1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27
28 package org.apache.hc.core5.http.protocol;
29
30 import java.io.IOException;
31
32 import org.apache.hc.core5.annotation.Contract;
33 import org.apache.hc.core5.annotation.ThreadingBehavior;
34 import org.apache.hc.core5.http.EntityDetails;
35 import org.apache.hc.core5.http.HeaderElements;
36 import org.apache.hc.core5.http.HttpException;
37 import org.apache.hc.core5.http.HttpHeaders;
38 import org.apache.hc.core5.http.HttpRequest;
39 import org.apache.hc.core5.http.HttpRequestInterceptor;
40 import org.apache.hc.core5.http.HttpVersion;
41 import org.apache.hc.core5.http.ProtocolVersion;
42 import org.apache.hc.core5.util.Args;
43
44 /**
45 * This request interceptor is responsible for activation of the 'expect-continue'
46 * handshake by adding a {@code Expect} header describing client expectations.
47 * <p>
48 * This interceptor is recommended for the HTTP protocol conformance and
49 * the correct operation of the client-side message processing pipeline.
50 * </p>
51 *
52 * @since 4.0
53 */
54 @Contract(threading = ThreadingBehavior.IMMUTABLE)
55 public class RequestExpectContinue implements HttpRequestInterceptor {
56
57 /**
58 * Singleton instance.
59 *
60 * @since 5.2
61 */
62 public static final RequestExpectContinue INSTANCE = new RequestExpectContinue();
63
64 public RequestExpectContinue() {
65 super();
66 }
67
68 @Override
69 public void process(final HttpRequest request, final EntityDetails entity, final HttpContext context)
70 throws HttpException, IOException {
71 Args.notNull(request, "HTTP request");
72
73 if (!request.containsHeader(HttpHeaders.EXPECT)) {
74 if (entity != null) {
75 final ProtocolVersion ver = context.getProtocolVersion();
76 // Do not send the expect header if request body is known to be empty
77 if (entity.getContentLength() != 0 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
78 request.addHeader(HttpHeaders.EXPECT, HeaderElements.CONTINUE);
79 }
80 }
81 }
82 }
83
84 }