1 /*
   2  * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.security.ssl;
  27 
  28 import java.io.IOException;
  29 import javax.net.ssl.SSLProtocolException;
  30 
  31 /**
  32  * Extended Master Secret TLS extension (TLS 1.0+). This extension
  33  * defines how to calculate the TLS connection master secret and
  34  * mitigates some types of man-in-the-middle attacks.
  35  *
  36  * See further information in
  37  * <a href="https://tools.ietf.org/html/rfc7627">RFC 7627</a>.
  38  *
  39  * @author Martin Balao (mbalao@redhat.com)
  40  */
  41 final class ExtendedMasterSecretExtension extends HelloExtension {
  42     ExtendedMasterSecretExtension() {
  43         super(ExtensionType.EXT_EXTENDED_MASTER_SECRET);
  44     }
  45 
  46     ExtendedMasterSecretExtension(HandshakeInStream s,
  47             int len) throws IOException {
  48         super(ExtensionType.EXT_EXTENDED_MASTER_SECRET);
  49 
  50         if (len != 0) {
  51             throw new SSLProtocolException("Invalid " + type + " extension");
  52         }
  53     }
  54 
  55     @Override
  56     int length() {
  57         return 4;       // 4: extension type and length fields
  58     }
  59 
  60     @Override
  61     void send(HandshakeOutStream s) throws IOException {
  62         s.putInt16(type.id);    // ExtensionType extension_type;
  63         s.putInt16(0);          // extension_data length
  64     }
  65 
  66     @Override
  67     public String toString() {
  68         return "Extension " + type;
  69     }
  70 }
  71