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
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31 using System;
  32 using System.Collections;
  33 using System.Globalization;
  34 using System.IO;
  35 using System.Text;
  36 using System.Web.Util;
  37
  38 namespace System.Web {
  39         public sealed class HttpUtility {
  40
  41                 #region Fields
  42
  43                 const string _hex = "0123456789ABCDEF";
  44                 const string _chars = "<>;:.?=&@*+%/\\";
  45                 static Hashtable entities;
  46                 static object lock_ = new object ();
  47
  48                 #endregion // Fields
  49
  50                 static Hashtable Entities {
  51                         get {
  52                                 lock (lock_) {
  53                                         if (entities == null)
  54                                                 InitEntities ();
  55
  56                                         return entities;
  57                                 }
  58                         }
  59                 }
  60
  61                 #region Constructors
  62
  63                 static void InitEntities ()
  64                 {
  65                         // Build the hash table of HTML entity references.  This list comes
  66                         // from the HTML 4.01 W3C recommendation.
  67                         entities = new Hashtable ();
  68                         entities.Add ("nbsp", '\u00A0');
  69                         entities.Add ("iexcl", '\u00A1');
  70                         entities.Add ("cent", '\u00A2');
  71                         entities.Add ("pound", '\u00A3');
  72                         entities.Add ("curren", '\u00A4');
  73                         entities.Add ("yen", '\u00A5');
  74                         entities.Add ("brvbar", '\u00A6');
  75                         entities.Add ("sect", '\u00A7');
  76                         entities.Add ("uml", '\u00A8');
  77                         entities.Add ("copy", '\u00A9');
  78                         entities.Add ("ordf", '\u00AA');
  79                         entities.Add ("laquo", '\u00AB');
  80                         entities.Add ("not", '\u00AC');
  81                         entities.Add ("shy", '\u00AD');
  82                         entities.Add ("reg", '\u00AE');
  83                         entities.Add ("macr", '\u00AF');
  84                         entities.Add ("deg", '\u00B0');
  85                         entities.Add ("plusmn", '\u00B1');
  86                         entities.Add ("sup2", '\u00B2');
  87                         entities.Add ("sup3", '\u00B3');
  88                         entities.Add ("acute", '\u00B4');
  89                         entities.Add ("micro", '\u00B5');
  90                         entities.Add ("para", '\u00B6');
  91                         entities.Add ("middot", '\u00B7');
  92                         entities.Add ("cedil", '\u00B8');
  93                         entities.Add ("sup1", '\u00B9');
  94                         entities.Add ("ordm", '\u00BA');
  95                         entities.Add ("raquo", '\u00BB');
  96                         entities.Add ("frac14", '\u00BC');
  97                         entities.Add ("frac12", '\u00BD');
  98                         entities.Add ("frac34", '\u00BE');
  99                         entities.Add ("iquest", '\u00BF');
 100                         entities.Add ("Agrave", '\u00C0');
 101                         entities.Add ("Aacute", '\u00C1');
 102                         entities.Add ("Acirc", '\u00C2');
 103                         entities.Add ("Atilde", '\u00C3');
 104                         entities.Add ("Auml", '\u00C4');
 105                         entities.Add ("Aring", '\u00C5');
 106                         entities.Add ("AElig", '\u00C6');
 107                         entities.Add ("Ccedil", '\u00C7');
 108                         entities.Add ("Egrave", '\u00C8');
 109                         entities.Add ("Eacute", '\u00C9');
 110                         entities.Add ("Ecirc", '\u00CA');
 111                         entities.Add ("Euml", '\u00CB');
 112                         entities.Add ("Igrave", '\u00CC');
 113                         entities.Add ("Iacute", '\u00CD');
 114                         entities.Add ("Icirc", '\u00CE');
 115                         entities.Add ("Iuml", '\u00CF');
 116                         entities.Add ("ETH", '\u00D0');
 117                         entities.Add ("Ntilde", '\u00D1');
 118                         entities.Add ("Ograve", '\u00D2');
 119                         entities.Add ("Oacute", '\u00D3');
 120                         entities.Add ("Ocirc", '\u00D4');
 121                         entities.Add ("Otilde", '\u00D5');
 122                         entities.Add ("Ouml", '\u00D6');
 123                         entities.Add ("times", '\u00D7');
 124                         entities.Add ("Oslash", '\u00D8');
 125                         entities.Add ("Ugrave", '\u00D9');
 126                         entities.Add ("Uacute", '\u00DA');
 127                         entities.Add ("Ucirc", '\u00DB');
 128                         entities.Add ("Uuml", '\u00DC');
 129                         entities.Add ("Yacute", '\u00DD');
 130                         entities.Add ("THORN", '\u00DE');
 131                         entities.Add ("szlig", '\u00DF');
 132                         entities.Add ("agrave", '\u00E0');
 133                         entities.Add ("aacute", '\u00E1');
 134                         entities.Add ("acirc", '\u00E2');
 135                         entities.Add ("atilde", '\u00E3');
 136                         entities.Add ("auml", '\u00E4');
 137                         entities.Add ("aring", '\u00E5');
 138                         entities.Add ("aelig", '\u00E6');
 139                         entities.Add ("ccedil", '\u00E7');
 140                         entities.Add ("egrave", '\u00E8');
 141                         entities.Add ("eacute", '\u00E9');
 142                         entities.Add ("ecirc", '\u00EA');
 143                         entities.Add ("euml", '\u00EB');
 144                         entities.Add ("igrave", '\u00EC');
 145                         entities.Add ("iacute", '\u00ED');
 146                         entities.Add ("icirc", '\u00EE');
 147                         entities.Add ("iuml", '\u00EF');
 148                         entities.Add ("eth", '\u00F0');
 149                         entities.Add ("ntilde", '\u00F1');
 150                         entities.Add ("ograve", '\u00F2');
 151                         entities.Add ("oacute", '\u00F3');
 152                         entities.Add ("ocirc", '\u00F4');
 153                         entities.Add ("otilde", '\u00F5');
 154                         entities.Add ("ouml", '\u00F6');
 155                         entities.Add ("divide", '\u00F7');
 156                         entities.Add ("oslash", '\u00F8');
 157                         entities.Add ("ugrave", '\u00F9');
 158                         entities.Add ("uacute", '\u00FA');
 159                         entities.Add ("ucirc", '\u00FB');
 160                         entities.Add ("uuml", '\u00FC');
 161                         entities.Add ("yacute", '\u00FD');
 162                         entities.Add ("thorn", '\u00FE');
 163                         entities.Add ("yuml", '\u00FF');
 164                         entities.Add ("fnof", '\u0192');
 165                         entities.Add ("Alpha", '\u0391');
 166                         entities.Add ("Beta", '\u0392');
 167                         entities.Add ("Gamma", '\u0393');
 168                         entities.Add ("Delta", '\u0394');
 169                         entities.Add ("Epsilon", '\u0395');
 170                         entities.Add ("Zeta", '\u0396');
 171                         entities.Add ("Eta", '\u0397');
 172                         entities.Add ("Theta", '\u0398');
 173                         entities.Add ("Iota", '\u0399');
 174                         entities.Add ("Kappa", '\u039A');
 175                         entities.Add ("Lambda", '\u039B');
 176                         entities.Add ("Mu", '\u039C');
 177                         entities.Add ("Nu", '\u039D');
 178                         entities.Add ("Xi", '\u039E');
 179                         entities.Add ("Omicron", '\u039F');
 180                         entities.Add ("Pi", '\u03A0');
 181                         entities.Add ("Rho", '\u03A1');
 182                         entities.Add ("Sigma", '\u03A3');
 183                         entities.Add ("Tau", '\u03A4');
 184                         entities.Add ("Upsilon", '\u03A5');
 185                         entities.Add ("Phi", '\u03A6');
 186                         entities.Add ("Chi", '\u03A7');
 187                         entities.Add ("Psi", '\u03A8');
 188                         entities.Add ("Omega", '\u03A9');
 189                         entities.Add ("alpha", '\u03B1');
 190                         entities.Add ("beta", '\u03B2');
 191                         entities.Add ("gamma", '\u03B3');
 192                         entities.Add ("delta", '\u03B4');
 193                         entities.Add ("epsilon", '\u03B5');
 194                         entities.Add ("zeta", '\u03B6');
 195                         entities.Add ("eta", '\u03B7');
 196                         entities.Add ("theta", '\u03B8');
 197                         entities.Add ("iota", '\u03B9');
 198                         entities.Add ("kappa", '\u03BA');
 199                         entities.Add ("lambda", '\u03BB');
 200                         entities.Add ("mu", '\u03BC');
 201                         entities.Add ("nu", '\u03BD');
 202                         entities.Add ("xi", '\u03BE');
 203                         entities.Add ("omicron", '\u03BF');
 204                         entities.Add ("pi", '\u03C0');
 205                         entities.Add ("rho", '\u03C1');
 206                         entities.Add ("sigmaf", '\u03C2');
 207                         entities.Add ("sigma", '\u03C3');
 208                         entities.Add ("tau", '\u03C4');
 209                         entities.Add ("upsilon", '\u03C5');
 210                         entities.Add ("phi", '\u03C6');
 211                         entities.Add ("chi", '\u03C7');
 212                         entities.Add ("psi", '\u03C8');
 213                         entities.Add ("omega", '\u03C9');
 214                         entities.Add ("thetasym", '\u03D1');
 215                         entities.Add ("upsih", '\u03D2');
 216                         entities.Add ("piv", '\u03D6');
 217                         entities.Add ("bull", '\u2022');
 218                         entities.Add ("hellip", '\u2026');
 219                         entities.Add ("prime", '\u2032');
 220                         entities.Add ("Prime", '\u2033');
 221                         entities.Add ("oline", '\u203E');
 222                         entities.Add ("frasl", '\u2044');
 223                         entities.Add ("weierp", '\u2118');
 224                         entities.Add ("image", '\u2111');
 225                         entities.Add ("real", '\u211C');
 226                         entities.Add ("trade", '\u2122');
 227                         entities.Add ("alefsym", '\u2135');
 228                         entities.Add ("larr", '\u2190');
 229                         entities.Add ("uarr", '\u2191');
 230                         entities.Add ("rarr", '\u2192');
 231                         entities.Add ("darr", '\u2193');
 232                         entities.Add ("harr", '\u2194');
 233                         entities.Add ("crarr", '\u21B5');
 234                         entities.Add ("lArr", '\u21D0');
 235                         entities.Add ("uArr", '\u21D1');
 236                         entities.Add ("rArr", '\u21D2');
 237                         entities.Add ("dArr", '\u21D3');
 238                         entities.Add ("hArr", '\u21D4');
 239                         entities.Add ("forall", '\u2200');
 240                         entities.Add ("part", '\u2202');
 241                         entities.Add ("exist", '\u2203');
 242                         entities.Add ("empty", '\u2205');
 243                         entities.Add ("nabla", '\u2207');
 244                         entities.Add ("isin", '\u2208');
 245                         entities.Add ("notin", '\u2209');
 246                         entities.Add ("ni", '\u220B');
 247                         entities.Add ("prod", '\u220F');
 248                         entities.Add ("sum", '\u2211');
 249                         entities.Add ("minus", '\u2212');
 250                         entities.Add ("lowast", '\u2217');
 251                         entities.Add ("radic", '\u221A');
 252                         entities.Add ("prop", '\u221D');
 253                         entities.Add ("infin", '\u221E');
 254                         entities.Add ("ang", '\u2220');
 255                         entities.Add ("and", '\u2227');
 256                         entities.Add ("or", '\u2228');
 257                         entities.Add ("cap", '\u2229');
 258                         entities.Add ("cup", '\u222A');
 259                         entities.Add ("int", '\u222B');
 260                         entities.Add ("there4", '\u2234');
 261                         entities.Add ("sim", '\u223C');
 262                         entities.Add ("cong", '\u2245');
 263                         entities.Add ("asymp", '\u2248');
 264                         entities.Add ("ne", '\u2260');
 265                         entities.Add ("equiv", '\u2261');
 266                         entities.Add ("le", '\u2264');
 267                         entities.Add ("ge", '\u2265');
 268                         entities.Add ("sub", '\u2282');
 269                         entities.Add ("sup", '\u2283');
 270                         entities.Add ("nsub", '\u2284');
 271                         entities.Add ("sube", '\u2286');
 272                         entities.Add ("supe", '\u2287');
 273                         entities.Add ("oplus", '\u2295');
 274                         entities.Add ("otimes", '\u2297');
 275                         entities.Add ("perp", '\u22A5');
 276                         entities.Add ("sdot", '\u22C5');
 277                         entities.Add ("lceil", '\u2308');
 278                         entities.Add ("rceil", '\u2309');
 279                         entities.Add ("lfloor", '\u230A');
 280                         entities.Add ("rfloor", '\u230B');
 281                         entities.Add ("lang", '\u2329');
 282                         entities.Add ("rang", '\u232A');
 283                         entities.Add ("loz", '\u25CA');
 284                         entities.Add ("spades", '\u2660');
 285                         entities.Add ("clubs", '\u2663');
 286                         entities.Add ("hearts", '\u2665');
 287                         entities.Add ("diams", '\u2666');
 288                         entities.Add ("quot", '\u0022');
 289                         entities.Add ("amp", '\u0026');
 290                         entities.Add ("lt", '\u003C');
 291                         entities.Add ("gt", '\u003E');
 292                         entities.Add ("OElig", '\u0152');
 293                         entities.Add ("oelig", '\u0153');
 294                         entities.Add ("Scaron", '\u0160');
 295                         entities.Add ("scaron", '\u0161');
 296                         entities.Add ("Yuml", '\u0178');
 297                         entities.Add ("circ", '\u02C6');
 298                         entities.Add ("tilde", '\u02DC');
 299                         entities.Add ("ensp", '\u2002');
 300                         entities.Add ("emsp", '\u2003');
 301                         entities.Add ("thinsp", '\u2009');
 302                         entities.Add ("zwnj", '\u200C');
 303                         entities.Add ("zwj", '\u200D');
 304                         entities.Add ("lrm", '\u200E');
 305                         entities.Add ("rlm", '\u200F');
 306                         entities.Add ("ndash", '\u2013');
 307                         entities.Add ("mdash", '\u2014');
 308                         entities.Add ("lsquo", '\u2018');
 309                         entities.Add ("rsquo", '\u2019');
 310                         entities.Add ("sbquo", '\u201A');
 311                         entities.Add ("ldquo", '\u201C');
 312                         entities.Add ("rdquo", '\u201D');
 313                         entities.Add ("bdquo", '\u201E');
 314                         entities.Add ("dagger", '\u2020');
 315                         entities.Add ("Dagger", '\u2021');
 316                         entities.Add ("permil", '\u2030');
 317                         entities.Add ("lsaquo", '\u2039');
 318                         entities.Add ("rsaquo", '\u203A');
 319                         entities.Add ("euro", '\u20AC');
 320                 }
 321
 322                 public HttpUtility ()
 323                 {
 324                 }
 325
 326                 #endregion // Constructors
 327
 328                 #region Methods
 329
 330                 public static void HtmlAttributeEncode (string s, TextWriter output)
 331                 {
 332                         output.Write(HtmlAttributeEncode(s));
 333                 }
 334
 335                 public static string HtmlAttributeEncode (string s)
 336                 {
 337                         if (null == s)
 338                                 return null;
 339
 340                         if (s.IndexOf ('&') == -1 && s.IndexOf ('"') == -1)
 341                                 return s;
 342
 343                         StringBuilder output = new StringBuilder ();
 344                         foreach (char c in s)
 345                                 switch (c) {
 346                                 case '&' :
 347                                         output.Append ("&amp;");
 348                                         break;
 349                                 case '"' :
 350                                         output.Append ("&quot;");
 351                                         break;
 352                                 default:
 353                                         output.Append (c);
 354                                         break;
 355                                 }
 356
 357                         return output.ToString();
 358                 }
 359
 360                 public static string UrlDecode (string str)
 361                 {
 362                         return UrlDecode(str, Encoding.UTF8);
 363                 }
 364
 365                 private static char [] GetChars (MemoryStream b, Encoding e)
 366                 {
 367                         return e.GetChars (b.GetBuffer (), 0, (int) b.Length);
 368                 }
 369
 370                 public static string UrlDecode (string s, Encoding e)
 371                 {
 372                         if (null == s)
 373                                 return null;
 374
 375                         if (s.IndexOf ('%') == -1 && s.IndexOf ('+') == -1)
 376                                 return s;
 377
 378                         if (e == null)
 379                                 e = Encoding.UTF8;
 380
 381                         StringBuilder output = new StringBuilder ();
 382                         long len = s.Length;
 383                         NumberStyles hexa = NumberStyles.HexNumber;
 384                         MemoryStream bytes = new MemoryStream ();
 385
 386                         for (int i = 0; i < len; i++) {
 387                                 if (s [i] == '%' && i + 2 < len) {
 388                                         if (s [i + 1] == 'u' && i + 5 < len) {
 389                                                 if (bytes.Length > 0) {
 390                                                         output.Append (GetChars (bytes, e));
 391                                                         bytes.SetLength (0);
 392                                                 }
 393                                                 output.Append ((char) Int32.Parse (s.Substring (i + 2, 4), hexa));
 394                                                 i += 5;
 395                                         } else {
 396                                                 bytes.WriteByte ((byte) Int32.Parse (s.Substring (i + 1, 2), hexa));
 397                                                 i += 2;
 398                                         }
 399                                         continue;
 400                                 }
 401
 402                                 if (bytes.Length > 0) {
 403                                         output.Append (GetChars (bytes, e));
 404                                         bytes.SetLength (0);
 405                                 }
 406
 407                                 if (s [i] == '+') {
 408                                         output.Append (' ');
 409                                 } else {
 410                                         output.Append (s [i]);
 411                                 }
 412                         }
 413
 414                         if (bytes.Length > 0) {
 415                                 output.Append (GetChars (bytes, e));
 416                         }
 417
 418                         bytes = null;
 419                         return output.ToString ();
 420                 }
 421
 422                 public static string UrlDecode (byte [] bytes, Encoding e)
 423                 {
 424                         if (bytes == null)
 425                                 return null;
 426
 427                         return UrlDecode (bytes, 0, bytes.Length, e);
 428                 }
 429
 430                 private static int GetInt (byte b)
 431                 {
 432                         char c = Char.ToUpper ((char) b);
 433                         if (c >= '0' && c <= '9')
 434                                 return c - '0';
 435
 436                         if (c < 'A' || c > 'F')
 437                                 return 0;
 438
 439                         return (c - 'A' + 10);
 440                 }
 441
 442                 private static char GetChar (byte [] bytes, int offset, int length)
 443                 {
 444                         int value = 0;
 445                         int end = length + offset;
 446                         for (int i = offset; i < end; i++)
 447                                 value = (value << 4) + GetInt (bytes [i]);
 448
 449                         return (char) value;
 450                 }
 451
 452                 public static string UrlDecode (byte [] bytes, int offset, int count, Encoding e)
 453                 {
 454                         if (bytes == null || count == 0)
 455                                 return null;
 456
 457                         if (bytes == null)
 458                                 throw new ArgumentNullException ("bytes");
 459
 460                         if (offset < 0 || offset > bytes.Length)
 461                                 throw new ArgumentOutOfRangeException ("offset");
 462
 463                         if (count < 0 || offset + count > bytes.Length)
 464                                 throw new ArgumentOutOfRangeException ("count");
 465
 466                         StringBuilder output = new StringBuilder ();
 467                         MemoryStream acc = new MemoryStream ();
 468
 469                         int end = count + offset;
 470                         for (int i = offset; i < end; i++) {
 471                                 if (bytes [i] == '%' && i + 2 < count) {
 472                                         if (bytes [i + 1] == (byte) 'u' && i + 5 < end) {
 473                                                 if (acc.Length > 0) {
 474                                                         output.Append (GetChars (acc, e));
 475                                                         acc.SetLength (0);
 476                                                 }
 477                                                 output.Append (GetChar (bytes, i + 2, 4));
 478                                                 i += 5;
 479                                         } else {
 480                                                 acc.WriteByte ((byte) GetChar (bytes, i + 1, 2));
 481                                                 i += 2;
 482                                         }
 483                                         continue;
 484                                 }
 485
 486                                 if (acc.Length > 0) {
 487                                         output.Append (GetChars (acc, e));
 488                                         acc.SetLength (0);
 489                                 }
 490
 491                                 if (bytes [i] == '+') {
 492                                         output.Append (' ');
 493                                 } else {
 494                                         output.Append ((char) bytes [i]);
 495                                 }
 496                         }
 497
 498                         if (acc.Length > 0) {
 499                                 output.Append (GetChars (acc, e));
 500                         }
 501
 502                         acc = null;
 503                         return output.ToString ();
 504                 }
 505
 506                 public static byte [] UrlDecodeToBytes (byte [] bytes)
 507                 {
 508                         if (bytes == null)
 509                                 return null;
 510
 511                         return UrlDecodeToBytes (bytes, 0, bytes.Length);
 512                 }
 513
 514                 public static byte [] UrlDecodeToBytes (string str)
 515                 {
 516                         return UrlDecodeToBytes (str, Encoding.UTF8);
 517                 }
 518
 519                 public static byte [] UrlDecodeToBytes (string str, Encoding e)
 520                 {
 521                         if (str == null)
 522                                 return null;
 523
 524                         if (e == null)
 525                                 throw new ArgumentNullException ("e");
 526
 527                         return UrlDecodeToBytes (e.GetBytes (str));
 528                 }
 529
 530                 public static byte [] UrlDecodeToBytes (byte [] bytes, int offset, int count)
 531                 {
 532                         if (bytes == null)
 533                                 return null;
 534
 535                         int len = bytes.Length;
 536                         if (offset < 0 || offset >= len)
 537                                 throw new ArgumentOutOfRangeException("offset");
 538
 539                         if (count < 0 || offset > len - count)
 540                                 throw new ArgumentOutOfRangeException("count");
 541
 542                         MemoryStream result = new MemoryStream ();
 543                         int end = offset + count;
 544                         for (int i = offset; i < end; i++){
 545                                 char c = (char) bytes [i];
 546                                 if (c == '+')
 547                                         c = ' ';
 548                                 else if (c == '%' && i < end - 2) {
 549                                         c = GetChar (bytes, i, 2);
 550                                         i += 2;
 551                                 }
 552                                 result.WriteByte ((byte) c);
 553                         }
 554
 555                         return result.ToArray ();
 556                 }
 557
 558                 public static string UrlEncode(string str)
 559                 {
 560                         return UrlEncode(str, Encoding.UTF8);
 561                 }
 562
 563                 public static string UrlEncode (string s, Encoding Enc)
 564                 {
 565                         if (s == null)
 566                                 return null;
 567
 568                         if (s == "")
 569                                 return "";
 570
 571                         byte [] bytes = Enc.GetBytes (s);
 572                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 573                 }
 574
 575                 public static string UrlEncode (byte [] bytes)
 576                 {
 577                         if (bytes == null)
 578                                 return null;
 579
 580                         if (bytes.Length == 0)
 581                                 return "";
 582
 583                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 584                 }
 585
 586                 public static string UrlEncode (byte [] bytes, int offset, int count)
 587                 {
 588                         if (bytes == null)
 589                                 return null;
 590
 591                         if (bytes.Length == 0)
 592                                 return "";
 593
 594                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, offset, count));
 595                 }
 596
 597                 public static byte [] UrlEncodeToBytes (string str)
 598                 {
 599                         return UrlEncodeToBytes (str, Encoding.UTF8);
 600                 }
 601
 602                 public static byte [] UrlEncodeToBytes (string str, Encoding e)
 603                 {
 604                         if (str == null)
 605                                 return null;
 606
 607                         if (str == "")
 608                                 return new byte [0];
 609
 610                         byte [] bytes = e.GetBytes (str);
 611                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 612                 }
 613
 614                 public static byte [] UrlEncodeToBytes (byte [] bytes)
 615                 {
 616                         if (bytes == null)
 617                                 return null;
 618
 619                         if (bytes.Length == 0)
 620                                 return new byte [0];
 621
 622                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 623                 }
 624
 625                 static char [] hexChars = "0123456789abcdef".ToCharArray ();
 626
 627                 public static byte [] UrlEncodeToBytes (byte [] bytes, int offset, int count)
 628                 {
 629                         if (bytes == null)
 630                                 return null;
 631
 632                         int len = bytes.Length;
 633                         if (len == 0)
 634                                 return new byte [0];
 635
 636                         if (offset < 0 || offset >= len)
 637                                 throw new ArgumentOutOfRangeException("offset");
 638
 639                         if (count < 0 || count > len - offset)
 640                                 throw new ArgumentOutOfRangeException("count");
 641
 642                         MemoryStream result = new MemoryStream ();
 643                         int end = offset + count;
 644                         for (int i = offset; i < end; i++) {
 645                                 char c = (char) bytes [i];
 646                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 647                                     (c < 'A' && c > '9') ||
 648                                     (c > 'Z' && c < 'a' && c != '_') ||
 649                                     (c > 'z')) {
 650                                         result.WriteByte ((byte) '%');
 651                                         int idx = ((int) c) >> 4;
 652                                         result.WriteByte ((byte) hexChars [idx]);
 653                                         idx = ((int) c) & 0x0F;
 654                                         result.WriteByte ((byte) hexChars [idx]);
 655                                 } else {
 656                                         result.WriteByte ((byte) c);
 657                                 }
 658                         }
 659
 660                         return result.ToArray ();
 661                 }
 662
 663                 public static string UrlEncodeUnicode (string str)
 664                 {
 665                         if (str == null)
 666                                 return null;
 667
 668                         StringBuilder result = new StringBuilder ();
 669                         int end = str.Length;
 670                         for (int i = 0; i < end; i++) {
 671                                 int idx;
 672                                 char c = str [i];
 673                                 if (c > 255) {
 674                                         result.Append ("%u");
 675                                         idx = ((int) c) >> 24;
 676                                         result.Append (hexChars [idx]);
 677                                         idx = (((int) c) >> 16) & 0x0F;
 678                                         result.Append (hexChars [idx]);
 679                                         idx = (((int) c) >> 8) & 0x0F;
 680                                         result.Append (hexChars [idx]);
 681                                         idx = ((int) c) & 0x0F;
 682                                         result.Append (hexChars [idx]);
 683                                         continue;
 684                                 }
 685
 686                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 687                                     (c < 'A' && c > '9') ||
 688                                     (c > 'Z' && c < 'a' && c != '_') ||
 689                                     (c > 'z')) {
 690                                         result.Append ('%');
 691                                         idx = ((int) c) >> 4;
 692                                         result.Append (hexChars [idx]);
 693                                         idx = ((int) c) & 0x0F;
 694                                         result.Append (hexChars [idx]);
 695                                         continue;
 696                                 }
 697
 698                                 result.Append (c);
 699                         }
 700
 701                         return result.ToString ();
 702                 }
 703
 704                 public static byte [] UrlEncodeUnicodeToBytes (string str)
 705                 {
 706                         if (str == null)
 707                                 return null;
 708
 709                         if (str == "")
 710                                 return new byte [0];
 711
 712                         return Encoding.ASCII.GetBytes (UrlEncodeUnicode (str));
 713                 }
 714
 715                 /// <summary>
 716                 /// Decodes an HTML-encoded string and returns the decoded string.
 717                 /// </summary>
 718                 /// <param name="s">The HTML string to decode. </param>
 719                 /// <returns>The decoded text.</returns>
 720                 public static string HtmlDecode (string s)
 721                 {
 722                         if (s == null)
 723                                 throw new ArgumentNullException ("s");
 724
 725                         if (s.IndexOf ('&') == -1)
 726                                 return s;
 727
 728                         bool insideEntity = false; // used to indicate that we are in a potential entity
 729                         string entity = String.Empty;
 730                         StringBuilder output = new StringBuilder ();
 731                         int len = s.Length;
 732
 733                         for (int i = 0; i < len; i++) {
 734                                 char c = s [i];
 735                                 switch (c) {
 736                                 case '&' :
 737                                         output.Append (entity);
 738                                         entity = "&";
 739                                         insideEntity = true;
 740                                         break;
 741                                 case ';' :
 742                                         if (!insideEntity) {
 743                                                 output.Append (c);
 744                                                 break;
 745                                         }
 746
 747                                         entity += c;
 748                                         int length = entity.Length;
 749                                         if (length >= 2 && entity[1] == '#' && entity[2] != ';')
 750                                                 entity = ((char) Int32.Parse (entity.Substring (2, entity.Length - 3))).ToString();
 751                                         else if (length > 1 && Entities.ContainsKey (entity.Substring (1, entity.Length - 2)))
 752                                                 entity = Entities [entity.Substring (1, entity.Length - 2)].ToString ();
 753
 754                                         output.Append (entity);
 755                                         entity = String.Empty;
 756                                         insideEntity = false;
 757                                         break;
 758                                 default :
 759                                         if (insideEntity)
 760                                                 entity += c;
 761                                         else
 762                                                 output.Append (c);
 763                                         break;
 764                                 }
 765                         }
 766                         output.Append (entity);
 767                         return output.ToString ();
 768                 }
 769
 770                 /// <summary>
 771                 /// Decodes an HTML-encoded string and sends the resulting output to a TextWriter output stream.
 772                 /// </summary>
 773                 /// <param name="s">The HTML string to decode</param>
 774                 /// <param name="output">The TextWriter output stream containing the decoded string. </param>
 775                 public static void HtmlDecode(string s, TextWriter output)
 776                 {
 777                         if (s != null)
 778                                 output.Write (HtmlDecode (s));
 779                 }
 780
 781                 /// <summary>
 782                 /// HTML-encodes a string and returns the encoded string.
 783                 /// </summary>
 784                 /// <param name="s">The text string to encode. </param>
 785                 /// <returns>The HTML-encoded text.</returns>
 786                 public static string HtmlEncode (string s)
 787                 {
 788                         if (s == null)
 789                                 return null;
 790
 791                         StringBuilder output = new StringBuilder ();
 792
 793                         foreach (char c in s)
 794                                 switch (c) {
 795                                 case '&' :
 796                                         output.Append ("&amp;");
 797                                         break;
 798                                 case '>' :
 799                                         output.Append ("&gt;");
 800                                         break;
 801                                 case '<' :
 802                                         output.Append ("&lt;");
 803                                         break;
 804                                 case '"' :
 805                                         output.Append ("&quot;");
 806                                         break;
 807                                 default:
 808                                         if ((int) c > 128) {
 809                                                 output.Append ("&#");
 810                                                 output.Append (((int) c).ToString ());
 811                                                 output.Append (";");
 812                                         }
 813                                         else
 814                                                 output.Append (c);
 815                                         break;
 816                                 }
 817                         return output.ToString ();
 818                 }
 819
 820                 /// <summary>
 821                 /// HTML-encodes a string and sends the resulting output to a TextWriter output stream.
 822                 /// </summary>
 823                 /// <param name="s">The string to encode. </param>
 824                 /// <param name="output">The TextWriter output stream containing the encoded string. </param>
 825                 public static void HtmlEncode(string s, TextWriter output)
 826                 {
 827                         if (s != null)
 828                                 output.Write (HtmlEncode (s));
 829                 }
 830
 831 #if NET_1_1
 832                 public static string UrlPathEncode (string s)
 833                 {
 834                         if (s == null)
 835                                 return null;
 836
 837                         int idx = s.IndexOf ("?");
 838                         string s2 = null;
 839                         if (idx != -1) {
 840                                 s2 = s.Substring (0, idx-1);
 841                                 s2 = UrlEncode (s2) + s.Substring (idx);
 842                         } else {
 843                                 s2 = UrlEncode (s);
 844                         }
 845
 846                         return s2;
 847                 }
 848 #endif
 849                 #endregion // Methods
 850         }
 851 }