/*

 * Copyright (c) 2012, 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 javax.net.ssl;

import java.util.Arrays;

/**

 * Instances of this class represent a server name in a Server Name

 * Indication (SNI) extension.

 * <P>

 * The SNI extension is a feature that extends the SSL/TLS/DTLS protocols to

 * indicate what server name the client is attempting to connect to during

 * handshaking.  See section 3, "Server Name Indication", of <A

 * HREF="http://www.ietf.org/rfc/rfc6066.txt">TLS Extensions (RFC 6066)</A>.

 * <P>

 * {@code SNIServerName} objects are immutable.  Subclasses should not provide

 * methods that can change the state of an instance once it has been created.

 *

 * @see SSLParameters#getServerNames()

 * @see SSLParameters#setServerNames(List)

 *

 * @since 1.8

 */

public abstract class SNIServerName {

    // the type of the server name

    private final int type;

    // the encoded value of the server name

    private final byte[] encoded;

    // the hex digitals

    private static final char[] HEXES = "0123456789ABCDEF".toCharArray();

    /**

     * Creates an {@code SNIServerName} using the specified name type and

     * encoded value.

     * <P>

     * Note that the {@code encoded} byte array is cloned to protect against

     * subsequent modification.

     *

     * @param  type

     *         the type of the server name

     * @param  encoded

     *         the encoded value of the server name

     *

     * @throws IllegalArgumentException if {@code type} is not in the range

     *         of 0 to 255, inclusive.

     * @throws NullPointerException if {@code encoded} is null

     */

    protected SNIServerName(int type, byte[] encoded) {

        if (type < 0) {

            throw new IllegalArgumentException(

                "Server name type cannot be less than zero");

        } else if (type > 255) {

            throw new IllegalArgumentException(

                "Server name type cannot be greater than 255");

        }

        this.type = type;

        if (encoded == null) {

            throw new NullPointerException(

                "Server name encoded value cannot be null");

        }

        this.encoded = encoded.clone();

    }

    /**

     * Returns the name type of this server name.

     *

     * @return the name type of this server name

     */

    public final int getType() {

        return type;

    }

    /**

     * Returns a copy of the encoded server name value of this server name.

     *

     * @return a copy of the encoded server name value of this server name

     */

    public final byte[] getEncoded() {

        return encoded.clone();

    }

    /**

     * Indicates whether some other object is "equal to" this server name.

     *

     * @return true if, and only if, {@code other} is of the same class

     *         of this object, and has the same name type and

     *         encoded value as this server name.

     */

    @Override

    public boolean equals(Object other) {

        if (this == other) {

            return true;

        }

        if (this.getClass() != other.getClass()) {

            return false;

        }

        SNIServerName that = (SNIServerName)other;

        return (this.type == that.type) &&

                    Arrays.equals(this.encoded, that.encoded);

    }

    /**

     * Returns a hash code value for this server name.

     * <P>

     * The hash code value is generated using the name type and encoded

     * value of this server name.

     *

     * @return a hash code value for this server name.

     */

    @Override

    public int hashCode() {

        int result = 17;    // 17/31: prime number to decrease collisions

        result = 31 * result + type;

        result = 31 * result + Arrays.hashCode(encoded);

        return result;

    }

    /**

     * Returns a string representation of this server name, including the server

     * name type and the encoded server name value in this

     * {@code SNIServerName} object.

     * <P>

     * The exact details of the representation are unspecified and subject

     * to change, but the following may be regarded as typical:

     * <pre>

     *     "type={@literal <name type>}, value={@literal <name value>}"

     * </pre>

     * <P>

     * In this class, the format of "{@literal <name type>}" is

     * "[LITERAL] (INTEGER)", where the optional "LITERAL" is the literal

     * name, and INTEGER is the integer value of the name type.  The format

     * of "{@literal <name value>}" is "XX:...:XX", where "XX" is the

     * hexadecimal digit representation of a byte value. For example, a

     * returned value of an pseudo server name may look like:

     * <pre>

     *     "type=(31), value=77:77:77:2E:65:78:61:6D:70:6C:65:2E:63:6E"

     * </pre>

     * or

     * <pre>

     *     "type=host_name (0), value=77:77:77:2E:65:78:61:6D:70:6C:65:2E:63:6E"

     * </pre>

     *

     * <P>

     * Please NOTE that the exact details of the representation are unspecified

     * and subject to change, and subclasses may override the method with

     * their own formats.

     *

     * @return a string representation of this server name

     */

    @Override

    public String toString() {

        if (type == StandardConstants.SNI_HOST_NAME) {

            return "type=host_name (0), value=" + toHexString(encoded);

        } else {

            return "type=(" + type + "), value=" + toHexString(encoded);

        }

    }

    // convert byte array to hex string

    private static String toHexString(byte[] bytes) {

        if (bytes.length == 0) {

            return "(empty)";

        }

        StringBuilder sb = new StringBuilder(bytes.length * 3 - 1);

        boolean isInitial = true;

        for (byte b : bytes) {

            if (isInitial) {

                isInitial = false;

            } else {

                sb.append(':');

            }

            int k = b & 0xFF;

            sb.append(HEXES[k >>> 4]);

            sb.append(HEXES[k & 0xF]);

        }

        return sb.toString();

    }

}