1 /*
   2  * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  */
  24 
  25 package sun.security.ssl;
  26 
  27 import java.io.IOException;
  28 import javax.net.ssl.SSLProtocolException;
  29 
  30 /**
  31  * Extended Master Secret TLS extension (TLS 1.0+). This extension
  32  * defines how to calculate the TLS connection master secret and
  33  * mitigates some types of man-in-the-middle attacks.
  34  *
  35  * See further information in
  36  * <a href="https://tools.ietf.org/html/rfc7627">RFC 7627</a>.
  37  *
  38  * @author Martin Balao (mbalao@redhat.com)
  39  */
  40 final class ExtendedMasterSecretExtension extends HelloExtension {
  41     ExtendedMasterSecretExtension() {
  42         super(ExtensionType.EXT_EXTENDED_MASTER_SECRET);
  43     }
  44 
  45     ExtendedMasterSecretExtension(HandshakeInStream s,
  46             int len) throws IOException {
  47         super(ExtensionType.EXT_EXTENDED_MASTER_SECRET);
  48 
  49         if (len != 0) {
  50             throw new SSLProtocolException("Invalid " + type + " extension");
  51         }
  52     }
  53 
  54     @Override
  55     int length() {
  56         return 4;       // 4: extension type and length fields
  57     }
  58 
  59     @Override
  60     void send(HandshakeOutStream s) throws IOException {
  61         s.putInt16(type.id);    // ExtensionType extension_type;
  62         s.putInt16(0);          // extension_data length
  63     }
  64 
  65     @Override
  66     public String toString() {
  67         return "Extension " + type;
  68     }
  69 }
  70