Complex classes like Xss often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Xss, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 19 | class Xss |
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| 20 | { |
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| 21 | |||
| 22 | private $_xss_found = null; |
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| 23 | private $neverAllowed; |
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| 24 | private $exploded; |
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| 25 | private $string; |
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| 26 | private $attributes; |
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| 27 | private $javascript; |
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| 28 | private $html; |
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| 29 | private $utf7; |
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| 30 | private $utf8; |
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| 31 | private $strings; |
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| 32 | private $system; |
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| 33 | private $input; |
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| 34 | private $output; |
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| 35 | |||
| 36 | |||
| 37 | 6 | function __construct() |
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| 41 | |||
| 42 | 6 | function init() |
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| 59 | |||
| 60 | |||
| 61 | function setString($str) |
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| 65 | |||
| 66 | public function cleanArray($array) |
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| 70 | |||
| 71 | /** |
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| 72 | * @param $str |
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| 73 | * @return array|mixed |
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| 74 | */ |
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| 75 | 6 | public function clean($str) |
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| 76 | { |
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| 77 | // reset |
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| 78 | 6 | $this->_xss_found = null; |
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| 79 | |||
| 80 | // check for an array of strings |
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| 81 | 6 | if (\is_array($str)) { |
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| 82 | 2 | foreach ($str as $key => $value) { |
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| 83 | 2 | $str[$key] = $this->clean($value); |
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| 84 | } |
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| 85 | 2 | return $str; |
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| 86 | } |
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| 87 | |||
| 88 | 6 | $this->input = $str; |
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| 89 | 6 | $this->output = $this->process($str); |
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| 90 | 6 | return $this->output; |
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| 91 | } |
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| 92 | |||
| 93 | 6 | private function process($str) |
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| 94 | { |
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| 95 | |||
| 96 | // process |
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| 97 | do { |
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| 98 | 6 | $old_str = $str; |
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| 99 | 6 | $str = $this->_do($str); |
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| 100 | 6 | } while ($old_str !== $str); |
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| 101 | |||
| 102 | // keep the old value, if there wasn't any XSS attack |
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| 103 | 6 | if ($this->_xss_found !== true) { |
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| 104 | 6 | $str = $this->input; |
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| 105 | } |
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| 106 | |||
| 107 | 6 | return $str; |
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| 108 | } |
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| 109 | |||
| 110 | /** |
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| 111 | * @param StringResource $str |
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| 112 | * |
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| 113 | * @return mixed |
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| 114 | */ |
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| 115 | 6 | private function _do($str) |
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| 116 | { |
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| 117 | 6 | $str = (string)$str; |
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| 118 | 6 | $strInt = (int)$str; |
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| 119 | 6 | $strFloat = (float)$str; |
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| 120 | 6 | if (!$str || (string)$strInt === $str || (string)$strFloat === $str) { |
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| 121 | |||
| 122 | // no xss found |
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| 123 | 6 | if ($this->_xss_found !== true) { |
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| 124 | 6 | $this->_xss_found = false; |
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| 125 | } |
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| 126 | |||
| 127 | 6 | return $str; |
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| 128 | } |
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| 129 | |||
| 130 | // remove the BOM from UTF-8 / UTF-16 / UTF-32 strings |
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| 131 | 6 | $str = $this->utf8->remove_bom($str); |
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| 132 | |||
| 133 | // replace the diamond question mark (�) and invalid-UTF8 chars |
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| 134 | 6 | $str = $this->utf8->replace_diamond_question_mark($str, ''); |
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| 135 | |||
| 136 | // replace invisible characters with one single space |
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| 137 | 6 | $str = $this->utf8->remove_invisible_characters($str, true, ' '); |
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| 138 | |||
| 139 | 6 | $str = $this->utf8->normalize_whitespace($str); |
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| 140 | 6 | $str = $this->strings->replace($str); |
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| 141 | |||
| 142 | // decode UTF-7 characters |
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| 143 | 6 | $str = $this->utf7->repack($str); |
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| 144 | |||
| 145 | // decode the string |
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| 146 | 6 | $str = $this->decodeString($str); // RW Partly DONE |
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| 147 | |||
| 148 | // backup the string (for later comparision) |
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| 149 | 6 | $str_backup = $str; |
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| 150 | |||
| 151 | // remove strings that are never allowed |
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| 152 | 6 | $str = $this->neverAllowed->doNeverAllowed($str); //RW DONE |
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| 153 | |||
| 154 | // corrects words before the browser will do it |
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| 155 | 6 | $str = $this->exploded->compactExplodedString($str); //RW DONE |
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| 156 | |||
| 157 | // remove disallowed javascript calls in links, images etc. |
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| 158 | 6 | $str = $this->javascript->removeDisallowedJavascript($str); |
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| 159 | |||
| 160 | // remove evil attributes such as style, onclick and xmlns |
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| 161 | 6 | $str = $this->attributes->removeEvilAttributes($str); |
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| 162 | |||
| 163 | // sanitize naughty JavaScript elements |
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| 164 | 6 | $str = $this->javascript->naughtyJavascript($str); |
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| 165 | |||
| 166 | // sanitize naughty HTML elements |
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| 167 | 6 | $str = $this->html->naughtyHtml($str); |
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| 168 | |||
| 169 | // final clean up |
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| 170 | // |
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| 171 | // -> This adds a bit of extra precaution in case something got through the above filters. |
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| 172 | 6 | $str = $this->neverAllowed->doNeverAllowedAfterwards($str); |
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| 173 | |||
| 174 | // check for xss |
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| 175 | 6 | if ($this->_xss_found !== true) { |
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| 176 | 6 | $this->_xss_found = !($str_backup === $str); |
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| 177 | } |
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| 178 | |||
| 179 | 6 | return $str; |
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| 180 | } |
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| 181 | |||
| 182 | 6 | public function decodeString($str) |
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| 183 | { |
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| 184 | // init |
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| 185 | 6 | $regExForHtmlTags = '/<\p{L}+.*+/us'; |
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| 186 | |||
| 187 | 6 | if (strpos($str, '<') !== false && preg_match($regExForHtmlTags, $str, $matches) === 1) { |
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| 188 | 6 | $str = (string)preg_replace_callback( |
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| 189 | 6 | $regExForHtmlTags, |
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| 190 | function ($matches) { |
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| 191 | 6 | return $this->decodeEntity($matches); |
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| 192 | 6 | }, |
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| 193 | 6 | $str |
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| 194 | ); |
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| 195 | } else { |
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| 196 | 6 | $str = $this->utf8->rawurldecode($str); |
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| 197 | } |
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| 198 | |||
| 199 | 6 | return $str; |
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| 200 | } |
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| 201 | |||
| 202 | 6 | private function decodeEntity(array $match) |
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| 203 | { |
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| 204 | // init |
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| 205 | 6 | $str = $match[0]; |
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| 206 | |||
| 207 | // protect GET variables without XSS in URLs |
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| 208 | 6 | if (preg_match_all("/[\?|&]?[\\p{L}0-9_\-\[\]]+\s*=\s*(?<wrapped>\"|\042|'|\047)(?<attr>[^\\1]*?)\\g{wrapped}/ui", $str, $matches)) { |
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| 209 | 6 | if (isset($matches['attr'])) { |
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| 210 | 6 | foreach ($matches['attr'] as $matchInner) { |
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| 211 | 6 | $tmpAntiXss = clone $this; |
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| 212 | 6 | $urlPartClean = $tmpAntiXss->clean($matchInner); |
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| 213 | |||
| 214 | 6 | if ($tmpAntiXss->isXssFound() === true) { |
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| 215 | 6 | $this->_xss_found = true; |
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| 216 | 6 | $str = \str_replace($matchInner, $this->utf8->rawurldecode($urlPartClean), $str); |
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| 217 | } |
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| 218 | } |
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| 219 | } |
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| 220 | } else { |
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| 221 | 6 | $str = $this->_entity_decode($this->utf8->rawurldecode($str)); |
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| 222 | } |
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| 223 | |||
| 224 | 6 | return $str; |
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| 225 | } |
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| 226 | |||
| 227 | /** |
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| 228 | * @return null |
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| 229 | */ |
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| 230 | 6 | public function isXssFound() |
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| 234 | |||
| 235 | /** |
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| 236 | * Entity-decoding. |
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| 237 | * |
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| 238 | * @param StringResource $str |
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| 239 | * |
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| 240 | * @return StringResource |
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| 241 | */ |
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| 242 | 6 | private function _entity_decode($str) |
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| 243 | { |
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| 244 | 6 | static $HTML_ENTITIES_CACHE; |
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| 245 | |||
| 246 | 6 | $flags = ENT_QUOTES | ENT_HTML5 | ENT_DISALLOWED | ENT_SUBSTITUTE; |
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| 247 | |||
| 248 | // decode |
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| 249 | 6 | $str = html_entity_decode($str, $flags); |
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| 250 | |||
| 251 | |||
| 252 | // decode-again, for e.g. HHVM or miss configured applications ... |
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| 253 | 6 | if (preg_match_all('/(?<html_entity>&[A-Za-z]{2,}[;]{0})/', $str, $matches)) { |
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| 254 | if ($HTML_ENTITIES_CACHE === null) { |
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| 255 | |||
| 256 | // links: |
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| 257 | // - http://dev.w3.org/html5/html-author/charref |
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| 258 | // - http://www.w3schools.com/charsets/ref_html_entities_n.asp |
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| 259 | $entitiesSecurity = [ |
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| 260 | '�' => '', |
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| 261 | '�' => '', |
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| 262 | '' => '', |
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| 263 | '' => '', |
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| 264 | '>⃒' => '', |
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| 265 | '' => '', |
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| 266 | '' => '', |
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| 267 | '­' => '', |
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| 268 | '­' => '', |
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| 269 | '­' => '', |
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| 270 | ':' => ':', |
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| 271 | ':' => ':', |
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| 272 | ':' => ':', |
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| 273 | '(' => '(', |
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| 274 | '(' => '(', |
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| 275 | '(' => '(', |
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| 276 | ')' => ')', |
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| 277 | ')' => ')', |
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| 278 | ')' => ')', |
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| 279 | '?' => '?', |
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| 280 | '?' => '?', |
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| 281 | '?' => '?', |
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| 282 | '/' => '/', |
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| 283 | '/' => '/', |
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| 284 | '/' => '/', |
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| 285 | ''' => '\'', |
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| 286 | ''' => '\'', |
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| 287 | ''' => '\'', |
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| 288 | ''' => '\'', |
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| 289 | ''' => '\'', |
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| 290 | '\' => '\'', |
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| 291 | '\' => '\\', |
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| 292 | '\' => '\\', |
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| 293 | ',' => ',', |
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| 294 | ',' => ',', |
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| 295 | ',' => ',', |
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| 296 | '.' => '.', |
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| 297 | '.' => '.', |
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| 298 | '"' => '"', |
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| 299 | '"' => '"', |
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| 300 | '"' => '"', |
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| 301 | '"' => '"', |
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| 302 | '`' => '`', |
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| 303 | '`' => '`', |
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| 304 | '`' => '`', |
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| 305 | '`' => '`', |
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| 306 | '.' => '.', |
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| 307 | '=' => '=', |
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| 308 | '=' => '=', |
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| 309 | '=' => '=', |
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| 310 | '&newline;' => "\n", |
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| 311 | '
' => "\n", |
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| 312 | ' ' => "\n", |
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| 313 | '&tab;' => "\t", |
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| 314 | '	' => "\t", |
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| 315 | '	' => "\t", |
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| 316 | ]; |
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| 317 | |||
| 318 | $HTML_ENTITIES_CACHE = \array_merge( |
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| 319 | $entitiesSecurity, |
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| 320 | \array_flip(\get_html_translation_table(HTML_ENTITIES, $flags)), |
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| 321 | \array_flip($this->_get_data('entities_fallback')) |
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| 322 | ); |
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| 323 | } |
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| 324 | |||
| 325 | $search = []; |
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| 326 | $replace = []; |
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| 327 | foreach ($matches['html_entity'] as $match) { |
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| 328 | $match .= ';'; |
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| 329 | if (isset($HTML_ENTITIES_CACHE[$match])) { |
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| 330 | $search[$match] = $match; |
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| 331 | $replace[$match] = $HTML_ENTITIES_CACHE[$match]; |
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| 332 | } |
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| 333 | } |
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| 334 | |||
| 335 | if (\count($replace) > 0) { |
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| 336 | $str = \str_replace($search, $replace, $str); |
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| 337 | } |
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| 338 | } |
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| 339 | |||
| 340 | 6 | return $str; |
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| 341 | } |
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| 342 | |||
| 343 | private function _get_data($file) |
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| 348 | |||
| 349 | public function cleanString($str) |
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| 353 | |||
| 354 | /** |
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| 355 | * @param $str |
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| 356 | * @return array|mixed |
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| 357 | */ |
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| 358 | 3 | public function cleanUrl($str) |
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| 359 | { |
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| 383 | |||
| 384 | function result() |
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| 392 | } |
This check marks property names that have not been written in camelCase.
In camelCase names are written without any punctuation, the start of each new word being marked by a capital letter. Thus the name database connection string becomes
databaseConnectionString.