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 package org.apache.hc.core5.http.io.support;
28
29 import java.io.IOException;
30
31 import org.apache.hc.core5.annotation.Contract;
32 import org.apache.hc.core5.annotation.ThreadingBehavior;
33 import org.apache.hc.core5.http.ClassicHttpRequest;
34 import org.apache.hc.core5.http.ClassicHttpResponse;
35 import org.apache.hc.core5.http.Header;
36 import org.apache.hc.core5.http.HeaderElements;
37 import org.apache.hc.core5.http.HttpEntity;
38 import org.apache.hc.core5.http.HttpException;
39 import org.apache.hc.core5.http.HttpHeaders;
40 import org.apache.hc.core5.http.HttpResponse;
41 import org.apache.hc.core5.http.HttpStatus;
42 import org.apache.hc.core5.http.io.HttpFilterChain;
43 import org.apache.hc.core5.http.io.HttpFilterHandler;
44 import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
45 import org.apache.hc.core5.http.protocol.HttpContext;
46
47 /**
48 * HttpServerExpectationFilter add support for the Expect-Continue handshake
49 * to the request processing pipeline.
50 *
51 * @since 5.0
52 */
53 @Contract(threading = ThreadingBehavior.STATELESS)
54 public class HttpServerExpectationFilter implements HttpFilterHandler {
55
56 /**
57 * Verifies the HTTP request and decides whether it meets server expectations and the request
58 * processing can continue.
59 *
60 * @param request the incoming HTTP request.
61 * @param context the actual execution context.
62 * @return {@code true} if the request meets expectations or {@code false} otherwise.
63 */
64 protected boolean verify(final ClassicHttpRequest request, final HttpContext context) throws HttpException {
65 return true;
66 }
67
68 /**
69 * Generates response content entity for the final HTTP response with an error status
70 * representing the cause of expectation failure.
71 *
72 * @param expectationFailed the final HTTP response.
73 * @return the content entity for the final HTTP response with an error status
74 * representing the cause of expectation failure.
75 */
76 protected HttpEntity generateResponseContent(final HttpResponse expectationFailed) throws HttpException {
77 return null;
78 }
79
80 @Override
81 public final void handle(
82 final ClassicHttpRequest request,
83 final HttpFilterChain.ResponseTrigger responseTrigger,
84 final HttpContext context,
85 final HttpFilterChain chain) throws HttpException, IOException {
86 final Header expect = request.getFirstHeader(HttpHeaders.EXPECT);
87 final boolean expectContinue = expect != null && HeaderElements.CONTINUE.equalsIgnoreCase(expect.getValue());
88 if (expectContinue) {
89 final boolean verified = verify(request, context);
90 if (verified) {
91 responseTrigger.sendInformation(new BasicClassicHttpResponse(HttpStatus.SC_CONTINUE));
92 } else {
93 final ClassicHttpResponse expectationFailed = new BasicClassicHttpResponse(HttpStatus.SC_EXPECTATION_FAILED);
94 final HttpEntity responseContent = generateResponseContent(expectationFailed);
95 expectationFailed.setEntity(responseContent);
96 responseTrigger.submitResponse(expectationFailed);
97 return;
98 }
99 }
100 chain.proceed(request, responseTrigger, context);
101 }
102 }