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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    *   http://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 javax.net.ssl.SSLEngine;
19  import java.util.ArrayList;
20  import java.util.List;
21  import java.util.Set;
22  
23  /**
24   * This class will filter all requested ciphers out that are not supported by the current {@link SSLEngine}.
25   */
26  public final class SupportedCipherSuiteFilter implements CipherSuiteFilter {
27      public static final SupportedCipherSuiteFilter INSTANCE = new SupportedCipherSuiteFilter();
28  
29      private SupportedCipherSuiteFilter() { }
30  
31      @Override
32      public String[] filterCipherSuites(Iterable<String> ciphers, List<String> defaultCiphers,
33              Set<String> supportedCiphers) {
34          if (defaultCiphers == null) {
35              throw new NullPointerException("defaultCiphers");
36          }
37          if (supportedCiphers == null) {
38              throw new NullPointerException("supportedCiphers");
39          }
40  
41          final List<String> newCiphers;
42          if (ciphers == null) {
43              newCiphers = new ArrayList<String>(defaultCiphers.size());
44              ciphers = defaultCiphers;
45          } else {
46              newCiphers = new ArrayList<String>(supportedCiphers.size());
47          }
48          for (String c : ciphers) {
49              if (c == null) {
50                  break;
51              }
52              if (supportedCiphers.contains(c)) {
53                  newCiphers.add(c);
54              }
55          }
56          return newCiphers.toArray(new String[0]);
57      }
58  
59  }