1 /* |
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2 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package sun.security.ssl; |
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27 |
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28 import java.util.Arrays; |
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29 |
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30 /** |
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31 * This class represents an SSL/TLS message authentication token, |
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32 * which encapsulates a sequence number and ensures that attempts to |
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33 * delete or reorder messages can be detected. |
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34 * |
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35 * Each SSL/TLS connection state contains a sequence number, which |
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36 * is maintained separately for read and write states. The sequence |
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37 * number MUST be set to zero whenever a connection state is made the |
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38 * active state. Sequence numbers are of type uint64 and may not |
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39 * exceed 2^64-1. Sequence numbers do not wrap. If a SSL/TLS |
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40 * implementation would need to wrap a sequence number, it must |
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41 * renegotiate instead. A sequence number is incremented after each |
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42 * record: specifically, the first record transmitted under a |
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43 * particular connection state MUST use sequence number 0. |
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44 */ |
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45 class Authenticator { |
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46 |
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47 // byte array containing the additional authentication information for |
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48 // each record |
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49 private final byte[] block; |
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50 |
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51 // the block size of SSL v3.0: |
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52 // sequence number + record type + + record length |
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53 private static final int BLOCK_SIZE_SSL = 8 + 1 + 2; |
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54 |
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55 // the block size of TLS v1.0 and later: |
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56 // sequence number + record type + protocol version + record length |
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57 private static final int BLOCK_SIZE_TLS = 8 + 1 + 2 + 2; |
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58 |
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59 /** |
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60 * Default construct, no message authentication token is initialized. |
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61 * |
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62 * Note that this construct can only be called for null MAC |
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63 */ |
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64 Authenticator() { |
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65 block = new byte[0]; |
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66 } |
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67 |
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68 /** |
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69 * Constructs the message authentication token for the specified |
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70 * SSL/TLS protocol. |
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71 */ |
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72 Authenticator(ProtocolVersion protocolVersion) { |
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73 if (protocolVersion.v >= ProtocolVersion.TLS10.v) { |
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74 block = new byte[BLOCK_SIZE_TLS]; |
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75 block[9] = protocolVersion.major; |
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76 block[10] = protocolVersion.minor; |
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77 } else { |
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78 block = new byte[BLOCK_SIZE_SSL]; |
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79 } |
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80 } |
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81 |
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82 /** |
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83 * Checks whether the sequence number is close to wrap. |
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84 * |
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85 * Sequence numbers are of type uint64 and may not exceed 2^64-1. |
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86 * Sequence numbers do not wrap. When the sequence number is near |
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87 * to wrap, we need to close the connection immediately. |
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88 * |
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89 * @return true if the sequence number is close to wrap |
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90 */ |
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91 final boolean seqNumOverflow() { |
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92 /* |
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93 * Conservatively, we don't allow more records to be generated |
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94 * when there are only 2^8 sequence numbers left. |
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95 */ |
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96 return (block.length != 0 && |
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97 block[0] == (byte)0xFF && block[1] == (byte)0xFF && |
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98 block[2] == (byte)0xFF && block[3] == (byte)0xFF && |
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99 block[4] == (byte)0xFF && block[5] == (byte)0xFF && |
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100 block[6] == (byte)0xFF); |
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101 } |
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102 |
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103 /** |
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104 * Checks whether the sequence number close to renew. |
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105 * |
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106 * Sequence numbers are of type uint64 and may not exceed 2^64-1. |
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107 * Sequence numbers do not wrap. If a TLS |
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108 * implementation would need to wrap a sequence number, it must |
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109 * renegotiate instead. |
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110 * |
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111 * @return true if the sequence number is huge enough to renew |
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112 */ |
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113 final boolean seqNumIsHuge() { |
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114 /* |
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115 * Conservatively, we should ask for renegotiation when there are |
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116 * only 2^48 sequence numbers left. |
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117 */ |
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118 return (block.length != 0 && |
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119 block[0] == (byte)0xFF && block[1] == (byte)0xFF); |
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120 } |
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121 |
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122 /** |
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123 * Gets the current sequence number. |
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124 * |
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125 * @return the byte array of the current sequence number |
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126 */ |
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127 final byte[] sequenceNumber() { |
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128 return Arrays.copyOf(block, 8); |
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129 } |
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130 |
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131 /** |
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132 * Acquires the current message authentication information with the |
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133 * specified record type and fragment length, and then increases the |
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134 * sequence number. |
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135 * |
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136 * @param type the record type |
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137 * @param length the fragment of the record |
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138 * @return the byte array of the current message authentication information |
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139 */ |
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140 final byte[] acquireAuthenticationBytes(byte type, int length) { |
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141 byte[] copy = block.clone(); |
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142 |
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143 if (block.length != 0) { |
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144 copy[8] = type; |
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145 copy[copy.length - 2] = (byte)(length >> 8); |
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146 copy[copy.length - 1] = (byte)(length); |
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147 |
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148 /* |
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149 * Increase the sequence number in the block array |
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150 * it is a 64-bit number stored in big-endian format |
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151 */ |
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152 int k = 7; |
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153 while ((k >= 0) && (++block[k] == 0)) { |
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154 k--; |
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155 } |
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156 } |
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157 |
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158 return copy; |
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159 } |
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160 |
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161 } |
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