code: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied. See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.cxf.ws.security.trust.delegation;
  
  import java.io.IOException;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.UnsupportedCallbackException;
  
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  
  import org.apache.cxf.helpers.DOMUtils;
  import org.apache.cxf.message.Message;
  import org.apache.cxf.ws.security.SecurityConstants;
  import org.apache.ws.security.message.token.UsernameToken;
  
  /**
   * This CallbackHandler implementation obtains a username via the jaxws property 
   * "ws-security.username", as defined in SecurityConstants, and creates a wss UsernameToken 
   * (with no password) to be used as the delegation token.
   */
  public class WSSUsernameCallbackHandler implements CallbackHandler {
      
      public void handle(Callback[] callbacks)
          throws IOException, UnsupportedCallbackException {
          for (int i = 0; i < callbacks.length; i++) {
              if (callbacks[i] instanceof DelegationCallback) {
                  DelegationCallback callback = (DelegationCallback) callbacks[i];
                  Message message = callback.getCurrentMessage();
                  
                  String username = 
                      (String)message.getContextualProperty(SecurityConstants.USERNAME);
                  if (username != null) {
                      Node contentNode = message.getContent(Node.class);
                      Document doc = null;
                      if (contentNode != null) {
                          doc = contentNode.getOwnerDocument();
                      } else {
                          doc = DOMUtils.createDocument();
                      }
                      UsernameToken usernameToken = createWSSEUsernameToken(username, doc);
                      callback.setToken(usernameToken.getElement());
                  }
              } else {
                  throw new UnsupportedCallbackException(callbacks[i], "Unrecognized Callback");
              }
          }
      }
      
      private UsernameToken createWSSEUsernameToken(String username, Document doc) {
          UsernameToken usernameToken = new UsernameToken(true, doc, null);
          usernameToken.setName(username);
          usernameToken.addWSUNamespace();
          usernameToken.addWSSENamespace();
          usernameToken.setID("id-" + username);
          
          return usernameToken;
      }
      
  }
  