/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.security.x509;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Enumeration;

import sun.security.util.*;

/**

 * This represents the Subject Alternative Name Extension.

 *

 * This extension, if present, allows the subject to specify multiple

 * alternative names.

 *

 * <p>Extensions are represented as a sequence of the extension identifier

 * (Object Identifier), a boolean flag stating whether the extension is to

 * be treated as being critical and the extension value itself (this is again

 * a DER encoding of the extension value).

 * <p>

 * The ASN.1 syntax for this is:

 * <pre>

 * SubjectAltName ::= GeneralNames

 * GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

 * </pre>

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 * @see Extension

 * @see CertAttrSet

 */

public class SubjectAlternativeNameExtension extends Extension

implements CertAttrSet<String> {

    /**

     * Identifier for this attribute, to be used with the

     * get, set, delete methods of Certificate, x509 type.

     */

    public static final String IDENT =

                         "x509.info.extensions.SubjectAlternativeName";

    /**

     * Attribute names.

     */

    public static final String NAME = "SubjectAlternativeName";

    public static final String SUBJECT_NAME = "subject_name";

    // private data members

    GeneralNames        names = null;

    // Encode this extension

    private void encodeThis() throws IOException {

        if (names == null || names.isEmpty()) {

            this.extensionValue = null;

            return;

        }

        DerOutputStream os = new DerOutputStream();

        names.encode(os);

        this.extensionValue = os.toByteArray();

    }

    /**

     * Create a SubjectAlternativeNameExtension with the passed GeneralNames.

     * The extension is marked non-critical.

     *

     * @param names the GeneralNames for the subject.

     * @exception IOException on error.

     */

    public SubjectAlternativeNameExtension(GeneralNames names)

    throws IOException {

        this(Boolean.FALSE, names);

    }

    /**

     * Create a SubjectAlternativeNameExtension with the specified

     * criticality and GeneralNames.

     *

     * @param critical true if the extension is to be treated as critical.

     * @param names the GeneralNames for the subject.

     * @exception IOException on error.

     */

    public SubjectAlternativeNameExtension(Boolean critical, GeneralNames names)

    throws IOException {

        this.names = names;

        this.extensionId = PKIXExtensions.SubjectAlternativeName_Id;

        this.critical = critical.booleanValue();

        encodeThis();

    }

    /**

     * Create a default SubjectAlternativeNameExtension. The extension

     * is marked non-critical.

     */

    public SubjectAlternativeNameExtension() {

        extensionId = PKIXExtensions.SubjectAlternativeName_Id;

        critical = false;

        names = new GeneralNames();

    }

    /**

     * Create the extension from the passed DER encoded value.

     *

     * @param critical true if the extension is to be treated as critical.

     * @param value an array of DER encoded bytes of the actual value.

     * @exception ClassCastException if value is not an array of bytes

     * @exception IOException on error.

     */

    public SubjectAlternativeNameExtension(Boolean critical, Object value)

    throws IOException {

        this.extensionId = PKIXExtensions.SubjectAlternativeName_Id;

        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;

        DerValue val = new DerValue(this.extensionValue);

        if (val.data == null) {

            names = new GeneralNames();

            return;

        }

        names = new GeneralNames(val);

    }

    /**

     * Returns a printable representation of the SubjectAlternativeName.

     */

    public String toString() {

        String result = super.toString() + "SubjectAlternativeName [\n";

        if(names == null) {

            result += "  null\n";

        } else {

            for(GeneralName name: names.names()) {

                result += "  "+name+"\n";

            }

        }

        result += "]\n";

        return result;

    }

    /**

     * Write the extension to the OutputStream.

     *

     * @param out the OutputStream to write the extension to.

     * @exception IOException on encoding errors.

     */

    public void encode(OutputStream out) throws IOException {

        DerOutputStream tmp = new DerOutputStream();

        if (extensionValue == null) {

            extensionId = PKIXExtensions.SubjectAlternativeName_Id;

            critical = false;

            encodeThis();

        }

        super.encode(tmp);

        out.write(tmp.toByteArray());

    }

    /**

     * Set the attribute value.

     */

    public void set(String name, Object obj) throws IOException {

        if (name.equalsIgnoreCase(SUBJECT_NAME)) {

            if (!(obj instanceof GeneralNames)) {

              throw new IOException("Attribute value should be of " +

                                    "type GeneralNames.");

            }

            names = (GeneralNames)obj;

        } else {

          throw new IOException("Attribute name not recognized by " +

                        "CertAttrSet:SubjectAlternativeName.");

        }

        encodeThis();

    }

    /**

     * Get the attribute value.

     */

    public Object get(String name) throws IOException {

        if (name.equalsIgnoreCase(SUBJECT_NAME)) {

            return (names);

        } else {

          throw new IOException("Attribute name not recognized by " +

                        "CertAttrSet:SubjectAlternativeName.");

        }

    }

    /**

     * Delete the attribute value.

     */

    public void delete(String name) throws IOException {

        if (name.equalsIgnoreCase(SUBJECT_NAME)) {

            names = null;

        } else {

          throw new IOException("Attribute name not recognized by " +

                        "CertAttrSet:SubjectAlternativeName.");

        }

        encodeThis();

    }

    /**

     * Return an enumeration of names of attributes existing within this

     * attribute.

     */

    public Enumeration<String> getElements() {

        AttributeNameEnumeration elements = new AttributeNameEnumeration();

        elements.addElement(SUBJECT_NAME);

        return (elements.elements());

    }

    /**

     * Return the name of this attribute.

     */

    public String getName() {

        return (NAME);

    }

}