1/*
2 * Copyright (c) 2002, 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
26package sun.security.ssl;
27
28import java.util.*;
29
30/**
31 * A list of ProtocolVersions. Also maintains the list of supported protocols.
32 * Instances of this class are immutable. Some member variables are final
33 * and can be accessed directly without method accessors.
34 *
35 * @author  Andreas Sterbenz
36 * @since   1.4.1
37 */
38final class ProtocolList {
39
40    // the sorted protocol version list
41    private final ArrayList<ProtocolVersion> protocols;
42
43    private String[] protocolNames;
44
45    // the minimum and maximum ProtocolVersions in this list
46    final ProtocolVersion min, max;
47
48    // the format for the hello version to use
49    final ProtocolVersion helloVersion;
50
51    ProtocolList(String[] names) {
52        this(convert(names));
53    }
54
55    ProtocolList(ArrayList<ProtocolVersion> versions) {
56        this.protocols = versions;
57
58        if ((protocols.size() == 1) &&
59                protocols.contains(ProtocolVersion.SSL20Hello)) {
60            throw new IllegalArgumentException("SSLv2Hello cannot be " +
61                "enabled unless at least one other supported version " +
62                "is also enabled.");
63        }
64
65        if (protocols.size() != 0) {
66            Collections.sort(protocols);
67            min = protocols.get(0);
68            max = protocols.get(protocols.size() - 1);
69            helloVersion = protocols.get(0);
70        } else {
71            min = ProtocolVersion.NONE;
72            max = ProtocolVersion.NONE;
73            helloVersion = ProtocolVersion.NONE;
74        }
75    }
76
77    private static ArrayList<ProtocolVersion> convert(String[] names) {
78        if (names == null) {
79            throw new IllegalArgumentException("Protocols may not be null");
80        }
81
82        ArrayList<ProtocolVersion> versions = new ArrayList<>(names.length);
83        for (int i = 0; i < names.length; i++ ) {
84            ProtocolVersion version = ProtocolVersion.valueOf(names[i]);
85            if (versions.contains(version) == false) {
86                versions.add(version);
87            }
88        }
89
90        return versions;
91    }
92
93    /**
94     * Return whether this list contains the specified protocol version.
95     * SSLv2Hello is not a real protocol version we support, we always
96     * return false for it.
97     */
98    boolean contains(ProtocolVersion protocolVersion) {
99        if (protocolVersion == ProtocolVersion.SSL20Hello) {
100            return false;
101        }
102        return protocols.contains(protocolVersion);
103    }
104
105    /**
106     * Return a reference to the internal Collection of CipherSuites.
107     * The Collection MUST NOT be modified.
108     */
109    Collection<ProtocolVersion> collection() {
110        return protocols;
111    }
112
113    /**
114     * Select a protocol version from the list.
115     *
116     * Return the lower of the protocol version of that suggested by
117     * the <code>protocolVersion</code> and the highest version of this
118     * protocol list, or null if no protocol version is available.
119     *
120     * The method is used by TLS server to negotiated the protocol
121     * version between client suggested protocol version in the
122     * client hello and protocol versions supported by the server.
123     */
124    ProtocolVersion selectProtocolVersion(ProtocolVersion protocolVersion) {
125        ProtocolVersion selectedVersion = null;
126        for (ProtocolVersion pv : protocols) {
127            if (pv.compareTo(protocolVersion) > 0) {
128                break;      // Safe to break here as this.protocols is sorted,
129                            // and DTLS and SSL/TLS protocols are not mixed.
130            }
131            selectedVersion = pv;
132        }
133
134        return selectedVersion;
135    }
136
137    /**
138     * Return an array with the names of the ProtocolVersions in this list.
139     */
140    synchronized String[] toStringArray() {
141        if (protocolNames == null) {
142            protocolNames = new String[protocols.size()];
143            int i = 0;
144            for (ProtocolVersion version : protocols) {
145                protocolNames[i++] = version.name;
146            }
147        }
148        return protocolNames.clone();
149    }
150
151    @Override
152    public String toString() {
153        return protocols.toString();
154    }
155}
156