1 /*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
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 import java.security.MessageDigest;
31 import java.security.SecureRandom;
32
33 import sun.security.ssl.HandshakeMessage.ClientHello;
34
35 /*
36 * HelloVerifyRequest cookie manager
37 */
38 final class HelloCookieManager {
39 // the cookie secret life time
40 private static long COOKIE_TIMING_WINDOW = 3600000; // in milliseconds
41 private static int COOKIE_MAX_LENGTH_DTLS10 = 32; // 32 bytes
42 private static int COOKIE_MAX_LENGTH_DTLS12 = 0xFF; // 2^8 -1 bytes
43
44 private final SecureRandom secureRandom;
45 private final MessageDigest cookieDigest;
46
47 private int cookieVersion; // allow to wrap
48 private long secretLifetime;
49 private byte[] cookieSecret;
50
51 private int prevCookieVersion;
52 private byte[] prevCookieSecret;
53
54 HelloCookieManager(SecureRandom secureRandom) {
55 this.secureRandom = secureRandom;
56 this.cookieDigest = JsseJce.getMessageDigest("SHA-256");
57
58 this.cookieVersion = secureRandom.nextInt();
59 this.secretLifetime = 0;
60 this.cookieSecret = null;
61
62 this.prevCookieVersion = 0;
63 this.prevCookieSecret = null;
64 }
65
66 // Used by server side to generate cookies in HelloVerifyRequest message.
67 synchronized byte[] getCookie(ClientHello clientHelloMsg) {
68 if (secretLifetime < System.currentTimeMillis()) {
69 if (cookieSecret != null) {
70 prevCookieVersion = cookieVersion;
71 prevCookieSecret = cookieSecret.clone();
72 } else {
73 cookieSecret = new byte[32];
74 }
75
76 cookieVersion++;
77 secureRandom.nextBytes(cookieSecret);
78 secretLifetime = System.currentTimeMillis() + COOKIE_TIMING_WINDOW;
79 }
80
81 clientHelloMsg.updateHelloCookie(cookieDigest);
82 byte[] cookie = cookieDigest.digest(cookieSecret); // 32 bytes
83 cookie[0] = (byte)((cookieVersion >> 24) & 0xFF);
84 cookie[1] = (byte)((cookieVersion >> 16) & 0xFF);
85 cookie[2] = (byte)((cookieVersion >> 8) & 0xFF);
86 cookie[3] = (byte)(cookieVersion & 0xFF);
87
88 return cookie;
89 }
90
91 // Used by server side to check the cookie in ClientHello message.
92 synchronized boolean isValid(ClientHello clientHelloMsg) {
93 byte[] cookie = clientHelloMsg.cookie;
94
95 // no cookie exchange or not a valid cookie length
96 if ((cookie == null) || (cookie.length != 32)) {
97 return false;
98 }
99
100 int version = ((cookie[0] & 0xFF) << 24) |
101 ((cookie[1] & 0xFF) << 16) |
102 ((cookie[2] & 0xFF) << 8) |
103 (cookie[3] & 0xFF);
104
105 byte[] secret;
106 if (version == cookieVersion) {
107 secret = cookieSecret;
108 } else if (version == prevCookieVersion) {
109 secret = prevCookieSecret;
110 } else {
111 return false; // may be out of the timing window
112 }
113
114 clientHelloMsg.updateHelloCookie(cookieDigest);
115 byte[] target = cookieDigest.digest(secret); // 32 bytes
116
117 for (int i = 4; i < 32; i++) {
118 if (cookie[i] != target[i]) {
119 return false;
120 }
121 }
122
123 return true;
124 }
125
126 // Used by client side to check the cookie in HelloVerifyRequest message.
127 static void checkCookie(ProtocolVersion protocolVersion,
128 byte[] cookie) throws IOException {
129 if (cookie != null && cookie.length != 0) {
130 int limit = COOKIE_MAX_LENGTH_DTLS12;
131 if (protocolVersion.v == ProtocolVersion.DTLS10.v) {
132 limit = COOKIE_MAX_LENGTH_DTLS10;
133 }
134
135 if (cookie.length > COOKIE_MAX_LENGTH_DTLS10) {
136 throw new SSLProtocolException(
137 "Invalid HelloVerifyRequest.cookie (length = " +
138 cookie.length + " bytes)");
139 }
140 }
141
142 // Otherwise, no cookie exchange.
143 }
144 }