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 $output; |
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35 | |||
36 | |||
37 | 6 | function __construct() |
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41 | |||
42 | 6 | function init() |
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60 | |||
61 | |||
62 | function setString($str) |
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66 | |||
67 | public function cleanArray($array) |
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71 | |||
72 | /** |
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73 | * @param $str |
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74 | * @return array|mixed |
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75 | */ |
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76 | 6 | public function clean($str) |
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77 | { |
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78 | // reset |
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79 | 6 | $this->_xss_found = null; |
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80 | |||
81 | // check for an array of strings |
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82 | 6 | if (\is_array($str)) { |
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83 | 2 | foreach ($str as $key => $value) { |
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84 | 2 | $str[$key] = $this->clean($value); |
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85 | } |
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86 | 2 | return $str; |
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87 | } |
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88 | |||
89 | 6 | $this->input = $str; |
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90 | 6 | $this->output = $this->process($str); |
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91 | 6 | return $this->output; |
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92 | } |
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93 | |||
94 | 6 | private function process($str) |
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95 | { |
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96 | |||
97 | // process |
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98 | do { |
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99 | 6 | $old_str = $str; |
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100 | 6 | $str = $this->_do($str); |
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101 | 6 | } while ($old_str !== $str); |
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102 | |||
103 | // keep the old value, if there wasn't any XSS attack |
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104 | 6 | if ($this->_xss_found !== true) { |
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105 | 6 | $str = $this->input; |
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106 | } |
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107 | |||
108 | 6 | return $str; |
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109 | } |
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110 | |||
111 | /** |
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112 | * @param StringResource $str |
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113 | * |
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114 | * @return mixed |
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115 | */ |
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116 | 6 | private function _do($str) |
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117 | { |
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118 | 6 | $str = (string)$str; |
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119 | 6 | $strInt = (int)$str; |
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120 | 6 | $strFloat = (float)$str; |
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121 | 6 | if (!$str || (string)$strInt === $str || (string)$strFloat === $str) { |
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122 | |||
123 | // no xss found |
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124 | 6 | if ($this->_xss_found !== true) { |
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125 | 6 | $this->_xss_found = false; |
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126 | } |
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127 | |||
128 | 6 | return $str; |
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129 | } |
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130 | |||
131 | // remove the BOM from UTF-8 / UTF-16 / UTF-32 strings |
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132 | 6 | $str = $this->utf8->remove_bom($str); |
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133 | |||
134 | // replace the diamond question mark (�) and invalid-UTF8 chars |
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135 | 6 | $str = $this->utf8->replace_diamond_question_mark($str, ''); |
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136 | |||
137 | // replace invisible characters with one single space |
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138 | 6 | $str = $this->utf8->remove_invisible_characters($str, true, ' '); |
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139 | |||
140 | 6 | $str = $this->utf8->normalize_whitespace($str); |
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141 | 6 | $str = $this->strings->replace($str); |
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142 | |||
143 | // decode UTF-7 characters |
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144 | 6 | $str = $this->utf7->repack($str); |
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145 | |||
146 | // decode the string |
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147 | 6 | $str = $this->decodeString($str); // RW Partly DONE |
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148 | |||
149 | // backup the string (for later comparision) |
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150 | 6 | $str_backup = $str; |
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151 | |||
152 | // remove strings that are never allowed |
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153 | 6 | $str = $this->neverAllowed->doNeverAllowed($str); //RW DONE |
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154 | |||
155 | // corrects words before the browser will do it |
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156 | 6 | $str = $this->exploded->compactExplodedString($str); //RW DONE |
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157 | |||
158 | // remove disallowed javascript calls in links, images etc. |
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159 | 6 | $str = $this->javascript->removeDisallowedJavascript($str); |
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160 | |||
161 | // remove evil attributes such as style, onclick and xmlns |
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162 | 6 | $str = $this->attributes->removeEvilAttributes($str); |
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163 | |||
164 | // sanitize naughty JavaScript elements |
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165 | 6 | $str = $this->javascript->naughtyJavascript($str); |
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166 | |||
167 | // sanitize naughty HTML elements |
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168 | 6 | $str = $this->html->naughtyHtml($str); |
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169 | |||
170 | // final clean up |
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171 | // |
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172 | // -> This adds a bit of extra precaution in case something got through the above filters. |
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173 | 6 | $str = $this->neverAllowed->doNeverAllowedAfterwards($str); |
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174 | |||
175 | // check for xss |
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176 | 6 | if ($this->_xss_found !== true) { |
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177 | 6 | $this->_xss_found = !($str_backup === $str); |
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178 | } |
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179 | |||
180 | 6 | return $str; |
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181 | } |
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182 | |||
183 | 6 | public function decodeString($str) |
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184 | { |
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185 | // init |
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186 | 6 | $regExForHtmlTags = '/<\p{L}+.*+/us'; |
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187 | |||
188 | 6 | if (strpos($str, '<') !== false && preg_match($regExForHtmlTags, $str, $matches) === 1) { |
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189 | 6 | $str = (string)preg_replace_callback( |
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190 | 6 | $regExForHtmlTags, |
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191 | function ($matches) { |
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192 | 6 | return $this->decodeEntity($matches); |
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193 | 6 | }, |
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194 | 6 | $str |
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195 | ); |
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196 | } else { |
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197 | 6 | $str = $this->utf8->rawurldecode($str); |
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198 | } |
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199 | |||
200 | 6 | return $str; |
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201 | } |
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202 | |||
203 | 6 | private function decodeEntity(array $match) |
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204 | { |
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205 | // init |
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206 | 6 | $str = $match[0]; |
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207 | |||
208 | // protect GET variables without XSS in URLs |
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209 | 6 | if (preg_match_all("/[\?|&]?[\\p{L}0-9_\-\[\]]+\s*=\s*(?<wrapped>\"|\042|'|\047)(?<attr>[^\\1]*?)\\g{wrapped}/ui", $str, $matches)) { |
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210 | 6 | if (isset($matches['attr'])) { |
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211 | 6 | foreach ($matches['attr'] as $matchInner) { |
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212 | 6 | $tmpAntiXss = clone $this; |
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213 | 6 | $urlPartClean = $tmpAntiXss->clean($matchInner); |
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214 | |||
215 | 6 | if ($tmpAntiXss->isXssFound() === true) { |
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216 | 6 | $this->_xss_found = true; |
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217 | 6 | $str = \str_replace($matchInner, $this->utf8->rawurldecode($urlPartClean), $str); |
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218 | } |
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219 | } |
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220 | } |
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221 | } else { |
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222 | 6 | $str = $this->_entity_decode($this->utf8->rawurldecode($str)); |
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223 | } |
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224 | |||
225 | 6 | return $str; |
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226 | } |
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227 | |||
228 | /** |
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229 | * @return null |
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230 | */ |
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231 | 6 | public function isXssFound() |
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235 | |||
236 | /** |
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237 | * Entity-decoding. |
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238 | * |
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239 | * @param StringResource $str |
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240 | * |
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241 | * @return StringResource |
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242 | */ |
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243 | 6 | private function _entity_decode($str) |
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244 | { |
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245 | 6 | static $HTML_ENTITIES_CACHE; |
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246 | |||
247 | 6 | $flags = ENT_QUOTES | ENT_HTML5 | ENT_DISALLOWED | ENT_SUBSTITUTE; |
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248 | |||
249 | // decode |
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250 | 6 | $str = html_entity_decode($str, $flags); |
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251 | |||
252 | |||
253 | // decode-again, for e.g. HHVM or miss configured applications ... |
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254 | 6 | if (preg_match_all('/(?<html_entity>&[A-Za-z]{2,}[;]{0})/', $str, $matches)) { |
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255 | if ($HTML_ENTITIES_CACHE === null) { |
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256 | |||
257 | // links: |
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258 | // - http://dev.w3.org/html5/html-author/charref |
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259 | // - http://www.w3schools.com/charsets/ref_html_entities_n.asp |
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260 | $entitiesSecurity = [ |
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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 | '=' => '=', |
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311 | '&newline;' => "\n", |
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312 | '
' => "\n", |
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313 | ' ' => "\n", |
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314 | '&tab;' => "\t", |
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315 | '	' => "\t", |
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316 | '	' => "\t", |
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317 | ]; |
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318 | |||
319 | $HTML_ENTITIES_CACHE = \array_merge( |
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320 | $entitiesSecurity, |
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321 | \array_flip(\get_html_translation_table(HTML_ENTITIES, $flags)), |
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322 | \array_flip($this->_get_data('entities_fallback')) |
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323 | ); |
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324 | } |
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325 | |||
326 | $search = []; |
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327 | $replace = []; |
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328 | foreach ($matches['html_entity'] as $match) { |
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329 | $match .= ';'; |
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330 | if (isset($HTML_ENTITIES_CACHE[$match])) { |
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331 | $search[$match] = $match; |
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332 | $replace[$match] = $HTML_ENTITIES_CACHE[$match]; |
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333 | } |
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334 | } |
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335 | |||
336 | if (\count($replace) > 0) { |
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337 | $str = \str_replace($search, $replace, $str); |
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338 | } |
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339 | } |
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340 | |||
341 | 6 | return $str; |
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342 | } |
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343 | |||
344 | private function _get_data($file) |
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349 | |||
350 | public function cleanString($str) |
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354 | |||
355 | /** |
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356 | * @param $str |
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357 | * @return array|mixed |
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358 | */ |
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359 | 3 | public function cleanUrl($str) |
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360 | { |
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384 | |||
385 | function result() |
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393 | } |
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
.