/*

 * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.security.ssl;

import java.util.*;

import java.security.CryptoPrimitive;

import sun.security.ssl.CipherSuite.*;

/**

 * Type safe enum for an SSL/TLS protocol version. Instances are obtained

 * using the static factory methods or by referencing the static members

 * in this class. Member variables are final and can be accessed without

 * accessor methods.

 *

 * There is only ever one instance per supported protocol version, this

 * means == can be used for comparision instead of equals() if desired.

 *

 * Checks for a particular version number should generally take this form:

 *

 * <pre>{@code

 * if (protocolVersion.v >= ProtocolVersion.TLS10) {

 *   // TLS 1.0 code goes here

 * } else {

 *   // SSL 3.0 code here

 * }

 * }</pre>

 *

 * @author  Andreas Sterbenz

 * @since   1.4.1

 */

public final class ProtocolVersion implements Comparable<ProtocolVersion> {

    // The limit of maximum protocol version

    final static int LIMIT_MAX_VALUE = 0xFFFF;

    // The limit of minimum protocol version

    final static int LIMIT_MIN_VALUE = 0x0000;

    // Dummy protocol version value for invalid SSLSession

    final static ProtocolVersion NONE = new ProtocolVersion(-1, "NONE");

    // If enabled, send/accept SSLv2 hello messages

    final static ProtocolVersion SSL20Hello =

                                new ProtocolVersion(0x0002, "SSLv2Hello");

    // SSL 3.0

    final static ProtocolVersion SSL30 = new ProtocolVersion(0x0300, "SSLv3");

    // TLS 1.0

    final static ProtocolVersion TLS10 = new ProtocolVersion(0x0301, "TLSv1");

    // TLS 1.1

    final static ProtocolVersion TLS11 = new ProtocolVersion(0x0302, "TLSv1.1");

    // TLS 1.2

    final static ProtocolVersion TLS12 = new ProtocolVersion(0x0303, "TLSv1.2");

    // DTLS 1.0

    // {254, 255}, the version value of DTLS 1.0.

    final static ProtocolVersion DTLS10 =

                                new ProtocolVersion(0xFEFF, "DTLSv1.0");

    // No DTLS 1.1, that version number was skipped in order to harmonize

    // version numbers with TLS.

    // DTLS 1.2

    // {254, 253}, the version value of DTLS 1.2.

    final static ProtocolVersion DTLS12 =

                                new ProtocolVersion(0xFEFD, "DTLSv1.2");

    private static final boolean FIPS = SunJSSE.isFIPS();

    // minimum version we implement (SSL 3.0)

    final static ProtocolVersion MIN = FIPS ? TLS10 : SSL30;

    // maximum version we implement (TLS 1.2)

    final static ProtocolVersion MAX = TLS12;

    // SSL/TLS ProtocolVersion to use by default (TLS 1.2)

    final static ProtocolVersion DEFAULT_TLS = TLS12;

    // DTLS ProtocolVersion to use by default (TLS 1.2)

    final static ProtocolVersion DEFAULT_DTLS = DTLS12;

    // Default version for hello messages (SSLv2Hello)

    final static ProtocolVersion DEFAULT_HELLO = FIPS ? TLS10 : SSL30;

    // Available protocols

    //

    // Including all supported protocols except the disabled ones.

    final static Set<ProtocolVersion> availableProtocols;

    // version in 16 bit MSB format as it appears in records and

    // messages, i.e. 0x0301 for TLS 1.0

    public final int v;

    // major and minor version

    public final byte major, minor;

    // name used in JSSE (e.g. TLSv1 for TLS 1.0)

    final String name;

    // Initialize the available protocols.

    static {

        Set<ProtocolVersion> protocols = new HashSet<>(7);

        ProtocolVersion[] pvs = new ProtocolVersion[] {

                SSL20Hello, SSL30, TLS10, TLS11, TLS12, DTLS10, DTLS12};

        EnumSet<CryptoPrimitive> cryptoPrimitives =

            EnumSet.<CryptoPrimitive>of(CryptoPrimitive.KEY_AGREEMENT);

        for (ProtocolVersion p : pvs) {

            if (SSLAlgorithmConstraints.DEFAULT_SSL_ONLY.permits(

                    cryptoPrimitives, p.name, null)) {

                protocols.add(p);

            }

        }

        availableProtocols =

                Collections.<ProtocolVersion>unmodifiableSet(protocols);

    }

    // private

    private ProtocolVersion(int v, String name) {

        this.v = v;

        this.name = name;

        major = (byte)(v >>> 8);

        minor = (byte)(v & 0xFF);

    }

    // private

    private static ProtocolVersion valueOf(int v) {

        if (v == SSL30.v) {

            return SSL30;

        } else if (v == TLS10.v) {

            return TLS10;

        } else if (v == TLS11.v) {

            return TLS11;

        } else if (v == TLS12.v) {

            return TLS12;

        } else if (v == SSL20Hello.v) {

            return SSL20Hello;

        } else if (v == DTLS10.v) {

            return DTLS10;

        } else if (v == DTLS12.v) {

            return DTLS12;

        } else {

            int major = (v >>> 8) & 0xFF;

            int minor = v & 0xFF;

            return new ProtocolVersion(v, "Unknown-" + major + "." + minor);

        }

    }

    /**

     * Return a ProtocolVersion with the specified major and minor version

     * numbers. Never throws exceptions.

     */

    public static ProtocolVersion valueOf(int major, int minor) {

        return valueOf(((major & 0xFF) << 8) | (minor & 0xFF));

    }

    /**

     * Return a ProtocolVersion for the given name.

     *

     * @exception IllegalArgumentException if name is null or does not

     * identify a supported protocol

     */

    static ProtocolVersion valueOf(String name) {

        if (name == null) {

            throw new IllegalArgumentException("Protocol cannot be null");

        }

        if (FIPS && (name.equals(SSL30.name) || name.equals(SSL20Hello.name))) {

            throw new IllegalArgumentException(

                    "Only TLS 1.0 or later allowed in FIPS mode");

        }

        if (name.equals(SSL30.name)) {

            return SSL30;

        } else if (name.equals(TLS10.name)) {

            return TLS10;

        } else if (name.equals(TLS11.name)) {

            return TLS11;

        } else if (name.equals(TLS12.name)) {

            return TLS12;

        } else if (name.equals(SSL20Hello.name)) {

            return SSL20Hello;

        } else if (name.equals(DTLS10.name)) {

            return DTLS10;

        } else if (name.equals(DTLS12.name)) {

            return DTLS12;

        } else {

            throw new IllegalArgumentException(name);

        }

    }

    @Override

    public String toString() {

        return name;

    }

    /**

     * Compares this object with the specified object for order.

     */

    @Override

    public int compareTo(ProtocolVersion protocolVersion) {

        if (maybeDTLSProtocol()) {

            if (!protocolVersion.maybeDTLSProtocol()) {

                throw new IllegalArgumentException("Not DTLS protocol");

            }

            return protocolVersion.v - this.v;

        } else {

            if (protocolVersion.maybeDTLSProtocol()) {

                throw new IllegalArgumentException("Not TLS protocol");

            }

            return this.v - protocolVersion.v;

        }

    }

    /**

     * Returns true if a ProtocolVersion represents a DTLS protocol.

     */

    boolean isDTLSProtocol() {

        return this.v == DTLS12.v || this.v == DTLS10.v;

    }

    /**

     * Returns true if a ProtocolVersion may represent a DTLS protocol.

     */

    boolean maybeDTLSProtocol() {

        return (this.major & 0x80) != 0;

    }

    boolean useTLS12PlusSpec() {

        return maybeDTLSProtocol() ? (this.v <= DTLS12.v) : (this.v >= TLS12.v);

    }

    boolean useTLS11PlusSpec() {

        return maybeDTLSProtocol() ? true : (this.v >= TLS11.v);

    }

    boolean useTLS10PlusSpec() {

        return maybeDTLSProtocol() ? true : (this.v >= TLS10.v);

    }

    boolean obsoletes(CipherSuite suite) {

        ProtocolVersion proto = this;

        if (proto.isDTLSProtocol()) {

            // DTLS bans stream ciphers.

            if (suite.cipher.cipherType == CipherType.STREAM_CIPHER) {

                return true;

            }

            proto = mapToTLSProtocol(this);

        }

        return (proto.v >= suite.obsoleted);

    }

    boolean supports(CipherSuite suite) {

        ProtocolVersion proto = this;

        if (proto.isDTLSProtocol()) {

            // DTLS bans stream ciphers.

            if (suite.cipher.cipherType == CipherType.STREAM_CIPHER) {

                return false;

            }

            proto = mapToTLSProtocol(this);

        }

        return (proto.v >= suite.supported);

    }

    // Map a specified protocol to the corresponding TLS version.

    //

    // DTLS 1.2 -> TLS 1.2

    // DTLS 1.0 -> TLS 1.1

    private static ProtocolVersion mapToTLSProtocol(

            ProtocolVersion protocolVersion) {

        if (protocolVersion.isDTLSProtocol()) {

            if (protocolVersion.v == DTLS10.v) {

                protocolVersion = TLS11;

            } else {    // DTLS12

                protocolVersion = TLS12;

            }

        }

        return protocolVersion;

    }

}