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package sun.security.jgss.krb5;

import org.ietf.jgss.*;

import sun.security.jgss.spi.*;

import sun.security.krb5.PrincipalName;

import sun.security.krb5.KrbException;

import java.io.UnsupportedEncodingException;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.security.Provider;

import java.util.Locale;

/**

 * Implements the GSSNameSpi for the krb5 mechanism.

 *

 * @author Mayank Upadhyay

 */

public class Krb5NameElement

    implements GSSNameSpi {

    private PrincipalName krb5PrincipalName;

    private String gssNameStr = null;

    private Oid gssNameType = null;

    // XXX Move this concept into PrincipalName's asn1Encode() sometime

    private static String CHAR_ENCODING = "UTF-8";

    private Krb5NameElement(PrincipalName principalName,

                            String gssNameStr,

                            Oid gssNameType) {

        this.krb5PrincipalName = principalName;

        this.gssNameStr = gssNameStr;

        this.gssNameType = gssNameType;

    }

    /**

     * Instantiates a new Krb5NameElement object. Internally it stores the

     * information provided by the input parameters so that they may later

     * be used for output when a printable representaion of this name is

     * needed in GSS-API format rather than in Kerberos format.

     *

     */

    static Krb5NameElement getInstance(String gssNameStr, Oid gssNameType)

        throws GSSException {

        /*

         * A null gssNameType implies that the mechanism default

         * Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL be used.

         */

        if (gssNameType == null)

            gssNameType = Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL;

        else

            if (!gssNameType.equals(GSSName.NT_USER_NAME) &&

                !gssNameType.equals(GSSName.NT_HOSTBASED_SERVICE) &&

                !gssNameType.equals(Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL) &&

                !gssNameType.equals(GSSName.NT_EXPORT_NAME))

                throw new GSSException(GSSException.BAD_NAMETYPE, -1,

                                       gssNameType.toString()

                                       +" is an unsupported nametype");

        PrincipalName principalName;

        try {

            if (gssNameType.equals(GSSName.NT_EXPORT_NAME) ||

                gssNameType.equals(Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL)) {

                principalName = new PrincipalName(gssNameStr,

                                  PrincipalName.KRB_NT_PRINCIPAL);

            } else {

                String[] components = getComponents(gssNameStr);

                /*

                 * We have forms of GSS name strings that can come in:

                 *

                 * 1. names of the form "foo" with just one

                 * component. (This might include a "@" but only in escaped

                 * form like "\@")

                 * 2. names of the form "foo@bar" with two components

                 *

                 * The nametypes that are accepted are NT_USER_NAME, and

                 * NT_HOSTBASED_SERVICE.

                 */

                if (gssNameType.equals(GSSName.NT_USER_NAME))

                    principalName = new PrincipalName(gssNameStr,

                                    PrincipalName.KRB_NT_PRINCIPAL);

                else {

                    String hostName = null;

                    String service = components[0];

                    if (components.length >= 2)

                        hostName = components[1];

                    String principal = getHostBasedInstance(service, hostName);

                    principalName = new PrincipalName(principal,

                            PrincipalName.KRB_NT_SRV_HST);

                }

            }

        } catch (KrbException e) {

            throw new GSSException(GSSException.BAD_NAME, -1, e.getMessage());

        }

        return new Krb5NameElement(principalName, gssNameStr, gssNameType);

    }

    static Krb5NameElement getInstance(PrincipalName principalName) {

        return new Krb5NameElement(principalName,

                                   principalName.getName(),

                                   Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL);

    }

    private static String[] getComponents(String gssNameStr)

        throws GSSException {

        String[] retVal;

        // XXX Perhaps provide this parsing code in PrincipalName

        // Look for @ as in service@host

        // Assumes host name will not have an escaped '@'

        int separatorPos = gssNameStr.lastIndexOf('@', gssNameStr.length());

        // Not really a separator if it is escaped. Then this is just part

        // of the principal name or service name

        if ((separatorPos > 0) &&

                (gssNameStr.charAt(separatorPos-1) == '\\')) {

            // Is the `\` character escaped itself?

            if ((separatorPos - 2 < 0) ||

                (gssNameStr.charAt(separatorPos-2) != '\\'))

                separatorPos = -1;

        }

        if (separatorPos > 0) {

            String serviceName = gssNameStr.substring(0, separatorPos);

            String hostName = gssNameStr.substring(separatorPos+1);

            retVal = new String[] { serviceName, hostName};

        } else {

            retVal = new String[] {gssNameStr};

        }

        return retVal;

    }

    private static String getHostBasedInstance(String serviceName,

                                               String hostName)

        throws GSSException {

            StringBuffer temp = new StringBuffer(serviceName);

            try {

                // A lack of "@" defaults to the service being on the local

                // host as per RFC 2743

                // XXX Move this part into JGSS framework

                if (hostName == null)

                    hostName = InetAddress.getLocalHost().getHostName();

            } catch (UnknownHostException e) {

                // use hostname as it is

            }

            hostName = hostName.toLowerCase(Locale.ENGLISH);

            temp = temp.append('/').append(hostName);

            return temp.toString();

    }

    public final PrincipalName getKrb5PrincipalName() {

        return krb5PrincipalName;

    }

    /**

     * Equal method for the GSSNameSpi objects.

     * If either name denotes an anonymous principal, the call should

     * return false.

     *

     * @param name to be compared with

     * @returns true if they both refer to the same entity, else false

     * @exception GSSException with major codes of BAD_NAMETYPE,

     *  BAD_NAME, FAILURE

     */

    public boolean equals(GSSNameSpi other) throws GSSException {

        if (other == this)

            return true;

        if (other instanceof Krb5NameElement) {

                Krb5NameElement that = (Krb5NameElement) other;

                return (this.krb5PrincipalName.getName().equals(

                            that.krb5PrincipalName.getName()));

        }

        return false;

    }

    /**

     * Compares this <code>GSSNameSpi</code> object to another Object

     * that might be a <code>GSSNameSpi</code>. The behaviour is exactly

     * the same as in {@link #equals(GSSNameSpi) equals} except that

     * no GSSException is thrown; instead, false will be returned in the

     * situation where an error occurs.

     *

     * @param another the object to be compared to

     * @returns true if they both refer to the same entity, else false

     * @see #equals(GSSNameSpi)

     */

    public boolean equals(Object another) {

        if (this == another) {

            return true;

        }

        try {

            if (another instanceof Krb5NameElement)

                 return equals((Krb5NameElement) another);

        } catch (GSSException e) {

            // ignore exception

        }

        return false;

    }

    /**

     * Returns a hashcode value for this GSSNameSpi.

     *

     * @return a hashCode value

     */

    public int hashCode() {

        return 37 * 17 + krb5PrincipalName.getName().hashCode();

    }

    /**

     * Returns the principal name in the form user@REALM or

     * host/service@REALM but with the following contraints that are

     * imposed by RFC 1964:

     * <pre>

     *  (1) all occurrences of the characters `@`,  `/`, and `\` within

     *   principal components or realm names shall be quoted with an

     *   immediately-preceding `\`.

     *

     *   (2) all occurrences of the null, backspace, tab, or newline

     *   characters within principal components or realm names will be

     *   represented, respectively, with `\0`, `\b`, `\t`, or `\n`.

     *

     *   (3) the `\` quoting character shall not be emitted within an

     *   exported name except to accomodate cases (1) and (2).

     * </pre>

     */

    public byte[] export() throws GSSException {

        // XXX Apply the above constraints.

        byte[] retVal = null;

        try {

            retVal = krb5PrincipalName.getName().getBytes(CHAR_ENCODING);

        } catch (UnsupportedEncodingException e) {

            // Can't happen

        }

        return retVal;

    }

    /**

     * Get the mechanism type that this NameElement corresponds to.

     *

     * @return the Oid of the mechanism type

     */

    public Oid getMechanism() {

        return (Krb5MechFactory.GSS_KRB5_MECH_OID);

    }

    /**

     * Returns a string representation for this name. The printed

     * name type can be obtained by calling getStringNameType().

     *

     * @return string form of this name

     * @see #getStringNameType()

     * @overrides Object#toString

     */

    public String toString() {

        return (gssNameStr);

        // For testing: return (super.toString());

    }

    /**

     * Returns the name type oid.

     */

    public Oid getGSSNameType() {

        return (gssNameType);

    }

    /**

     * Returns the oid describing the format of the printable name.

     *

     * @return the Oid for the format of the printed name

     */

    public Oid getStringNameType() {

        // XXX For NT_EXPORT_NAME return a different name type. Infact,

        // don't even store NT_EXPORT_NAME in the cons.

        return (gssNameType);

    }

    /**

     * Indicates if this name object represents an Anonymous name.

     */

    public boolean isAnonymousName() {

        return (gssNameType.equals(GSSName.NT_ANONYMOUS));

    }

    public Provider getProvider() {

        return Krb5MechFactory.PROVIDER;

    }

}