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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.HttpEntity;
37  import org.apache.hc.core5.http.HttpException;
38  import org.apache.hc.core5.http.HttpHeaders;
39  import org.apache.hc.core5.http.HttpResponse;
40  import org.apache.hc.core5.http.HttpStatus;
41  import org.apache.hc.core5.http.io.HttpFilterChain;
42  import org.apache.hc.core5.http.io.HttpFilterHandler;
43  import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
44  import org.apache.hc.core5.http.protocol.HttpContext;
45  
46  /**
47   * @since 5.0
48   */
49  @Contract(threading = ThreadingBehavior.STATELESS)
50  public class HttpServerExpectationFilter implements HttpFilterHandler {
51  
52      protected boolean verify(final ClassicHttpRequest request, final HttpContext context) throws HttpException {
53          return true;
54      }
55  
56      protected HttpEntity generateResponseContent(final HttpResponse expectationFailed) throws HttpException {
57          return null;
58      }
59  
60      @Override
61      public final void handle(
62              final ClassicHttpRequest request,
63              final HttpFilterChain.ResponseTrigger responseTrigger,
64              final HttpContext context,
65              final HttpFilterChain chain) throws HttpException, IOException {
66          final Header expect = request.getFirstHeader(HttpHeaders.EXPECT);
67          final boolean expectContinue = expect != null && "100-continue".equalsIgnoreCase(expect.getValue());
68          if (expectContinue) {
69              final boolean verified = verify(request, context);
70              if (verified) {
71                  responseTrigger.sendInformation(new BasicClassicHttpResponse(HttpStatus.SC_CONTINUE));
72              } else {
73                  final ClassicHttpResponse expectationFailed = new BasicClassicHttpResponse(HttpStatus.SC_EXPECTATION_FAILED);
74                  final HttpEntity responseContent = generateResponseContent(expectationFailed);
75                  expectationFailed.setEntity(responseContent);
76                  responseTrigger.submitResponse(expectationFailed);
77                  return;
78              }
79          }
80          chain.proceed(request, responseTrigger, context);
81      }
82  }