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 * distributed with this work for additional information
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 * to you 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
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package org.apache.http.impl.auth;

import java.util.Locale;

import org.apache.http.FormattedHeader;
import org.apache.http.Header;
import org.apache.http.HttpRequest;
import org.apache.http.auth.AUTH;
import org.apache.http.auth.AuthenticationException;
import org.apache.http.auth.ChallengeState;
import org.apache.http.auth.ContextAwareAuthScheme;
import org.apache.http.auth.Credentials;
import org.apache.http.auth.MalformedChallengeException;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Args;
import org.apache.http.util.CharArrayBuffer;

Abstract authentication scheme class that serves as a basis
for all authentication schemes supported by HttpClient. This class
defines the generic way of parsing an authentication challenge. It
does not make any assumptions regarding the format of the challenge
nor does it impose any specific way of responding to that challenge.
Since:
4.0/**
 * Abstract authentication scheme class that serves as a basis
 * for all authentication schemes supported by HttpClient. This class
 * defines the generic way of parsing an authentication challenge. It
 * does not make any assumptions regarding the format of the challenge
 * nor does it impose any specific way of responding to that challenge.
 *
 *
 * @since 4.0
 */
public abstract class AuthSchemeBase implements ContextAwareAuthScheme {

    protected ChallengeState challengeState;

    
Creates an instance of AuthSchemeBase with the given challenge state. 
Since:
4.2
Deprecated:
(4.3) do not use./**
     * Creates an instance of {@code AuthSchemeBase} with the given challenge
     * state.
     *
     * @since 4.2
     *
     * @deprecated (4.3) do not use.
     */
    @Deprecated
    public AuthSchemeBase(final ChallengeState challengeState) {
        super();
        this.challengeState = challengeState;
    }

    public AuthSchemeBase() {
        super();
    }

    
Processes the given challenge token. Some authentication schemes
may involve multiple challenge-response exchanges. Such schemes must be able
to maintain the state information when dealing with sequential challenges
Params:
header – the challenge header
Throws:
MalformedChallengeException – is thrown if the authentication challenge
is malformed/**
     * Processes the given challenge token. Some authentication schemes
     * may involve multiple challenge-response exchanges. Such schemes must be able
     * to maintain the state information when dealing with sequential challenges
     *
     * @param header the challenge header
     *
     * @throws MalformedChallengeException is thrown if the authentication challenge
     * is malformed
     */
    @Override
    public void processChallenge(final Header header) throws MalformedChallengeException {
        Args.notNull(header, "Header");
        final String authheader = header.getName();
        if (authheader.equalsIgnoreCase(AUTH.WWW_AUTH)) {
            this.challengeState = ChallengeState.TARGET;
        } else if (authheader.equalsIgnoreCase(AUTH.PROXY_AUTH)) {
            this.challengeState = ChallengeState.PROXY;
        } else {
            throw new MalformedChallengeException("Unexpected header name: " + authheader);
        }

        final CharArrayBuffer buffer;
        int pos;
        if (header instanceof FormattedHeader) {
            buffer = ((FormattedHeader) header).getBuffer();
            pos = ((FormattedHeader) header).getValuePos();
        } else {
            final String s = header.getValue();
            if (s == null) {
                throw new MalformedChallengeException("Header value is null");
            }
            buffer = new CharArrayBuffer(s.length());
            buffer.append(s);
            pos = 0;
        }
        while (pos < buffer.length() && HTTP.isWhitespace(buffer.charAt(pos))) {
            pos++;
        }
        final int beginIndex = pos;
        while (pos < buffer.length() && !HTTP.isWhitespace(buffer.charAt(pos))) {
            pos++;
        }
        final int endIndex = pos;
        final String s = buffer.substring(beginIndex, endIndex);
        if (!s.equalsIgnoreCase(getSchemeName())) {
            throw new MalformedChallengeException("Invalid scheme identifier: " + s);
        }

        parseChallenge(buffer, pos, buffer.length());
    }


    @Override
    @SuppressWarnings("deprecation")
    public Header authenticate(
            final Credentials credentials,
            final HttpRequest request,
            final HttpContext context) throws AuthenticationException {
        return authenticate(credentials, request);
    }

    protected abstract void parseChallenge(
            CharArrayBuffer buffer, int beginIndex, int endIndex) throws MalformedChallengeException;

    
Returns true if authenticating against a proxy, false otherwise. /**
     * Returns {@code true} if authenticating against a proxy, {@code false}
     * otherwise.
     */
    public boolean isProxy() {
        return this.challengeState != null && this.challengeState == ChallengeState.PROXY;
    }

    
Returns ChallengeState value or null if unchallenged. 
Since:
4.2/**
     * Returns {@link ChallengeState} value or {@code null} if unchallenged.
     *
     * @since 4.2
     */
    public ChallengeState getChallengeState() {
        return this.challengeState;
    }

    @Override
    public String toString() {
        final String name = getSchemeName();
        return name != null ? name.toUpperCase(Locale.ROOT) : super.toString();
    }

}