/*

 * Copyright 1997-2000 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 sun.security.util.*;

/**

 * This class implements the DNSName as required by the GeneralNames

 * ASN.1 object.

 * <p>

 * [RFC2459] When the subjectAltName extension contains a domain name service

 * label, the domain name MUST be stored in the dNSName (an IA5String).

 * The name MUST be in the "preferred name syntax," as specified by RFC

 * 1034 [RFC 1034]. Note that while upper and lower case letters are

 * allowed in domain names, no signifigance is attached to the case.  In

 * addition, while the string " " is a legal domain name, subjectAltName

 * extensions with a dNSName " " are not permitted.  Finally, the use of

 * the DNS representation for Internet mail addresses (wpolk.nist.gov

 * instead of wpolk@nist.gov) is not permitted; such identities are to

 * be encoded as rfc822Name.

 * <p>

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 */

public class DNSName implements GeneralNameInterface {

    private String name;

    private static final String alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    private static final String digitsAndHyphen = "0123456789-";

    private static final String alphaDigitsAndHyphen = alpha + digitsAndHyphen;

    /**

     * Create the DNSName object from the passed encoded Der value.

     *

     * @param derValue the encoded DER DNSName.

     * @exception IOException on error.

     */

    public DNSName(DerValue derValue) throws IOException {

        name = derValue.getIA5String();

    }

    /**

     * Create the DNSName object with the specified name.

     *

     * @param name the DNSName.

     * @throws IOException if the name is not a valid DNSName subjectAltName

     */

    public DNSName(String name) throws IOException {

        if (name == null || name.length() == 0)

            throw new IOException("DNS name must not be null");

        if (name.indexOf(' ') != -1)

            throw new IOException("DNS names or NameConstraints with blank components are not permitted");

        if (name.charAt(0) == '.' || name.charAt(name.length() -1) == '.')

            throw new IOException("DNS names or NameConstraints may not begin or end with a .");

        //Name will consist of label components separated by "."

        //startIndex is the index of the first character of a component

        //endIndex is the index of the last character of a component plus 1

        for (int endIndex,startIndex=0; startIndex < name.length(); startIndex = endIndex+1) {

            endIndex = name.indexOf('.', startIndex);

            if (endIndex < 0) {

                endIndex = name.length();

            }

            if ((endIndex-startIndex) < 1)

                throw new IOException("DNSName SubjectAltNames with empty components are not permitted");

            //DNSName components must begin with a letter A-Z or a-z

            if (alpha.indexOf(name.charAt(startIndex)) < 0)

                throw new IOException("DNSName components must begin with a letter");

            //nonStartIndex: index for characters in the component beyond the first one

            for (int nonStartIndex=startIndex+1; nonStartIndex < endIndex; nonStartIndex++) {

                char x = name.charAt(nonStartIndex);

                if ((alphaDigitsAndHyphen).indexOf(x) < 0)

                    throw new IOException("DNSName components must consist of letters, digits, and hyphens");

            }

        }

        this.name = name;

    }

    /**

     * Return the type of the GeneralName.

     */

    public int getType() {

        return (GeneralNameInterface.NAME_DNS);

    }

    /**

     * Return the actual name value of the GeneralName.

     */

    public String getName() {

        return name;

    }

    /**

     * Encode the DNS name into the DerOutputStream.

     *

     * @param out the DER stream to encode the DNSName to.

     * @exception IOException on encoding errors.

     */

    public void encode(DerOutputStream out) throws IOException {

        out.putIA5String(name);

    }

    /**

     * Convert the name into user readable string.

     */

    public String toString() {

        return ("DNSName: " + name);

    }

    /**

     * Compares this name with another, for equality.

     *

     * @return true iff the names are equivalent

     * according to RFC2459.

     */

    public boolean equals(Object obj) {

        if (this == obj)

            return true;

        if (!(obj instanceof DNSName))

            return false;

        DNSName other = (DNSName)obj;

        // RFC2459 mandates that these names are

        // not case-sensitive

        return name.equalsIgnoreCase(other.name);

    }

    /**

     * Returns the hash code value for this object.

     *

     * @return a hash code value for this object.

     */

    public int hashCode() {

        return name.toUpperCase().hashCode();

    }

    /**

     * Return type of constraint inputName places on this name:<ul>

     *   <li>NAME_DIFF_TYPE = -1: input name is different type from name (i.e. does not constrain).

     *   <li>NAME_MATCH = 0: input name matches name.

     *   <li>NAME_NARROWS = 1: input name narrows name (is lower in the naming subtree)

     *   <li>NAME_WIDENS = 2: input name widens name (is higher in the naming subtree)

     *   <li>NAME_SAME_TYPE = 3: input name does not match or narrow name, but is same type.

     * </ul>.  These results are used in checking NameConstraints during

     * certification path verification.

     * <p>

     * RFC2459: DNS name restrictions are expressed as foo.bar.com. Any subdomain

     * satisfies the name constraint. For example, www.foo.bar.com would

     * satisfy the constraint but bigfoo.bar.com would not.

     * <p>

     * draft-ietf-pkix-new-part1-00.txt:  DNS name restrictions are expressed as foo.bar.com.

     * Any DNS name that

     * can be constructed by simply adding to the left hand side of the name

     * satisfies the name constraint. For example, www.foo.bar.com would

     * satisfy the constraint but foo1.bar.com would not.

     * <p>

     * RFC1034: By convention, domain names can be stored with arbitrary case, but

     * domain name comparisons for all present domain functions are done in a

     * case-insensitive manner, assuming an ASCII character set, and a high

     * order zero bit.

     * <p>

     * @param inputName to be checked for being constrained

     * @returns constraint type above

     * @throws UnsupportedOperationException if name is not exact match, but narrowing and widening are

     *          not supported for this name type.

     */

    public int constrains(GeneralNameInterface inputName) throws UnsupportedOperationException {

        int constraintType;

        if (inputName == null)

            constraintType = NAME_DIFF_TYPE;

        else if (inputName.getType() != NAME_DNS)

            constraintType = NAME_DIFF_TYPE;

        else {

            String inName = (((DNSName)inputName).getName()).toLowerCase();

            String thisName = name.toLowerCase();

            if (inName.equals(thisName))

                constraintType = NAME_MATCH;

            else if (thisName.endsWith(inName)) {

                int inNdx = thisName.lastIndexOf(inName);

                if (thisName.charAt(inNdx-1) == '.' )

                    constraintType = NAME_WIDENS;

                else

                    constraintType = NAME_SAME_TYPE;

            } else if (inName.endsWith(thisName)) {

                int ndx = inName.lastIndexOf(thisName);

                if (inName.charAt(ndx-1) == '.' )

                    constraintType = NAME_NARROWS;

                else

                    constraintType = NAME_SAME_TYPE;

            } else {

                constraintType = NAME_SAME_TYPE;

            }

        }

        return constraintType;

    }

    /**

     * Return subtree depth of this name for purposes of determining

     * NameConstraints minimum and maximum bounds and for calculating

     * path lengths in name subtrees.

     *

     * @returns distance of name from root

     * @throws UnsupportedOperationException if not supported for this name type

     */

    public int subtreeDepth() throws UnsupportedOperationException {

        String subtree=name;

        int i=1;

        /* count dots */

        for (; subtree.lastIndexOf('.') >= 0; i++) {

            subtree=subtree.substring(0,subtree.lastIndexOf('.'));

        }

        return i;

    }

}