Java > Open Source Codes > org > apache > commons > httpclient > ChunkedInputStream


1 /*
2  * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/ChunkedInputStream.java,v 1.16.2.2 2004/02/22 18:21:13 olegk Exp $
3  * $Revision: 1.16.2.2 $
4  * $Date: 2004/02/22 18:21:13 $
5  *
6  * ====================================================================
7  *
8  * Copyright 2002-2004 The Apache Software Foundation
9  *
10  * Licensed under the Apache License, Version 2.0 (the "License");
11  * you may not use this file except in compliance with the License.
12  * You may obtain a copy of the License at
13  *
14  * http://www.apache.org/licenses/LICENSE-2.0
15  *
16  * Unless required by applicable law or agreed to in writing, software
17  * distributed under the License is distributed on an "AS IS" BASIS,
18  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  * See the License for the specific language governing permissions and
20  * limitations under the License.
21  * ====================================================================
22  *
23  * This software consists of voluntary contributions made by many
24  * individuals on behalf of the Apache Software Foundation. For more
25  * information on the Apache Software Foundation, please see
26  * <http://www.apache.org/>.
27  *
28  * [Additional notices, if required by prior licensing conditions]
29  *
30  */
31
32 package org.apache.commons.httpclient;
33
34 import java.io.ByteArrayOutputStream ;
35 import java.io.IOException ;
36 import java.io.InputStream ;
37
38
39 /**
40  * <p>Transparently coalesces chunks of a HTTP stream that uses
41  * Transfer-Encoding chunked.</p>
42  *
43  * <p>Note that this class NEVER closes the underlying stream, even when close
44  * gets called. Instead, it will read until the "end" of its chunking on close,
45  * which allows for the seamless invocation of subsequent HTTP 1.1 calls, while
46  * not requiring the client to remember to read the entire contents of the
47  * response.</p>
48  *
49  * @see ResponseInputStream
50  *
51  * @author Ortwin Glück
52  * @author Sean C. Sullivan
53  * @author Martin Elwin
54  * @author Eric Johnson
55  * @author <a HREF="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
56  * @author Michael Becke
57  * @author <a HREF="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
58  *
59  * @since 2.0
60  *
61  */
62
63 public class ChunkedInputStream extends InputStream {
64     /** The inputstream that we're wrapping */
65     private InputStream in;
66
67     /** The chunk size */
68     private int chunkSize;
69
70     /** The current position within the current chunk */
71     private int pos;
72
73     /** True if we'are at the beginning of stream */
74     private boolean bof = true;
75
76     /** True if we've reached the end of stream */
77     private boolean eof = false;
78
79     /** True if this stream is closed */
80     private boolean closed = false;
81
82     /** The method that this stream came from */
83     private HttpMethod method;
84
85     /**
86      *
87      *
88      * @param in must be non-null
89      * @param method must be non-null
90      *
91      * @throws IOException If an IO error occurs
92      */
93     public ChunkedInputStream(
94         final InputStream in, final HttpMethod method) throws IOException {
95             
96       if (in == null) {
97         throw new IllegalArgumentException ("InputStream parameter may not be null");
98       }
99       if (method == null) {
100         throw new IllegalArgumentException ("HttpMethod parameter may not be null");
101       }
102         this.in = in;
103         this.method = method;
104         this.pos = 0;
105     }
106
107     /**
108      * <p> Returns all the data in a chunked stream in coalesced form. A chunk
109      * is followed by a CRLF. The method returns -1 as soon as a chunksize of 0
110      * is detected.</p>
111      *
112      * <p> Trailer headers are read automcatically at the end of the stream and
113      * can be obtained with the getResponseFooters() method.</p>
114      *
115      * @return -1 of the end of the stream has been reached or the next data
116      * byte
117      * @throws IOException If an IO problem occurs
118      *
119      * @see HttpMethod#getResponseFooters()
120      */
121     public int read() throws IOException {
122
123         if (closed) {
124             throw new IOException ("Attempted read from closed stream.");
125         }
126         if (eof) {
127             return -1;
128         }
129         if (pos >= chunkSize) {
130             nextChunk();
131             if (eof) {
132                 return -1;
133             }
134         }
135         pos++;
136         return in.read();
137     }
138
139     /**
140      * Read some bytes from the stream.
141      * @param b The byte array that will hold the contents from the stream.
142      * @param off The offset into the byte array at which bytes will start to be
143      * placed.
144      * @param len the maximum number of bytes that can be returned.
145      * @return The number of bytes returned or -1 if the end of stream has been
146      * reached.
147      * @see java.io.InputStream#read(byte[], int, int)
148      * @throws IOException if an IO problem occurs.
149      */
150     public int read (byte[] b, int off, int len) throws IOException {
151
152         if (closed) {
153             throw new IOException ("Attempted read from closed stream.");
154         }
155
156         if (eof) {
157             return -1;
158         }
159         if (pos >= chunkSize) {
160             nextChunk();
161             if (eof) {
162                 return -1;
163             }
164         }
165         len = Math.min(len, chunkSize - pos);
166         int count = in.read(b, off, len);
167         pos += count;
168         return count;
169     }
170
171     /**
172      * Read some bytes from the stream.
173      * @param b The byte array that will hold the contents from the stream.
174      * @return The number of bytes returned or -1 if the end of stream has been
175      * reached.
176      * @see java.io.InputStream#read(byte[])
177      * @throws IOException if an IO problem occurs.
178      */
179     public int read (byte[] b) throws IOException {
180         return read(b, 0, b.length);
181     }
182
183     /**
184      * Read the CRLF terminator.
185      * @throws IOException If an IO error occurs.
186      */
187     private void readCRLF() throws IOException {
188         int cr = in.read();
189         int lf = in.read();
190         if ((cr != '\r') || (lf != '\n')) {
191             throw new IOException (
192                 "CRLF expected at end of chunk: " + cr + "/" + lf);
193         }
194     }
195
196
197     /**
198      * Read the next chunk.
199      * @throws IOException If an IO error occurs.
200      */
201     private void nextChunk() throws IOException {
202         if (!bof) {
203             readCRLF();
204         }
205         chunkSize = getChunkSizeFromInputStream(in);
206         bof = false;
207         pos = 0;
208         if (chunkSize == 0) {
209             eof = true;
210             parseTrailerHeaders();
211         }
212     }
213
214     /**
215      * Expects the stream to start with a chunksize in hex with optional
216      * comments after a semicolon. The line must end with a CRLF: "a3; some
217      * comment\r\n" Positions the stream at the start of the next line.
218      *
219      * @param in The new input stream.
220      *
221      * @return the chunk size as integer
222      *
223      * @throws IOException when the chunk size could not be parsed
224      */
225     private static int getChunkSizeFromInputStream(final InputStream in)
226       throws IOException {
227             
228         ByteArrayOutputStream baos = new ByteArrayOutputStream ();
229         // States: 0=normal, 1=\r was scanned, 2=inside quoted string, -1=end
230 int state = 0;
231         while (state != -1) {
232         int b = in.read();
233             if (b == -1) {
234                 throw new IOException ("chunked stream ended unexpectedly");
235             }
236             switch (state) {
237                 case 0:
238                     switch (b) {
239                         case '\r':
240                             state = 1;
241                             break;
242                         case '\"':
243                             state = 2;
244                             /* fall through */
245                         default:
246                             baos.write(b);
247                     }
248                     break;
249
250                 case 1:
251                     if (b == '\n') {
252                         state = -1;
253                     } else {
254                         // this was not CRLF
255 throw new IOException ("Protocol violation: Unexpected"
256                             + " single newline character in chunk size");
257                     }
258                     break;
259
260                 case 2:
261                     switch (b) {
262                         case '\\':
263                             b = in.read();
264                             baos.write(b);
265                             break;
266                         case '\"':
267                             state = 0;
268                             /* fall through */
269                         default:
270                             baos.write(b);
271                     }
272                     break;
273                 default: throw new RuntimeException ("assertion failed");
274             }
275         }
276
277         //parse data
278 String dataString = HttpConstants.getString(baos.toByteArray());
279         int separator = dataString.indexOf(';');
280         dataString = (separator > 0)
281             ? dataString.substring(0, separator).trim()
282             : dataString.trim();
283
284         int result;
285         try {
286             result = Integer.parseInt(dataString.trim(), 16);
287         } catch (NumberFormatException e) {
288             throw new IOException ("Bad chunk size: " + dataString);
289         }
290         return result;
291     }
292
293     /**
294      * Reads and stores the Trailer headers.
295      * @throws IOException If an IO problem occurs
296      */
297     private void parseTrailerHeaders() throws IOException {
298         Header[] footers = HttpParser.parseHeaders(in);
299         
300         for (int i = 0; i < footers.length; i++) {
301             method.addResponseFooter(footers[i]);
302         }
303     }
304
305     /**
306      * Upon close, this reads the remainder of the chunked message,
307      * leaving the underlying socket at a position to start reading the
308      * next response without scanning.
309      * @throws IOException If an IO problem occurs.
310      */
311     public void close() throws IOException {
312         if (!closed) {
313             try {
314                 if (!eof) {
315                     exhaustInputStream(this);
316                 }
317             } finally {
318                 eof = true;
319                 closed = true;
320             }
321         }
322     }
323
324     /**
325      * Exhaust an input stream, reading until EOF has been encountered.
326      *
327      * <p>Note that this function is intended as a non-public utility.
328      * This is a little weird, but it seemed silly to make a utility
329      * class for this one function, so instead it is just static and
330      * shared that way.</p>
331      *
332      * @param inStream The {@link InputStream} to exhaust.
333      * @throws IOException If an IO problem occurs
334      */
335     static void exhaustInputStream(InputStream inStream) throws IOException {
336         // read and discard the remainder of the message
337 byte buffer[] = new byte[1024];
338         while (inStream.read(buffer) >= 0) {
339             ;
340         }
341     }
342 }
343

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