DOMElement - attributes and namespace

Here's my function - private function filterAttributes($node) {

      // filters the attribute names and content
      $attributes = $node->attributes;
      foreach ($attributes as $attribute) {
         // allow colon as it is used in namespace attributes -
         //  needs to be tested though, may require different handling??
         //  I should get a MathML document and try it out.
         $pattern = '/[^a-z0-9:-]+/i';
         $clean = strtolower(preg_replace($pattern,'',$attribute->name));
         if (strcmp($clean,$attribute->name) != 0) {
            $this->policyReport("Invalid Attribute Name");
            }
         $saniAtt[] = $clean;
         if (strcmp($clean,"value") != 0) {
            if ($clean == "src") {
               $saniVal[] = $this->obfus($attribute->value,1);
               } elseif ($clean == "data") {
               $saniVal[] = $this->obfus($attribute->value,1);
               } elseif ($clean == "code") {
               $saniVal[] = $this->obfus($attribute->value,1);
               } else {
               $saniVal[] = $this->obfus($attribute->value);
               }
            } else {
            // do not alter value attributes
            $saniVal[] = $attribute->value;
            }
         $oldAtt[]  = $attribute->name;
         }
      if (isset($oldAtt)) {
         for ($i=0; $i<sizeof($oldAtt);$i++) {
            $node->removeAttribute($oldAtt[$i]);
            }
         }
      if (isset($saniAtt)) {
         for ($i=0; $i<sizeof($saniAtt);$i++) {
            $check = " " . $saniAtt[$i] . " ";
            if (substr_count($this->blacklist, $check) == 0) {
               $node->setAttribute($saniAtt[$i],$saniVal[$i]);
               } else {
               $string = "Blacklisted Event Attribute: " . $saniAtt[$i];
               $this->policyReport($string);
               }
            }
         }
      }

(entire class here - http://www.clfsrpm.net/xss/cspfilter_class.phps) Here's the problem - $attributes = $node->attributes; creates a list that has both regular attributes and namespaced attributes. But I don't know how to programatically tell them apart. Here's the problem - when the attribute involves a namespace, IE xml:lang - $node->removeAttribute($oldAtt[$i]); doesn't remove it. $node->setAttribute($saniAtt[$i],$saniVal[$i]); creates a new attribute WITHOUT the namespace. So if we have xml:lang="something" after the function is run, the result is that there is an additional attribute lang="filtered something" but xml:lang remains with the unfiltered attribute content. If I knew a way to tell whether or not an attribute was namespaced I could deal with it by using the correct $node->removeAttributeNS and $node->setAttributeNS for those attributes, but I don't know how to tell them apart programatically. It seems that $attribute->name when the attribute is foo:bar will just return bar, and I can't tell if it was originally foo:bar, xml:bar, freak:bar, or just plain bar. The extremely sparse documentation in the php manual on this area isn't exactly helping me figure it out. Any help would be appreciated. To see the problem - http://www.clfsrpm.net/xss/dom_script_test.php Put <p xml:bar = "javascript:something else">A Paragraph</p> into the textarea and hit submit - and you'll see what the function does with the attribute.