/*

 * 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

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

 *

 * 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.

 *

 */

package org.ietf.jgss;

import java.net.InetAddress;

import java.util.Arrays;

/**

 * This class encapsulates the concept of caller-provided channel

 * binding information. Channel bindings are used to strengthen the

 * quality with which peer entity authentication is provided during

 * context establishment.  They enable the GSS-API callers to bind the

 * establishment of the security context to relevant characteristics

 * like addresses or to application specific data.<p>

 *

 * The caller initiating the security context must determine the

 * appropriate channel binding values to set in the GSSContext object.

 * The acceptor must provide an identical binding in order to validate

 * that received tokens possess correct channel-related characteristics.<p>

 *

 * Use of channel bindings is optional in GSS-API. ChannelBinding can be

 * set for the {@link GSSContext GSSContext} using the {@link

 * GSSContext#setChannelBinding(ChannelBinding) setChannelBinding} method

 * before the first call to {@link GSSContext#initSecContext(byte[], int, int)

 * initSecContext} or {@link GSSContext#acceptSecContext(byte[], int, int)

 * acceptSecContext} has been performed.  Unless the <code>setChannelBinding</code>

 * method has been used to set the ChannelBinding for a GSSContext object,

 * <code>null</code> ChannelBinding will be assumed. <p>

 *

 * Conceptually, the GSS-API concatenates the initiator and acceptor

 * address information, and the application supplied byte array to form an

 * octet string.  The mechanism calculates a MIC over this octet string and

 * binds the MIC to the context establishment token emitted by

 * <code>initSecContext</code> method of the <code>GSSContext</code>

 * interface.  The same bindings are set by the context acceptor for its

 * <code>GSSContext</code> object and during processing of the

 * <code>acceptSecContext</code> method a MIC is calculated in the same

 * way. The calculated MIC is compared with that found in the token, and if

 * the MICs differ, accept will throw a <code>GSSException</code> with the

 * major code set to {@link GSSException#BAD_BINDINGS BAD_BINDINGS}, and

 * the context will not be established. Some mechanisms may include the

 * actual channel binding data in the token (rather than just a MIC);

 * applications should therefore not use confidential data as

 * channel-binding components.<p>

 *

 *  Individual mechanisms may impose additional constraints on addresses

 *  that may appear in channel bindings.  For example, a mechanism may

 *  verify that the initiator address field of the channel binding

 *  contains the correct network address of the host system.  Portable

 *  applications should therefore ensure that they either provide correct

 *  information for the address fields, or omit setting of the addressing

 *  information.

 *

 * @author Mayank Upadhyay

 * @since 1.4

 */

public class ChannelBinding {

    private InetAddress initiator;

    private InetAddress acceptor;

    private  byte[] appData;

    /**

     * Create a ChannelBinding object with user supplied address information

     * and data.  <code>null</code> values can be used for any fields which the

     * application does not want to specify.

     *

     * @param initAddr the address of the context initiator.

     * <code>null</code> value can be supplied to indicate that the

     * application does not want to set this value.

     * @param acceptAddr the address of the context

     * acceptor. <code>null</code> value can be supplied to indicate that

     * the application does not want to set this value.

     * @param appData application supplied data to be used as part of the

     * channel bindings. <code>null</code> value can be supplied to

     * indicate that the application does not want to set this value.

     */

    public ChannelBinding(InetAddress initAddr, InetAddress acceptAddr,

                        byte[] appData) {

        initiator = initAddr;

        acceptor = acceptAddr;

        if (appData != null) {

            this.appData = new byte[appData.length];

            java.lang.System.arraycopy(appData, 0, this.appData, 0,

                                appData.length);

        }

    }

    /**

     * Creates a ChannelBinding object without any addressing information.

     *

     * @param appData application supplied data to be used as part of the

     * channel bindings.

     */

    public ChannelBinding(byte[] appData) {

        this(null, null, appData);

    }

    /**

     * Get the initiator's address for this channel binding.

     *

     * @return the initiator's address. <code>null</code> is returned if

     * the address has not been set.

     */

    public InetAddress getInitiatorAddress() {

        return initiator;

    }

    /**

     * Get the acceptor's address for this channel binding.

     *

     * @return the acceptor's address. null is returned if the address has

     * not been set.

     */

    public InetAddress getAcceptorAddress() {

        return acceptor;

    }

    /**

     * Get the application specified data for this channel binding.

     *

     * @return the application data being used as part of the

     * ChannelBinding. <code>null</code> is returned if no application data

     * has been specified for the channel binding.

     */

    public byte[] getApplicationData() {

        if (appData == null) {

            return null;

        }

        byte[] retVal = new byte[appData.length];

        System.arraycopy(appData, 0, retVal, 0, appData.length);

        return retVal;

    }

    /**

     * Compares two instances of ChannelBinding.

     *

     * @param obj another ChannelBinding to compare this one with

     * @return true if the two ChannelBinding's contain

     * the same values for the initiator and acceptor addresses and the

     * application data.

     */

    public boolean equals(Object obj) {

        if (this == obj)

            return true;

        if (! (obj instanceof ChannelBinding))

            return false;

        ChannelBinding cb = (ChannelBinding) obj;

        if ((initiator != null && cb.initiator == null) ||

            (initiator == null && cb.initiator != null))

            return false;

        if (initiator != null && !initiator.equals(cb.initiator))

            return false;

        if ((acceptor != null && cb.acceptor == null) ||

            (acceptor == null && cb.acceptor != null))

            return false;

        if (acceptor != null && !acceptor.equals(cb.acceptor))

            return false;

        return Arrays.equals(appData, cb.appData);

    }

    /**

     * Returns a hashcode value for this ChannelBinding object.

     *

     * @return a hashCode value

     */

    public int hashCode() {

        if (initiator != null)

            return initiator.hashCode();

        else if (acceptor != null)

            return acceptor.hashCode();

        else if (appData != null)

            return new String(appData).hashCode();

        else

            return 1;

    }

}