Source for gnu.java.util.Base64

   1: /* Base64.java -- Base64 encoding and decoding.
   2:    Copyright (C) 2006, 2007  Free Software Foundation, Inc.
   3: 
   4: This file is a part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2 of the License, or (at
   9: your option) any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: USA
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version.
  37: 
  38: --
  39: Base64 encoding derived from ISC's DHCP. Copyright notices from DHCP
  40: follow. See http://www.isc.org/products/DHCP/.
  41: 
  42: Copyright (c) 1996 by Internet Software Consortium.
  43: 
  44: Permission to use, copy, modify, and distribute this software for any
  45: purpose with or without fee is hereby granted, provided that the above
  46: copyright notice and this permission notice appear in all copies.
  47: 
  48: THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
  49: DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  50: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  51: INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  52: INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  53: FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  54: NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  55: WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  56: 
  57: --
  58: Portions Copyright (c) 1995 by International Business Machines, Inc.
  59: 
  60: International Business Machines, Inc. (hereinafter called IBM) grants
  61: permission under its copyrights to use, copy, modify, and distribute
  62: this Software with or without fee, provided that the above copyright
  63: notice and all paragraphs of this notice appear in all copies, and
  64: that the name of IBM not be used in connection with the marketing of
  65: any product incorporating the Software or modifications thereof,
  66: without specific, written prior permission.
  67: 
  68: To the extent it has a right to do so, IBM grants an immunity from
  69: suit under its patents, if any, for the use, sale or manufacture of
  70: products to the extent that such products are used for performing
  71: Domain Name System dynamic updates in TCP/IP networks by means of the
  72: Software.  No immunity is granted for any product per se or for any
  73: other function of any product.
  74: 
  75: THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
  76: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  77: PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
  78: DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
  79: ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  80: SOFTWARE, EVEN IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH
  81: DAMAGES.  */
  82: 
  83: 
  84: package gnu.java.util;
  85: 
  86: import java.io.ByteArrayOutputStream;
  87: import java.io.IOException;
  88: 
  89: public final class Base64
  90: {
  91: 
  92:   // No constructor.
  93:   private Base64() { }
  94: 
  95:   // Class methods.
  96:   // -------------------------------------------------------------------------
  97: 
  98:   /** Base-64 characters. */
  99:   private static final String BASE_64 =
 100:     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 101: 
 102:   /** Base-64 padding character. */
 103:   private static final char BASE_64_PAD = '=';
 104: 
 105:   /**
 106:    * Base64 encode a byte array, with no line wrapping.
 107:    *
 108:    * @param buf The byte array to encode.
 109:    * @return <tt>buf</tt> encoded in Base64.
 110:    */
 111:   public static String encode(byte[] buf)
 112:   {
 113:     return encode(buf, 0);
 114:   }
 115:   
 116:   /**
 117:    * Base64 encode a byte array, returning the returning string.
 118:    *
 119:    * @param buf The byte array to encode.
 120:    * @param tw  The total length of any line, 0 for unlimited.
 121:    * @return <tt>buf</tt> encoded in Base64.
 122:    */
 123:   public static String encode(byte[] buf, int tw)
 124:   {
 125:     return encode(buf, 0, buf.length, tw);
 126:   }
 127: 
 128:   /**
 129:    * Base64 encode a byte array, returning the returning string.
 130:    * 
 131:    * @param buf The byte array to encode.
 132:    * @param offset The offset in the byte array to start.
 133:    * @param length The number of bytes to encode.
 134:    * @param tw The total length of any line, 0 for unlimited.
 135:    * @return <tt>buf</tt> encoded in Base64.
 136:    */
 137:   public static String encode(byte[] buf, int offset, int length, int tw)
 138:   {
 139:     if (offset < 0 || length < 0 || offset + length > buf.length)
 140:       throw new ArrayIndexOutOfBoundsException(buf.length  + " "
 141:                                                + offset + " "
 142:                                                + length);
 143:     int srcLength = buf.length - offset;
 144:     byte[] input = new byte[3];
 145:     int[] output = new int[4];
 146:     StringBuffer out = new StringBuffer();
 147:     int i = offset;
 148:     int chars = 0;
 149: 
 150:     while (srcLength > 2)
 151:       {
 152:         input[0] = buf[i++];
 153:         input[1] = buf[i++];
 154:         input[2] = buf[i++];
 155:         srcLength -= 3;
 156: 
 157:         output[0] = (input[0] & 0xff) >>> 2;
 158:         output[1] = ((input[0] & 0x03) << 4) + ((input[1] & 0xff) >>> 4);
 159:         output[2] = ((input[1] & 0x0f) << 2) + ((input[2] & 0xff) >>> 6);
 160:         output[3] = input[2] & 0x3f;
 161: 
 162:         out.append(BASE_64.charAt(output[0]));
 163:         if (tw > 0 && ++chars % tw == 0)
 164:           {
 165:             out.append("\n");
 166:           }
 167:         out.append(BASE_64.charAt(output[1]));
 168:         if (tw > 0 && ++chars % tw == 0)
 169:           {
 170:             out.append("\n");
 171:           }
 172:         out.append(BASE_64.charAt(output[2]));
 173:         if (tw > 0 && ++chars % tw == 0)
 174:           {
 175:             out.append("\n");
 176:           }
 177:         out.append(BASE_64.charAt(output[3]));
 178:         if (tw > 0 && ++chars % tw == 0)
 179:           {
 180:             out.append("\n");
 181:           }
 182:       }
 183: 
 184:     if (srcLength != 0)
 185:       {
 186:         input[0] = input[1] = input[2] = 0;
 187:         for (int j = 0; j < srcLength; j++)
 188:           {
 189:             input[j] = buf[i+j];
 190:           }
 191:         output[0] = (input[0] & 0xff) >>> 2;
 192:         output[1] = ((input[0] & 0x03) << 4) + ((input[1] & 0xff) >>> 4);
 193:         output[2] = ((input[1] & 0x0f) << 2) + ((input[2] & 0xff) >>> 6);
 194: 
 195:         out.append(BASE_64.charAt(output[0]));
 196:         if (tw > 0 && ++chars % tw == 0)
 197:           {
 198:             out.append("\n");
 199:           }
 200:         out.append(BASE_64.charAt(output[1]));
 201:         if (tw > 0 && ++chars % tw == 0)
 202:           {
 203:             out.append("\n");
 204:           }
 205:         if (srcLength == 1)
 206:           {
 207:             out.append(BASE_64_PAD);
 208:           }
 209:         else
 210:           {
 211:             out.append(BASE_64.charAt(output[2]));
 212:           }
 213:         if (tw > 0 && ++chars % tw == 0)
 214:           {
 215:             out.append("\n");
 216:           }
 217:         out.append(BASE_64_PAD);
 218:         if (tw > 0 && ++chars % tw == 0)
 219:           {
 220:             out.append("\n");
 221:           }
 222:       }
 223:     if (tw > 0)
 224:       {
 225:         out.append("\n");
 226:       }
 227: 
 228:     return out.toString();
 229:   }
 230: 
 231:   /**
 232:    * Decode a Base-64 string into a byte array.
 233:    *
 234:    * @param b64 The Base-64 encoded string.
 235:    * @return The decoded bytes.
 236:    * @throws java.io.IOException If the argument is not a valid Base-64
 237:    *    encoding.
 238:    */
 239:   public static byte[] decode(String b64) throws IOException
 240:   {
 241:     ByteArrayOutputStream result = new ByteArrayOutputStream(b64.length() / 3);
 242:     int state = 0, i;
 243:     byte temp = 0;
 244: 
 245:     for (i = 0; i < b64.length(); i++)
 246:       {
 247:         if (Character.isWhitespace(b64.charAt(i)))
 248:           {
 249:             continue;
 250:           }
 251:         if (b64.charAt(i) == BASE_64_PAD)
 252:           {
 253:             break;
 254:           }
 255: 
 256:         int pos = BASE_64.indexOf(b64.charAt(i));
 257:         if (pos < 0)
 258:           {
 259:             throw new IOException("non-Base64 character " + b64.charAt(i));
 260:           }
 261:         switch (state)
 262:           {
 263:           case 0:
 264:             temp = (byte) (pos - BASE_64.indexOf('A') << 2);
 265:             state = 1;
 266:             break;
 267: 
 268:           case 1:
 269:             temp |= (byte) (pos - BASE_64.indexOf('A') >>> 4);
 270:             result.write(temp);
 271:             temp = (byte) ((pos - BASE_64.indexOf('A') & 0x0f) << 4);
 272:             state = 2;
 273:             break;
 274: 
 275:           case 2:
 276:             temp |= (byte) ((pos - BASE_64.indexOf('A') & 0x7f) >>> 2);
 277:             result.write(temp);
 278:             temp = (byte) ((pos - BASE_64.indexOf('A') & 0x03) << 6);
 279:             state = 3;
 280:             break;
 281: 
 282:           case 3:
 283:             temp |= (byte) (pos - BASE_64.indexOf('A') & 0xff);
 284:             result.write(temp);
 285:             state = 0;
 286:             break;
 287: 
 288:           default:
 289:             throw new Error("this statement should be unreachable");
 290:           }
 291:       }
 292: 
 293:     if (i < b64.length() && b64.charAt(i) == BASE_64_PAD)
 294:       {
 295:         switch (state)
 296:           {
 297:           case 0:
 298:           case 1:
 299:             throw new IOException("malformed Base64 sequence");
 300: 
 301:           case 2:
 302:             i++;
 303:             for ( ; i < b64.length(); i++)
 304:               {
 305:                 if (!Character.isWhitespace(b64.charAt(i)))
 306:                   {
 307:                     break;
 308:                   }
 309:               }
 310:             // We must see a second pad character here.
 311:             if (b64.charAt(i) != BASE_64_PAD)
 312:               {
 313:                 throw new IOException("malformed Base64 sequence");
 314:               }
 315:             i++;
 316:             // Fall-through.
 317: 
 318:           case 3:
 319:             i++;
 320:             for ( ; i < b64.length(); i++)
 321:               {
 322:                 // We should only see whitespace after this.
 323:                 if (!Character.isWhitespace(b64.charAt(i)))
 324:                   {
 325:                     throw new IOException("malformed Base64 sequence");
 326:                   }
 327:               }
 328:           }
 329:       }
 330:     else
 331:       {
 332:         if (state != 0)
 333:           {
 334:             throw new IOException("malformed Base64 sequence");
 335:           }
 336:       }
 337: 
 338:     return result.toByteArray();
 339:   }
 340: }