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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package sun.security.ssl;

import java.util.*;
import java.security.CryptoPrimitive;

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:
if (protocolVersion.v >= ProtocolVersion.TLS10) {
  // TLS 1.0 code goes here
} else {
  // SSL 3.0 code here
}
Author:
 Andreas Sterbenz
Since:
  1.4.1/**
 * 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:
 *
 * if (protocolVersion.v >= ProtocolVersion.TLS10) {
 *   // TLS 1.0 code goes here
 * } else {
 *   // SSL 3.0 code here
 * }
 *
 * @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");

    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;

    // ProtocolVersion to use by default (TLS 1.2)
    final static ProtocolVersion DEFAULT = TLS12;

    // 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<>(5);

        ProtocolVersion[] pvs = new ProtocolVersion[] {
                SSL20Hello, SSL30, TLS10, TLS11, TLS12};
        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 {
            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.
/**
     * Return a ProtocolVersion with the specified major and minor version
     * numbers. Never throws exceptions.
     */
    public static ProtocolVersion valueOf(int major, int minor) {
        major &= 0xff;
        minor &= 0xff;
        int v = (major << 8) | minor;
        return valueOf(v);
    }

    
Return a ProtocolVersion for the given name.
Throws:
IllegalArgumentException – if name is null or does not
identify a supported protocol/**
     * 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 {
            throw new IllegalArgumentException(name);
        }
    }

    public String toString() {
        return name;
    }

    
Compares this object with the specified object for order.
/**
     * Compares this object with the specified object for order.
     */
    public int compareTo(ProtocolVersion protocolVersion) {
        return this.v - protocolVersion.v;
    }
}