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   1  <?php
   2  
   3  /**
   4   * Base class for all validating attribute definitions.
   5   *
   6   * This family of classes forms the core for not only HTML attribute validation,
   7   * but also any sort of string that needs to be validated or cleaned (which
   8   * means CSS properties and composite definitions are defined here too).
   9   * Besides defining (through code) what precisely makes the string valid,
  10   * subclasses are also responsible for cleaning the code if possible.
  11   */
  12  
  13  abstract class HTMLPurifier_AttrDef
  14  {
  15  
  16      /**
  17       * Tells us whether or not an HTML attribute is minimized.
  18       * Has no meaning in other contexts.
  19       * @type bool
  20       */
  21      public $minimized = false;
  22  
  23      /**
  24       * Tells us whether or not an HTML attribute is required.
  25       * Has no meaning in other contexts
  26       * @type bool
  27       */
  28      public $required = false;
  29  
  30      /**
  31       * Validates and cleans passed string according to a definition.
  32       *
  33       * @param string $string String to be validated and cleaned.
  34       * @param HTMLPurifier_Config $config Mandatory HTMLPurifier_Config object.
  35       * @param HTMLPurifier_Context $context Mandatory HTMLPurifier_Context object.
  36       */
  37      abstract public function validate($string, $config, $context);
  38  
  39      /**
  40       * Convenience method that parses a string as if it were CDATA.
  41       *
  42       * This method process a string in the manner specified at
  43       * <http://www.w3.org/TR/html4/types.html#h-6.2> by removing
  44       * leading and trailing whitespace, ignoring line feeds, and replacing
  45       * carriage returns and tabs with spaces.  While most useful for HTML
  46       * attributes specified as CDATA, it can also be applied to most CSS
  47       * values.
  48       *
  49       * @note This method is not entirely standards compliant, as trim() removes
  50       *       more types of whitespace than specified in the spec. In practice,
  51       *       this is rarely a problem, as those extra characters usually have
  52       *       already been removed by HTMLPurifier_Encoder.
  53       *
  54       * @warning This processing is inconsistent with XML's whitespace handling
  55       *          as specified by section 3.3.3 and referenced XHTML 1.0 section
  56       *          4.7.  However, note that we are NOT necessarily
  57       *          parsing XML, thus, this behavior may still be correct. We
  58       *          assume that newlines have been normalized.
  59       */
  60      public function parseCDATA($string)
  61      {
  62          $string = trim($string);
  63          $string = str_replace(array("\n", "\t", "\r"), ' ', $string);
  64          return $string;
  65      }
  66  
  67      /**
  68       * Factory method for creating this class from a string.
  69       * @param string $string String construction info
  70       * @return HTMLPurifier_AttrDef Created AttrDef object corresponding to $string
  71       */
  72      public function make($string)
  73      {
  74          // default implementation, return a flyweight of this object.
  75          // If $string has an effect on the returned object (i.e. you
  76          // need to overload this method), it is best
  77          // to clone or instantiate new copies. (Instantiation is safer.)
  78          return $this;
  79      }
  80  
  81      /**
  82       * Removes spaces from rgb(0, 0, 0) so that shorthand CSS properties work
  83       * properly. THIS IS A HACK!
  84       * @param string $string a CSS colour definition
  85       * @return string
  86       */
  87      protected function mungeRgb($string)
  88      {
  89          return preg_replace('/rgb\((\d+)\s*,\s*(\d+)\s*,\s*(\d+)\)/', 'rgb(\1,\2,\3)', $string);
  90      }
  91  
  92      /**
  93       * Parses a possibly escaped CSS string and returns the "pure"
  94       * version of it.
  95       */
  96      protected function expandCSSEscape($string)
  97      {
  98          // flexibly parse it
  99          $ret = '';
 100          for ($i = 0, $c = strlen($string); $i < $c; $i++) {
 101              if ($string[$i] === '\\') {
 102                  $i++;
 103                  if ($i >= $c) {
 104                      $ret .= '\\';
 105                      break;
 106                  }
 107                  if (ctype_xdigit($string[$i])) {
 108                      $code = $string[$i];
 109                      for ($a = 1, $i++; $i < $c && $a < 6; $i++, $a++) {
 110                          if (!ctype_xdigit($string[$i])) {
 111                              break;
 112                          }
 113                          $code .= $string[$i];
 114                      }
 115                      // We have to be extremely careful when adding
 116                      // new characters, to make sure we're not breaking
 117                      // the encoding.
 118                      $char = HTMLPurifier_Encoder::unichr(hexdec($code));
 119                      if (HTMLPurifier_Encoder::cleanUTF8($char) === '') {
 120                          continue;
 121                      }
 122                      $ret .= $char;
 123                      if ($i < $c && trim($string[$i]) !== '') {
 124                          $i--;
 125                      }
 126                      continue;
 127                  }
 128                  if ($string[$i] === "\n") {
 129                      continue;
 130                  }
 131              }
 132              $ret .= $string[$i];
 133          }
 134          return $ret;
 135      }
 136  }
 137  
 138  // vim: et sw=4 sts=4