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1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  You may obtain a copy of the License at:
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.codec.http;
17  
18  import java.util.List;
19  
20  import org.jboss.netty.buffer.ChannelBuffer;
21  import org.jboss.netty.buffer.ChannelBuffers;
22  import org.jboss.netty.channel.Channel;
23  import org.jboss.netty.channel.ChannelHandlerContext;
24  import org.jboss.netty.channel.ChannelPipeline;
25  import org.jboss.netty.handler.codec.frame.TooLongFrameException;
26  import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
27  
28  /**
29   * Decodes {@link ChannelBuffer}s into {@link HttpMessage}s and
30   * {@link HttpChunk}s.
31   *
32   * <h3>Parameters that prevents excessive memory consumption</h3>
33   * <table border="1">
34   * <tr>
35   * <th>Name</th><th>Meaning</th>
36   * </tr>
37   * <tr>
38   * <td>{@code maxInitialLineLength}</td>
39   * <td>The maximum length of the initial line
40   *     (e.g. {@code "GET / HTTP/1.0"} or {@code "HTTP/1.0 200 OK"})
41   *     If the length of the initial line exceeds this value, a
42   *     {@link TooLongFrameException} will be raised.</td>
43   * </tr>
44   * <tr>
45   * <td>{@code maxHeaderSize}</td>
46   * <td>The maximum length of all headers.  If the sum of the length of each
47   *     header exceeds this value, a {@link TooLongFrameException} will be raised.</td>
48   * </tr>
49   * <tr>
50   * <td>{@code maxChunkSize}</td>
51   * <td>The maximum length of the content or each chunk.  If the content length
52   *     (or the length of each chunk) exceeds this value, the content or chunk
53   *     will be split into multiple {@link HttpChunk}s whose length is
54   *     {@code maxChunkSize} at maximum.</td>
55   * </tr>
56   * </table>
57   *
58   * <h3>Chunked Content</h3>
59   *
60   * If the content of an HTTP message is greater than {@code maxChunkSize} or
61   * the transfer encoding of the HTTP message is 'chunked', this decoder
62   * generates one {@link HttpMessage} instance and its following
63   * {@link HttpChunk}s per single HTTP message to avoid excessive memory
64   * consumption. For example, the following HTTP message:
65   * <pre>
66   * GET / HTTP/1.1
67   * Transfer-Encoding: chunked
68   *
69   * 1a
70   * abcdefghijklmnopqrstuvwxyz
71   * 10
72   * 1234567890abcdef
73   * 0
74   * Content-MD5: ...
75   * <i>[blank line]</i>
76   * </pre>
77   * triggers {@link HttpRequestDecoder} to generate 4 objects:
78   * <ol>
79   * <li>An {@link HttpRequest} whose {@link HttpMessage#isChunked() chunked}
80   *     property is {@code true},</li>
81   * <li>The first {@link HttpChunk} whose content is {@code 'abcdefghijklmnopqrstuvwxyz'},</li>
82   * <li>The second {@link HttpChunk} whose content is {@code '1234567890abcdef'}, and</li>
83   * <li>An {@link HttpChunkTrailer} which marks the end of the content.</li>
84   * </ol>
85   *
86   * If you prefer not to handle {@link HttpChunk}s by yourself for your
87   * convenience, insert {@link HttpChunkAggregator} after this decoder in the
88   * {@link ChannelPipeline}.  However, please note that your server might not
89   * be as memory efficient as without the aggregator.
90   *
91   * <h3>Extensibility</h3>
92   *
93   * Please note that this decoder is designed to be extended to implement
94   * a protocol derived from HTTP, such as
95   * <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
96   * <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
97   * To implement the decoder of such a derived protocol, extend this class and
98   * implement all abstract methods properly.
99   *
100  * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
101  * @author Andy Taylor (andy.taylor@jboss.org)
102  * @author <a href="http://gleamynode.net/">Trustin Lee</a>
103  * @version $Rev: 2370 $, $Date: 2010-10-19 14:40:44 +0900 (Tue, 19 Oct 2010) $
104  *
105  * @apiviz.landmark
106  */
107 public abstract class HttpMessageDecoder extends ReplayingDecoder<HttpMessageDecoder.State> {
108 
109     private final int maxInitialLineLength;
110     private final int maxHeaderSize;
111     private final int maxChunkSize;
112     private HttpMessage message;
113     private ChannelBuffer content;
114     private long chunkSize;
115     private int headerSize;
116 
117     /**
118      * The internal state of {@link HttpMessageDecoder}.
119      * <em>Internal use only</em>.
120      *
121      * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
122      * @author <a href="http://gleamynode.net/">Trustin Lee</a>
123      * @version $Rev: 2370 $, $Date: 2010-10-19 14:40:44 +0900 (Tue, 19 Oct 2010) $
124      *
125      * @apiviz.exclude
126      */
127     protected static enum State {
128         SKIP_CONTROL_CHARS,
129         READ_INITIAL,
130         READ_HEADER,
131         READ_VARIABLE_LENGTH_CONTENT,
132         READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS,
133         READ_FIXED_LENGTH_CONTENT,
134         READ_FIXED_LENGTH_CONTENT_AS_CHUNKS,
135         READ_CHUNK_SIZE,
136         READ_CHUNKED_CONTENT,
137         READ_CHUNKED_CONTENT_AS_CHUNKS,
138         READ_CHUNK_DELIMITER,
139         READ_CHUNK_FOOTER;
140     }
141 
142     /**
143      * Creates a new instance with the default
144      * {@code maxInitialLineLength (4096}}, {@code maxHeaderSize (8192)}, and
145      * {@code maxChunkSize (8192)}.
146      */
147     protected HttpMessageDecoder() {
148         this(4096, 8192, 8192);
149     }
150 
151     /**
152      * Creates a new instance with the specified parameters.
153      */
154     protected HttpMessageDecoder(
155             int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) {
156 
157         super(State.SKIP_CONTROL_CHARS, true);
158 
159         if (maxInitialLineLength <= 0) {
160             throw new IllegalArgumentException(
161                     "maxInitialLineLength must be a positive integer: " +
162                     maxInitialLineLength);
163         }
164         if (maxHeaderSize <= 0) {
165             throw new IllegalArgumentException(
166                     "maxHeaderSize must be a positive integer: " +
167                     maxHeaderSize);
168         }
169         if (maxChunkSize < 0) {
170             throw new IllegalArgumentException(
171                     "maxChunkSize must be a positive integer: " +
172                     maxChunkSize);
173         }
174         this.maxInitialLineLength = maxInitialLineLength;
175         this.maxHeaderSize = maxHeaderSize;
176         this.maxChunkSize = maxChunkSize;
177     }
178 
179     @Override
180     protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, State state) throws Exception {
181         switch (state) {
182         case SKIP_CONTROL_CHARS: {
183             try {
184                 skipControlCharacters(buffer);
185                 checkpoint(State.READ_INITIAL);
186             } finally {
187                 checkpoint();
188             }
189         }
190         case READ_INITIAL: {
191             String[] initialLine = splitInitialLine(readLine(buffer, maxInitialLineLength));
192             if (initialLine.length < 3) {
193                 // Invalid initial line - ignore.
194                 checkpoint(State.SKIP_CONTROL_CHARS);
195                 return null;
196             }
197 
198             message = createMessage(initialLine);
199             checkpoint(State.READ_HEADER);
200         }
201         case READ_HEADER: {
202             State nextState = readHeaders(buffer);
203             checkpoint(nextState);
204             if (nextState == State.READ_CHUNK_SIZE) {
205                 // Chunked encoding
206                 message.setChunked(true);
207                 // Generate HttpMessage first.  HttpChunks will follow.
208                 return message;
209             } else if (nextState == State.SKIP_CONTROL_CHARS) {
210                 // No content is expected.
211                 // Remove the headers which are not supposed to be present not
212                 // to confuse subsequent handlers.
213                 message.removeHeader(HttpHeaders.Names.TRANSFER_ENCODING);
214                 return message;
215             } else {
216                 long contentLength = HttpHeaders.getContentLength(message, -1);
217                 if (contentLength == 0 || contentLength == -1 && isDecodingRequest()) {
218                     content = ChannelBuffers.EMPTY_BUFFER;
219                     return reset();
220                 }
221 
222                 switch (nextState) {
223                 case READ_FIXED_LENGTH_CONTENT:
224                     if (contentLength > maxChunkSize || HttpHeaders.is100ContinueExpected(message)) {
225                         // Generate HttpMessage first.  HttpChunks will follow.
226                         checkpoint(State.READ_FIXED_LENGTH_CONTENT_AS_CHUNKS);
227                         message.setChunked(true);
228                         // chunkSize will be decreased as the READ_FIXED_LENGTH_CONTENT_AS_CHUNKS
229                         // state reads data chunk by chunk.
230                         chunkSize = HttpHeaders.getContentLength(message, -1);
231                         return message;
232                     }
233                     break;
234                 case READ_VARIABLE_LENGTH_CONTENT:
235                     if (buffer.readableBytes() > maxChunkSize || HttpHeaders.is100ContinueExpected(message)) {
236                         // Generate HttpMessage first.  HttpChunks will follow.
237                         checkpoint(State.READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS);
238                         message.setChunked(true);
239                         return message;
240                     }
241                     break;
242                 default:
243                     throw new IllegalStateException("Unexpected state: " + nextState);
244                 }
245             }
246             // We return null here, this forces decode to be called again where we will decode the content
247             return null;
248         }
249         case READ_VARIABLE_LENGTH_CONTENT: {
250             if (content == null) {
251                 content = ChannelBuffers.dynamicBuffer(channel.getConfig().getBufferFactory());
252             }
253             //this will cause a replay error until the channel is closed where this will read what's left in the buffer
254             content.writeBytes(buffer.readBytes(buffer.readableBytes()));
255             return reset();
256         }
257         case READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS: {
258             // Keep reading data as a chunk until the end of connection is reached.
259             int chunkSize = Math.min(maxChunkSize, buffer.readableBytes());
260             HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes(chunkSize));
261 
262             if (!buffer.readable()) {
263                 // Reached to the end of the connection.
264                 reset();
265                 if (!chunk.isLast()) {
266                     // Append the last chunk.
267                     return new Object[] { chunk, HttpChunk.LAST_CHUNK };
268                 }
269             }
270             return chunk;
271         }
272         case READ_FIXED_LENGTH_CONTENT: {
273             //we have a content-length so we just read the correct number of bytes
274             readFixedLengthContent(buffer);
275             return reset();
276         }
277         case READ_FIXED_LENGTH_CONTENT_AS_CHUNKS: {
278             long chunkSize = this.chunkSize;
279             HttpChunk chunk;
280             if (chunkSize > maxChunkSize) {
281                 chunk = new DefaultHttpChunk(buffer.readBytes(maxChunkSize));
282                 chunkSize -= maxChunkSize;
283             } else {
284                 assert chunkSize <= Integer.MAX_VALUE;
285                 chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize));
286                 chunkSize = 0;
287             }
288             this.chunkSize = chunkSize;
289 
290             if (chunkSize == 0) {
291                 // Read all content.
292                 reset();
293                 if (!chunk.isLast()) {
294                     // Append the last chunk.
295                     return new Object[] { chunk, HttpChunk.LAST_CHUNK };
296                 }
297             }
298             return chunk;
299         }
300         /**
301          * everything else after this point takes care of reading chunked content. basically, read chunk size,
302          * read chunk, read and ignore the CRLF and repeat until 0
303          */
304         case READ_CHUNK_SIZE: {
305             String line = readLine(buffer, maxInitialLineLength);
306             int chunkSize = getChunkSize(line);
307             this.chunkSize = chunkSize;
308             if (chunkSize == 0) {
309                 checkpoint(State.READ_CHUNK_FOOTER);
310                 return null;
311             } else if (chunkSize > maxChunkSize) {
312                 // A chunk is too large. Split them into multiple chunks again.
313                 checkpoint(State.READ_CHUNKED_CONTENT_AS_CHUNKS);
314             } else {
315                 checkpoint(State.READ_CHUNKED_CONTENT);
316             }
317         }
318         case READ_CHUNKED_CONTENT: {
319             assert chunkSize <= Integer.MAX_VALUE;
320             HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize));
321             checkpoint(State.READ_CHUNK_DELIMITER);
322             return chunk;
323         }
324         case READ_CHUNKED_CONTENT_AS_CHUNKS: {
325             long chunkSize = this.chunkSize;
326             HttpChunk chunk;
327             if (chunkSize > maxChunkSize) {
328                 chunk = new DefaultHttpChunk(buffer.readBytes(maxChunkSize));
329                 chunkSize -= maxChunkSize;
330             } else {
331                 assert chunkSize <= Integer.MAX_VALUE;
332                 chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize));
333                 chunkSize = 0;
334             }
335             this.chunkSize = chunkSize;
336 
337             if (chunkSize == 0) {
338                 // Read all content.
339                 checkpoint(State.READ_CHUNK_DELIMITER);
340             }
341 
342             if (!chunk.isLast()) {
343                 return chunk;
344             }
345         }
346         case READ_CHUNK_DELIMITER: {
347             for (;;) {
348                 byte next = buffer.readByte();
349                 if (next == HttpCodecUtil.CR) {
350                     if (buffer.readByte() == HttpCodecUtil.LF) {
351                         checkpoint(State.READ_CHUNK_SIZE);
352                         return null;
353                     }
354                 } else if (next == HttpCodecUtil.LF) {
355                     checkpoint(State.READ_CHUNK_SIZE);
356                     return null;
357                 }
358             }
359         }
360         case READ_CHUNK_FOOTER: {
361             HttpChunkTrailer trailer = readTrailingHeaders(buffer);
362             if (maxChunkSize == 0) {
363                 // Chunked encoding disabled.
364                 return reset();
365             } else {
366                 reset();
367                 // The last chunk, which is empty
368                 return trailer;
369             }
370         }
371         default: {
372             throw new Error("Shouldn't reach here.");
373         }
374 
375         }
376     }
377 
378     protected boolean isContentAlwaysEmpty(HttpMessage msg) {
379         if (msg instanceof HttpResponse) {
380             HttpResponse res = (HttpResponse) msg;
381             int code = res.getStatus().getCode();
382             if (code < 200) {
383                 return true;
384             }
385             switch (code) {
386             case 204: case 205: case 304:
387                 return true;
388             }
389         }
390         return false;
391     }
392 
393     private Object reset() {
394         HttpMessage message = this.message;
395         ChannelBuffer content = this.content;
396 
397         if (content != null) {
398             message.setContent(content);
399             this.content = null;
400         }
401         this.message = null;
402 
403         checkpoint(State.SKIP_CONTROL_CHARS);
404         return message;
405     }
406 
407     private void skipControlCharacters(ChannelBuffer buffer) {
408         for (;;) {
409             char c = (char) buffer.readUnsignedByte();
410             if (!Character.isISOControl(c) &&
411                 !Character.isWhitespace(c)) {
412                 buffer.readerIndex(buffer.readerIndex() - 1);
413                 break;
414             }
415         }
416     }
417 
418     private void readFixedLengthContent(ChannelBuffer buffer) {
419         long length = HttpHeaders.getContentLength(message, -1);
420         assert length <= Integer.MAX_VALUE;
421 
422         if (content == null) {
423             content = buffer.readBytes((int) length);
424         } else {
425             content.writeBytes(buffer.readBytes((int) length));
426         }
427     }
428 
429     private State readHeaders(ChannelBuffer buffer) throws TooLongFrameException {
430         headerSize = 0;
431         final HttpMessage message = this.message;
432         String line = readHeader(buffer);
433         String name = null;
434         String value = null;
435         if (line.length() != 0) {
436             message.clearHeaders();
437             do {
438                 char firstChar = line.charAt(0);
439                 if (name != null && (firstChar == ' ' || firstChar == '\t')) {
440                     value = value + ' ' + line.trim();
441                 } else {
442                     if (name != null) {
443                         message.addHeader(name, value);
444                     }
445                     String[] header = splitHeader(line);
446                     name = header[0];
447                     value = header[1];
448                 }
449 
450                 line = readHeader(buffer);
451             } while (line.length() != 0);
452 
453             // Add the last header.
454             if (name != null) {
455                 message.addHeader(name, value);
456             }
457         }
458 
459         State nextState;
460 
461         if (isContentAlwaysEmpty(message)) {
462             nextState = State.SKIP_CONTROL_CHARS;
463         } else if (message.isChunked()) {
464             // HttpMessage.isChunked() returns true when either:
465             // 1) HttpMessage.setChunked(true) was called or
466             // 2) 'Transfer-Encoding' is 'chunked'.
467             // Because this decoder did not call HttpMessage.setChunked(true)
468             // yet, HttpMessage.isChunked() should return true only when
469             // 'Transfer-Encoding' is 'chunked'.
470             nextState = State.READ_CHUNK_SIZE;
471         } else if (HttpHeaders.getContentLength(message, -1) >= 0) {
472             nextState = State.READ_FIXED_LENGTH_CONTENT;
473         } else {
474             nextState = State.READ_VARIABLE_LENGTH_CONTENT;
475         }
476         return nextState;
477     }
478 
479     private HttpChunkTrailer readTrailingHeaders(ChannelBuffer buffer) throws TooLongFrameException {
480         headerSize = 0;
481         String line = readHeader(buffer);
482         String lastHeader = null;
483         if (line.length() != 0) {
484             HttpChunkTrailer trailer = new DefaultHttpChunkTrailer();
485             do {
486                 char firstChar = line.charAt(0);
487                 if (lastHeader != null && (firstChar == ' ' || firstChar == '\t')) {
488                     List<String> current = trailer.getHeaders(lastHeader);
489                     if (current.size() != 0) {
490                         int lastPos = current.size() - 1;
491                         String newString = current.get(lastPos) + line.trim();
492                         current.set(lastPos, newString);
493                     } else {
494                         // Content-Length, Transfer-Encoding, or Trailer
495                     }
496                 } else {
497                     String[] header = splitHeader(line);
498                     String name = header[0];
499                     if (!name.equalsIgnoreCase(HttpHeaders.Names.CONTENT_LENGTH) &&
500                         !name.equalsIgnoreCase(HttpHeaders.Names.TRANSFER_ENCODING) &&
501                         !name.equalsIgnoreCase(HttpHeaders.Names.TRAILER)) {
502                         trailer.addHeader(name, header[1]);
503                     }
504                     lastHeader = name;
505                 }
506 
507                 line = readHeader(buffer);
508             } while (line.length() != 0);
509 
510             return trailer;
511         }
512 
513         return HttpChunk.LAST_CHUNK;
514     }
515 
516     private String readHeader(ChannelBuffer buffer) throws TooLongFrameException {
517         StringBuilder sb = new StringBuilder(64);
518         int headerSize = this.headerSize;
519 
520         loop:
521         for (;;) {
522             char nextByte = (char) buffer.readByte();
523             headerSize ++;
524 
525             switch (nextByte) {
526             case HttpCodecUtil.CR:
527                 nextByte = (char) buffer.readByte();
528                 headerSize ++;
529                 if (nextByte == HttpCodecUtil.LF) {
530                     break loop;
531                 }
532                 break;
533             case HttpCodecUtil.LF:
534                 break loop;
535             }
536 
537             // Abort decoding if the header part is too large.
538             if (headerSize >= maxHeaderSize) {
539                 // TODO: Respond with Bad Request and discard the traffic
540                 //    or close the connection.
541                 //       No need to notify the upstream handlers - just log.
542                 //       If decoding a response, just throw an exception.
543                 throw new TooLongFrameException(
544                         "HTTP header is larger than " +
545                         maxHeaderSize + " bytes.");
546 
547             }
548 
549             sb.append(nextByte);
550         }
551 
552         this.headerSize = headerSize;
553         return sb.toString();
554     }
555 
556     protected abstract boolean isDecodingRequest();
557     protected abstract HttpMessage createMessage(String[] initialLine) throws Exception;
558 
559     private int getChunkSize(String hex) {
560         hex = hex.trim();
561         for (int i = 0; i < hex.length(); i ++) {
562             char c = hex.charAt(i);
563             if (c == ';' || Character.isWhitespace(c) || Character.isISOControl(c)) {
564                 hex = hex.substring(0, i);
565                 break;
566             }
567         }
568 
569         return Integer.parseInt(hex, 16);
570     }
571 
572     private String readLine(ChannelBuffer buffer, int maxLineLength) throws TooLongFrameException {
573         StringBuilder sb = new StringBuilder(64);
574         int lineLength = 0;
575         while (true) {
576             byte nextByte = buffer.readByte();
577             if (nextByte == HttpCodecUtil.CR) {
578                 nextByte = buffer.readByte();
579                 if (nextByte == HttpCodecUtil.LF) {
580                     return sb.toString();
581                 }
582             }
583             else if (nextByte == HttpCodecUtil.LF) {
584                 return sb.toString();
585             }
586             else {
587                 if (lineLength >= maxLineLength) {
588                     // TODO: Respond with Bad Request and discard the traffic
589                     //    or close the connection.
590                     //       No need to notify the upstream handlers - just log.
591                     //       If decoding a response, just throw an exception.
592                     throw new TooLongFrameException(
593                             "An HTTP line is larger than " + maxLineLength +
594                             " bytes.");
595                 }
596                 lineLength ++;
597                 sb.append((char) nextByte);
598             }
599         }
600     }
601 
602     private String[] splitInitialLine(String sb) {
603         int aStart;
604         int aEnd;
605         int bStart;
606         int bEnd;
607         int cStart;
608         int cEnd;
609 
610         aStart = findNonWhitespace(sb, 0);
611         aEnd = findWhitespace(sb, aStart);
612 
613         bStart = findNonWhitespace(sb, aEnd);
614         bEnd = findWhitespace(sb, bStart);
615 
616         cStart = findNonWhitespace(sb, bEnd);
617         cEnd = findEndOfString(sb);
618 
619         return new String[] {
620                 sb.substring(aStart, aEnd),
621                 sb.substring(bStart, bEnd),
622                 cStart < cEnd? sb.substring(cStart, cEnd) : "" };
623     }
624 
625     private String[] splitHeader(String sb) {
626         final int length = sb.length();
627         int nameStart;
628         int nameEnd;
629         int colonEnd;
630         int valueStart;
631         int valueEnd;
632 
633         nameStart = findNonWhitespace(sb, 0);
634         for (nameEnd = nameStart; nameEnd < length; nameEnd ++) {
635             char ch = sb.charAt(nameEnd);
636             if (ch == ':' || Character.isWhitespace(ch)) {
637                 break;
638             }
639         }
640 
641         for (colonEnd = nameEnd; colonEnd < length; colonEnd ++) {
642             if (sb.charAt(colonEnd) == ':') {
643                 colonEnd ++;
644                 break;
645             }
646         }
647 
648         valueStart = findNonWhitespace(sb, colonEnd);
649         if (valueStart == length) {
650             return new String[] {
651                     sb.substring(nameStart, nameEnd),
652                     ""
653             };
654         }
655 
656         valueEnd = findEndOfString(sb);
657         return new String[] {
658                 sb.substring(nameStart, nameEnd),
659                 sb.substring(valueStart, valueEnd)
660         };
661     }
662 
663     private int findNonWhitespace(String sb, int offset) {
664         int result;
665         for (result = offset; result < sb.length(); result ++) {
666             if (!Character.isWhitespace(sb.charAt(result))) {
667                 break;
668             }
669         }
670         return result;
671     }
672 
673     private int findWhitespace(String sb, int offset) {
674         int result;
675         for (result = offset; result < sb.length(); result ++) {
676             if (Character.isWhitespace(sb.charAt(result))) {
677                 break;
678             }
679         }
680         return result;
681     }
682 
683     private int findEndOfString(String sb) {
684         int result;
685         for (result = sb.length(); result > 0; result --) {
686             if (!Character.isWhitespace(sb.charAt(result - 1))) {
687                 break;
688             }
689         }
690         return result;
691     }
692 }