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.client.protocol;
029
030import java.io.IOException;
031
032import org.apache.http.HttpEntity;
033import org.apache.http.HttpEntityEnclosingRequest;
034import org.apache.http.HttpException;
035import org.apache.http.HttpRequest;
036import org.apache.http.HttpRequestInterceptor;
037import org.apache.http.HttpVersion;
038import org.apache.http.ProtocolVersion;
039import org.apache.http.annotation.Contract;
040import org.apache.http.annotation.ThreadingBehavior;
041import org.apache.http.client.config.RequestConfig;
042import org.apache.http.protocol.HTTP;
043import org.apache.http.protocol.HttpContext;
044import org.apache.http.util.Args;
045
046/**
047 * RequestExpectContinue is responsible for enabling the 'expect-continue'
048 * handshake by adding {@code Expect} header.
049 * <p>
050 * This interceptor takes into account {@link RequestConfig#isExpectContinueEnabled()}
051 * setting.
052 * </p>
053 *
054 * @since 4.3
055 */
056@Contract(threading = ThreadingBehavior.IMMUTABLE)
057public class RequestExpectContinue implements HttpRequestInterceptor {
058
059    public RequestExpectContinue() {
060        super();
061    }
062
063    @Override
064    public void process(final HttpRequest request, final HttpContext context)
065            throws HttpException, IOException {
066        Args.notNull(request, "HTTP request");
067
068        if (!request.containsHeader(HTTP.EXPECT_DIRECTIVE)) {
069            if (request instanceof HttpEntityEnclosingRequest) {
070                final ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
071                final HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
072                // Do not send the expect header if request body is known to be empty
073                if (entity != null
074                        && entity.getContentLength() != 0 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
075                    final HttpClientContext clientContext = HttpClientContext.adapt(context);
076                    final RequestConfig config = clientContext.getRequestConfig();
077                    if (config.isExpectContinueEnabled()) {
078                        request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
079                    }
080                }
081            }
082        }
083    }
084
085}