1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/impl/auth/AuthSchemeBase.java $
3 * $Revision: 653867 $
4 * $Date: 2008-05-06 11:17:29 -0700 (Tue, 06 May 2008) $
5 *
6 * ====================================================================
7 *
8 *  Licensed to the Apache Software Foundation (ASF) under one or more
9 *  contributor license agreements.  See the NOTICE file distributed with
10 *  this work for additional information regarding copyright ownership.
11 *  The ASF licenses this file to You under the Apache License, Version 2.0
12 *  (the "License"); you may not use this file except in compliance with
13 *  the License.  You may obtain a copy of the License at
14 *
15 *      http://www.apache.org/licenses/LICENSE-2.0
16 *
17 *  Unless required by applicable law or agreed to in writing, software
18 *  distributed under the License is distributed on an "AS IS" BASIS,
19 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20 *  See the License for the specific language governing permissions and
21 *  limitations under the License.
22 * ====================================================================
23 *
24 * This software consists of voluntary contributions made by many
25 * individuals on behalf of the Apache Software Foundation.  For more
26 * information on the Apache Software Foundation, please see
27 * <http://www.apache.org/>.
28 *
29 */
30
31package org.apache.http.impl.auth;
32
33import org.apache.http.FormattedHeader;
34import org.apache.http.Header;
35import org.apache.http.auth.AUTH;
36import org.apache.http.auth.AuthScheme;
37import org.apache.http.auth.MalformedChallengeException;
38import org.apache.http.protocol.HTTP;
39import org.apache.http.util.CharArrayBuffer;
40
41/**
42 * Abstract authentication scheme class that serves as a basis
43 * for all authentication schemes supported by HttpClient. This class
44 * defines the generic way of parsing an authentication challenge. It
45 * does not make any assumptions regarding the format of the challenge
46 * nor does it impose any specific way of responding to that challenge.
47 *
48 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
49*/
50public abstract class AuthSchemeBase implements AuthScheme {
51
52    /**
53     * Flag whether authenticating against a proxy.
54     */
55    private boolean proxy;
56
57    public AuthSchemeBase() {
58        super();
59    }
60
61    /**
62     * Processes the given challenge token. Some authentication schemes
63     * may involve multiple challenge-response exchanges. Such schemes must be able
64     * to maintain the state information when dealing with sequential challenges
65     *
66     * @param header the challenge header
67     *
68     * @throws MalformedChallengeException is thrown if the authentication challenge
69     * is malformed
70     */
71    public void processChallenge(final Header header) throws MalformedChallengeException {
72        if (header == null) {
73            throw new IllegalArgumentException("Header may not be null");
74        }
75        String authheader = header.getName();
76        if (authheader.equalsIgnoreCase(AUTH.WWW_AUTH)) {
77            this.proxy = false;
78        } else if (authheader.equalsIgnoreCase(AUTH.PROXY_AUTH)) {
79            this.proxy = true;
80        } else {
81            throw new MalformedChallengeException("Unexpected header name: " + authheader);
82        }
83
84        CharArrayBuffer buffer;
85        int pos;
86        if (header instanceof FormattedHeader) {
87            buffer = ((FormattedHeader) header).getBuffer();
88            pos = ((FormattedHeader) header).getValuePos();
89        } else {
90            String s = header.getValue();
91            if (s == null) {
92                throw new MalformedChallengeException("Header value is null");
93            }
94            buffer = new CharArrayBuffer(s.length());
95            buffer.append(s);
96            pos = 0;
97        }
98        while (pos < buffer.length() && HTTP.isWhitespace(buffer.charAt(pos))) {
99            pos++;
100        }
101        int beginIndex = pos;
102        while (pos < buffer.length() && !HTTP.isWhitespace(buffer.charAt(pos))) {
103            pos++;
104        }
105        int endIndex = pos;
106        String s = buffer.substring(beginIndex, endIndex);
107        if (!s.equalsIgnoreCase(getSchemeName())) {
108            throw new MalformedChallengeException("Invalid scheme identifier: " + s);
109        }
110
111        parseChallenge(buffer, pos, buffer.length());
112    }
113
114    protected abstract void parseChallenge(
115            CharArrayBuffer buffer, int pos, int len) throws MalformedChallengeException;
116
117    /**
118     * Returns <code>true</code> if authenticating against a proxy, <code>false</code>
119     * otherwise.
120     *
121     * @return <code>true</code> if authenticating against a proxy, <code>false</code>
122     * otherwise
123     */
124    public boolean isProxy() {
125        return this.proxy;
126    }
127
128}
129