001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.codec.binary;
019
020 import java.util.Arrays;
021
022 import org.apache.commons.codec.BinaryDecoder;
023 import org.apache.commons.codec.BinaryEncoder;
024 import org.apache.commons.codec.DecoderException;
025 import org.apache.commons.codec.EncoderException;
026
027 /**
028 * Abstract superclass for Base-N encoders and decoders.
029 *
030 * <p>
031 * This class is thread-safe.
032 * </p>
033 *
034 * @version $Id: BaseNCodec.html 889935 2013-12-11 05:05:13Z ggregory $
035 */
036 public abstract class BaseNCodec implements BinaryEncoder, BinaryDecoder {
037
038 /**
039 * Holds thread context so classes can be thread-safe.
040 *
041 * This class is not itself thread-safe; each thread must allocate its own copy.
042 *
043 * @since 1.7
044 */
045 static class Context {
046
047 /**
048 * Place holder for the bytes we're dealing with for our based logic.
049 * Bitwise operations store and extract the encoding or decoding from this variable.
050 */
051 int ibitWorkArea;
052
053 /**
054 * Place holder for the bytes we're dealing with for our based logic.
055 * Bitwise operations store and extract the encoding or decoding from this variable.
056 */
057 long lbitWorkArea;
058
059 /**
060 * Buffer for streaming.
061 */
062 byte[] buffer;
063
064 /**
065 * Position where next character should be written in the buffer.
066 */
067 int pos;
068
069 /**
070 * Position where next character should be read from the buffer.
071 */
072 int readPos;
073
074 /**
075 * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless,
076 * and must be thrown away.
077 */
078 boolean eof;
079
080 /**
081 * Variable tracks how many characters have been written to the current line. Only used when encoding. We use
082 * it to make sure each encoded line never goes beyond lineLength (if lineLength > 0).
083 */
084 int currentLinePos;
085
086 /**
087 * Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding. This
088 * variable helps track that.
089 */
090 int modulus;
091
092 Context() {
093 }
094
095 /**
096 * Returns a String useful for debugging (especially within a debugger.)
097 *
098 * @return a String useful for debugging.
099 */
100 @SuppressWarnings("boxing") // OK to ignore boxing here
101 @Override
102 public String toString() {
103 return String.format("%s[buffer=%s, currentLinePos=%s, eof=%s, ibitWorkArea=%s, lbitWorkArea=%s, " +
104 "modulus=%s, pos=%s, readPos=%s]", this.getClass().getSimpleName(), Arrays.toString(buffer),
105 currentLinePos, eof, ibitWorkArea, lbitWorkArea, modulus, pos, readPos);
106 }
107 }
108
109 /**
110 * EOF
111 *
112 * @since 1.7
113 */
114 static final int EOF = -1;
115
116 /**
117 * MIME chunk size per RFC 2045 section 6.8.
118 *
119 * <p>
120 * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
121 * equal signs.
122 * </p>
123 *
124 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
125 */
126 public static final int MIME_CHUNK_SIZE = 76;
127
128 /**
129 * PEM chunk size per RFC 1421 section 4.3.2.4.
130 *
131 * <p>
132 * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
133 * equal signs.
134 * </p>
135 *
136 * @see <a href="http://tools.ietf.org/html/rfc1421">RFC 1421 section 4.3.2.4</a>
137 */
138 public static final int PEM_CHUNK_SIZE = 64;
139
140 private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
141
142 /**
143 * Defines the default buffer size - currently {@value}
144 * - must be large enough for at least one encoded block+separator
145 */
146 private static final int DEFAULT_BUFFER_SIZE = 8192;
147
148 /** Mask used to extract 8 bits, used in decoding bytes */
149 protected static final int MASK_8BITS = 0xff;
150
151 /**
152 * Byte used to pad output.
153 */
154 protected static final byte PAD_DEFAULT = '='; // Allow static access to default
155
156 protected final byte PAD = PAD_DEFAULT; // instance variable just in case it needs to vary later
157
158 /** Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32 */
159 private final int unencodedBlockSize;
160
161 /** Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32 */
162 private final int encodedBlockSize;
163
164 /**
165 * Chunksize for encoding. Not used when decoding.
166 * A value of zero or less implies no chunking of the encoded data.
167 * Rounded down to nearest multiple of encodedBlockSize.
168 */
169 protected final int lineLength;
170
171 /**
172 * Size of chunk separator. Not used unless {@link #lineLength} > 0.
173 */
174 private final int chunkSeparatorLength;
175
176 /**
177 * Note <code>lineLength</code> is rounded down to the nearest multiple of {@link #encodedBlockSize}
178 * If <code>chunkSeparatorLength</code> is zero, then chunking is disabled.
179 * @param unencodedBlockSize the size of an unencoded block (e.g. Base64 = 3)
180 * @param encodedBlockSize the size of an encoded block (e.g. Base64 = 4)
181 * @param lineLength if > 0, use chunking with a length <code>lineLength</code>
182 * @param chunkSeparatorLength the chunk separator length, if relevant
183 */
184 protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize,
185 final int lineLength, final int chunkSeparatorLength) {
186 this.unencodedBlockSize = unencodedBlockSize;
187 this.encodedBlockSize = encodedBlockSize;
188 final boolean useChunking = lineLength > 0 && chunkSeparatorLength > 0;
189 this.lineLength = useChunking ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;
190 this.chunkSeparatorLength = chunkSeparatorLength;
191 }
192
193 /**
194 * Returns true if this object has buffered data for reading.
195 *
196 * @param context the context to be used
197 * @return true if there is data still available for reading.
198 */
199 boolean hasData(final Context context) { // package protected for access from I/O streams
200 return context.buffer != null;
201 }
202
203 /**
204 * Returns the amount of buffered data available for reading.
205 *
206 * @param context the context to be used
207 * @return The amount of buffered data available for reading.
208 */
209 int available(final Context context) { // package protected for access from I/O streams
210 return context.buffer != null ? context.pos - context.readPos : 0;
211 }
212
213 /**
214 * Get the default buffer size. Can be overridden.
215 *
216 * @return {@link #DEFAULT_BUFFER_SIZE}
217 */
218 protected int getDefaultBufferSize() {
219 return DEFAULT_BUFFER_SIZE;
220 }
221
222 /**
223 * Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
224 * @param context the context to be used
225 */
226 private byte[] resizeBuffer(final Context context) {
227 if (context.buffer == null) {
228 context.buffer = new byte[getDefaultBufferSize()];
229 context.pos = 0;
230 context.readPos = 0;
231 } else {
232 final byte[] b = new byte[context.buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
233 System.arraycopy(context.buffer, 0, b, 0, context.buffer.length);
234 context.buffer = b;
235 }
236 return context.buffer;
237 }
238
239 /**
240 * Ensure that the buffer has room for <code>size</code> bytes
241 *
242 * @param size minimum spare space required
243 * @param context the context to be used
244 */
245 protected byte[] ensureBufferSize(final int size, final Context context){
246 if ((context.buffer == null) || (context.buffer.length < context.pos + size)){
247 return resizeBuffer(context);
248 }
249 return context.buffer;
250 }
251
252 /**
253 * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
254 * bytes. Returns how many bytes were actually extracted.
255 * <p>
256 * Package protected for access from I/O streams.
257 *
258 * @param b
259 * byte[] array to extract the buffered data into.
260 * @param bPos
261 * position in byte[] array to start extraction at.
262 * @param bAvail
263 * amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
264 * @param context
265 * the context to be used
266 * @return The number of bytes successfully extracted into the provided byte[] array.
267 */
268 int readResults(final byte[] b, final int bPos, final int bAvail, final Context context) {
269 if (context.buffer != null) {
270 final int len = Math.min(available(context), bAvail);
271 System.arraycopy(context.buffer, context.readPos, b, bPos, len);
272 context.readPos += len;
273 if (context.readPos >= context.pos) {
274 context.buffer = null; // so hasData() will return false, and this method can return -1
275 }
276 return len;
277 }
278 return context.eof ? EOF : 0;
279 }
280
281 /**
282 * Checks if a byte value is whitespace or not.
283 * Whitespace is taken to mean: space, tab, CR, LF
284 * @param byteToCheck
285 * the byte to check
286 * @return true if byte is whitespace, false otherwise
287 */
288 protected static boolean isWhiteSpace(final byte byteToCheck) {
289 switch (byteToCheck) {
290 case ' ' :
291 case '\n' :
292 case '\r' :
293 case '\t' :
294 return true;
295 default :
296 return false;
297 }
298 }
299
300 /**
301 * Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
302 * the Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
303 *
304 * @param obj
305 * Object to encode
306 * @return An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.
307 * @throws EncoderException
308 * if the parameter supplied is not of type byte[]
309 */
310 @Override
311 public Object encode(final Object obj) throws EncoderException {
312 if (!(obj instanceof byte[])) {
313 throw new EncoderException("Parameter supplied to Base-N encode is not a byte[]");
314 }
315 return encode((byte[]) obj);
316 }
317
318 /**
319 * Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet.
320 * Uses UTF8 encoding.
321 *
322 * @param pArray
323 * a byte array containing binary data
324 * @return A String containing only Base-N character data
325 */
326 public String encodeToString(final byte[] pArray) {
327 return StringUtils.newStringUtf8(encode(pArray));
328 }
329
330 /**
331 * Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
332 * Uses UTF8 encoding.
333 *
334 * @param pArray a byte array containing binary data
335 * @return String containing only character data in the appropriate alphabet.
336 */
337 public String encodeAsString(final byte[] pArray){
338 return StringUtils.newStringUtf8(encode(pArray));
339 }
340
341 /**
342 * Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
343 * the Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
344 *
345 * @param obj
346 * Object to decode
347 * @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String
348 * supplied.
349 * @throws DecoderException
350 * if the parameter supplied is not of type byte[]
351 */
352 @Override
353 public Object decode(final Object obj) throws DecoderException {
354 if (obj instanceof byte[]) {
355 return decode((byte[]) obj);
356 } else if (obj instanceof String) {
357 return decode((String) obj);
358 } else {
359 throw new DecoderException("Parameter supplied to Base-N decode is not a byte[] or a String");
360 }
361 }
362
363 /**
364 * Decodes a String containing characters in the Base-N alphabet.
365 *
366 * @param pArray
367 * A String containing Base-N character data
368 * @return a byte array containing binary data
369 */
370 public byte[] decode(final String pArray) {
371 return decode(StringUtils.getBytesUtf8(pArray));
372 }
373
374 /**
375 * Decodes a byte[] containing characters in the Base-N alphabet.
376 *
377 * @param pArray
378 * A byte array containing Base-N character data
379 * @return a byte array containing binary data
380 */
381 @Override
382 public byte[] decode(final byte[] pArray) {
383 if (pArray == null || pArray.length == 0) {
384 return pArray;
385 }
386 final Context context = new Context();
387 decode(pArray, 0, pArray.length, context);
388 decode(pArray, 0, EOF, context); // Notify decoder of EOF.
389 final byte[] result = new byte[context.pos];
390 readResults(result, 0, result.length, context);
391 return result;
392 }
393
394 /**
395 * Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
396 *
397 * @param pArray
398 * a byte array containing binary data
399 * @return A byte array containing only the basen alphabetic character data
400 */
401 @Override
402 public byte[] encode(final byte[] pArray) {
403 if (pArray == null || pArray.length == 0) {
404 return pArray;
405 }
406 final Context context = new Context();
407 encode(pArray, 0, pArray.length, context);
408 encode(pArray, 0, EOF, context); // Notify encoder of EOF.
409 final byte[] buf = new byte[context.pos - context.readPos];
410 readResults(buf, 0, buf.length, context);
411 return buf;
412 }
413
414 // package protected for access from I/O streams
415 abstract void encode(byte[] pArray, int i, int length, Context context);
416
417 // package protected for access from I/O streams
418 abstract void decode(byte[] pArray, int i, int length, Context context);
419
420 /**
421 * Returns whether or not the <code>octet</code> is in the current alphabet.
422 * Does not allow whitespace or pad.
423 *
424 * @param value The value to test
425 *
426 * @return {@code true} if the value is defined in the current alphabet, {@code false} otherwise.
427 */
428 protected abstract boolean isInAlphabet(byte value);
429
430 /**
431 * Tests a given byte array to see if it contains only valid characters within the alphabet.
432 * The method optionally treats whitespace and pad as valid.
433 *
434 * @param arrayOctet byte array to test
435 * @param allowWSPad if {@code true}, then whitespace and PAD are also allowed
436 *
437 * @return {@code true} if all bytes are valid characters in the alphabet or if the byte array is empty;
438 * {@code false}, otherwise
439 */
440 public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
441 for (int i = 0; i < arrayOctet.length; i++) {
442 if (!isInAlphabet(arrayOctet[i]) &&
443 (!allowWSPad || (arrayOctet[i] != PAD) && !isWhiteSpace(arrayOctet[i]))) {
444 return false;
445 }
446 }
447 return true;
448 }
449
450 /**
451 * Tests a given String to see if it contains only valid characters within the alphabet.
452 * The method treats whitespace and PAD as valid.
453 *
454 * @param basen String to test
455 * @return {@code true} if all characters in the String are valid characters in the alphabet or if
456 * the String is empty; {@code false}, otherwise
457 * @see #isInAlphabet(byte[], boolean)
458 */
459 public boolean isInAlphabet(final String basen) {
460 return isInAlphabet(StringUtils.getBytesUtf8(basen), true);
461 }
462
463 /**
464 * Tests a given byte array to see if it contains any characters within the alphabet or PAD.
465 *
466 * Intended for use in checking line-ending arrays
467 *
468 * @param arrayOctet
469 * byte array to test
470 * @return {@code true} if any byte is a valid character in the alphabet or PAD; {@code false} otherwise
471 */
472 protected boolean containsAlphabetOrPad(final byte[] arrayOctet) {
473 if (arrayOctet == null) {
474 return false;
475 }
476 for (final byte element : arrayOctet) {
477 if (PAD == element || isInAlphabet(element)) {
478 return true;
479 }
480 }
481 return false;
482 }
483
484 /**
485 * Calculates the amount of space needed to encode the supplied array.
486 *
487 * @param pArray byte[] array which will later be encoded
488 *
489 * @return amount of space needed to encoded the supplied array.
490 * Returns a long since a max-len array will require > Integer.MAX_VALUE
491 */
492 public long getEncodedLength(final byte[] pArray) {
493 // Calculate non-chunked size - rounded up to allow for padding
494 // cast to long is needed to avoid possibility of overflow
495 long len = ((pArray.length + unencodedBlockSize-1) / unencodedBlockSize) * (long) encodedBlockSize;
496 if (lineLength > 0) { // We're using chunking
497 // Round up to nearest multiple
498 len += ((len + lineLength-1) / lineLength) * chunkSeparatorLength;
499 }
500 return len;
501 }
502 }