feat: add support for null namespace in findAttr function

Author: shunkica

src/types.ts

@@ -363,7 +363,7 @@ export interface XmlDSigVerifierOptions {
    * Names of XML attributes to treat as element identifiers.
    * Used when resolving URI references in signatures.
    * When passing strings, only the localName is matched, ignoring namespace.
-   * To explicitly match attributes without namespaces, use: { localName: "Id", namespaceUri: undefined }
+   * To explicitly match attributes without namespaces, use: { localName: "Id", namespaceUri: null }
    * @default {@link SignedXml.getDefaultIdAttributes()}
    * @example For WS-Security: [{ localName: "Id", namespaceUri: "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" }]
    */

src/utils.ts

@@ -6,18 +6,33 @@ export function isArrayHasLength(array: unknown): array is unknown[] {
   return Array.isArray(array) && array.length > 0;
 }
 
-function attrEqualsExplicitly(attr: Attr, localName: string, namespace?: string) {
+function attrEqualsExplicitly(attr: Attr, localName: string, namespace?: string | null) {
+  if (namespace === null) {
+    return attr.localName === localName && !attr.namespaceURI;
+  }
   return attr.localName === localName && (attr.namespaceURI === namespace || namespace == null);
 }
 
-function attrEqualsImplicitly(attr: Attr, localName: string, namespace?: string, node?: Element) {
+function attrEqualsImplicitly(
+  attr: Attr,
+  localName: string,
+  namespace?: string | null,
+  node?: Element,
+) {
+  if (namespace === null) {
+    return attr.localName === localName && !attr.namespaceURI;
+  }
   return (
     attr.localName === localName &&
     ((!attr.namespaceURI && node?.namespaceURI === namespace) || namespace == null)
   );
 }
 
-export function findAttr(element: Element, localName: string, namespace?: string | undefined) {
+export function findAttr(
+  element: Element,
+  localName: string,
+  namespace?: string | null | undefined,
+) {
   for (let i = 0; i < element.attributes.length; i++) {
     const attr = element.attributes[i];
 

test/utils-tests.spec.ts

@@ -80,4 +80,60 @@ describe("Utils tests", function () {
       expect(() => utils.pemToDer("not a pem")).to.throw();
     });
   });
+
+  describe("findAttr", function () {
+    it("should find attribute with no namespace when null is passed as namespace", function () {
+      const xml =
+        '<root testAttr="value" xmlns:ns="http://example.com" ns:testAttr="nsValue"></root>';
+      const doc = new xmldom.DOMParser().parseFromString(xml);
+      const rootElement = doc.documentElement;
+
+      const attr = utils.findAttr(rootElement, "testAttr", null);
+
+      expect(attr).to.not.be.null;
+      expect(attr?.value).to.equal("value");
+      expect(attr?.namespaceURI).to.be.undefined;
+    });
+
+    it("should not find namespaced attribute when null is passed as namespace", function () {
+      const xml = '<root xmlns:ns="http://example.com" ns:testAttr="nsValue"></root>';
+      const doc = new xmldom.DOMParser().parseFromString(xml);
+      const rootElement = doc.documentElement;
+
+      const attr = utils.findAttr(rootElement, "testAttr", null);
+
+      expect(attr).to.be.null;
+    });
+
+    it("should find namespaced attribute when matching namespace is provided", function () {
+      const xml = '<root xmlns:ns="http://example.com" ns:testAttr="nsValue"></root>';
+      const doc = new xmldom.DOMParser().parseFromString(xml);
+      const rootElement = doc.documentElement;
+
+      const attr = utils.findAttr(rootElement, "testAttr", "http://example.com");
+
+      expect(attr).to.not.be.null;
+      expect(attr?.value).to.equal("nsValue");
+      expect(attr?.namespaceURI).to.equal("http://example.com");
+    });
+
+    it("should distinguish between namespaced and non-namespaced attributes with same localName", function () {
+      const xml =
+        '<root testAttr="noNsValue" xmlns:ns="http://example.com" ns:testAttr="nsValue"></root>';
+      const doc = new xmldom.DOMParser().parseFromString(xml);
+      const rootElement = doc.documentElement;
+
+      // Find the non-namespaced attribute
+      const noNsAttr = utils.findAttr(rootElement, "testAttr", null);
+      expect(noNsAttr).to.not.be.null;
+      expect(noNsAttr?.value).to.equal("noNsValue");
+      expect(noNsAttr?.namespaceURI).to.be.undefined;
+
+      // Find the namespaced attribute
+      const nsAttr = utils.findAttr(rootElement, "testAttr", "http://example.com");
+      expect(nsAttr).to.not.be.null;
+      expect(nsAttr?.value).to.equal("nsValue");
+      expect(nsAttr?.namespaceURI).to.equal("http://example.com");
+    });
+  });
 });