/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/RequestTargetHost.java $
 * $Revision: 573864 $
 * $Date: 2007-09-08 08:53:25 -0700 (Sat, 08 Sep 2007) $
 *
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * 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
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.protocol;

import java.io.IOException;
import java.net.InetAddress;

import org.apache.http.HttpConnection;
import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpInetConnection;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.HttpVersion;
import org.apache.http.ProtocolVersion;
import org.apache.http.ProtocolException;

/**
 * A request interceptor that sets the Host header for HTTP/1.1 requests.
 *
 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
 *
 * @version $Revision: 573864 $
 * 
 * @since 4.0
 */
public class RequestTargetHost implements HttpRequestInterceptor {

    public RequestTargetHost() {
        super();
    }
    
    public void process(final HttpRequest request, final HttpContext context) 
            throws HttpException, IOException {
        if (request == null) {
            throw new IllegalArgumentException("HTTP request may not be null");
        }
        if (context == null) {
            throw new IllegalArgumentException("HTTP context may not be null");
        }
        if (!request.containsHeader(HTTP.TARGET_HOST)) {
            HttpHost targethost = (HttpHost) context
                .getAttribute(ExecutionContext.HTTP_TARGET_HOST);
            if (targethost == null) {
                HttpConnection conn = (HttpConnection) context
                    .getAttribute(ExecutionContext.HTTP_CONNECTION);
                if (conn instanceof HttpInetConnection) {
                    // Populate the context with a default HTTP host based on the 
                    // inet address of the target host
                    InetAddress address = ((HttpInetConnection) conn).getRemoteAddress();
                    int port = ((HttpInetConnection) conn).getRemotePort();
                    if (address != null) {
                        targethost = new HttpHost(address.getHostName(), port);
                    }
                }
                if (targethost == null) {
                    ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
                    if (ver.lessEquals(HttpVersion.HTTP_1_0)) {
                        return;
                    } else {
                        throw new ProtocolException("Target host missing");
                    }
                }
            }
            request.addHeader(HTTP.TARGET_HOST, targethost.toHostString());
        }
    }
    
}