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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  
28  package org.apache.http.protocol;
29  
30  import java.io.IOException;
31  
32  import org.apache.http.HttpClientConnection;
33  import org.apache.http.HttpEntityEnclosingRequest;
34  import org.apache.http.HttpException;
35  import org.apache.http.HttpRequest;
36  import org.apache.http.HttpResponse;
37  import org.apache.http.HttpStatus;
38  import org.apache.http.HttpVersion;
39  import org.apache.http.ProtocolException;
40  import org.apache.http.ProtocolVersion;
41  import org.apache.http.annotation.Immutable;
42  import org.apache.http.util.Args;
43  
44  /**
45   * {@code HttpRequestExecutor} is a client side HTTP protocol handler based
46   * on the blocking (classic) I/O model.
47   * <p>
48   * {@code HttpRequestExecutor} relies on {@link HttpProcessor} to generate
49   * mandatory protocol headers for all outgoing messages and apply common,
50   * cross-cutting message transformations to all incoming and outgoing messages.
51   * Application specific processing can be implemented outside
52   * {@code HttpRequestExecutor} once the request has been executed and
53   * a response has been received.
54   *
55   * @since 4.0
56   */
57  @Immutable
58  public class HttpRequestExecutor {
59  
60      public static final int DEFAULT_WAIT_FOR_CONTINUE = 3000;
61  
62      private final int waitForContinue;
63  
64      /**
65       * Creates new instance of HttpRequestExecutor.
66       *
67       * @since 4.3
68       */
69      public HttpRequestExecutor(final int waitForContinue) {
70          super();
71          this.waitForContinue = Args.positive(waitForContinue, "Wait for continue time");
72      }
73  
74      public HttpRequestExecutor() {
75          this(DEFAULT_WAIT_FOR_CONTINUE);
76      }
77  
78      /**
79       * Decide whether a response comes with an entity.
80       * The implementation in this class is based on RFC 2616.
81       * <p>
82       * Derived executors can override this method to handle
83       * methods and response codes not specified in RFC 2616.
84       * </p>
85       *
86       * @param request   the request, to obtain the executed method
87       * @param response  the response, to obtain the status code
88       */
89      protected boolean canResponseHaveBody(final HttpRequest request,
90                                            final HttpResponse response) {
91  
92          if ("HEAD".equalsIgnoreCase(request.getRequestLine().getMethod())) {
93              return false;
94          }
95          final int status = response.getStatusLine().getStatusCode();
96          return status >= HttpStatus.SC_OK
97              && status != HttpStatus.SC_NO_CONTENT
98              && status != HttpStatus.SC_NOT_MODIFIED
99              && status != HttpStatus.SC_RESET_CONTENT;
100     }
101 
102     /**
103      * Sends the request and obtain a response.
104      *
105      * @param request   the request to execute.
106      * @param conn      the connection over which to execute the request.
107      *
108      * @return  the response to the request.
109      *
110      * @throws IOException in case of an I/O error.
111      * @throws HttpException in case of HTTP protocol violation or a processing
112      *   problem.
113      */
114     public HttpResponse execute(
115             final HttpRequest request,
116             final HttpClientConnection conn,
117             final HttpContext context) throws IOException, HttpException {
118         Args.notNull(request, "HTTP request");
119         Args.notNull(conn, "Client connection");
120         Args.notNull(context, "HTTP context");
121         try {
122             HttpResponse response = doSendRequest(request, conn, context);
123             if (response == null) {
124                 response = doReceiveResponse(request, conn, context);
125             }
126             return response;
127         } catch (final IOException ex) {
128             closeConnection(conn);
129             throw ex;
130         } catch (final HttpException ex) {
131             closeConnection(conn);
132             throw ex;
133         } catch (final RuntimeException ex) {
134             closeConnection(conn);
135             throw ex;
136         }
137     }
138 
139     private static void closeConnection(final HttpClientConnection conn) {
140         try {
141             conn.close();
142         } catch (final IOException ignore) {
143         }
144     }
145 
146     /**
147      * Pre-process the given request using the given protocol processor and
148      * initiates the process of request execution.
149      *
150      * @param request   the request to prepare
151      * @param processor the processor to use
152      * @param context   the context for sending the request
153      *
154      * @throws IOException in case of an I/O error.
155      * @throws HttpException in case of HTTP protocol violation or a processing
156      *   problem.
157      */
158     public void preProcess(
159             final HttpRequest request,
160             final HttpProcessor processor,
161             final HttpContext context) throws HttpException, IOException {
162         Args.notNull(request, "HTTP request");
163         Args.notNull(processor, "HTTP processor");
164         Args.notNull(context, "HTTP context");
165         context.setAttribute(HttpCoreContext.HTTP_REQUEST, request);
166         processor.process(request, context);
167     }
168 
169     /**
170      * Send the given request over the given connection.
171      * <p>
172      * This method also handles the expect-continue handshake if necessary.
173      * If it does not have to handle an expect-continue handshake, it will
174      * not use the connection for reading or anything else that depends on
175      * data coming in over the connection.
176      *
177      * @param request   the request to send, already
178      *                  {@link #preProcess preprocessed}
179      * @param conn      the connection over which to send the request,
180      *                  already established
181      * @param context   the context for sending the request
182      *
183      * @return  a terminal response received as part of an expect-continue
184      *          handshake, or
185      *          {@code null} if the expect-continue handshake is not used
186      *
187      * @throws IOException in case of an I/O error.
188      * @throws HttpException in case of HTTP protocol violation or a processing
189      *   problem.
190      */
191     protected HttpResponse doSendRequest(
192             final HttpRequest request,
193             final HttpClientConnection conn,
194             final HttpContext context) throws IOException, HttpException {
195         Args.notNull(request, "HTTP request");
196         Args.notNull(conn, "Client connection");
197         Args.notNull(context, "HTTP context");
198 
199         HttpResponse response = null;
200 
201         context.setAttribute(HttpCoreContext.HTTP_CONNECTION, conn);
202         context.setAttribute(HttpCoreContext.HTTP_REQ_SENT, Boolean.FALSE);
203 
204         conn.sendRequestHeader(request);
205         if (request instanceof HttpEntityEnclosingRequest) {
206             // Check for expect-continue handshake. We have to flush the
207             // headers and wait for an 100-continue response to handle it.
208             // If we get a different response, we must not send the entity.
209             boolean sendentity = true;
210             final ProtocolVersion ver =
211                 request.getRequestLine().getProtocolVersion();
212             if (((HttpEntityEnclosingRequest) request).expectContinue() &&
213                 !ver.lessEquals(HttpVersion.HTTP_1_0)) {
214 
215                 conn.flush();
216                 // As suggested by RFC 2616 section 8.2.3, we don't wait for a
217                 // 100-continue response forever. On timeout, send the entity.
218                 if (conn.isResponseAvailable(this.waitForContinue)) {
219                     response = conn.receiveResponseHeader();
220                     if (canResponseHaveBody(request, response)) {
221                         conn.receiveResponseEntity(response);
222                     }
223                     final int status = response.getStatusLine().getStatusCode();
224                     if (status < 200) {
225                         if (status != HttpStatus.SC_CONTINUE) {
226                             throw new ProtocolException(
227                                     "Unexpected response: " + response.getStatusLine());
228                         }
229                         // discard 100-continue
230                         response = null;
231                     } else {
232                         sendentity = false;
233                     }
234                 }
235             }
236             if (sendentity) {
237                 conn.sendRequestEntity((HttpEntityEnclosingRequest) request);
238             }
239         }
240         conn.flush();
241         context.setAttribute(HttpCoreContext.HTTP_REQ_SENT, Boolean.TRUE);
242         return response;
243     }
244 
245     /**
246      * Waits for and receives a response.
247      * This method will automatically ignore intermediate responses
248      * with status code 1xx.
249      *
250      * @param request   the request for which to obtain the response
251      * @param conn      the connection over which the request was sent
252      * @param context   the context for receiving the response
253      *
254      * @return  the terminal response, not yet post-processed
255      *
256      * @throws IOException in case of an I/O error.
257      * @throws HttpException in case of HTTP protocol violation or a processing
258      *   problem.
259      */
260     protected HttpResponse doReceiveResponse(
261             final HttpRequest request,
262             final HttpClientConnection conn,
263             final HttpContext context) throws HttpException, IOException {
264         Args.notNull(request, "HTTP request");
265         Args.notNull(conn, "Client connection");
266         Args.notNull(context, "HTTP context");
267         HttpResponse response = null;
268         int statusCode = 0;
269 
270         while (response == null || statusCode < HttpStatus.SC_OK) {
271 
272             response = conn.receiveResponseHeader();
273             if (canResponseHaveBody(request, response)) {
274                 conn.receiveResponseEntity(response);
275             }
276             statusCode = response.getStatusLine().getStatusCode();
277 
278         } // while intermediate response
279 
280         return response;
281     }
282 
283     /**
284      * Post-processes the given response using the given protocol processor and
285      * completes the process of request execution.
286      * <p>
287      * This method does <i>not</i> read the response entity, if any.
288      * The connection over which content of the response entity is being
289      * streamed from cannot be reused until
290      * {@link org.apache.http.util.EntityUtils#consume(org.apache.http.HttpEntity)}
291      * has been invoked.
292      *
293      * @param response  the response object to post-process
294      * @param processor the processor to use
295      * @param context   the context for post-processing the response
296      *
297      * @throws IOException in case of an I/O error.
298      * @throws HttpException in case of HTTP protocol violation or a processing
299      *   problem.
300      */
301     public void postProcess(
302             final HttpResponse response,
303             final HttpProcessor processor,
304             final HttpContext context) throws HttpException, IOException {
305         Args.notNull(response, "HTTP response");
306         Args.notNull(processor, "HTTP processor");
307         Args.notNull(context, "HTTP context");
308         context.setAttribute(HttpCoreContext.HTTP_RESPONSE, response);
309         processor.process(response, context);
310     }
311 
312 } // class HttpRequestExecutor