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 java.lang.ref.WeakReference;
  import java.util.List;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.UnsupportedCallbackException;
  
  import org.w3c.dom.Element;
  
  import org.apache.cxf.binding.soap.SoapMessage;
  import org.apache.cxf.helpers.CastUtils;
  import org.apache.cxf.message.Message;
  import org.apache.cxf.phase.PhaseInterceptorChain;
  import org.apache.ws.security.WSConstants;
  import org.apache.ws.security.WSSecurityEngineResult;
  import org.apache.ws.security.handler.WSHandlerConstants;
  import org.apache.ws.security.handler.WSHandlerResult;
  import org.apache.ws.security.message.token.BinarySecurity;
  import org.apache.ws.security.message.token.UsernameToken;
  import org.apache.ws.security.saml.ext.AssertionWrapper;
  
  /**
   * This CallbackHandler implementation obtains the previously received message from a 
   * DelegationCallback object, and obtains a received token 
   * (SAML/UsernameToken/BinarySecurityToken) from it to be used as the delegation token.
   */
  public class ReceivedTokenCallbackHandler implements CallbackHandler {
      
      @SuppressWarnings("unchecked")
      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();
                  
                  if (message != null 
                      && message.get(PhaseInterceptorChain.PREVIOUS_MESSAGE) != null) {
                      WeakReference<SoapMessage> wr = 
                          (WeakReference<SoapMessage>)
                              message.get(PhaseInterceptorChain.PREVIOUS_MESSAGE);
                      SoapMessage previousSoapMessage = wr.get();
                      Element token = getTokenFromMessage(previousSoapMessage);
                      if (token != null) {
                          callback.setToken(token);
                      }
                  }
                  
              } else {
                  throw new UnsupportedCallbackException(callbacks[i], "Unrecognized Callback");
              }
          }
      }
      
      private Element getTokenFromMessage(SoapMessage soapMessage) {
          if (soapMessage != null) {
              List<WSHandlerResult> results = 
                  CastUtils.cast((List<?>)soapMessage.get(WSHandlerConstants.RECV_RESULTS));
              if (results != null) {
                  for (WSHandlerResult rResult : results) {
                      Element token = findToken(rResult.getResults());
                      if (token != null) {
                          return token;
                      }
                  }
              }
          }
          return null;
      }
      
      private Element findToken(
          List<WSSecurityEngineResult> wsSecEngineResults
      ) {
          for (WSSecurityEngineResult wser : wsSecEngineResults) {
              Integer actInt = (Integer)wser.get(WSSecurityEngineResult.TAG_ACTION);
              if (actInt.intValue() == WSConstants.ST_SIGNED
                  || actInt.intValue() == WSConstants.ST_UNSIGNED) {
                  AssertionWrapper assertion = 
                      (AssertionWrapper)wser.get(WSSecurityEngineResult.TAG_SAML_ASSERTION);
                  return assertion.getElement();
              } else if (actInt.intValue() == WSConstants.UT
                  || actInt.intValue() == WSConstants.UT_NOPASSWORD) {
                  UsernameToken token =
                      (UsernameToken)wser.get(WSSecurityEngineResult.TAG_USERNAME_TOKEN);
                  return token.getElement();
              } else if (actInt.intValue() == WSConstants.BST) {
                  BinarySecurity token = 
                      (BinarySecurity)wser.get(WSSecurityEngineResult.TAG_BINARY_SECURITY_TOKEN);
                  return token.getElement();
              }
          }
          return null;
      }
      
  }
  