Reduce duplicate namespaces

Author: tvdijen

src/XML/CanonicalizableElementTrait.php

@@ -7,6 +7,8 @@
 use DOMElement;
 use SimpleSAML\XMLSecurity\Constants as C;
 use SimpleSAML\XMLSecurity\Exception\CanonicalizationFailedException;
+use SimpleSAML\XMLSecurity\Exception\ReferenceValidationFailedException;
+use SimpleSAML\XMLSecurity\Utils\XPath;
 use SimpleSAML\XMLSecurity\XML\ds\Transforms;
 use SimpleSAML\XPath\Constants as XPATH_C;
 
@@ -140,15 +142,22 @@ public function processTransforms(
                         $arXPath = [];
                         $xpathValue = $xpath->getContent()->getValue();
                         $arXPath['query'] = '(.//. | .//@* | .//namespace::*)[' . $xpathValue . ']';
-
-//                        $arXpath['namespaces'] = $xpath->getNamespaces();
-                        // TODO: review if $nsnode->localName is equivalent to the keys in getNamespaces()
-//                        $nslist = $xp->query('./namespace::*', $node);
-//                        foreach ($nslist as $nsnode) {
-//                            if ($nsnode->localName != "xml") {
-//                                $arXPath['namespaces'][$nsnode->localName] = $nsnode->nodeValue;
-//                            }
-//                        }
+                        $arXpath['namespaces'] = $xpath->getNamespaces();
+
+                        $xpCache = XPath::getXPath($data);
+                        $nslist = $xpCache->query('./namespace::*', $xpath->toXML());
+                        Assert::lessThanEq(
+                            $nslist->count(),
+                            C::MAX_XPATH_NAMESPACES,
+                            ReferenceValidationFailedException::class,
+                            'Too many namespaces.',
+                        );
+
+                        foreach ($nslist as $nsnode) {
+                            if ($nsnode->localName != "xml") {
+                                $arXPath['namespaces'][$nsnode->localName] = $nsnode->nodeValue;
+                            }
+                        }
                     }
                     break;
             }