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