/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/auth/NTLMScheme.java,v 1.6.2.3 2004/02/22 18:21:15 olegk Exp $
 * $Revision: 1.6.2.3 $
 * $Date: 2004/02/22 18:21:15 $
 *
 * ====================================================================
 *
 *  Copyright 2002-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */

package org.apache.commons.httpclient.auth;

import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.NTLM;
import org.apache.commons.httpclient.Credentials;
import org.apache.commons.httpclient.NTCredentials;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/** An implementation of the Microsoft proprietary NTLM authentication scheme.  For a detailed
 * explanation of the NTLM scheme please see 
 * http://davenport.sourceforge.net/ntlm.html.
 * 
 * @author Remy Maucherat
 * @author Rodney Waldhoff
 * @author Jeff Dever
 * @author Ortwin Glück
 * @author Sean C. Sullivan
 * @author Adrian Sutton
 * @author Mike Bowler
 * @author Oleg Kalnichevski
 */
public class NTLMScheme extends AuthSchemeBase {

    /** Log object for this class. */
    private static final Log LOG = LogFactory.getLog(NTLMScheme.class);

    /** NTLM challenge string. */
    private String ntlmchallenge = null;

    /**
     * Constructor for the NTLM authentication scheme.
     * 
     * @param challenge The authentication challenge
     * 
     * @throws MalformedChallengeException is thrown if the authentication challenge
     * is malformed
     */
    public NTLMScheme(final String challenge) throws MalformedChallengeException {
        super(challenge);
        String s = AuthChallengeParser.extractScheme(challenge);
        if (!s.equalsIgnoreCase(getSchemeName())) {
            throw new MalformedChallengeException("Invalid NTLM challenge: " + challenge);
        }
        int i = challenge.indexOf(' ');
        if (i != -1) {
            s = challenge.substring(i, challenge.length());
            this.ntlmchallenge = s.trim();
        } else {
            this.ntlmchallenge = "";
        }
    }

    /**
     * Returns textual designation of the NTLM authentication scheme.
     * 
     * @return ntlm
     */
    public String getSchemeName() {
        return "ntlm";
    }

    /**
     * The concept of an authentication realm is not supported by the NTLM 
     * authentication scheme. Always returns null.
     * 
     * @return null
     */
    public String getRealm() {
        return null;
    }
    
    /**
     * Returns a String identifying the authentication challenge.  This is
     * used, in combination with the host and port to determine if
     * authorization has already been attempted or not.  Schemes which
     * require multiple requests to complete the authentication should
     * return a different value for each stage in the request.
     * 
     * 
Additionally, the ID should take into account any changes to the
     * authentication challenge and return a different value when appropriate.
     * For example when the realm changes in basic authentication it should be
     * considered a different authentication attempt and a different value should
     * be returned.
     * 
     * @return String a String identifying the authentication challenge.  The
     * returned value may be null.
     */
    public String getID() {
        return ntlmchallenge;
    }
    

    /**
     * Returns the authentication parameter with the given name, if available.
     * 
     * 
There are no valid parameters for NTLM authentication so this method always returns
     * null.
     * 
     * @param name The name of the parameter to be returned
     * 
     * @return the parameter with the given name
     */
    public String getParameter(String name) {
        if (name == null) {
            throw new IllegalArgumentException("Parameter name may not be null"); 
        }
        return null;
    }

    /**
     * Create a NTLM authorization string for the given
     * challenge and NT credentials.
     *
     * @param challenge The challenge.
     * @param credentials {@link NTCredentials}
     *
     * @return a ntlm authorization string
     * @throws AuthenticationException is thrown if authentication fails
     */
    public static String authenticate(
     final NTCredentials credentials, final String challenge) 
      throws AuthenticationException {

        LOG.trace("enter NTLMScheme.authenticate(NTCredentials, String)");

        if (credentials == null) {
            throw new IllegalArgumentException("Credentials may not be null");
        }
        
        NTLM ntlm = new NTLM();
        String s = null;
        try {
            s = ntlm.getResponseFor(challenge,
              credentials.getUserName(), credentials.getPassword(),
              credentials.getHost(), credentials.getDomain());
        } catch (HttpException e) {
            throw new AuthenticationException(e.getMessage());
        }
        return "NTLM " + s;
    }
    
    /**
     * Produces NTLM authorization string for the given set of 
     * {@link Credentials}.
     * 
     * @param credentials The set of credentials to be used for athentication
     * @param method Method name is ignored by the NTLM authentication scheme
     * @param uri URI is ignored by the NTLM authentication scheme
     * @throws AuthenticationException if authorization string cannot 
     *   be generated due to an authentication failure
     * 
     * @return an NTLM authorization string
     */
    public String authenticate(Credentials credentials, String method, String uri) 
      throws AuthenticationException {
        LOG.trace("enter NTLMScheme.authenticate(Credentials, String, String)");

        NTCredentials ntcredentials = null;
        try {
            ntcredentials = (NTCredentials) credentials;
        } catch (ClassCastException e) {
            throw new AuthenticationException(
             "Credentials cannot be used for NTLM authentication: " 
              + credentials.getClass().getName());
        }
        return NTLMScheme.authenticate(ntcredentials, this.ntlmchallenge);
    }    
}