libjava/classpath/gnu/java/security/util/Util.java

   1 /* Util.java -- various utility routines.
   2    Copyright (C) 2001, 2002, 2003, 2006 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 package gnu.java.security.util;
  40
  41 import java.math.BigInteger;
  42
  43 /**
  44  * <p>A collection of utility methods used throughout this project.</p>
  45  */
  46 public class Util
  47 {
  48
  49   // Constants and variables
  50   // -------------------------------------------------------------------------
  51
  52   // Hex charset
  53   private static final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
  54
  55   // Base-64 charset
  56   private static final String BASE64_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  57
  58   private static final char[] BASE64_CHARSET = BASE64_CHARS.toCharArray();
  59
  60   // Constructor(s)
  61   // -------------------------------------------------------------------------
  62
  63   /** Trivial constructor to enforce Singleton pattern. */
  64   private Util()
  65   {
  66     super();
  67   }
  68
  69   // Class methods
  70   // -------------------------------------------------------------------------
  71
  72   /**
  73    * <p>Returns a string of hexadecimal digits from a byte array. Each byte is
  74    * converted to 2 hex symbols; zero(es) included.</p>
  75    *
  76    * <p>This method calls the method with same name and three arguments as:</p>
  77    *
  78    * <pre>
  79    *    toString(ba, 0, ba.length);
  80    * </pre>
  81    *
  82    * @param ba the byte array to convert.
  83    * @return a string of hexadecimal characters (two for each byte)
  84    * representing the designated input byte array.
  85    */
  86   public static String toString(byte[] ba)
  87   {
  88     return toString(ba, 0, ba.length);
  89   }
  90
  91   /**
  92    * <p>Returns a string of hexadecimal digits from a byte array, starting at
  93    * <code>offset</code> and consisting of <code>length</code> bytes. Each byte
  94    * is converted to 2 hex symbols; zero(es) included.</p>
  95    *
  96    * @param ba the byte array to convert.
  97    * @param offset the index from which to start considering the bytes to
  98    * convert.
  99    * @param length the count of bytes, starting from the designated offset to
 100    * convert.
 101    * @return a string of hexadecimal characters (two for each byte)
 102    * representing the designated input byte sub-array.
 103    */
 104   public static final String toString(byte[] ba, int offset, int length)
 105   {
 106     char[] buf = new char[length * 2];
 107     for (int i = 0, j = 0, k; i < length;)
 108       {
 109         k = ba[offset + i++];
 110         buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
 111         buf[j++] = HEX_DIGITS[k & 0x0F];
 112       }
 113     return new String(buf);
 114   }
 115
 116   /**
 117    * <p>Returns a string of hexadecimal digits from a byte array. Each byte is
 118    * converted to 2 hex symbols; zero(es) included. The argument is
 119    * treated as a large little-endian integer and is returned as a
 120    * large big-endian integer.</p>
 121    *
 122    * <p>This method calls the method with same name and three arguments as:</p>
 123    *
 124    * <pre>
 125    *    toReversedString(ba, 0, ba.length);
 126    * </pre>
 127    *
 128    * @param ba the byte array to convert.
 129    * @return a string of hexadecimal characters (two for each byte)
 130    * representing the designated input byte array.
 131    */
 132   public static String toReversedString(byte[] ba)
 133   {
 134     return toReversedString(ba, 0, ba.length);
 135   }
 136
 137   /**
 138    * <p>Returns a string of hexadecimal digits from a byte array, starting at
 139    * <code>offset</code> and consisting of <code>length</code> bytes. Each byte
 140    * is converted to 2 hex symbols; zero(es) included.</p>
 141    *
 142    * <p>The byte array is treated as a large little-endian integer, and
 143    * is returned as a large big-endian integer.</p>
 144    *
 145    * @param ba the byte array to convert.
 146    * @param offset the index from which to start considering the bytes to
 147    * convert.
 148    * @param length the count of bytes, starting from the designated offset to
 149    * convert.
 150    * @return a string of hexadecimal characters (two for each byte)
 151    * representing the designated input byte sub-array.
 152    */
 153   public static final String toReversedString(byte[] ba, int offset, int length)
 154   {
 155     char[] buf = new char[length * 2];
 156     for (int i = offset + length - 1, j = 0, k; i >= offset;)
 157       {
 158         k = ba[offset + i--];
 159         buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
 160         buf[j++] = HEX_DIGITS[k & 0x0F];
 161       }
 162     return new String(buf);
 163   }
 164
 165   /**
 166    * <p>Returns a byte array from a string of hexadecimal digits.</p>
 167    *
 168    * @param s a string of hexadecimal ASCII characters
 169    * @return the decoded byte array from the input hexadecimal string.
 170    */
 171   public static byte[] toBytesFromString(String s)
 172   {
 173     int limit = s.length();
 174     byte[] result = new byte[((limit + 1) / 2)];
 175     int i = 0, j = 0;
 176     if ((limit % 2) == 1)
 177       {
 178         result[j++] = (byte) fromDigit(s.charAt(i++));
 179       }
 180     while (i < limit)
 181       {
 182         result[j] = (byte) (fromDigit(s.charAt(i++)) << 4);
 183         result[j++] |= (byte) fromDigit(s.charAt(i++));
 184       }
 185     return result;
 186   }
 187
 188   /**
 189    * <p>Returns a byte array from a string of hexadecimal digits, interpreting
 190    * them as a large big-endian integer and returning it as a large
 191    * little-endian integer.</p>
 192    *
 193    * @param s a string of hexadecimal ASCII characters
 194    * @return the decoded byte array from the input hexadecimal string.
 195    */
 196   public static byte[] toReversedBytesFromString(String s)
 197   {
 198     int limit = s.length();
 199     byte[] result = new byte[((limit + 1) / 2)];
 200     int i = 0;
 201     if ((limit % 2) == 1)
 202       {
 203         result[i++] = (byte) fromDigit(s.charAt(--limit));
 204       }
 205     while (limit > 0)
 206       {
 207         result[i] = (byte) fromDigit(s.charAt(--limit));
 208         result[i++] |= (byte) (fromDigit(s.charAt(--limit)) << 4);
 209       }
 210     return result;
 211   }
 212
 213   /**
 214    * <p>Returns a number from <code>0</code> to <code>15</code> corresponding
 215    * to the designated hexadecimal digit.</p>
 216    *
 217    * @param c a hexadecimal ASCII symbol.
 218    */
 219   public static int fromDigit(char c)
 220   {
 221     if (c >= '0' && c <= '9')
 222       {
 223         return c - '0';
 224       }
 225     else if (c >= 'A' && c <= 'F')
 226       {
 227         return c - 'A' + 10;
 228       }
 229     else if (c >= 'a' && c <= 'f')
 230       {
 231         return c - 'a' + 10;
 232       }
 233     else
 234       throw new IllegalArgumentException("Invalid hexadecimal digit: " + c);
 235   }
 236
 237   /**
 238    * <p>Returns a string of 8 hexadecimal digits (most significant digit first)
 239    * corresponding to the unsigned integer <code>n</code>.</p>
 240    *
 241    * @param n the unsigned integer to convert.
 242    * @return a hexadecimal string 8-character long.
 243    */
 244   public static String toString(int n)
 245   {
 246     char[] buf = new char[8];
 247     for (int i = 7; i >= 0; i--)
 248       {
 249         buf[i] = HEX_DIGITS[n & 0x0F];
 250         n >>>= 4;
 251       }
 252     return new String(buf);
 253   }
 254
 255   /**
 256    * <p>Returns a string of hexadecimal digits from an integer array. Each int
 257    * is converted to 4 hex symbols.</p>
 258    */
 259   public static String toString(int[] ia)
 260   {
 261     int length = ia.length;
 262     char[] buf = new char[length * 8];
 263     for (int i = 0, j = 0, k; i < length; i++)
 264       {
 265         k = ia[i];
 266         buf[j++] = HEX_DIGITS[(k >>> 28) & 0x0F];
 267         buf[j++] = HEX_DIGITS[(k >>> 24) & 0x0F];
 268         buf[j++] = HEX_DIGITS[(k >>> 20) & 0x0F];
 269         buf[j++] = HEX_DIGITS[(k >>> 16) & 0x0F];
 270         buf[j++] = HEX_DIGITS[(k >>> 12) & 0x0F];
 271         buf[j++] = HEX_DIGITS[(k >>> 8) & 0x0F];
 272         buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
 273         buf[j++] = HEX_DIGITS[k & 0x0F];
 274       }
 275     return new String(buf);
 276   }
 277
 278   /**
 279    * <p>Returns a string of 16 hexadecimal digits (most significant digit first)
 280    * corresponding to the unsigned long <code>n</code>.</p>
 281    *
 282    * @param n the unsigned long to convert.
 283    * @return a hexadecimal string 16-character long.
 284    */
 285   public static String toString(long n)
 286   {
 287     char[] b = new char[16];
 288     for (int i = 15; i >= 0; i--)
 289       {
 290         b[i] = HEX_DIGITS[(int) (n & 0x0FL)];
 291         n >>>= 4;
 292       }
 293     return new String(b);
 294   }
 295
 296   /**
 297    * <p>Similar to the <code>toString()</code> method except that the Unicode
 298    * escape character is inserted before every pair of bytes. Useful to
 299    * externalise byte arrays that will be constructed later from such strings;
 300    * eg. s-box values.</p>
 301    *
 302    * @throws ArrayIndexOutOfBoundsException if the length is odd.
 303    */
 304   public static String toUnicodeString(byte[] ba)
 305   {
 306     return toUnicodeString(ba, 0, ba.length);
 307   }
 308
 309   /**
 310    * <p>Similar to the <code>toString()</code> method except that the Unicode
 311    * escape character is inserted before every pair of bytes. Useful to
 312    * externalise byte arrays that will be constructed later from such strings;
 313    * eg. s-box values.</p>
 314    *
 315    * @throws ArrayIndexOutOfBoundsException if the length is odd.
 316    */
 317   public static final String toUnicodeString(byte[] ba, int offset, int length)
 318   {
 319     StringBuffer sb = new StringBuffer();
 320     int i = 0;
 321     int j = 0;
 322     int k;
 323     sb.append('\n').append("\"");
 324     while (i < length)
 325       {
 326         sb.append("\\u");
 327
 328         k = ba[offset + i++];
 329         sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
 330         sb.append(HEX_DIGITS[k & 0x0F]);
 331
 332         k = ba[offset + i++];
 333         sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
 334         sb.append(HEX_DIGITS[k & 0x0F]);
 335
 336         if ((++j % 8) == 0)
 337           {
 338             sb.append("\"+").append('\n').append("\"");
 339           }
 340       }
 341     sb.append("\"").append('\n');
 342     return sb.toString();
 343   }
 344
 345   /**
 346    * <p>Similar to the <code>toString()</code> method except that the Unicode
 347    * escape character is inserted before every pair of bytes. Useful to
 348    * externalise integer arrays that will be constructed later from such
 349    * strings; eg. s-box values.</p>
 350    *
 351    * @throws ArrayIndexOutOfBoundsException if the length is not a multiple of 4.
 352    */
 353   public static String toUnicodeString(int[] ia)
 354   {
 355     StringBuffer sb = new StringBuffer();
 356     int i = 0;
 357     int j = 0;
 358     int k;
 359     sb.append('\n').append("\"");
 360     while (i < ia.length)
 361       {
 362         k = ia[i++];
 363         sb.append("\\u");
 364         sb.append(HEX_DIGITS[(k >>> 28) & 0x0F]);
 365         sb.append(HEX_DIGITS[(k >>> 24) & 0x0F]);
 366         sb.append(HEX_DIGITS[(k >>> 20) & 0x0F]);
 367         sb.append(HEX_DIGITS[(k >>> 16) & 0x0F]);
 368         sb.append("\\u");
 369         sb.append(HEX_DIGITS[(k >>> 12) & 0x0F]);
 370         sb.append(HEX_DIGITS[(k >>> 8) & 0x0F]);
 371         sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
 372         sb.append(HEX_DIGITS[k & 0x0F]);
 373
 374         if ((++j % 4) == 0)
 375           {
 376             sb.append("\"+").append('\n').append("\"");
 377           }
 378       }
 379     sb.append("\"").append('\n');
 380     return sb.toString();
 381   }
 382
 383   public static byte[] toBytesFromUnicode(String s)
 384   {
 385     int limit = s.length() * 2;
 386     byte[] result = new byte[limit];
 387     char c;
 388     for (int i = 0; i < limit; i++)
 389       {
 390         c = s.charAt(i >>> 1);
 391         result[i] = (byte) (((i & 1) == 0) ? c >>> 8 : c);
 392       }
 393     return result;
 394   }
 395
 396   /**
 397    * <p>Dumps a byte array as a string, in a format that is easy to read for
 398    * debugging. The string <code>m</code> is prepended to the start of each
 399    * line.</p>
 400    *
 401    * <p>If <code>offset</code> and <code>length</code> are omitted, the whole
 402    * array is used. If <code>m</code> is omitted, nothing is prepended to each
 403    * line.</p>
 404    *
 405    * @param data the byte array to be dumped.
 406    * @param offset the offset within <i>data</i> to start from.
 407    * @param length the number of bytes to dump.
 408    * @param m a string to be prepended to each line.
 409    * @return a string containing the result.
 410    */
 411   public static String dumpString(byte[] data, int offset, int length, String m)
 412   {
 413     if (data == null)
 414       {
 415         return m + "null\n";
 416       }
 417     StringBuffer sb = new StringBuffer(length * 3);
 418     if (length > 32)
 419       {
 420         sb.append(m).append("Hexadecimal dump of ").append(length).append(
 421                                                                           " bytes...\n");
 422       }
 423     // each line will list 32 bytes in 4 groups of 8 each
 424     int end = offset + length;
 425     String s;
 426     int l = Integer.toString(length).length();
 427     if (l < 4)
 428       {
 429         l = 4;
 430       }
 431     for (; offset < end; offset += 32)
 432       {
 433         if (length > 32)
 434           {
 435             s = "         " + offset;
 436             sb.append(m).append(s.substring(s.length() - l)).append(": ");
 437           }
 438         int i = 0;
 439         for (; i < 32 && offset + i + 7 < end; i += 8)
 440           {
 441             sb.append(toString(data, offset + i, 8)).append(' ');
 442           }
 443         if (i < 32)
 444           {
 445             for (; i < 32 && offset + i < end; i++)
 446               {
 447                 sb.append(byteToString(data[offset + i]));
 448               }
 449           }
 450         sb.append('\n');
 451       }
 452     return sb.toString();
 453   }
 454
 455   public static String dumpString(byte[] data)
 456   {
 457     return (data == null) ? "null\n" : dumpString(data, 0, data.length, "");
 458   }
 459
 460   public static String dumpString(byte[] data, String m)
 461   {
 462     return (data == null) ? "null\n" : dumpString(data, 0, data.length, m);
 463   }
 464
 465   public static String dumpString(byte[] data, int offset, int length)
 466   {
 467     return dumpString(data, offset, length, "");
 468   }
 469
 470   /**
 471    * <p>Returns a string of 2 hexadecimal digits (most significant digit first)
 472    * corresponding to the lowest 8 bits of <code>n</code>.</p>
 473    *
 474    * @param n the byte value to convert.
 475    * @return a string of 2 hex characters representing the input.
 476    */
 477   public static String byteToString(int n)
 478   {
 479     char[] buf = { HEX_DIGITS[(n >>> 4) & 0x0F], HEX_DIGITS[n & 0x0F] };
 480     return new String(buf);
 481   }
 482
 483   /**
 484    * <p>Converts a designated byte array to a Base-64 representation, with the
 485    * exceptions that (a) leading 0-byte(s) are ignored, and (b) the character
 486    * '.' (dot) shall be used instead of "+' (plus).</p>
 487    *
 488    * <p>Used by SASL password file manipulation primitives.</p>
 489    *
 490    * @param buffer an arbitrary sequence of bytes to represent in Base-64.
 491    * @return unpadded (without the '=' character(s)) Base-64 representation of
 492    * the input.
 493    */
 494   public static final String toBase64(byte[] buffer)
 495   {
 496     int len = buffer.length, pos = len % 3;
 497     byte b0 = 0, b1 = 0, b2 = 0;
 498     switch (pos)
 499       {
 500       case 1:
 501         b2 = buffer[0];
 502         break;
 503       case 2:
 504         b1 = buffer[0];
 505         b2 = buffer[1];
 506         break;
 507       }
 508     StringBuffer sb = new StringBuffer();
 509     int c;
 510     boolean notleading = false;
 511     do
 512       {
 513         c = (b0 & 0xFC) >>> 2;
 514         if (notleading || c != 0)
 515           {
 516             sb.append(BASE64_CHARSET[c]);
 517             notleading = true;
 518           }
 519         c = ((b0 & 0x03) << 4) | ((b1 & 0xF0) >>> 4);
 520         if (notleading || c != 0)
 521           {
 522             sb.append(BASE64_CHARSET[c]);
 523             notleading = true;
 524           }
 525         c = ((b1 & 0x0F) << 2) | ((b2 & 0xC0) >>> 6);
 526         if (notleading || c != 0)
 527           {
 528             sb.append(BASE64_CHARSET[c]);
 529             notleading = true;
 530           }
 531         c = b2 & 0x3F;
 532         if (notleading || c != 0)
 533           {
 534             sb.append(BASE64_CHARSET[c]);
 535             notleading = true;
 536           }
 537         if (pos >= len)
 538           {
 539             break;
 540           }
 541         else
 542           {
 543             try
 544               {
 545                 b0 = buffer[pos++];
 546                 b1 = buffer[pos++];
 547                 b2 = buffer[pos++];
 548               }
 549             catch (ArrayIndexOutOfBoundsException x)
 550               {
 551                 break;
 552               }
 553           }
 554       }
 555     while (true);
 556
 557     if (notleading)
 558       {
 559         return sb.toString();
 560       }
 561     return "0";
 562   }
 563
 564   /**
 565    * <p>The inverse function of the above.</p>
 566    *
 567    * <p>Converts a string representing the encoding of some bytes in Base-64
 568    * to their original form.</p>
 569    *
 570    * @param str the Base-64 encoded representation of some byte(s).
 571    * @return the bytes represented by the <code>str</code>.
 572    * @throws NumberFormatException if <code>str</code> is <code>null</code>, or
 573    * <code>str</code> contains an illegal Base-64 character.
 574    * @see #toBase64(byte[])
 575    */
 576   public static final byte[] fromBase64(String str)
 577   {
 578     int len = str.length();
 579     if (len == 0)
 580       {
 581         throw new NumberFormatException("Empty string");
 582       }
 583     byte[] a = new byte[len + 1];
 584     int i, j;
 585     for (i = 0; i < len; i++)
 586       {
 587         try
 588           {
 589             a[i] = (byte) BASE64_CHARS.indexOf(str.charAt(i));
 590           }
 591         catch (ArrayIndexOutOfBoundsException x)
 592           {
 593             throw new NumberFormatException("Illegal character at #" + i);
 594           }
 595       }
 596     i = len - 1;
 597     j = len;
 598     try
 599       {
 600         while (true)
 601           {
 602             a[j] = a[i];
 603             if (--i < 0)
 604               {
 605                 break;
 606               }
 607             a[j] |= (a[i] & 0x03) << 6;
 608             j--;
 609             a[j] = (byte) ((a[i] & 0x3C) >>> 2);
 610             if (--i < 0)
 611               {
 612                 break;
 613               }
 614             a[j] |= (a[i] & 0x0F) << 4;
 615             j--;
 616             a[j] = (byte) ((a[i] & 0x30) >>> 4);
 617             if (--i < 0)
 618               {
 619                 break;
 620               }
 621             a[j] |= (a[i] << 2);
 622             j--;
 623             a[j] = 0;
 624             if (--i < 0)
 625               {
 626                 break;
 627               }
 628           }
 629       }
 630     catch (Exception ignored)
 631       {
 632       }
 633
 634     try
 635       { // ignore leading 0-bytes
 636         while (a[j] == 0)
 637           {
 638             j++;
 639           }
 640       }
 641     catch (Exception x)
 642       {
 643         return new byte[1]; // one 0-byte
 644       }
 645     byte[] result = new byte[len - j + 1];
 646     System.arraycopy(a, j, result, 0, len - j + 1);
 647     return result;
 648   }
 649
 650   // BigInteger utilities ----------------------------------------------------
 651
 652   /**
 653    * <p>Treats the input as the MSB representation of a number, and discards
 654    * leading zero elements. For efficiency, the input is simply returned if no
 655    * leading zeroes are found.</p>
 656    *
 657    * @param n the {@link BigInteger} to trim.
 658    * @return the byte array representation of the designated {@link BigInteger}
 659    * with no leading 0-bytes.
 660    */
 661   public static final byte[] trim(BigInteger n)
 662   {
 663     byte[] in = n.toByteArray();
 664     if (in.length == 0 || in[0] != 0)
 665       {
 666         return in;
 667       }
 668     int len = in.length;
 669     int i = 1;
 670     while (in[i] == 0 && i < len)
 671       {
 672         ++i;
 673       }
 674     byte[] result = new byte[len - i];
 675     System.arraycopy(in, i, result, 0, len - i);
 676     return result;
 677   }
 678
 679   /**
 680    * <p>Returns a hexadecimal dump of the trimmed bytes of a {@link BigInteger}.
 681    * </p>
 682    *
 683    * @param x the {@link BigInteger} to display.
 684    * @return the string representation of the designated {@link BigInteger}.
 685    */
 686   public static final String dump(BigInteger x)
 687   {
 688     return dumpString(trim(x));
 689   }
 690 }