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42 aurelien 1
<?php
2
 
3
/**
4
 * This is the HTML pseudo-parser for the Yadis library.
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 *
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 * PHP versions 4 and 5
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 *
8
 * LICENSE: See the COPYING file included in this distribution.
9
 *
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 * @package Yadis
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 * @author JanRain, Inc. <openid@janrain.com>
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 * @copyright 2005 Janrain, Inc.
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 * @license http://www.gnu.org/copyleft/lesser.html LGPL
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 */
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/**
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 * This class is responsible for scanning an HTML string to find META
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 * tags and their attributes.  This is used by the Yadis discovery
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 * process.  This class must be instantiated to be used.
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 *
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 * @package Yadis
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 */
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class Services_Yadis_ParseHTML {
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    /**
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     * @access private
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     */
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    var $_re_flags = "si";
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    /**
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     * @access private
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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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     * @access private
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     */
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    var $_tag_expr = "<%s%s(?:\s.*?)?%s>";
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41
    /**
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     * @access private
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     */
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    var $_attr_find = '\b([-\w]+)=(".*?"|\'.*?\'|.+?)[\s>]';
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46
    function Services_Yadis_ParseHTML()
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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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52
        $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->_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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63
        $this->_ent_replace =
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            sprintf("&(%s);", implode("|",
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                                      $this->_entity_replacements));
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    }
67
 
68
    /**
69
     * Replace HTML entities (amp, lt, gt, and quot) as well as
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     * numeric entities (e.g. #x9f;) with their actual values and
71
     * return the new string.
72
     *
73
     * @access private
74
     * @param string $str The string in which to look for entities
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     * @return string $new_str The new string entities decoded
76
     */
77
    function replaceEntities($str)
78
    {
79
        foreach ($this->_entity_replacements as $old => $new) {
80
            $str = preg_replace(sprintf("/&%s;/", $old), $new, $str);
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        }
82
 
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        // Replace numeric entities because html_entity_decode doesn't
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        // do it for us.
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        $str = preg_replace('~&#x([0-9a-f]+);~ei', 'chr(hexdec("\\1"))', $str);
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        $str = preg_replace('~&#([0-9]+);~e', 'chr(\\1)', $str);
87
 
88
        return $str;
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    }
90
 
91
    /**
92
     * Strip single and double quotes off of a string, if they are
93
     * present.
94
     *
95
     * @access private
96
     * @param string $str The original string
97
     * @return string $new_str The new string with leading and
98
     * trailing quotes removed
99
     */
100
    function removeQuotes($str)
101
    {
102
        $matches = array();
103
        $double = '/^"(.*)"$/';
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        $single = "/^\'(.*)\'$/";
105
 
106
        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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    }
114
 
115
    /**
116
     * Create a regular expression that will match an opening
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     * or closing tag from a set of names.
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     *
119
     * @access private
120
     * @param mixed $tag_names Tag names to match
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     * @param mixed $close false/0 = no, true/1 = yes, other = maybe
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     * @param mixed $self_close false/0 = no, true/1 = yes, other = maybe
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     * @return string $regex A regular expression string to be used
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     * in, say, preg_match.
125
     */
126
    function tagPattern($tag_names, $close, $self_close)
127
    {
128
        if (is_array($tag_names)) {
129
            $tag_names = '(?:'.implode('|',$tag_names).')';
130
        }
131
        if ($close) {
132
            $close = '\/' . (($close == 1)? '' : '?');
133
        } else {
134
            $close = '';
135
        }
136
        if ($self_close) {
137
            $self_close = '(?:\/\s*)' . (($self_close == 1)? '' : '?');
138
        } else {
139
            $self_close = '';
140
        }
141
        $expr = sprintf($this->_tag_expr, $close, $tag_names, $self_close);
142
 
143
        return sprintf("/%s/%s", $expr, $this->_re_flags);
144
    }
145
 
146
    /**
147
     * Given an HTML document string, this finds all the META tags in
148
     * the document, provided they are found in the
149
     * <HTML><HEAD>...</HEAD> section of the document.  The <HTML> tag
150
     * may be missing.
151
     *
152
     * @access private
153
     * @param string $html_string An HTMl document string
154
     * @return array $tag_list Array of tags; each tag is an array of
155
     * attribute -> value.
156
     */
157
    function getMetaTags($html_string)
158
    {
159
        $html_string = preg_replace($this->_removed_re,
160
                                    "",
161
                                    $html_string);
162
 
163
        $key_tags = array($this->tagPattern('html', false, false),
164
                          $this->tagPattern('head', false, false),
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                          $this->tagPattern('head', true, false),
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                          $this->tagPattern('html', true, false),
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                          $this->tagPattern(array(
168
                          'body', 'frameset', 'frame', 'p', 'div',
169
                          'table','span','a'), 'maybe', 'maybe'));
170
        $key_tags_pos = array();
171
        foreach ($key_tags as $pat) {
172
            $matches = array();
173
            preg_match($pat, $html_string, $matches, PREG_OFFSET_CAPTURE);
174
            if($matches) {
175
                $key_tags_pos[] = $matches[0][1];
176
            } else {
177
                $key_tags_pos[] = null;
178
            }
179
        }
180
        // no opening head tag
181
        if (is_null($key_tags_pos[1])) {
182
            return array();
183
        }
184
        // the effective </head> is the min of the following
185
        if (is_null($key_tags_pos[2])) {
186
            $key_tags_pos[2] = strlen($html_string);
187
        }
188
        foreach (array($key_tags_pos[3], $key_tags_pos[4]) as $pos) {
189
            if (!is_null($pos) && $pos < $key_tags_pos[2]) {
190
                $key_tags_pos[2] = $pos;
191
            }
192
        }
193
        // closing head tag comes before opening head tag
194
        if ($key_tags_pos[1] > $key_tags_pos[2]) {
195
            return array();
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        }
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        // if there is an opening html tag, make sure the opening head tag
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        // comes after it
199
        if (!is_null($key_tags_pos[0]) && $key_tags_pos[1] < $key_tags_pos[0]) {
200
            return array();
201
        }
202
        $html_string = substr($html_string, $key_tags_pos[1], ($key_tags_pos[2]-$key_tags_pos[1]));
203
 
204
        $link_data = array();
205
        $link_matches = array();
206
 
207
        if (!preg_match_all($this->tagPattern('meta', false, 'maybe'),
208
                            $html_string, $link_matches)) {
209
            return array();
210
        }
211
 
212
        foreach ($link_matches[0] as $link) {
213
            $attr_matches = array();
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            preg_match_all($this->_attr_find, $link, $attr_matches);
215
            $link_attrs = array();
216
            foreach ($attr_matches[0] as $index => $full_match) {
217
                $name = $attr_matches[1][$index];
218
                $value = $this->replaceEntities(
219
                              $this->removeQuotes($attr_matches[2][$index]));
220
 
221
                $link_attrs[strtolower($name)] = $value;
222
            }
223
            $link_data[] = $link_attrs;
224
        }
225
 
226
        return $link_data;
227
    }
228
 
229
    /**
230
     * Looks for a META tag with an "http-equiv" attribute whose value
231
     * is one of ("x-xrds-location", "x-yadis-location"), ignoring
232
     * case.  If such a META tag is found, its "content" attribute
233
     * value is returned.
234
     *
235
     * @param string $html_string An HTML document in string format
236
     * @return mixed $content The "content" attribute value of the
237
     * META tag, if found, or null if no such tag was found.
238
     */
239
    function getHTTPEquiv($html_string)
240
    {
241
        $meta_tags = $this->getMetaTags($html_string);
242
 
243
        if ($meta_tags) {
244
            foreach ($meta_tags as $tag) {
245
                if (array_key_exists('http-equiv', $tag) &&
246
                    (in_array(strtolower($tag['http-equiv']),
247
                              array('x-xrds-location', 'x-yadis-location'))) &&
248
                    array_key_exists('content', $tag)) {
249
                    return $tag['content'];
250
                }
251
            }
252
        }
253
 
254
        return null;
255
    }
256
}
257
 
258
?>