243 lines
9.2 KiB
PHP
243 lines
9.2 KiB
PHP
<?php
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/**
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* HTML Purifier's internal representation of a URI.
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* @note
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* Internal data-structures are completely escaped. If the data needs
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* to be used in a non-URI context (which is very unlikely), be sure
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* to decode it first. The URI may not necessarily be well-formed until
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* validate() is called.
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*/
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class HTMLPurifier_URI
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{
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public $scheme, $userinfo, $host, $port, $path, $query, $fragment;
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/**
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* @note Automatically normalizes scheme and port
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*/
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public function __construct($scheme, $userinfo, $host, $port, $path, $query, $fragment) {
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$this->scheme = is_null($scheme) || ctype_lower($scheme) ? $scheme : strtolower($scheme);
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$this->userinfo = $userinfo;
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$this->host = $host;
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$this->port = is_null($port) ? $port : (int) $port;
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$this->path = $path;
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$this->query = $query;
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$this->fragment = $fragment;
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}
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/**
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* Retrieves a scheme object corresponding to the URI's scheme/default
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* @param $config Instance of HTMLPurifier_Config
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* @param $context Instance of HTMLPurifier_Context
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* @return Scheme object appropriate for validating this URI
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*/
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public function getSchemeObj($config, $context) {
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$registry = HTMLPurifier_URISchemeRegistry::instance();
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if ($this->scheme !== null) {
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$scheme_obj = $registry->getScheme($this->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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$def = $config->getDefinition('URI');
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$scheme_obj = $def->getDefaultScheme($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 "' . $def->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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return $scheme_obj;
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}
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/**
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* Generic validation method applicable for all schemes. May modify
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* this URI in order to get it into a compliant form.
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* @param $config Instance of HTMLPurifier_Config
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* @param $context Instance of HTMLPurifier_Context
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* @return True if validation/filtering succeeds, false if failure
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*/
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public function validate($config, $context) {
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// ABNF definitions from RFC 3986
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$chars_sub_delims = '!$&\'()*+,;=';
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$chars_gen_delims = ':/?#[]@';
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$chars_pchar = $chars_sub_delims . ':@';
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// validate host
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if (!is_null($this->host)) {
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$host_def = new HTMLPurifier_AttrDef_URI_Host();
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$this->host = $host_def->validate($this->host, $config, $context);
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if ($this->host === false) $this->host = null;
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}
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// validate scheme
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// NOTE: It's not appropriate to check whether or not this
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// scheme is in our registry, since a URIFilter may convert a
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// URI that we don't allow into one we do. So instead, we just
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// check if the scheme can be dropped because there is no host
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// and it is our default scheme.
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if (!is_null($this->scheme) && is_null($this->host) || $this->host === '') {
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// support for relative paths is pretty abysmal when the
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// scheme is present, so axe it when possible
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$def = $config->getDefinition('URI');
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if ($def->defaultScheme === $this->scheme) {
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$this->scheme = null;
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}
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}
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// validate username
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if (!is_null($this->userinfo)) {
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$encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . ':');
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$this->userinfo = $encoder->encode($this->userinfo);
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}
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// validate port
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if (!is_null($this->port)) {
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if ($this->port < 1 || $this->port > 65535) $this->port = null;
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}
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// validate path
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$path_parts = array();
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$segments_encoder = new HTMLPurifier_PercentEncoder($chars_pchar . '/');
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if (!is_null($this->host)) { // this catches $this->host === ''
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// path-abempty (hier and relative)
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// http://www.example.com/my/path
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// //www.example.com/my/path (looks odd, but works, and
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// recognized by most browsers)
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// (this set is valid or invalid on a scheme by scheme
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// basis, so we'll deal with it later)
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// file:///my/path
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// ///my/path
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$this->path = $segments_encoder->encode($this->path);
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} elseif ($this->path !== '') {
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if ($this->path[0] === '/') {
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// path-absolute (hier and relative)
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// http:/my/path
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// /my/path
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if (strlen($this->path) >= 2 && $this->path[1] === '/') {
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// This could happen if both the host gets stripped
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// out
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// http://my/path
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// //my/path
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$this->path = '';
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} else {
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$this->path = $segments_encoder->encode($this->path);
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}
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} elseif (!is_null($this->scheme)) {
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// path-rootless (hier)
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// http:my/path
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// Short circuit evaluation means we don't need to check nz
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$this->path = $segments_encoder->encode($this->path);
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} else {
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// path-noscheme (relative)
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// my/path
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// (once again, not checking nz)
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$segment_nc_encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . '@');
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$c = strpos($this->path, '/');
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if ($c !== false) {
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$this->path =
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$segment_nc_encoder->encode(substr($this->path, 0, $c)) .
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$segments_encoder->encode(substr($this->path, $c));
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} else {
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$this->path = $segment_nc_encoder->encode($this->path);
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}
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}
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} else {
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// path-empty (hier and relative)
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$this->path = ''; // just to be safe
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}
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// qf = query and fragment
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$qf_encoder = new HTMLPurifier_PercentEncoder($chars_pchar . '/?');
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if (!is_null($this->query)) {
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$this->query = $qf_encoder->encode($this->query);
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}
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if (!is_null($this->fragment)) {
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$this->fragment = $qf_encoder->encode($this->fragment);
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}
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return true;
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}
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/**
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* Convert URI back to string
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* @return String URI appropriate for output
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*/
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public function toString() {
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// reconstruct authority
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$authority = null;
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// there is a rendering difference between a null authority
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// (http:foo-bar) and an empty string authority
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// (http:///foo-bar).
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if (!is_null($this->host)) {
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$authority = '';
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if(!is_null($this->userinfo)) $authority .= $this->userinfo . '@';
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$authority .= $this->host;
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if(!is_null($this->port)) $authority .= ':' . $this->port;
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}
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// Reconstruct the result
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// One might wonder about parsing quirks from browsers after
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// this reconstruction. Unfortunately, parsing behavior depends
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// on what *scheme* was employed (file:///foo is handled *very*
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// differently than http:///foo), so unfortunately we have to
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// defer to the schemes to do the right thing.
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$result = '';
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if (!is_null($this->scheme)) $result .= $this->scheme . ':';
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if (!is_null($authority)) $result .= '//' . $authority;
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$result .= $this->path;
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if (!is_null($this->query)) $result .= '?' . $this->query;
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if (!is_null($this->fragment)) $result .= '#' . $this->fragment;
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return $result;
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}
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/**
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* Returns true if this URL might be considered a 'local' URL given
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* the current context. This is true when the host is null, or
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* when it matches the host supplied to the configuration.
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*
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* Note that this does not do any scheme checking, so it is mostly
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* only appropriate for metadata that doesn't care about protocol
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* security. isBenign is probably what you actually want.
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*/
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public function isLocal($config, $context) {
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if ($this->host === null) return true;
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$uri_def = $config->getDefinition('URI');
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if ($uri_def->host === $this->host) return true;
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return false;
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}
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/**
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* Returns true if this URL should be considered a 'benign' URL,
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* that is:
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*
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* - It is a local URL (isLocal), and
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* - It has a equal or better level of security
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*/
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public function isBenign($config, $context) {
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if (!$this->isLocal($config, $context)) return false;
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$scheme_obj = $this->getSchemeObj($config, $context);
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if (!$scheme_obj) return false; // conservative approach
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$current_scheme_obj = $config->getDefinition('URI')->getDefaultScheme($config, $context);
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if ($current_scheme_obj->secure) {
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if (!$scheme_obj->secure) {
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return false;
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}
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}
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return true;
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}
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}
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// vim: et sw=4 sts=4
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