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1   /*
2    * Copyright 2014 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.ssl;
17  
18  import io.netty.util.internal.ObjectUtil;
19  
20  import javax.net.ssl.SSLEngine;
21  import java.util.ArrayList;
22  import java.util.List;
23  import java.util.Set;
24  
25  /**
26   * This class will filter all requested ciphers out that are not supported by the current {@link SSLEngine}.
27   */
28  public final class SupportedCipherSuiteFilter implements CipherSuiteFilter {
29      public static final SupportedCipherSuiteFilter INSTANCE = new SupportedCipherSuiteFilter();
30  
31      private SupportedCipherSuiteFilter() { }
32  
33      @Override
34      public String[] filterCipherSuites(Iterable<String> ciphers, List<String> defaultCiphers,
35              Set<String> supportedCiphers) {
36          ObjectUtil.checkNotNull(defaultCiphers, "defaultCiphers");
37          ObjectUtil.checkNotNull(supportedCiphers, "supportedCiphers");
38  
39          final List<String> newCiphers;
40          if (ciphers == null) {
41              newCiphers = new ArrayList<String>(defaultCiphers.size());
42              ciphers = defaultCiphers;
43          } else {
44              newCiphers = new ArrayList<String>(supportedCiphers.size());
45          }
46          for (String c : ciphers) {
47              if (c == null) {
48                  break;
49              }
50              if (supportedCiphers.contains(c)) {
51                  newCiphers.add(c);
52              }
53          }
54          return newCiphers.toArray(new String[0]);
55      }
56  
57  }