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<?php
/**
* This is the HTML pseudo-parser for the Yadis library.
*
* PHP versions 4 and 5
*
* LICENSE: See the COPYING file included in this distribution.
*
* @package OpenID
* @author JanRain, Inc. <openid@janrain.com>
* @copyright 2005-2008 Janrain, Inc.
* @license http://www.apache.org/licenses/LICENSE-2.0 Apache
*/
/**
* This class is responsible for scanning an HTML string to find META
* tags and their attributes. This is used by the Yadis discovery
* process. This class must be instantiated to be used.
*
* @package OpenID
*/
class Auth_Yadis_ParseHTML {
/**
* @access private
*/
var $_re_flags = "si";
/**
* @access private
*/
var $_removed_re =
"<!--.*?-->|<!\[CDATA\[.*?\]\]>|<script\b(?!:)[^>]*>.*?<\/script>";
/**
* @access private
*/
var $_tag_expr = "<%s%s(?:\s.*?)?%s>";
/**
* @access private
*/
var $_attr_find = '\b([-\w]+)=(".*?"|\'.*?\'|.+?)[\/\s>]';
function Auth_Yadis_ParseHTML()
{
$this->_attr_find = sprintf("/%s/%s",
$this->_attr_find,
$this->_re_flags);
$this->_removed_re = sprintf("/%s/%s",
$this->_removed_re,
$this->_re_flags);
$this->_entity_replacements = array(
'amp' => '&',
'lt' => '<',
'gt' => '>',
'quot' => '"'
);
$this->_ent_replace =
sprintf("&(%s);", implode("|",
$this->_entity_replacements));
}
/**
* Replace HTML entities (amp, lt, gt, and quot) as well as
* numeric entities (e.g. #x9f;) with their actual values and
* return the new string.
*
* @access private
* @param string $str The string in which to look for entities
* @return string $new_str The new string entities decoded
*/
function replaceEntities($str)
{
foreach ($this->_entity_replacements as $old => $new) {
$str = preg_replace(sprintf("/&%s;/", $old), $new, $str);
}
// Replace numeric entities because html_entity_decode doesn't
// do it for us.
$str = preg_replace('~&#x([0-9a-f]+);~ei', 'chr(hexdec("\\1"))', $str);
$str = preg_replace('~&#([0-9]+);~e', 'chr(\\1)', $str);
return $str;
}
/**
* Strip single and double quotes off of a string, if they are
* present.
*
* @access private
* @param string $str The original string
* @return string $new_str The new string with leading and
* trailing quotes removed
*/
function removeQuotes($str)
{
$matches = array();
$double = '/^"(.*)"$/';
$single = "/^\'(.*)\'$/";
if (preg_match($double, $str, $matches)) {
return $matches[1];
} else if (preg_match($single, $str, $matches)) {
return $matches[1];
} else {
return $str;
}
}
/**
* Create a regular expression that will match an opening
* or closing tag from a set of names.
*
* @access private
* @param mixed $tag_names Tag names to match
* @param mixed $close false/0 = no, true/1 = yes, other = maybe
* @param mixed $self_close false/0 = no, true/1 = yes, other = maybe
* @return string $regex A regular expression string to be used
* in, say, preg_match.
*/
function tagPattern($tag_names, $close, $self_close)
{
if (is_array($tag_names)) {
$tag_names = '(?:'.implode('|',$tag_names).')';
}
if ($close) {
$close = '\/' . (($close == 1)? '' : '?');
} else {
$close = '';
}
if ($self_close) {
$self_close = '(?:\/\s*)' . (($self_close == 1)? '' : '?');
} else {
$self_close = '';
}
$expr = sprintf($this->_tag_expr, $close, $tag_names, $self_close);
return sprintf("/%s/%s", $expr, $this->_re_flags);
}
/**
* Given an HTML document string, this finds all the META tags in
* the document, provided they are found in the
* <HTML><HEAD>...</HEAD> section of the document. The <HTML> tag
* may be missing.
*
* @access private
* @param string $html_string An HTMl document string
* @return array $tag_list Array of tags; each tag is an array of
* attribute -> value.
*/
function getMetaTags($html_string)
{
$html_string = preg_replace($this->_removed_re,
"",
$html_string);
$key_tags = array($this->tagPattern('html', false, false),
$this->tagPattern('head', false, false),
$this->tagPattern('head', true, false),
$this->tagPattern('html', true, false),
$this->tagPattern(array(
'body', 'frameset', 'frame', 'p', 'div',
'table','span','a'), 'maybe', 'maybe'));
$key_tags_pos = array();
foreach ($key_tags as $pat) {
$matches = array();
preg_match($pat, $html_string, $matches, PREG_OFFSET_CAPTURE);
if($matches) {
$key_tags_pos[] = $matches[0][1];
} else {
$key_tags_pos[] = null;
}
}
// no opening head tag
if (is_null($key_tags_pos[1])) {
return array();
}
// the effective </head> is the min of the following
if (is_null($key_tags_pos[2])) {
$key_tags_pos[2] = strlen($html_string);
}
foreach (array($key_tags_pos[3], $key_tags_pos[4]) as $pos) {
if (!is_null($pos) && $pos < $key_tags_pos[2]) {
$key_tags_pos[2] = $pos;
}
}
// closing head tag comes before opening head tag
if ($key_tags_pos[1] > $key_tags_pos[2]) {
return array();
}
// if there is an opening html tag, make sure the opening head tag
// comes after it
if (!is_null($key_tags_pos[0]) && $key_tags_pos[1] < $key_tags_pos[0]) {
return array();
}
$html_string = substr($html_string, $key_tags_pos[1],
($key_tags_pos[2]-$key_tags_pos[1]));
$link_data = array();
$link_matches = array();
if (!preg_match_all($this->tagPattern('meta', false, 'maybe'),
$html_string, $link_matches)) {
return array();
}
foreach ($link_matches[0] as $link) {
$attr_matches = array();
preg_match_all($this->_attr_find, $link, $attr_matches);
$link_attrs = array();
foreach ($attr_matches[0] as $index => $full_match) {
$name = $attr_matches[1][$index];
$value = $this->replaceEntities(
$this->removeQuotes($attr_matches[2][$index]));
$link_attrs[strtolower($name)] = $value;
}
$link_data[] = $link_attrs;
}
return $link_data;
}
/**
* Looks for a META tag with an "http-equiv" attribute whose value
* is one of ("x-xrds-location", "x-yadis-location"), ignoring
* case. If such a META tag is found, its "content" attribute
* value is returned.
*
* @param string $html_string An HTML document in string format
* @return mixed $content The "content" attribute value of the
* META tag, if found, or null if no such tag was found.
*/
function getHTTPEquiv($html_string)
{
$meta_tags = $this->getMetaTags($html_string);
if ($meta_tags) {
foreach ($meta_tags as $tag) {
if (array_key_exists('http-equiv', $tag) &&
(in_array(strtolower($tag['http-equiv']),
array('x-xrds-location', 'x-yadis-location'))) &&
array_key_exists('content', $tag)) {
return $tag['content'];
}
}
}
return null;
}
}
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