forked from GNUsocial/gnu-social
382 lines
12 KiB
PHP
382 lines
12 KiB
PHP
<?php
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/**
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* This module implements a VERY limited parser that finds <link> tags
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* in the head of HTML or XHTML documents and parses out their
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* attributes according to the OpenID spec. It is a liberal parser,
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* but it requires these things from the data in order to work:
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*
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* - There must be an open <html> tag
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*
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* - There must be an open <head> tag inside of the <html> tag
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*
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* - Only <link>s that are found inside of the <head> tag are parsed
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* (this is by design)
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*
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* - The parser follows the OpenID specification in resolving the
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* attributes of the link tags. This means that the attributes DO
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* NOT get resolved as they would by an XML or HTML parser. In
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* particular, only certain entities get replaced, and href
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* attributes do not get resolved relative to a base URL.
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*
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* From http://openid.net/specs.bml:
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*
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* - The openid.server URL MUST be an absolute URL. OpenID consumers
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* MUST NOT attempt to resolve relative URLs.
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*
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* - The openid.server URL MUST NOT include entities other than &,
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* <, >, and ".
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*
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* The parser ignores SGML comments and <![CDATA[blocks]]>. Both kinds
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* of quoting are allowed for attributes.
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*
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* The parser deals with invalid markup in these ways:
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*
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* - Tag names are not case-sensitive
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*
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* - The <html> tag is accepted even when it is not at the top level
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*
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* - The <head> tag is accepted even when it is not a direct child of
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* the <html> tag, but a <html> tag must be an ancestor of the
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* <head> tag
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*
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* - <link> tags are accepted even when they are not direct children
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* of the <head> tag, but a <head> tag must be an ancestor of the
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* <link> tag
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*
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* - If there is no closing tag for an open <html> or <head> tag, the
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* remainder of the document is viewed as being inside of the
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* tag. If there is no closing tag for a <link> tag, the link tag is
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* treated as a short tag. Exceptions to this rule are that <html>
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* closes <html> and <body> or <head> closes <head>
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*
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* - Attributes of the <link> tag are not required to be quoted.
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*
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* - In the case of duplicated attribute names, the attribute coming
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* last in the tag will be the value returned.
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*
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* - Any text that does not parse as an attribute within a link tag
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* will be ignored. (e.g. <link pumpkin rel='openid.server' /> will
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* ignore pumpkin)
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*
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* - If there are more than one <html> or <head> tag, the parser only
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* looks inside of the first one.
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*
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* - The contents of <script> tags are ignored entirely, except
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* unclosed <script> tags. Unclosed <script> tags are ignored.
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*
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* - Any other invalid markup is ignored, including unclosed SGML
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* comments and unclosed <![CDATA[blocks.
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*
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* PHP versions 4 and 5
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*
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* LICENSE: See the COPYING file included in this distribution.
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*
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* @access private
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* @package OpenID
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* @author JanRain, Inc. <openid@janrain.com>
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* @copyright 2005-2008 Janrain, Inc.
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* @license http://www.apache.org/licenses/LICENSE-2.0 Apache
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*/
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/**
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* Require Auth_OpenID::arrayGet().
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*/
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require_once "Auth/OpenID.php";
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class Auth_OpenID_Parse {
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/**
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* Specify some flags for use with regex matching.
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*/
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var $_re_flags = "si";
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/**
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* Stuff to remove before we start looking for tags
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*/
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var $_removed_re =
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"<!--.*?-->|<!\[CDATA\[.*?\]\]>|<script\b(?!:)[^>]*>.*?<\/script>";
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/**
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* Starts with the tag name at a word boundary, where the tag name
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* is not a namespace
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*/
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var $_tag_expr = "<%s\b(?!:)([^>]*?)(?:\/>|>(.*)(?:<\/?%s\s*>|\Z))";
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var $_attr_find = '\b(\w+)=("[^"]*"|\'[^\']*\'|[^\'"\s\/<>]+)';
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var $_open_tag_expr = "<%s\b";
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var $_close_tag_expr = "<((\/%s\b)|(%s[^>\/]*\/))>";
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function Auth_OpenID_Parse()
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{
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$this->_link_find = sprintf("/<link\b(?!:)([^>]*)(?!<)>/%s",
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$this->_re_flags);
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$this->_entity_replacements = array(
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'amp' => '&',
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'lt' => '<',
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'gt' => '>',
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'quot' => '"'
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);
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$this->_attr_find = sprintf("/%s/%s",
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$this->_attr_find,
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$this->_re_flags);
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$this->_removed_re = sprintf("/%s/%s",
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$this->_removed_re,
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$this->_re_flags);
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$this->_ent_replace =
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sprintf("&(%s);", implode("|",
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$this->_entity_replacements));
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}
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/**
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* Returns a regular expression that will match a given tag in an
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* SGML string.
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*/
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function tagMatcher($tag_name, $close_tags = null)
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{
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$expr = $this->_tag_expr;
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if ($close_tags) {
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$options = implode("|", array_merge(array($tag_name), $close_tags));
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$closer = sprintf("(?:%s)", $options);
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} else {
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$closer = $tag_name;
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}
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$expr = sprintf($expr, $tag_name, $closer);
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return sprintf("/%s/%s", $expr, $this->_re_flags);
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}
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function openTag($tag_name)
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{
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$expr = sprintf($this->_open_tag_expr, $tag_name);
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return sprintf("/%s/%s", $expr, $this->_re_flags);
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}
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function closeTag($tag_name)
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{
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$expr = sprintf($this->_close_tag_expr, $tag_name, $tag_name);
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return sprintf("/%s/%s", $expr, $this->_re_flags);
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}
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function htmlBegin($s)
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{
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$matches = array();
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$result = preg_match($this->openTag('html'), $s,
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$matches, PREG_OFFSET_CAPTURE);
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if ($result === false || !$matches) {
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return false;
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}
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// Return the offset of the first match.
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return $matches[0][1];
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}
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function htmlEnd($s)
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{
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$matches = array();
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$result = preg_match($this->closeTag('html'), $s,
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$matches, PREG_OFFSET_CAPTURE);
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if ($result === false || !$matches) {
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return false;
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}
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// Return the offset of the first match.
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return $matches[count($matches) - 1][1];
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}
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function headFind()
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{
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return $this->tagMatcher('head', array('body', 'html'));
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}
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function replaceEntities($str)
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{
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foreach ($this->_entity_replacements as $old => $new) {
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$str = preg_replace(sprintf("/&%s;/", $old), $new, $str);
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}
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return $str;
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}
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function removeQuotes($str)
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{
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$matches = array();
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$double = '/^"(.*)"$/';
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$single = "/^\'(.*)\'$/";
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if (preg_match($double, $str, $matches)) {
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return $matches[1];
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} else if (preg_match($single, $str, $matches)) {
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return $matches[1];
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} else {
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return $str;
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}
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}
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function match($regexp, $text, &$match)
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{
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if (!is_callable('mb_ereg_search_init')) {
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if (!preg_match($regexp, $text, $match)) {
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return false;
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}
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$match = $match[0];
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return true;
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}
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$regexp = substr($regexp, 1, strlen($regexp) - 2 - strlen($this->_re_flags));
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mb_ereg_search_init($text);
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if (!mb_ereg_search($regexp)) {
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return false;
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}
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$match = mb_ereg_search_getregs();
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return true;
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}
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/**
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* Find all link tags in a string representing a HTML document and
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* return a list of their attributes.
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*
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* @todo This is quite ineffective and may fail with the default
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* pcre.backtrack_limit of 100000 in PHP 5.2, if $html is big.
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* It should rather use stripos (in PHP5) or strpos()+strtoupper()
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* in PHP4 to manage this.
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*
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* @param string $html The text to parse
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* @return array $list An array of arrays of attributes, one for each
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* link tag
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*/
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function parseLinkAttrs($html)
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{
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$stripped = preg_replace($this->_removed_re,
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"",
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$html);
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$html_begin = $this->htmlBegin($stripped);
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$html_end = $this->htmlEnd($stripped);
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if ($html_begin === false) {
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return array();
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}
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if ($html_end === false) {
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$html_end = strlen($stripped);
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}
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$stripped = substr($stripped, $html_begin,
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$html_end - $html_begin);
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// Workaround to prevent PREG_BACKTRACK_LIMIT_ERROR:
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$old_btlimit = ini_set( 'pcre.backtrack_limit', -1 );
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// Try to find the <HEAD> tag.
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$head_re = $this->headFind();
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$head_match = array();
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if (!$this->match($head_re, $stripped, $head_match)) {
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ini_set( 'pcre.backtrack_limit', $old_btlimit );
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return array();
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}
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$link_data = array();
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$link_matches = array();
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if (!preg_match_all($this->_link_find, $head_match[0],
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$link_matches)) {
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ini_set( 'pcre.backtrack_limit', $old_btlimit );
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return array();
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}
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foreach ($link_matches[0] as $link) {
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$attr_matches = array();
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preg_match_all($this->_attr_find, $link, $attr_matches);
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$link_attrs = array();
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foreach ($attr_matches[0] as $index => $full_match) {
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$name = $attr_matches[1][$index];
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$value = $this->replaceEntities(
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$this->removeQuotes($attr_matches[2][$index]));
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$link_attrs[strtolower($name)] = $value;
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}
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$link_data[] = $link_attrs;
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}
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ini_set( 'pcre.backtrack_limit', $old_btlimit );
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return $link_data;
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}
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function relMatches($rel_attr, $target_rel)
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{
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// Does this target_rel appear in the rel_str?
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// XXX: TESTME
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$rels = preg_split("/\s+/", trim($rel_attr));
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foreach ($rels as $rel) {
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$rel = strtolower($rel);
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if ($rel == $target_rel) {
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return 1;
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}
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}
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return 0;
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}
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function linkHasRel($link_attrs, $target_rel)
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{
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// Does this link have target_rel as a relationship?
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// XXX: TESTME
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$rel_attr = Auth_OpeniD::arrayGet($link_attrs, 'rel', null);
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return ($rel_attr && $this->relMatches($rel_attr,
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$target_rel));
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}
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function findLinksRel($link_attrs_list, $target_rel)
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{
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// Filter the list of link attributes on whether it has
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// target_rel as a relationship.
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// XXX: TESTME
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$result = array();
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foreach ($link_attrs_list as $attr) {
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if ($this->linkHasRel($attr, $target_rel)) {
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$result[] = $attr;
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}
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}
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return $result;
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}
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function findFirstHref($link_attrs_list, $target_rel)
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{
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// Return the value of the href attribute for the first link
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// tag in the list that has target_rel as a relationship.
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// XXX: TESTME
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$matches = $this->findLinksRel($link_attrs_list,
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$target_rel);
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if (!$matches) {
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return null;
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}
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$first = $matches[0];
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return Auth_OpenID::arrayGet($first, 'href', null);
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}
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}
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function Auth_OpenID_legacy_discover($html_text, $server_rel,
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$delegate_rel)
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{
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$p = new Auth_OpenID_Parse();
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$link_attrs = $p->parseLinkAttrs($html_text);
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$server_url = $p->findFirstHref($link_attrs,
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$server_rel);
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if ($server_url === null) {
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return false;
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} else {
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$delegate_url = $p->findFirstHref($link_attrs,
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$delegate_rel);
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return array($delegate_url, $server_url);
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}
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}
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