001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.protocol;
029
030import java.io.IOException;
031
032import org.apache.http.HttpException;
033import org.apache.http.HttpResponse;
034import org.apache.http.HttpResponseInterceptor;
035import org.apache.http.annotation.ThreadingBehavior;
036import org.apache.http.annotation.Contract;
037import org.apache.http.util.Args;
038
039/**
040 * ResponseServer is responsible for adding {@code Server} header. This
041 * interceptor is recommended for server side protocol processors.
042 *
043 * @since 4.0
044 */
045@Contract(threading = ThreadingBehavior.IMMUTABLE)
046public class ResponseServer implements HttpResponseInterceptor {
047
048    private final String originServer;
049
050    /**
051     * @since 4.3
052     */
053    public ResponseServer(final String originServer) {
054        super();
055        this.originServer = originServer;
056    }
057
058    public ResponseServer() {
059        this(null);
060    }
061
062    @Override
063    public void process(final HttpResponse response, final HttpContext context)
064            throws HttpException, IOException {
065        Args.notNull(response, "HTTP response");
066        if (!response.containsHeader(HTTP.SERVER_HEADER)) {
067            if (this.originServer != null) {
068                response.addHeader(HTTP.SERVER_HEADER, this.originServer);
069            }
070        }
071    }
072
073}