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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.util.internal.ObjectUtil.checkNotNull;
  import io.netty.handler.ssl.JdkApplicationProtocolNegotiator.ProtocolSelectionListener;
  import io.netty.handler.ssl.JdkApplicationProtocolNegotiator.ProtocolSelector;
  import io.netty.util.internal.PlatformDependent;
  
  import java.util.LinkedHashSet;
  import java.util.List;
  
  import javax.net.ssl.SSLEngine;
  import javax.net.ssl.SSLException;
  
  import org.eclipse.jetty.npn.NextProtoNego;
  import org.eclipse.jetty.npn.NextProtoNego.ClientProvider;
  import org.eclipse.jetty.npn.NextProtoNego.ServerProvider;
  
  final class JettyNpnSslEngine extends JdkSslEngine {
      private static boolean available;
  
      static boolean isAvailable() {
          updateAvailability();
          return available;
      }
  
      private static void updateAvailability() {
          if (available) {
              return;
          }
          try {
              // Always use bootstrap class loader.
              Class.forName("sun.security.ssl.NextProtoNegoExtension", true, null);
              available = true;
          } catch (Exception ignore) {
              // npn-boot was not loaded.
          }
      }
  
      JettyNpnSslEngine(SSLEngine engine, final JdkApplicationProtocolNegotiator applicationNegotiator, boolean server) {
          super(engine);
          checkNotNull(applicationNegotiator, "applicationNegotiator");
  
          if (server) {
              final ProtocolSelectionListener protocolListener = checkNotNull(applicationNegotiator
                      .protocolListenerFactory().newListener(this, applicationNegotiator.protocols()),
                      "protocolListener");
              NextProtoNego.put(engine, new ServerProvider() {
                  @Override
                  public void unsupported() {
                      protocolListener.unsupported();
                  }
  
                  @Override
                  public List<String> protocols() {
                      return applicationNegotiator.protocols();
                  }
  
                  @Override
                  public void protocolSelected(String protocol) {
                      try {
                          protocolListener.selected(protocol);
                      } catch (Throwable t) {
                          PlatformDependent.throwException(t);
                      }
                  }
              });
          } else {
              final ProtocolSelector protocolSelector = checkNotNull(applicationNegotiator.protocolSelectorFactory()
                      .newSelector(this, new LinkedHashSet<String>(applicationNegotiator.protocols())),
                      "protocolSelector");
              NextProtoNego.put(engine, new ClientProvider() {
                  @Override
                  public boolean supports() {
                      return true;
                  }
  
                  @Override
                  public void unsupported() {
                      protocolSelector.unsupported();
                  }
  
                  @Override
                  public String selectProtocol(List<String> protocols) {
                     try {
                         return protocolSelector.select(protocols);
                     } catch (Throwable t) {
                         PlatformDependent.throwException(t);
                         return null;
                     }
                 }
             });
         }
     }
 
     @Override
     public void closeInbound() throws SSLException {
         NextProtoNego.remove(getWrappedEngine());
         super.closeInbound();
     }
 
     @Override
     public void closeOutbound() {
         NextProtoNego.remove(getWrappedEngine());
         super.closeOutbound();
     }
 }