/*
    * ====================================================================
    * 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;
  import org.apache.http.annotation.Immutable;
  
  /**
   * RequestTargetHost is responsible for adding <code>Host</code> header. This
   * interceptor is required for client side protocol processors.
   *
   * @since 4.0
   */
  @Immutable
  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");
          }
  
          ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
          String method = request.getRequestLine().getMethod();
          if (method.equalsIgnoreCase("CONNECT") && ver.lessEquals(HttpVersion.HTTP_1_0)) {
              return;
          }
  
          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) {
                      if (ver.lessEquals(HttpVersion.HTTP_1_0)) {
                          return;
                      } else {
                          throw new ProtocolException("Target host missing");
                      }
                  }
              }
              request.addHeader(HTTP.TARGET_HOST, targethost.toHostString());
          }
      }
  
  }