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   /*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.handler.ssl;
  
  import static io.netty.handler.ssl.ApplicationProtocolUtil.toList;
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  
  import javax.net.ssl.SSLEngine;
  import javax.net.ssl.SSLHandshakeException;
  
  /**
   * Common base class for {@link JdkApplicationProtocolNegotiator} classes to inherit from.
   */
  class JdkBaseApplicationProtocolNegotiator implements JdkApplicationProtocolNegotiator {
      private final List<String> protocols;
      private final ProtocolSelectorFactory selectorFactory;
      private final ProtocolSelectionListenerFactory listenerFactory;
      private final SslEngineWrapperFactory wrapperFactory;
  
      /**
       * Create a new instance.
       * @param wrapperFactory Determines which application protocol will be used by wrapping the SSLEngine in use.
       * @param selectorFactory How the peer selecting the protocol should behave.
       * @param listenerFactory How the peer being notified of the selected protocol should behave.
       * @param protocols The order of iteration determines the preference of support for protocols.
       */
      JdkBaseApplicationProtocolNegotiator(SslEngineWrapperFactory wrapperFactory,
              ProtocolSelectorFactory selectorFactory, ProtocolSelectionListenerFactory listenerFactory,
              Iterable<String> protocols) {
          this(wrapperFactory, selectorFactory, listenerFactory, toList(protocols));
      }
  
      /**
       * Create a new instance.
       * @param wrapperFactory Determines which application protocol will be used by wrapping the SSLEngine in use.
       * @param selectorFactory How the peer selecting the protocol should behave.
       * @param listenerFactory How the peer being notified of the selected protocol should behave.
       * @param protocols The order of iteration determines the preference of support for protocols.
       */
      JdkBaseApplicationProtocolNegotiator(SslEngineWrapperFactory wrapperFactory,
              ProtocolSelectorFactory selectorFactory, ProtocolSelectionListenerFactory listenerFactory,
              String... protocols) {
          this(wrapperFactory, selectorFactory, listenerFactory, toList(protocols));
      }
  
      /**
       * Create a new instance.
       * @param wrapperFactory Determines which application protocol will be used by wrapping the SSLEngine in use.
       * @param selectorFactory How the peer selecting the protocol should behave.
       * @param listenerFactory How the peer being notified of the selected protocol should behave.
       * @param protocols The order of iteration determines the preference of support for protocols.
       */
      private JdkBaseApplicationProtocolNegotiator(SslEngineWrapperFactory wrapperFactory,
              ProtocolSelectorFactory selectorFactory, ProtocolSelectionListenerFactory listenerFactory,
              List<String> protocols) {
          this.wrapperFactory = checkNotNull(wrapperFactory, "wrapperFactory");
          this.selectorFactory = checkNotNull(selectorFactory, "selectorFactory");
          this.listenerFactory = checkNotNull(listenerFactory, "listenerFactory");
          this.protocols = Collections.unmodifiableList(checkNotNull(protocols, "protocols"));
      }
  
      @Override
      public List<String> protocols() {
          return protocols;
      }
  
      @Override
      public ProtocolSelectorFactory protocolSelectorFactory() {
          return selectorFactory;
      }
  
      @Override
      public ProtocolSelectionListenerFactory protocolListenerFactory() {
          return listenerFactory;
      }
  
      @Override
      public SslEngineWrapperFactory wrapperFactory() {
          return wrapperFactory;
      }
  
      static final ProtocolSelectorFactory FAIL_SELECTOR_FACTORY = new ProtocolSelectorFactory() {
         @Override
         public ProtocolSelector newSelector(SSLEngine engine, Set<String> supportedProtocols) {
             return new FailProtocolSelector((JdkSslEngine) engine, supportedProtocols);
         }
     };
 
     static final ProtocolSelectorFactory NO_FAIL_SELECTOR_FACTORY = new ProtocolSelectorFactory() {
         @Override
         public ProtocolSelector newSelector(SSLEngine engine, Set<String> supportedProtocols) {
             return new NoFailProtocolSelector((JdkSslEngine) engine, supportedProtocols);
         }
     };
 
     static final ProtocolSelectionListenerFactory FAIL_SELECTION_LISTENER_FACTORY =
             new ProtocolSelectionListenerFactory() {
         @Override
         public ProtocolSelectionListener newListener(SSLEngine engine, List<String> supportedProtocols) {
             return new FailProtocolSelectionListener((JdkSslEngine) engine, supportedProtocols);
         }
     };
 
     static final ProtocolSelectionListenerFactory NO_FAIL_SELECTION_LISTENER_FACTORY =
             new ProtocolSelectionListenerFactory() {
         @Override
         public ProtocolSelectionListener newListener(SSLEngine engine, List<String> supportedProtocols) {
             return new NoFailProtocolSelectionListener((JdkSslEngine) engine, supportedProtocols);
         }
     };
 
     static class NoFailProtocolSelector implements ProtocolSelector {
         private final JdkSslEngine engineWrapper;
         private final Set<String> supportedProtocols;
 
         NoFailProtocolSelector(JdkSslEngine engineWrapper, Set<String> supportedProtocols) {
             this.engineWrapper = engineWrapper;
             this.supportedProtocols = supportedProtocols;
         }
 
         @Override
         public void unsupported() {
             engineWrapper.setNegotiatedApplicationProtocol(null);
         }
 
         @Override
         public String select(List<String> protocols) throws Exception {
             for (String p : supportedProtocols) {
                 if (protocols.contains(p)) {
                     engineWrapper.setNegotiatedApplicationProtocol(p);
                     return p;
                 }
             }
             return noSelectMatchFound();
         }
 
         public String noSelectMatchFound() throws Exception {
             engineWrapper.setNegotiatedApplicationProtocol(null);
             return null;
         }
     }
 
     private static final class FailProtocolSelector extends NoFailProtocolSelector {
         FailProtocolSelector(JdkSslEngine engineWrapper, Set<String> supportedProtocols) {
             super(engineWrapper, supportedProtocols);
         }
 
         @Override
         public String noSelectMatchFound() throws Exception {
             throw new SSLHandshakeException("Selected protocol is not supported");
         }
     }
 
     private static class NoFailProtocolSelectionListener implements ProtocolSelectionListener {
         private final JdkSslEngine engineWrapper;
         private final List<String> supportedProtocols;
 
         NoFailProtocolSelectionListener(JdkSslEngine engineWrapper, List<String> supportedProtocols) {
             this.engineWrapper = engineWrapper;
             this.supportedProtocols = supportedProtocols;
         }
 
         @Override
         public void unsupported() {
             engineWrapper.setNegotiatedApplicationProtocol(null);
         }
 
         @Override
         public void selected(String protocol) throws Exception {
             if (supportedProtocols.contains(protocol)) {
                 engineWrapper.setNegotiatedApplicationProtocol(protocol);
             } else {
                 noSelectedMatchFound(protocol);
             }
         }
 
         protected void noSelectedMatchFound(String protocol) throws Exception {
             // Will never be called.
         }
     }
 
     private static final class FailProtocolSelectionListener extends NoFailProtocolSelectionListener {
         FailProtocolSelectionListener(JdkSslEngine engineWrapper, List<String> supportedProtocols) {
             super(engineWrapper, supportedProtocols);
         }
 
         @Override
         protected void noSelectedMatchFound(String protocol) throws Exception {
             throw new SSLHandshakeException("No compatible protocols found");
         }
     }
 }