创建 QName 异常时，Opensaml unmarshallMessage 给出的 opensaml 本地部分不能为“null”

Posted 2023-02-27

【中文标题】创建 QName 异常时，Opensaml unmarshallMessage 给出的 opensaml 本地部分不能为“null”

【英文标题】：Opensaml unmarshallMessage giving opensaml local part cannot be "null" when creating a QName Exception

【发布时间】：2021-07-30 17:49:54

【问题描述】：

我正在使用 Spring SAML，来自 IDP 响应我收到 issuer 作为属性 ID，所以我想在 spring saml 接收后更改响应，所以我已覆盖方法 unmarshall，它将解析消息并为此更改 xml 元素。这样做时，如果我在解析解组后直接使用 Element，它正在工作，但如果我进行 dom 操作，则会给出以下异常。我不明白为什么它在第一个代码中抛出异常，但在下面附加的第二个代码中却没有。如何在不再次转换为字符串并获取 dom 对象的情况下使其工作。

Exception in thread "main" java.lang.IllegalArgumentException: local part cannot be "null" when creating a QName
    at java.xml/javax.xml.namespace.QName.<init>(QName.java:185)
    at java.xml/javax.xml.namespace.QName.<init>(QName.java:129)
    at org.opensaml.xml.util.XMLHelper.constructQName(XMLHelper.java:433)
    at org.opensaml.xml.util.XMLHelper.getNodeQName(XMLHelper.java:171)
    at org.opensaml.xml.io.UnmarshallerFactory.getUnmarshaller(UnmarshallerFactory.java:81)
    at org.opensaml.xml.io.AbstractXMLObjectUnmarshaller.unmarshallChildElement(AbstractXMLObjectUnmarshaller.java:334)
    at org.opensaml.xml.io.AbstractXMLObjectUnmarshaller.unmarshall(AbstractXMLObjectUnmarshaller.java:127)
    at org.opensaml.xml.io.AbstractXMLObjectUnmarshaller.unmarshallChildElement(AbstractXMLObjectUnmarshaller.java:355)
    at org.opensaml.xml.io.AbstractXMLObjectUnmarshaller.unmarshall(AbstractXMLObjectUnmarshaller.java:127)
    at org.opensaml.ws.message.decoder.BaseMessageDecoder.unmarshallMessage(unmarshallMessage.java:208)

对于下面的代码，如上所述，它会抛出异常。

protected XMLObject unmarshallMessage(InputStream messageStream) throws MessageDecodingException 
     log.debug("Parsing message stream into DOM document");

     try 
         Document messageDoc = parserPool.parse(messageStream);
         Element messageElem = messageDoc.getDocumentElement();
         Element elementsByTagName = (Element) messageElem.getElementsByTagName("saml2:Assertion").item(0);
         Element issuer = messageDoc.createElement("saml2:Issuer");
         issuer.setTextContent("emIDAM");
         issuer.setAttribute("Format", "urn:oasis:names:tc:SAML:2.0:nameid-format:entity");
         log.debug("Unmarshalling message DOM");
         Unmarshaller unmarshaller = Configuration.getUnmarshallerFactory().getUnmarshaller(messageElem);
         if (unmarshaller == null) 
             log.debug("Unable to unmarshall message, no unmarshaller registered for message element "
                     + XMLHelper.getNodeQName(messageElem));
             throw new MessageDecodingException(
                     "Unable to unmarshall message, no unmarshaller registered for message element "
                             + XMLHelper.getNodeQName(messageElem));
         
         XMLObject message = unmarshaller.unmarshall(messageElem);

         return message;
      catch (XMLParserException e) 
         log.error("Encountered error parsing message into its DOM representation", e);
         throw new MessageDecodingException("Encountered error parsing message into its DOM representation", e);
      catch (UnmarshallingException e) 
         log.error("Encountered error unmarshalling message from its DOM representation", e);
         throw new MessageDecodingException("Encountered error unmarshalling message from its DOM representation", e);
     
     catch (Exception e) 
         log.warn("Encountered error unmarshalling message from its DOM representation --->", e);
         throw new MessageDecodingException("Encountered error unmarshalling message from its DOM representation", e);
     
 

但对于下面的代码，它工作正常，因为在这里我再次转换为字符串并创建输入流，然后获取传递给解组的 dom。

protected XMLObject unmarshallMessage(InputStream messageStream) throws MessageDecodingException 
     log.debug("Parsing message stream into DOM document");

     try 
         Document messageDoc = parserPool.parse(messageStream);
         Element messageElem = messageDoc.getDocumentElement();
         Element elementsByTagName = (Element) messageElem.getElementsByTagName("saml2:Assertion").item(0);
         Element issuer = messageDoc.createElement("saml2:Issuer");
         issuer.setTextContent("emIDAM");
         issuer.setAttribute("Format", "urn:oasis:names:tc:SAML:2.0:nameid-format:entity");

         //converting again to string and getting dom
         String xml = XMLHelper.nodeToString(messageElem);
         messageStream = new ByteArrayInputStream(xml.getBytes());
         messageDoc = parserPool.parse(messageStream);
         messageElem = messageDoc.getDocumentElement();


         log.debug("Unmarshalling message DOM");
         Unmarshaller unmarshaller = Configuration.getUnmarshallerFactory().getUnmarshaller(messageElem);
         if (unmarshaller == null) 
             log.debug("Unable to unmarshall message, no unmarshaller registered for message element "
                     + XMLHelper.getNodeQName(messageElem));
             throw new MessageDecodingException(
                     "Unable to unmarshall message, no unmarshaller registered for message element "
                             + XMLHelper.getNodeQName(messageElem));
         
         XMLObject message = unmarshaller.unmarshall(messageElem);

         return message;
      catch (XMLParserException e) 
         log.error("Encountered error parsing message into its DOM representation", e);
         throw new MessageDecodingException("Encountered error parsing message into its DOM representation", e);
      catch (UnmarshallingException e) 
         log.error("Encountered error unmarshalling message from its DOM representation", e);
         throw new MessageDecodingException("Encountered error unmarshalling message from its DOM representation", e);
     
     catch (Exception e) 
         log.warn("Encountered error unmarshalling message from its DOM representation --->", e);
         throw new MessageDecodingException("Encountered error unmarshalling message from its DOM representation", e);
     
 

【参考方案1】：

您的问题可能与您的解析器配置有关，可能未配置为支持命名空间。

请在初始化 parserPool 时使用类似于以下代码的代码：

DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
DocumentBuilder parserPool = documentBuilderFactory.newDocumentBuilder();

我的猜测是第二个测试成功运行，因为在后台 XMLHelper nodeToString 正在使用 writeNode，而 writeNode 又使用 LSSerializer 来执行实际的 XML 序列化。由于解析器被声明为非命名空间感知，因此生成的 XML 输出和对应的解析 Document 将不包含命名空间信息，或者至少，它包含的信息以这样一种方式，即随后由 Unmarshaller 执行的解析过程认为合适。

此外，请注意，问题可能与您创建新 Element 的方式有关，因为您也没有提供命名空间信息：当您使用 createElement 时，生成的 @987654333 @ 将不包含localName、prefix 或namespaceURI，都设置为null。请尝试以下代码：

Document messageDoc = parserPool.parse(messageStream);
Element messageElem = messageDoc.getDocumentElement();
Element assertionElem = (Element) messageElem.getElementsByTagName("saml2:Assertion").item(0);
Element issuerElement = messageDoc.createElementNS("urn:oasis:names:tc:SAML:2.0:assertion", "saml2:Issuer");
Attr formatAttr = messageDoc.createAttributeNS("urn:oasis:names:tc:SAML:2.0:assertion", "saml2:Format");
formatAttr.setNodeValue("urn:oasis:names:tc:SAML:2.0:nameid-format:entity");
issuerElement.setAttributeNode(formatAttr);
Text text = messageDoc.createTextNode("emIDAM");
issuerElement.appendChild(text);
assertionElem.appendChild(issuerElement);