mcs/class/System.Web/System.Web/HttpUtility.cs

   1 //
   2 // System.Web.HttpUtility
   3 //
   4 // Authors:
   5 //   Patrik Torstensson (Patrik.Torstensson@labs2.com)
   6 //   Wictor Wilén (decode/encode functions) (wictor@ibizkit.se)
   7 //   Tim Coleman (tim@timcoleman.com)
   8 //   Gonzalo Paniagua Javier (gonzalo@ximian.com)
   9 //
  10 using System;
  11 using System.Collections;
  12 using System.Globalization;
  13 using System.IO;
  14 using System.Text;
  15 using System.Web.Util;
  16
  17 namespace System.Web {
  18         public sealed class HttpUtility {
  19
  20                 #region Fields
  21
  22                 const string _hex = "0123456789ABCDEF";
  23                 const string _chars = "<>;:.?=&@*+%/\\";
  24                 static Hashtable entities;
  25
  26                 #endregion // Fields
  27
  28                 #region Constructors
  29
  30                 static HttpUtility ()
  31                 {
  32                         // Build the hash table of HTML entity references.  This list comes
  33                         // from the HTML 4.01 W3C recommendation.
  34                         entities = new Hashtable ();
  35                         entities.Add ("nbsp", '\u00A0');
  36                         entities.Add ("iexcl", '\u00A1');
  37                         entities.Add ("cent", '\u00A2');
  38                         entities.Add ("pound", '\u00A3');
  39                         entities.Add ("curren", '\u00A4');
  40                         entities.Add ("yen", '\u00A5');
  41                         entities.Add ("brvbar", '\u00A6');
  42                         entities.Add ("sect", '\u00A7');
  43                         entities.Add ("uml", '\u00A8');
  44                         entities.Add ("copy", '\u00A9');
  45                         entities.Add ("ordf", '\u00AA');
  46                         entities.Add ("laquo", '\u00AB');
  47                         entities.Add ("not", '\u00AC');
  48                         entities.Add ("shy", '\u00AD');
  49                         entities.Add ("reg", '\u00AE');
  50                         entities.Add ("macr", '\u00AF');
  51                         entities.Add ("deg", '\u00B0');
  52                         entities.Add ("plusmn", '\u00B1');
  53                         entities.Add ("sup2", '\u00B2');
  54                         entities.Add ("sup3", '\u00B3');
  55                         entities.Add ("acute", '\u00B4');
  56                         entities.Add ("micro", '\u00B5');
  57                         entities.Add ("para", '\u00B6');
  58                         entities.Add ("middot", '\u00B7');
  59                         entities.Add ("cedil", '\u00B8');
  60                         entities.Add ("sup1", '\u00B9');
  61                         entities.Add ("ordm", '\u00BA');
  62                         entities.Add ("raquo", '\u00BB');
  63                         entities.Add ("frac14", '\u00BC');
  64                         entities.Add ("frac12", '\u00BD');
  65                         entities.Add ("frac34", '\u00BE');
  66                         entities.Add ("iquest", '\u00BF');
  67                         entities.Add ("Agrave", '\u00C0');
  68                         entities.Add ("Aacute", '\u00C1');
  69                         entities.Add ("Acirc", '\u00C2');
  70                         entities.Add ("Atilde", '\u00C3');
  71                         entities.Add ("Auml", '\u00C4');
  72                         entities.Add ("Aring", '\u00C5');
  73                         entities.Add ("AElig", '\u00C6');
  74                         entities.Add ("Ccedil", '\u00C7');
  75                         entities.Add ("Egrave", '\u00C8');
  76                         entities.Add ("Eacute", '\u00C9');
  77                         entities.Add ("Ecirc", '\u00CA');
  78                         entities.Add ("Euml", '\u00CB');
  79                         entities.Add ("Igrave", '\u00CC');
  80                         entities.Add ("Iacute", '\u00CD');
  81                         entities.Add ("Icirc", '\u00CE');
  82                         entities.Add ("Iuml", '\u00CF');
  83                         entities.Add ("ETH", '\u00D0');
  84                         entities.Add ("Ntilde", '\u00D1');
  85                         entities.Add ("Ograve", '\u00D2');
  86                         entities.Add ("Oacute", '\u00D3');
  87                         entities.Add ("Ocirc", '\u00D4');
  88                         entities.Add ("Otilde", '\u00D5');
  89                         entities.Add ("Ouml", '\u00D6');
  90                         entities.Add ("times", '\u00D7');
  91                         entities.Add ("Oslash", '\u00D8');
  92                         entities.Add ("Ugrave", '\u00D9');
  93                         entities.Add ("Uacute", '\u00DA');
  94                         entities.Add ("Ucirc", '\u00DB');
  95                         entities.Add ("Uuml", '\u00DC');
  96                         entities.Add ("Yacute", '\u00DD');
  97                         entities.Add ("THORN", '\u00DE');
  98                         entities.Add ("szlig", '\u00DF');
  99                         entities.Add ("agrave", '\u00E0');
 100                         entities.Add ("aacute", '\u00E1');
 101                         entities.Add ("acirc", '\u00E2');
 102                         entities.Add ("atilde", '\u00E3');
 103                         entities.Add ("auml", '\u00E4');
 104                         entities.Add ("aring", '\u00E5');
 105                         entities.Add ("aelig", '\u00E6');
 106                         entities.Add ("ccedil", '\u00E7');
 107                         entities.Add ("egrave", '\u00E8');
 108                         entities.Add ("eacute", '\u00E9');
 109                         entities.Add ("ecirc", '\u00EA');
 110                         entities.Add ("euml", '\u00EB');
 111                         entities.Add ("igrave", '\u00EC');
 112                         entities.Add ("iacute", '\u00ED');
 113                         entities.Add ("icirc", '\u00EE');
 114                         entities.Add ("iuml", '\u00EF');
 115                         entities.Add ("eth", '\u00F0');
 116                         entities.Add ("ntilde", '\u00F1');
 117                         entities.Add ("ograve", '\u00F2');
 118                         entities.Add ("oacute", '\u00F3');
 119                         entities.Add ("ocirc", '\u00F4');
 120                         entities.Add ("otilde", '\u00F5');
 121                         entities.Add ("ouml", '\u00F6');
 122                         entities.Add ("divide", '\u00F7');
 123                         entities.Add ("oslash", '\u00F8');
 124                         entities.Add ("ugrave", '\u00F9');
 125                         entities.Add ("uacute", '\u00FA');
 126                         entities.Add ("ucirc", '\u00FB');
 127                         entities.Add ("uuml", '\u00FC');
 128                         entities.Add ("yacute", '\u00FD');
 129                         entities.Add ("thorn", '\u00FE');
 130                         entities.Add ("yuml", '\u00FF');
 131                         entities.Add ("fnof", '\u0192');
 132                         entities.Add ("Alpha", '\u0391');
 133                         entities.Add ("Beta", '\u0392');
 134                         entities.Add ("Gamma", '\u0393');
 135                         entities.Add ("Delta", '\u0394');
 136                         entities.Add ("Epsilon", '\u0395');
 137                         entities.Add ("Zeta", '\u0396');
 138                         entities.Add ("Eta", '\u0397');
 139                         entities.Add ("Theta", '\u0398');
 140                         entities.Add ("Iota", '\u0399');
 141                         entities.Add ("Kappa", '\u039A');
 142                         entities.Add ("Lambda", '\u039B');
 143                         entities.Add ("Mu", '\u039C');
 144                         entities.Add ("Nu", '\u039D');
 145                         entities.Add ("Xi", '\u039E');
 146                         entities.Add ("Omicron", '\u039F');
 147                         entities.Add ("Pi", '\u03A0');
 148                         entities.Add ("Rho", '\u03A1');
 149                         entities.Add ("Sigma", '\u03A3');
 150                         entities.Add ("Tau", '\u03A4');
 151                         entities.Add ("Upsilon", '\u03A5');
 152                         entities.Add ("Phi", '\u03A6');
 153                         entities.Add ("Chi", '\u03A7');
 154                         entities.Add ("Psi", '\u03A8');
 155                         entities.Add ("Omega", '\u03A9');
 156                         entities.Add ("alpha", '\u03B1');
 157                         entities.Add ("beta", '\u03B2');
 158                         entities.Add ("gamma", '\u03B3');
 159                         entities.Add ("delta", '\u03B4');
 160                         entities.Add ("epsilon", '\u03B5');
 161                         entities.Add ("zeta", '\u03B6');
 162                         entities.Add ("eta", '\u03B7');
 163                         entities.Add ("theta", '\u03B8');
 164                         entities.Add ("iota", '\u03B9');
 165                         entities.Add ("kappa", '\u03BA');
 166                         entities.Add ("lambda", '\u03BB');
 167                         entities.Add ("mu", '\u03BC');
 168                         entities.Add ("nu", '\u03BD');
 169                         entities.Add ("xi", '\u03BE');
 170                         entities.Add ("omicron", '\u03BF');
 171                         entities.Add ("pi", '\u03C0');
 172                         entities.Add ("rho", '\u03C1');
 173                         entities.Add ("sigmaf", '\u03C2');
 174                         entities.Add ("sigma", '\u03C3');
 175                         entities.Add ("tau", '\u03C4');
 176                         entities.Add ("upsilon", '\u03C5');
 177                         entities.Add ("phi", '\u03C6');
 178                         entities.Add ("chi", '\u03C7');
 179                         entities.Add ("psi", '\u03C8');
 180                         entities.Add ("omega", '\u03C9');
 181                         entities.Add ("thetasym", '\u03D1');
 182                         entities.Add ("upsih", '\u03D2');
 183                         entities.Add ("piv", '\u03D6');
 184                         entities.Add ("bull", '\u2022');
 185                         entities.Add ("hellip", '\u2026');
 186                         entities.Add ("prime", '\u2032');
 187                         entities.Add ("Prime", '\u2033');
 188                         entities.Add ("oline", '\u203E');
 189                         entities.Add ("frasl", '\u2044');
 190                         entities.Add ("weierp", '\u2118');
 191                         entities.Add ("image", '\u2111');
 192                         entities.Add ("real", '\u211C');
 193                         entities.Add ("trade", '\u2122');
 194                         entities.Add ("alefsym", '\u2135');
 195                         entities.Add ("larr", '\u2190');
 196                         entities.Add ("uarr", '\u2191');
 197                         entities.Add ("rarr", '\u2192');
 198                         entities.Add ("darr", '\u2193');
 199                         entities.Add ("harr", '\u2194');
 200                         entities.Add ("crarr", '\u21B5');
 201                         entities.Add ("lArr", '\u21D0');
 202                         entities.Add ("uArr", '\u21D1');
 203                         entities.Add ("rArr", '\u21D2');
 204                         entities.Add ("dArr", '\u21D3');
 205                         entities.Add ("hArr", '\u21D4');
 206                         entities.Add ("forall", '\u2200');
 207                         entities.Add ("part", '\u2202');
 208                         entities.Add ("exist", '\u2203');
 209                         entities.Add ("empty", '\u2205');
 210                         entities.Add ("nabla", '\u2207');
 211                         entities.Add ("isin", '\u2208');
 212                         entities.Add ("notin", '\u2209');
 213                         entities.Add ("ni", '\u220B');
 214                         entities.Add ("prod", '\u220F');
 215                         entities.Add ("sum", '\u2211');
 216                         entities.Add ("minus", '\u2212');
 217                         entities.Add ("lowast", '\u2217');
 218                         entities.Add ("radic", '\u221A');
 219                         entities.Add ("prop", '\u221D');
 220                         entities.Add ("infin", '\u221E');
 221                         entities.Add ("ang", '\u2220');
 222                         entities.Add ("and", '\u2227');
 223                         entities.Add ("or", '\u2228');
 224                         entities.Add ("cap", '\u2229');
 225                         entities.Add ("cup", '\u222A');
 226                         entities.Add ("int", '\u222B');
 227                         entities.Add ("there4", '\u2234');
 228                         entities.Add ("sim", '\u223C');
 229                         entities.Add ("cong", '\u2245');
 230                         entities.Add ("asymp", '\u2248');
 231                         entities.Add ("ne", '\u2260');
 232                         entities.Add ("equiv", '\u2261');
 233                         entities.Add ("le", '\u2264');
 234                         entities.Add ("ge", '\u2265');
 235                         entities.Add ("sub", '\u2282');
 236                         entities.Add ("sup", '\u2283');
 237                         entities.Add ("nsub", '\u2284');
 238                         entities.Add ("sube", '\u2286');
 239                         entities.Add ("supe", '\u2287');
 240                         entities.Add ("oplus", '\u2295');
 241                         entities.Add ("otimes", '\u2297');
 242                         entities.Add ("perp", '\u22A5');
 243                         entities.Add ("sdot", '\u22C5');
 244                         entities.Add ("lceil", '\u2308');
 245                         entities.Add ("rceil", '\u2309');
 246                         entities.Add ("lfloor", '\u230A');
 247                         entities.Add ("rfloor", '\u230B');
 248                         entities.Add ("lang", '\u2329');
 249                         entities.Add ("rang", '\u232A');
 250                         entities.Add ("loz", '\u25CA');
 251                         entities.Add ("spades", '\u2660');
 252                         entities.Add ("clubs", '\u2663');
 253                         entities.Add ("hearts", '\u2665');
 254                         entities.Add ("diams", '\u2666');
 255                         entities.Add ("quot", '\u0022');
 256                         entities.Add ("amp", '\u0026');
 257                         entities.Add ("lt", '\u003C');
 258                         entities.Add ("gt", '\u003E');
 259                         entities.Add ("OElig", '\u0152');
 260                         entities.Add ("oelig", '\u0153');
 261                         entities.Add ("Scaron", '\u0160');
 262                         entities.Add ("scaron", '\u0161');
 263                         entities.Add ("Yuml", '\u0178');
 264                         entities.Add ("circ", '\u02C6');
 265                         entities.Add ("tilde", '\u02DC');
 266                         entities.Add ("ensp", '\u2002');
 267                         entities.Add ("emsp", '\u2003');
 268                         entities.Add ("thinsp", '\u2009');
 269                         entities.Add ("zwnj", '\u200C');
 270                         entities.Add ("zwj", '\u200D');
 271                         entities.Add ("lrm", '\u200E');
 272                         entities.Add ("rlm", '\u200F');
 273                         entities.Add ("ndash", '\u2013');
 274                         entities.Add ("mdash", '\u2014');
 275                         entities.Add ("lsquo", '\u2018');
 276                         entities.Add ("rsquo", '\u2019');
 277                         entities.Add ("sbquo", '\u201A');
 278                         entities.Add ("ldquo", '\u201C');
 279                         entities.Add ("rdquo", '\u201D');
 280                         entities.Add ("bdquo", '\u201E');
 281                         entities.Add ("dagger", '\u2020');
 282                         entities.Add ("Dagger", '\u2021');
 283                         entities.Add ("permil", '\u2030');
 284                         entities.Add ("lsaquo", '\u2039');
 285                         entities.Add ("rsaquo", '\u203A');
 286                         entities.Add ("euro", '\u20AC');
 287                 }
 288
 289                 public HttpUtility ()
 290                 {
 291                 }
 292
 293                 #endregion // Constructors
 294
 295                 #region Methods
 296
 297                 public static void HtmlAttributeEncode (string s, TextWriter output)
 298                 {
 299                         output.Write(HtmlAttributeEncode(s));
 300                 }
 301
 302                 public static string HtmlAttributeEncode (string s)
 303                 {
 304                         if (null == s)
 305                                 return null;
 306
 307                         StringBuilder output = new StringBuilder ();
 308
 309                         foreach (char c in s)
 310                                 switch (c) {
 311                                 case '&' :
 312                                         output.Append ("&amp;");
 313                                         break;
 314                                 case '"' :
 315                                         output.Append ("&quot;");
 316                                         break;
 317                                 default:
 318                                         output.Append (c);
 319                                         break;
 320                                 }
 321
 322                         return output.ToString();
 323                 }
 324
 325                 public static string UrlDecode (string str)
 326                 {
 327                         return UrlDecode(str, Encoding.UTF8);
 328                 }
 329
 330                 private static char [] GetChars (MemoryStream b, Encoding e)
 331                 {
 332                         return e.GetChars (b.GetBuffer (), 0, (int) b.Length);
 333                 }
 334
 335                 public static string UrlDecode (string s, Encoding e)
 336                 {
 337                         if (null == s)
 338                                 return null;
 339
 340                         if (e == null)
 341                                 e = Encoding.UTF8;
 342
 343                         StringBuilder output = new StringBuilder ();
 344                         long len = s.Length;
 345                         NumberStyles hexa = NumberStyles.HexNumber;
 346                         MemoryStream bytes = new MemoryStream ();
 347
 348                         for (int i = 0; i < len; i++) {
 349                                 if (s [i] == '%' && i + 2 < len) {
 350                                         if (s [i + 1] == 'u' && i + 5 < len) {
 351                                                 if (bytes.Length > 0) {
 352                                                         output.Append (GetChars (bytes, e));
 353                                                         bytes.SetLength (0);
 354                                                 }
 355                                                 output.Append ((char) Int32.Parse (s.Substring (i + 2, 4), hexa));
 356                                                 i += 5;
 357                                         } else {
 358                                                 bytes.WriteByte ((byte) Int32.Parse (s.Substring (i + 1, 2), hexa));
 359                                                 i += 2;
 360                                         }
 361                                         continue;
 362                                 }
 363
 364                                 if (bytes.Length > 0) {
 365                                         output.Append (GetChars (bytes, e));
 366                                         bytes.SetLength (0);
 367                                 }
 368
 369                                 if (s [i] == '+') {
 370                                         output.Append (' ');
 371                                 } else {
 372                                         output.Append (s [i]);
 373                                 }
 374                         }
 375
 376                         if (bytes.Length > 0) {
 377                                 output.Append (GetChars (bytes, e));
 378                         }
 379
 380                         bytes = null;
 381                         return output.ToString ();
 382                 }
 383
 384                 public static string UrlDecode (byte [] bytes, Encoding e)
 385                 {
 386                         if (bytes == null)
 387                                 return null;
 388
 389                         return UrlDecode (bytes, 0, bytes.Length, e);
 390                 }
 391
 392                 private static int GetInt (byte b)
 393                 {
 394                         char c = Char.ToUpper ((char) b);
 395                         if (c >= '0' && c <= '9')
 396                                 return c - '0';
 397
 398                         if (c < 'A' || c > 'F')
 399                                 return 0;
 400
 401                         return (c - 'A' + 10);
 402                 }
 403
 404                 private static char GetChar (byte [] bytes, int offset, int length)
 405                 {
 406                         int value = 0;
 407                         int end = length + offset;
 408                         for (int i = offset; i < end; i++)
 409                                 value = (value << 4) + GetInt (bytes [offset]);
 410
 411                         return (char) value;
 412                 }
 413
 414                 public static string UrlDecode (byte [] bytes, int offset, int count, Encoding e)
 415                 {
 416                         if (bytes == null || count == 0)
 417                                 return null;
 418
 419                         if (bytes == null)
 420                                 throw new ArgumentNullException ("bytes");
 421
 422                         if (offset < 0 || offset > bytes.Length)
 423                                 throw new ArgumentOutOfRangeException ("offset");
 424
 425                         if (count < 0 || offset + count > bytes.Length)
 426                                 throw new ArgumentOutOfRangeException ("count");
 427
 428                         StringBuilder output = new StringBuilder ();
 429                         MemoryStream acc = new MemoryStream ();
 430
 431                         int end = count + offset;
 432                         for (int i = offset; i < end; i++) {
 433                                 if (bytes [i] == '%' && i + 2 < count) {
 434                                         if (bytes [i + 1] == (byte) 'u' && i + 5 < end) {
 435                                                 if (acc.Length > 0) {
 436                                                         output.Append (GetChars (acc, e));
 437                                                         acc.SetLength (0);
 438                                                 }
 439                                                 output.Append (GetChar (bytes, offset + 2, 4));
 440                                                 i += 5;
 441                                         } else {
 442                                                 acc.WriteByte ((byte) GetChar (bytes, offset + 1, 2));
 443                                                 i += 2;
 444                                         }
 445                                         continue;
 446                                 }
 447
 448                                 if (acc.Length > 0) {
 449                                         output.Append (GetChars (acc, e));
 450                                         acc.SetLength (0);
 451                                 }
 452
 453                                 if (bytes [i] == '+') {
 454                                         output.Append (' ');
 455                                 } else {
 456                                         output.Append ((char) bytes [i]);
 457                                 }
 458                         }
 459
 460                         if (acc.Length > 0) {
 461                                 output.Append (GetChars (acc, e));
 462                         }
 463
 464                         acc = null;
 465                         return output.ToString ();
 466                 }
 467
 468                 public static byte [] UrlDecodeToBytes (byte [] bytes)
 469                 {
 470                         if (bytes == null)
 471                                 return null;
 472
 473                         return UrlDecodeToBytes (bytes, 0, bytes.Length);
 474                 }
 475
 476                 public static byte [] UrlDecodeToBytes (string str)
 477                 {
 478                         return UrlDecodeToBytes (str, Encoding.UTF8);
 479                 }
 480
 481                 public static byte [] UrlDecodeToBytes (string str, Encoding e)
 482                 {
 483                         if (str == null)
 484                                 return null;
 485
 486                         if (e == null)
 487                                 throw new ArgumentNullException ("e");
 488
 489                         return UrlDecodeToBytes (e.GetBytes (str));
 490                 }
 491
 492                 public static byte [] UrlDecodeToBytes (byte [] bytes, int offset, int count)
 493                 {
 494                         if (bytes == null)
 495                                 return null;
 496
 497                         int len = bytes.Length;
 498                         if (offset < 0 || offset >= len)
 499                                 throw new ArgumentOutOfRangeException("offset");
 500
 501                         if (count < 0 || offset > len - count)
 502                                 throw new ArgumentOutOfRangeException("count");
 503
 504                         MemoryStream result = new MemoryStream ();
 505                         int end = offset + count;
 506                         for (int i = offset; i < end; i++){
 507                                 char c = (char) bytes [i];
 508                                 if (c == '+')
 509                                         c = ' ';
 510                                 else if (c == '%' && i < end - 2) {
 511                                         c = GetChar (bytes, i, 2);
 512                                         i += 2;
 513                                 }
 514                                 result.WriteByte ((byte) c);
 515                         }
 516
 517                         return result.ToArray ();
 518                 }
 519
 520                 public static string UrlEncode(string str)
 521                 {
 522                         return UrlEncode(str, Encoding.UTF8);
 523                 }
 524
 525                 public static string UrlEncode (string s, Encoding Enc)
 526                 {
 527                         if (s == null)
 528                                 return null;
 529
 530                         if (s == "")
 531                                 return "";
 532
 533                         byte [] bytes = Enc.GetBytes (s);
 534                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 535                 }
 536
 537                 public static string UrlEncode (byte [] bytes)
 538                 {
 539                         if (bytes == null)
 540                                 return null;
 541
 542                         if (bytes.Length == 0)
 543                                 return "";
 544
 545                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 546                 }
 547
 548                 public static string UrlEncode (byte [] bytes, int offset, int count)
 549                 {
 550                         if (bytes == null)
 551                                 return null;
 552
 553                         if (bytes.Length == 0)
 554                                 return "";
 555
 556                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, offset, count));
 557                 }
 558
 559                 public static byte [] UrlEncodeToBytes (string str)
 560                 {
 561                         return UrlEncodeToBytes (str, Encoding.UTF8);
 562                 }
 563
 564                 public static byte [] UrlEncodeToBytes (string str, Encoding e)
 565                 {
 566                         if (str == null)
 567                                 return null;
 568
 569                         if (str == "")
 570                                 return new byte [0];
 571
 572                         byte [] bytes = e.GetBytes (str);
 573                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 574                 }
 575
 576                 public static byte [] UrlEncodeToBytes (byte [] bytes)
 577                 {
 578                         if (bytes == null)
 579                                 return null;
 580
 581                         if (bytes.Length == 0)
 582                                 return new byte [0];
 583
 584                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 585                 }
 586
 587                 static char [] hexChars = "0123456789ABCDEF".ToCharArray ();
 588
 589                 public static byte [] UrlEncodeToBytes (byte [] bytes, int offset, int count)
 590                 {
 591                         if (bytes == null)
 592                                 return null;
 593
 594                         int len = bytes.Length;
 595                         if (len == 0)
 596                                 return new byte [0];
 597
 598                         if (offset < 0 || offset >= len)
 599                                 throw new ArgumentOutOfRangeException("offset");
 600
 601                         if (count < 0 || count > len - offset)
 602                                 throw new ArgumentOutOfRangeException("count");
 603
 604                         MemoryStream result = new MemoryStream ();
 605                         int end = offset + count;
 606                         for (int i = offset; i < end; i++) {
 607                                 char c = (char) bytes [i];
 608                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 609                                     (c < 'A' && c > '9') ||
 610                                     (c > 'Z' && c < 'a' && c != '_') ||
 611                                     (c > 'z')) {
 612                                         result.WriteByte ((byte) '%');
 613                                         int idx = ((int) c) >> 4;
 614                                         result.WriteByte ((byte) hexChars [idx]);
 615                                         idx = ((int) c) & 0x0F;
 616                                         result.WriteByte ((byte) hexChars [idx]);
 617                                 } else {
 618                                         result.WriteByte ((byte) c);
 619                                 }
 620                         }
 621
 622                         return result.ToArray ();
 623                 }
 624
 625                 public static string UrlEncodeUnicode (string str)
 626                 {
 627                         if (str == null)
 628                                 return null;
 629
 630                         StringBuilder result = new StringBuilder ();
 631                         int end = str.Length;
 632                         for (int i = 0; i < end; i++) {
 633                                 int idx;
 634                                 char c = str [i];
 635                                 if (c > 255) {
 636                                         result.Append ("%u");
 637                                         idx = ((int) c) >> 24;
 638                                         result.Append (hexChars [idx]);
 639                                         idx = (((int) c) >> 16) & 0x0F;
 640                                         result.Append (hexChars [idx]);
 641                                         idx = (((int) c) >> 8) & 0x0F;
 642                                         result.Append (hexChars [idx]);
 643                                         idx = ((int) c) & 0x0F;
 644                                         result.Append (hexChars [idx]);
 645                                         continue;
 646                                 }
 647
 648                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 649                                     (c < 'A' && c > '9') ||
 650                                     (c > 'Z' && c < 'a' && c != '_') ||
 651                                     (c > 'z')) {
 652                                         result.Append ('%');
 653                                         idx = ((int) c) >> 4;
 654                                         result.Append (hexChars [idx]);
 655                                         idx = ((int) c) & 0x0F;
 656                                         result.Append (hexChars [idx]);
 657                                         continue;
 658                                 }
 659
 660                                 result.Append (c);
 661                         }
 662
 663                         return result.ToString ();
 664                 }
 665
 666                 public static byte [] UrlEncodeUnicodeToBytes (string str)
 667                 {
 668                         if (str == null)
 669                                 return null;
 670
 671                         if (str == "")
 672                                 return new byte [0];
 673
 674                         return Encoding.ASCII.GetBytes (UrlEncodeUnicode (str));
 675                 }
 676
 677                 /// <summary>
 678                 /// Decodes an HTML-encoded string and returns the decoded string.
 679                 /// </summary>
 680                 /// <param name="s">The HTML string to decode. </param>
 681                 /// <returns>The decoded text.</returns>
 682                 public static string HtmlDecode (string s)
 683                 {
 684                         if (s == null)
 685                                 throw new ArgumentNullException ("s");
 686
 687                         bool insideEntity = false; // used to indicate that we are in a potential entity
 688                         string entity = String.Empty;
 689                         StringBuilder output = new StringBuilder ();
 690
 691                         foreach (char c in s) {
 692                                 switch (c) {
 693                                 case '&' :
 694                                         output.Append (entity);
 695                                         entity = "&";
 696                                         insideEntity = true;
 697                                         break;
 698                                 case ';' :
 699                                         if (!insideEntity) {
 700                                                 output.Append (c);
 701                                                 break;
 702                                         }
 703
 704                                         entity += c;
 705                                         int length = entity.Length;
 706                                         if (length >= 2 && entity[1] == '#' && entity[2] != ';')
 707                                                 entity = ((char) Int32.Parse (entity.Substring (2, entity.Length - 3))).ToString();
 708                                         else if (length > 1 && entities.ContainsKey (entity.Substring (1, entity.Length - 2)))
 709                                                 entity = entities [entity.Substring (1, entity.Length - 2)].ToString ();
 710
 711                                         output.Append (entity);
 712                                         entity = String.Empty;
 713                                         insideEntity = false;
 714                                         break;
 715                                 default :
 716                                         if (insideEntity)
 717                                                 entity += c;
 718                                         else
 719                                                 output.Append (c);
 720                                         break;
 721                                 }
 722                         }
 723                         output.Append (entity);
 724                         return output.ToString ();
 725                 }
 726
 727                 /// <summary>
 728                 /// Decodes an HTML-encoded string and sends the resulting output to a TextWriter output stream.
 729                 /// </summary>
 730                 /// <param name="s">The HTML string to decode</param>
 731                 /// <param name="output">The TextWriter output stream containing the decoded string. </param>
 732                 public static void HtmlDecode(string s, TextWriter output)
 733                 {
 734                         if (s != null)
 735                                 output.Write (HtmlDecode (s));
 736                 }
 737
 738                 /// <summary>
 739                 /// HTML-encodes a string and returns the encoded string.
 740                 /// </summary>
 741                 /// <param name="s">The text string to encode. </param>
 742                 /// <returns>The HTML-encoded text.</returns>
 743                 public static string HtmlEncode (string s)
 744                 {
 745                         if (s == null)
 746                                 throw new ArgumentNullException ("s");
 747
 748                         StringBuilder output = new StringBuilder ();
 749
 750                         foreach (char c in s)
 751                                 switch (c) {
 752                                 case '&' :
 753                                         output.Append ("&amp;");
 754                                         break;
 755                                 case '>' :
 756                                         output.Append ("&gt;");
 757                                         break;
 758                                 case '<' :
 759                                         output.Append ("&lt;");
 760                                         break;
 761                                 case '"' :
 762                                         output.Append ("&quot;");
 763                                         break;
 764                                 default:
 765                                         if ((int) c > 128) {
 766                                                 output.Append ("&#");
 767                                                 output.Append (((int) c).ToString ());
 768                                                 output.Append (";");
 769                                         }
 770                                         else
 771                                                 output.Append (c);
 772                                         break;
 773                                 }
 774                         return output.ToString ();
 775                 }
 776
 777                 /// <summary>
 778                 /// HTML-encodes a string and sends the resulting output to a TextWriter output stream.
 779                 /// </summary>
 780                 /// <param name="s">The string to encode. </param>
 781                 /// <param name="output">The TextWriter output stream containing the encoded string. </param>
 782                 public static void HtmlEncode(string s, TextWriter output)
 783                 {
 784                         if (s != null)
 785                                 output.Write (HtmlEncode (s));
 786                 }
 787
 788 #if NET_1_1
 789                 public string UrlPathEncode (string s)
 790                 {
 791                         if (s == null)
 792                                 return null;
 793
 794                         int idx = s.IndexOf ("?");
 795                         string s2 = null;
 796                         if (idx != -1) {
 797                                 s2 = s.Substring (0, idx-1);
 798                                 s2 = UrlEncode (s2) + s.Substring (idx);
 799                         } else {
 800                                 s2 = UrlEncode (s);
 801                         }
 802
 803                         return s2;
 804                 }
 805 #endif
 806                 #endregion // Methods
 807         }
 808 }