this->parser->parse($uri);
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if ($parsed_uri === false) return false;
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list($scheme, $userinfo, $host, $port, $path, $query, $fragment) = $parsed_uri;
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// retrieve the scheme object
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$registry =& HTMLPurifier_URISchemeRegistry::instance();
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$default_scheme = $config->get('URI', 'DefaultScheme');
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if ($scheme !== null) {
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// no need to validate the scheme's fmt since we do that when we
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// retrieve the specific scheme object from the registry
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$scheme = ctype_lower($scheme) ? $scheme : strtolower($scheme);
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$scheme_obj = $registry->getScheme($scheme, $config, $context);
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if (!$scheme_obj) return false; // invalid scheme, clean it out
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} else {
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// no scheme: retrieve the default one
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$scheme_obj = $registry->getScheme($default_scheme, $config, $context);
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if (!$scheme_obj) {
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// something funky happened to the default scheme object
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trigger_error(
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'Default scheme object "' . $config->get('URI', 'DefaultScheme') . '" was not readable',
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E_USER_WARNING
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);
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return false;
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}
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}
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if ($this->embeds_resource && !$scheme_obj->browsable) {
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// the URI we're processing embeds_resource a resource in the
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// page, but the URI it references cannot be physically retrieved
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return false;
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}
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// validate host
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if ($host !== null) {
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// remove URI if it's absolute and we disabled externals or
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// if it's absolute and embedded and we disabled external resources
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unset($our_host);
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if (
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$config->get('URI', 'DisableExternal') ||
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(
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$config->get('URI', 'DisableExternalResources') &&
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$this->embeds_resource
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)
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) {
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$our_host = $config->get('URI', 'Host');
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if ($our_host === null) return false;
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}
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$host = $this->host->validate($host, $config, $context);
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if ($host === false) $host = null;
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// check host against blacklist
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if ($this->checkBlacklist($host, $config, $context)) return false;
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// more lenient absolute checking
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if (isset($our_host)) {
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$host_parts = array_reverse(explode('.', $host));
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// could be cached
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$our_host_parts = array_reverse(explode('.', $our_host));
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foreach ($our_host_parts as $i => $discard) {
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if (!isset($host_parts[$i])) return false;
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if ($host_parts[$i] != $our_host_parts[$i]) return false;
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}
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}
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}
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// validate port
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if ($port !== null) {
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if ($port < 1 || $port > 65535) $port = null;
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}
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// query and fragment are quite simple in terms of definition:
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// *( pchar / "/" / "?" ), so define their validation routines
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// when we start fixing percent encoding
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// path gets to be validated against a hodge-podge of rules depending
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// on the status of authority and scheme, but it's not that important,
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// esp. since it won't be applicable to everyone
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// okay, now we defer execution to the subobject for more processing
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// note that $fragment is omitted
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list($userinfo, $host, $port, $path, $query) =
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$scheme_obj->validateComponents(
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$userinfo, $host, $port, $path, $query, $config, $context
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);
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// reconstruct authority
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$authority = null;
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if (!is_null($userinfo) || !is_null($host) || !is_null($port)) {
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$authority = '';
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if($userinfo !== null) $authority .= $userinfo . '@';
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$authority .= $host;
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if($port !== null) $authority .= ':' . $port;
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} else {
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if ($default_scheme == $scheme) $scheme = null; // munge scheme off when unnecessary
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}
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// reconstruct the result
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$result = '';
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if ($scheme !== null) $result .= "$scheme:";
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if ($authority !== null) $result .= "//$authority";
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$result .= $path;
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if ($query !== null) $result .= "?$query";
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if ($fragment !== null) $result .= "#$fragment";
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// munge if necessary
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$munge = $config->get('URI', 'Munge');
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if (!empty($scheme_obj->browsable) && $munge !== null) {
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if ($authority !== null) {
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$result = str_replace('%s', rawurlencode($result), $munge);
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}
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}
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return $result;
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}
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/**
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* Checks a host against an array blacklist
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* @param $host Host to check
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* @param $config HTMLPurifier_Config instance
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* @param $context HTMLPurifier_Context instance
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* @return bool Is spam?
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*/
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function checkBlacklist($host, &$config, &$context) {
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$blacklist = $config->get('URI', 'HostBlacklist');
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if (!empty($blacklist)) {
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foreach($blacklist as $blacklisted_host_fragment) {
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if (strpos($host, $blacklisted_host_fragment) !== false) {
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return true;
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}
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}
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}
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return false;
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}
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}
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