1 | <?php |
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2 | require_once('class.utils.php'); |
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3 | /** |
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4 | * Filters input of stray or malicious PHP, Javascript or HTML tags. |
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5 | * It can be used to prevent cross-site scripting (XSS) attacks. |
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6 | * It should be used to filter input supplied by the user, such as an HTML code |
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7 | * entered in form fields. You would create the filter object, configure it with your |
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8 | * own settings, then call its process method to clean the form input values. |
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9 | * |
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10 | * @author: Daniel Morris |
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11 | * @version: 1.2.2_php4/php5 |
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12 | * @package Workflow |
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13 | * @license http://www.gnu.org/copyleft/gpl.html GPL |
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14 | */ |
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15 | class SecurityUtils extends Utils { |
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16 | |
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17 | /** |
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18 | * @var array $tagsArray default = empty array |
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19 | * @access public |
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20 | */ |
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21 | var $tagsArray; |
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22 | |
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23 | /** |
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24 | * @var array $attrArray default = empty array |
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25 | * @access public |
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26 | */ |
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27 | var $attrArray; |
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28 | |
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29 | /** |
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30 | * @var $tagsMethod default = 0 |
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31 | * @access public |
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32 | */ |
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33 | var $tagsMethod; |
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34 | |
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35 | /** |
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36 | * @var $attrMethod default = 0 |
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37 | * @access public |
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38 | */ |
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39 | var $attrMethod; |
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40 | |
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41 | /** |
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42 | * @var $xssAuto default = 1 |
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43 | * @access public |
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44 | */ |
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45 | var $xssAuto; |
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46 | |
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47 | /** |
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48 | * @var array $tagBlacklist |
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49 | * @access public |
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50 | */ |
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51 | var $tagBlacklist = array('applet', 'body', 'bgsound', 'base', 'basefont', 'embed', 'frame', 'frameset', 'head', 'html', 'id', 'iframe', 'ilayer', 'layer', 'link', 'meta', 'name', 'object', 'script', 'style', 'title', 'xml'); |
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52 | |
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53 | /** |
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54 | * @var array $attrBlackList |
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55 | * @access public |
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56 | */ |
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57 | var $attrBlacklist = array('action', 'background', 'codebase', 'dynsrc', 'lowsrc'); // also will strip ALL event handlers |
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58 | |
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59 | /** |
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60 | * Constructor for inputFilter class. Only first parameter is required. |
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61 | * @access constructor |
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62 | * @param Array $tagsArray - list of user-defined tags |
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63 | * @param Array $attrArray - list of user-defined attributes |
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64 | * @param int $tagsMethod - 0= allow just user-defined, 1= allow all but user-defined |
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65 | * @param int $attrMethod - 0= allow just user-defined, 1= allow all but user-defined |
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66 | * @param int $xssAuto - 0= only auto clean essentials, 1= allow clean blacklisted tags/attr |
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67 | */ |
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68 | function SecurityUtils($tagsArray = array(), $attrArray = array(), $tagsMethod = 0, $attrMethod = 0, $xssAuto = 1) { |
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69 | // make sure user defined arrays are in lowercase |
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70 | for ($i = 0; $i < count($tagsArray); $i++) $tagsArray[$i] = strtolower($tagsArray[$i]); |
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71 | for ($i = 0; $i < count($attrArray); $i++) $attrArray[$i] = strtolower($attrArray[$i]); |
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72 | // assign to member vars |
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73 | $this->tagsArray = (array) $tagsArray; |
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74 | $this->attrArray = (array) $attrArray; |
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75 | $this->tagsMethod = $tagsMethod; |
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76 | $this->attrMethod = $attrMethod; |
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77 | $this->xssAuto = $xssAuto; |
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78 | } |
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79 | |
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80 | /** |
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81 | * Method to be called by another php script. Processes for XSS and specified bad code. |
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82 | * @access public |
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83 | * @param Mixed $source - input string/array-of-string to be 'cleaned' |
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84 | * @return String $source - 'cleaned' version of input parameter |
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85 | */ |
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86 | function process($source) { |
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87 | // clean all elements in this array |
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88 | if (is_array($source)) { |
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89 | foreach($source as $key => $value) |
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90 | // filter element for XSS and other 'bad' code etc. |
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91 | if (is_string($value)) $source[$key] = $this->remove($this->decode($value)); |
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92 | return $source; |
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93 | // clean this string |
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94 | } else if (is_string($source)) { |
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95 | // filter source for XSS and other 'bad' code etc. |
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96 | return $this->remove($this->decode($source)); |
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97 | // return parameter as given |
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98 | } else return $source; |
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99 | } |
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100 | |
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101 | /** |
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102 | * Internal method to iteratively remove all unwanted tags and attributes |
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103 | * @access protected |
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104 | * @param String $source - input string to be 'cleaned' |
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105 | * @return String $source - 'cleaned' version of input parameter |
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106 | */ |
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107 | function remove($source) { |
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108 | $loopCounter=0; |
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109 | // provides nested-tag protection |
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110 | while($source != $this->filterTags($source)) { |
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111 | $source = $this->filterTags($source); |
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112 | $loopCounter++; |
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113 | } |
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114 | return $source; |
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115 | } |
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116 | |
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117 | /** |
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118 | * Internal method to strip a string of certain tags |
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119 | * @access protected |
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120 | * @param String $source - input string to be 'cleaned' |
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121 | * @return String $source - 'cleaned' version of input parameter |
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122 | */ |
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123 | function filterTags($source) |
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124 | { |
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125 | return strip_tags($source); |
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126 | } |
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127 | |
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128 | /** |
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129 | * Internal method to strip a tag of certain attributes |
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130 | * @access protected |
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131 | * @param Array $attrSet |
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132 | * @return Array $newSet |
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133 | */ |
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134 | function filterAttr($attrSet) { |
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135 | $newSet = array(); |
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136 | // process attributes |
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137 | for ($i = 0; $i <count($attrSet); $i++) { |
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138 | // skip blank spaces in tag |
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139 | if (!$attrSet[$i]) continue; |
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140 | // split into attr name and value |
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141 | $attrSubSet = explode('=', trim($attrSet[$i])); |
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142 | list($attrSubSet[0]) = explode(' ', $attrSubSet[0]); |
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143 | // removes all "non-regular" attr names AND also attr blacklisted |
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144 | if ((!preg_match('/^[a-z]*$/i',$attrSubSet[0])) || (($this->xssAuto) && ((in_array(strtolower($attrSubSet[0]), $this->attrBlacklist)) || (substr($attrSubSet[0], 0, 2) == 'on')))) |
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145 | continue; |
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146 | // xss attr value filtering |
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147 | if ($attrSubSet[1]) { |
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148 | // strips unicode, hex, etc |
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149 | $attrSubSet[1] = str_replace('&#', '', $attrSubSet[1]); |
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150 | // strip normal newline within attr value |
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151 | $attrSubSet[1] = preg_replace('/\s+/', '', $attrSubSet[1]); |
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152 | // strip double quotes |
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153 | $attrSubSet[1] = str_replace('"', '', $attrSubSet[1]); |
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154 | // [requested feature] convert single quotes from either side to doubles (Single quotes shouldn't be used to pad attr value) |
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155 | if ((substr($attrSubSet[1], 0, 1) == "'") && (substr($attrSubSet[1], (strlen($attrSubSet[1]) - 1), 1) == "'")) |
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156 | $attrSubSet[1] = substr($attrSubSet[1], 1, (strlen($attrSubSet[1]) - 2)); |
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157 | // strip slashes |
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158 | $attrSubSet[1] = stripslashes($attrSubSet[1]); |
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159 | } |
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160 | // auto strip attr's with "javascript: |
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161 | if ( ((strpos(strtolower($attrSubSet[1]), 'expression') !== false) && (strtolower($attrSubSet[0]) == 'style')) || |
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162 | (strpos(strtolower($attrSubSet[1]), 'javascript:') !== false) || |
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163 | (strpos(strtolower($attrSubSet[1]), 'behaviour:') !== false) || |
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164 | (strpos(strtolower($attrSubSet[1]), 'vbscript:') !== false) || |
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165 | (strpos(strtolower($attrSubSet[1]), 'mocha:') !== false) || |
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166 | (strpos(strtolower($attrSubSet[1]), 'livescript:') !== false) |
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167 | ) continue; |
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168 | |
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169 | // if matches user defined array |
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170 | $attrFound = in_array(strtolower($attrSubSet[0]), $this->attrArray); |
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171 | // keep this attr on condition |
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172 | if ((!$attrFound && $this->attrMethod) || ($attrFound && !$this->attrMethod)) { |
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173 | // attr has value |
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174 | if ($attrSubSet[1]) $newSet[] = $attrSubSet[0] . '="' . $attrSubSet[1] . '"'; |
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175 | // attr has decimal zero as value |
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176 | else if ($attrSubSet[1] == "0") $newSet[] = $attrSubSet[0] . '="0"'; |
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177 | // reformat single attributes to XHTML |
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178 | else $newSet[] = $attrSubSet[0] . '="' . $attrSubSet[0] . '"'; |
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179 | } |
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180 | } |
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181 | return $newSet; |
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182 | } |
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183 | |
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184 | /** |
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185 | * Try to convert to plaintext |
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186 | * @access protected |
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187 | * @param String $source |
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188 | * @return String $source |
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189 | */ |
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190 | function decode($source) { |
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191 | // url decode |
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192 | $source = html_entity_decode($source, ENT_QUOTES, "ISO-8859-1"); |
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193 | // convert decimal |
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194 | $source = preg_replace('/&#(\d+);/me',"chr(\\1)", $source); // decimal notation |
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195 | // convert hex |
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196 | $source = preg_replace('/&#x([a-f0-9]+);/mei',"chr(0x\\1)", $source); // hex notation |
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197 | return $source; |
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198 | } |
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199 | |
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200 | /** |
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201 | * Method to be called by another php script. Processes for SQL injection |
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202 | * @access public |
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203 | * @param Mixed $source - input string/array-of-string to be 'cleaned' |
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204 | * @return String $source - 'cleaned' version of input parameter |
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205 | */ |
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206 | function safeSQL($source) { |
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207 | // clean all elements in this array |
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208 | if (is_array($source)) { |
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209 | foreach($source as $key => $value) |
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210 | // filter element for SQL injection |
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211 | if (is_string($value)) $source[$key] = $this->quoteSmart($this->decode($value)); |
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212 | return $source; |
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213 | // clean this string |
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214 | } else if (is_string($source)) { |
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215 | // filter source for SQL injection |
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216 | if (is_string($source)) return $this->quoteSmart($this->decode($source)); |
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217 | // return parameter as given |
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218 | } else return $source; |
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219 | } |
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220 | |
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221 | /** |
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222 | * @author Chris Tobin |
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223 | * @author Daniel Morris |
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224 | * @access protected |
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225 | * @param String $source |
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226 | * @return String $source |
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227 | */ |
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228 | function quoteSmart($source) { |
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229 | // strip slashes |
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230 | if (get_magic_quotes_gpc()) $source = stripslashes($source); |
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231 | // quote both numeric and text |
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232 | $source = $this->escapeString($source); |
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233 | return $source; |
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234 | } |
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235 | |
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236 | /** |
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237 | * @author Chris Tobin |
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238 | * @author Daniel Morris |
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239 | * @access protected |
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240 | * @param String $source |
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241 | * @return String $source |
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242 | */ |
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243 | function escapeString($string) { |
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244 | // depreciated function |
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245 | if (version_compare(phpversion(),"4.3.0", "<")) mysql_escape_string($string); |
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246 | // current function |
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247 | else mysql_real_escape_string($string); |
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248 | return $string; |
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249 | } |
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250 | |
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251 | /** |
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252 | * @author Sidnei Augusto Drovetto Jr. - drovetto@gmail.com |
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253 | * @param mixed $source A string or array of strings to be escaped |
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254 | * @return mixed $source An object of the same type of the input, only escaped |
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255 | * @access public |
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256 | */ |
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257 | function escapeHTML($source) |
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258 | { |
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259 | $output = $source; |
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260 | if (is_string($output)) |
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261 | $output = htmlentities($output, ENT_QUOTES, 'ISO-8859-1'); |
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262 | else |
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263 | if (is_array($output)) |
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264 | foreach ($output as &$element) |
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265 | $element = $this->escapeHTML($element); |
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266 | |
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267 | return $output; |
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268 | } |
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269 | } |
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270 | |
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271 | ?> |
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