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 // Copyright (C) 2005 Novell, Inc (http://www.novell.com)
  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
  32 using System.Collections;
  33 using System.Collections.Specialized;
  34 using System.Globalization;
  35 using System.IO;
  36 using System.Security.Permissions;
  37 using System.Text;
  38 using System.Web.Util;
  39
  40 namespace System.Web {
  41
  42         // CAS - no InheritanceDemand here as the class is sealed
  43         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  44         public sealed class HttpUtility {
  45
  46                 #region Fields
  47
  48                 static Hashtable entities;
  49                 static object lock_ = new object ();
  50
  51                 #endregion // Fields
  52
  53                 static Hashtable Entities {
  54                         get {
  55                                 lock (lock_) {
  56                                         if (entities == null)
  57                                                 InitEntities ();
  58
  59                                         return entities;
  60                                 }
  61                         }
  62                 }
  63
  64                 #region Constructors
  65
  66                 static void InitEntities ()
  67                 {
  68                         // Build the hash table of HTML entity references.  This list comes
  69                         // from the HTML 4.01 W3C recommendation.
  70                         entities = new Hashtable ();
  71                         entities.Add ("nbsp", '\u00A0');
  72                         entities.Add ("iexcl", '\u00A1');
  73                         entities.Add ("cent", '\u00A2');
  74                         entities.Add ("pound", '\u00A3');
  75                         entities.Add ("curren", '\u00A4');
  76                         entities.Add ("yen", '\u00A5');
  77                         entities.Add ("brvbar", '\u00A6');
  78                         entities.Add ("sect", '\u00A7');
  79                         entities.Add ("uml", '\u00A8');
  80                         entities.Add ("copy", '\u00A9');
  81                         entities.Add ("ordf", '\u00AA');
  82                         entities.Add ("laquo", '\u00AB');
  83                         entities.Add ("not", '\u00AC');
  84                         entities.Add ("shy", '\u00AD');
  85                         entities.Add ("reg", '\u00AE');
  86                         entities.Add ("macr", '\u00AF');
  87                         entities.Add ("deg", '\u00B0');
  88                         entities.Add ("plusmn", '\u00B1');
  89                         entities.Add ("sup2", '\u00B2');
  90                         entities.Add ("sup3", '\u00B3');
  91                         entities.Add ("acute", '\u00B4');
  92                         entities.Add ("micro", '\u00B5');
  93                         entities.Add ("para", '\u00B6');
  94                         entities.Add ("middot", '\u00B7');
  95                         entities.Add ("cedil", '\u00B8');
  96                         entities.Add ("sup1", '\u00B9');
  97                         entities.Add ("ordm", '\u00BA');
  98                         entities.Add ("raquo", '\u00BB');
  99                         entities.Add ("frac14", '\u00BC');
 100                         entities.Add ("frac12", '\u00BD');
 101                         entities.Add ("frac34", '\u00BE');
 102                         entities.Add ("iquest", '\u00BF');
 103                         entities.Add ("Agrave", '\u00C0');
 104                         entities.Add ("Aacute", '\u00C1');
 105                         entities.Add ("Acirc", '\u00C2');
 106                         entities.Add ("Atilde", '\u00C3');
 107                         entities.Add ("Auml", '\u00C4');
 108                         entities.Add ("Aring", '\u00C5');
 109                         entities.Add ("AElig", '\u00C6');
 110                         entities.Add ("Ccedil", '\u00C7');
 111                         entities.Add ("Egrave", '\u00C8');
 112                         entities.Add ("Eacute", '\u00C9');
 113                         entities.Add ("Ecirc", '\u00CA');
 114                         entities.Add ("Euml", '\u00CB');
 115                         entities.Add ("Igrave", '\u00CC');
 116                         entities.Add ("Iacute", '\u00CD');
 117                         entities.Add ("Icirc", '\u00CE');
 118                         entities.Add ("Iuml", '\u00CF');
 119                         entities.Add ("ETH", '\u00D0');
 120                         entities.Add ("Ntilde", '\u00D1');
 121                         entities.Add ("Ograve", '\u00D2');
 122                         entities.Add ("Oacute", '\u00D3');
 123                         entities.Add ("Ocirc", '\u00D4');
 124                         entities.Add ("Otilde", '\u00D5');
 125                         entities.Add ("Ouml", '\u00D6');
 126                         entities.Add ("times", '\u00D7');
 127                         entities.Add ("Oslash", '\u00D8');
 128                         entities.Add ("Ugrave", '\u00D9');
 129                         entities.Add ("Uacute", '\u00DA');
 130                         entities.Add ("Ucirc", '\u00DB');
 131                         entities.Add ("Uuml", '\u00DC');
 132                         entities.Add ("Yacute", '\u00DD');
 133                         entities.Add ("THORN", '\u00DE');
 134                         entities.Add ("szlig", '\u00DF');
 135                         entities.Add ("agrave", '\u00E0');
 136                         entities.Add ("aacute", '\u00E1');
 137                         entities.Add ("acirc", '\u00E2');
 138                         entities.Add ("atilde", '\u00E3');
 139                         entities.Add ("auml", '\u00E4');
 140                         entities.Add ("aring", '\u00E5');
 141                         entities.Add ("aelig", '\u00E6');
 142                         entities.Add ("ccedil", '\u00E7');
 143                         entities.Add ("egrave", '\u00E8');
 144                         entities.Add ("eacute", '\u00E9');
 145                         entities.Add ("ecirc", '\u00EA');
 146                         entities.Add ("euml", '\u00EB');
 147                         entities.Add ("igrave", '\u00EC');
 148                         entities.Add ("iacute", '\u00ED');
 149                         entities.Add ("icirc", '\u00EE');
 150                         entities.Add ("iuml", '\u00EF');
 151                         entities.Add ("eth", '\u00F0');
 152                         entities.Add ("ntilde", '\u00F1');
 153                         entities.Add ("ograve", '\u00F2');
 154                         entities.Add ("oacute", '\u00F3');
 155                         entities.Add ("ocirc", '\u00F4');
 156                         entities.Add ("otilde", '\u00F5');
 157                         entities.Add ("ouml", '\u00F6');
 158                         entities.Add ("divide", '\u00F7');
 159                         entities.Add ("oslash", '\u00F8');
 160                         entities.Add ("ugrave", '\u00F9');
 161                         entities.Add ("uacute", '\u00FA');
 162                         entities.Add ("ucirc", '\u00FB');
 163                         entities.Add ("uuml", '\u00FC');
 164                         entities.Add ("yacute", '\u00FD');
 165                         entities.Add ("thorn", '\u00FE');
 166                         entities.Add ("yuml", '\u00FF');
 167                         entities.Add ("fnof", '\u0192');
 168                         entities.Add ("Alpha", '\u0391');
 169                         entities.Add ("Beta", '\u0392');
 170                         entities.Add ("Gamma", '\u0393');
 171                         entities.Add ("Delta", '\u0394');
 172                         entities.Add ("Epsilon", '\u0395');
 173                         entities.Add ("Zeta", '\u0396');
 174                         entities.Add ("Eta", '\u0397');
 175                         entities.Add ("Theta", '\u0398');
 176                         entities.Add ("Iota", '\u0399');
 177                         entities.Add ("Kappa", '\u039A');
 178                         entities.Add ("Lambda", '\u039B');
 179                         entities.Add ("Mu", '\u039C');
 180                         entities.Add ("Nu", '\u039D');
 181                         entities.Add ("Xi", '\u039E');
 182                         entities.Add ("Omicron", '\u039F');
 183                         entities.Add ("Pi", '\u03A0');
 184                         entities.Add ("Rho", '\u03A1');
 185                         entities.Add ("Sigma", '\u03A3');
 186                         entities.Add ("Tau", '\u03A4');
 187                         entities.Add ("Upsilon", '\u03A5');
 188                         entities.Add ("Phi", '\u03A6');
 189                         entities.Add ("Chi", '\u03A7');
 190                         entities.Add ("Psi", '\u03A8');
 191                         entities.Add ("Omega", '\u03A9');
 192                         entities.Add ("alpha", '\u03B1');
 193                         entities.Add ("beta", '\u03B2');
 194                         entities.Add ("gamma", '\u03B3');
 195                         entities.Add ("delta", '\u03B4');
 196                         entities.Add ("epsilon", '\u03B5');
 197                         entities.Add ("zeta", '\u03B6');
 198                         entities.Add ("eta", '\u03B7');
 199                         entities.Add ("theta", '\u03B8');
 200                         entities.Add ("iota", '\u03B9');
 201                         entities.Add ("kappa", '\u03BA');
 202                         entities.Add ("lambda", '\u03BB');
 203                         entities.Add ("mu", '\u03BC');
 204                         entities.Add ("nu", '\u03BD');
 205                         entities.Add ("xi", '\u03BE');
 206                         entities.Add ("omicron", '\u03BF');
 207                         entities.Add ("pi", '\u03C0');
 208                         entities.Add ("rho", '\u03C1');
 209                         entities.Add ("sigmaf", '\u03C2');
 210                         entities.Add ("sigma", '\u03C3');
 211                         entities.Add ("tau", '\u03C4');
 212                         entities.Add ("upsilon", '\u03C5');
 213                         entities.Add ("phi", '\u03C6');
 214                         entities.Add ("chi", '\u03C7');
 215                         entities.Add ("psi", '\u03C8');
 216                         entities.Add ("omega", '\u03C9');
 217                         entities.Add ("thetasym", '\u03D1');
 218                         entities.Add ("upsih", '\u03D2');
 219                         entities.Add ("piv", '\u03D6');
 220                         entities.Add ("bull", '\u2022');
 221                         entities.Add ("hellip", '\u2026');
 222                         entities.Add ("prime", '\u2032');
 223                         entities.Add ("Prime", '\u2033');
 224                         entities.Add ("oline", '\u203E');
 225                         entities.Add ("frasl", '\u2044');
 226                         entities.Add ("weierp", '\u2118');
 227                         entities.Add ("image", '\u2111');
 228                         entities.Add ("real", '\u211C');
 229                         entities.Add ("trade", '\u2122');
 230                         entities.Add ("alefsym", '\u2135');
 231                         entities.Add ("larr", '\u2190');
 232                         entities.Add ("uarr", '\u2191');
 233                         entities.Add ("rarr", '\u2192');
 234                         entities.Add ("darr", '\u2193');
 235                         entities.Add ("harr", '\u2194');
 236                         entities.Add ("crarr", '\u21B5');
 237                         entities.Add ("lArr", '\u21D0');
 238                         entities.Add ("uArr", '\u21D1');
 239                         entities.Add ("rArr", '\u21D2');
 240                         entities.Add ("dArr", '\u21D3');
 241                         entities.Add ("hArr", '\u21D4');
 242                         entities.Add ("forall", '\u2200');
 243                         entities.Add ("part", '\u2202');
 244                         entities.Add ("exist", '\u2203');
 245                         entities.Add ("empty", '\u2205');
 246                         entities.Add ("nabla", '\u2207');
 247                         entities.Add ("isin", '\u2208');
 248                         entities.Add ("notin", '\u2209');
 249                         entities.Add ("ni", '\u220B');
 250                         entities.Add ("prod", '\u220F');
 251                         entities.Add ("sum", '\u2211');
 252                         entities.Add ("minus", '\u2212');
 253                         entities.Add ("lowast", '\u2217');
 254                         entities.Add ("radic", '\u221A');
 255                         entities.Add ("prop", '\u221D');
 256                         entities.Add ("infin", '\u221E');
 257                         entities.Add ("ang", '\u2220');
 258                         entities.Add ("and", '\u2227');
 259                         entities.Add ("or", '\u2228');
 260                         entities.Add ("cap", '\u2229');
 261                         entities.Add ("cup", '\u222A');
 262                         entities.Add ("int", '\u222B');
 263                         entities.Add ("there4", '\u2234');
 264                         entities.Add ("sim", '\u223C');
 265                         entities.Add ("cong", '\u2245');
 266                         entities.Add ("asymp", '\u2248');
 267                         entities.Add ("ne", '\u2260');
 268                         entities.Add ("equiv", '\u2261');
 269                         entities.Add ("le", '\u2264');
 270                         entities.Add ("ge", '\u2265');
 271                         entities.Add ("sub", '\u2282');
 272                         entities.Add ("sup", '\u2283');
 273                         entities.Add ("nsub", '\u2284');
 274                         entities.Add ("sube", '\u2286');
 275                         entities.Add ("supe", '\u2287');
 276                         entities.Add ("oplus", '\u2295');
 277                         entities.Add ("otimes", '\u2297');
 278                         entities.Add ("perp", '\u22A5');
 279                         entities.Add ("sdot", '\u22C5');
 280                         entities.Add ("lceil", '\u2308');
 281                         entities.Add ("rceil", '\u2309');
 282                         entities.Add ("lfloor", '\u230A');
 283                         entities.Add ("rfloor", '\u230B');
 284                         entities.Add ("lang", '\u2329');
 285                         entities.Add ("rang", '\u232A');
 286                         entities.Add ("loz", '\u25CA');
 287                         entities.Add ("spades", '\u2660');
 288                         entities.Add ("clubs", '\u2663');
 289                         entities.Add ("hearts", '\u2665');
 290                         entities.Add ("diams", '\u2666');
 291                         entities.Add ("quot", '\u0022');
 292                         entities.Add ("amp", '\u0026');
 293                         entities.Add ("lt", '\u003C');
 294                         entities.Add ("gt", '\u003E');
 295                         entities.Add ("OElig", '\u0152');
 296                         entities.Add ("oelig", '\u0153');
 297                         entities.Add ("Scaron", '\u0160');
 298                         entities.Add ("scaron", '\u0161');
 299                         entities.Add ("Yuml", '\u0178');
 300                         entities.Add ("circ", '\u02C6');
 301                         entities.Add ("tilde", '\u02DC');
 302                         entities.Add ("ensp", '\u2002');
 303                         entities.Add ("emsp", '\u2003');
 304                         entities.Add ("thinsp", '\u2009');
 305                         entities.Add ("zwnj", '\u200C');
 306                         entities.Add ("zwj", '\u200D');
 307                         entities.Add ("lrm", '\u200E');
 308                         entities.Add ("rlm", '\u200F');
 309                         entities.Add ("ndash", '\u2013');
 310                         entities.Add ("mdash", '\u2014');
 311                         entities.Add ("lsquo", '\u2018');
 312                         entities.Add ("rsquo", '\u2019');
 313                         entities.Add ("sbquo", '\u201A');
 314                         entities.Add ("ldquo", '\u201C');
 315                         entities.Add ("rdquo", '\u201D');
 316                         entities.Add ("bdquo", '\u201E');
 317                         entities.Add ("dagger", '\u2020');
 318                         entities.Add ("Dagger", '\u2021');
 319                         entities.Add ("permil", '\u2030');
 320                         entities.Add ("lsaquo", '\u2039');
 321                         entities.Add ("rsaquo", '\u203A');
 322                         entities.Add ("euro", '\u20AC');
 323                 }
 324
 325 #if NET_2_0
 326                 [Obsolete]
 327 #endif
 328                 public HttpUtility ()
 329                 {
 330                 }
 331
 332                 #endregion // Constructors
 333
 334                 #region Methods
 335
 336                 public static void HtmlAttributeEncode (string s, TextWriter output)
 337                 {
 338                         output.Write(HtmlAttributeEncode(s));
 339                 }
 340
 341                 public static string HtmlAttributeEncode (string s)
 342                 {
 343                         if (null == s)
 344                                 return null;
 345
 346                         if (s.IndexOf ('&') == -1 && s.IndexOf ('"') == -1)
 347                                 return s;
 348
 349                         StringBuilder output = new StringBuilder ();
 350                         foreach (char c in s)
 351                                 switch (c) {
 352                                 case '&' :
 353                                         output.Append ("&amp;");
 354                                         break;
 355                                 case '"' :
 356                                         output.Append ("&quot;");
 357                                         break;
 358                                 default:
 359                                         output.Append (c);
 360                                         break;
 361                                 }
 362
 363                         return output.ToString();
 364                 }
 365
 366                 public static string UrlDecode (string str)
 367                 {
 368                         return UrlDecode(str, Encoding.UTF8);
 369                 }
 370
 371                 private static char [] GetChars (MemoryStream b, Encoding e)
 372                 {
 373                         return e.GetChars (b.GetBuffer (), 0, (int) b.Length);
 374                 }
 375
 376                 public static string UrlDecode (string s, Encoding e)
 377                 {
 378                         if (null == s)
 379                                 return null;
 380
 381                         if (s.IndexOf ('%') == -1 && s.IndexOf ('+') == -1)
 382                                 return s;
 383
 384                         if (e == null)
 385                                 e = Encoding.UTF8;
 386
 387                         StringBuilder output = new StringBuilder ();
 388                         long len = s.Length;
 389                         NumberStyles hexa = NumberStyles.HexNumber;
 390                         MemoryStream bytes = new MemoryStream ();
 391
 392                         for (int i = 0; i < len; i++) {
 393                                 if (s [i] == '%' && i + 2 < len) {
 394                                         if (s [i + 1] == 'u' && i + 5 < len) {
 395                                                 if (bytes.Length > 0) {
 396                                                         output.Append (GetChars (bytes, e));
 397                                                         bytes.SetLength (0);
 398                                                 }
 399                                                 output.Append ((char) Int32.Parse (s.Substring (i + 2, 4), hexa));
 400                                                 i += 5;
 401                                         } else {
 402                                                 bytes.WriteByte ((byte) Int32.Parse (s.Substring (i + 1, 2), hexa));
 403                                                 i += 2;
 404                                         }
 405                                         continue;
 406                                 }
 407
 408                                 if (bytes.Length > 0) {
 409                                         output.Append (GetChars (bytes, e));
 410                                         bytes.SetLength (0);
 411                                 }
 412
 413                                 if (s [i] == '+') {
 414                                         output.Append (' ');
 415                                 } else {
 416                                         output.Append (s [i]);
 417                                 }
 418                         }
 419
 420                         if (bytes.Length > 0) {
 421                                 output.Append (GetChars (bytes, e));
 422                         }
 423
 424                         bytes = null;
 425                         return output.ToString ();
 426                 }
 427
 428                 public static string UrlDecode (byte [] bytes, Encoding e)
 429                 {
 430                         if (bytes == null)
 431                                 return null;
 432
 433                         return UrlDecode (bytes, 0, bytes.Length, e);
 434                 }
 435
 436                 private static int GetInt (byte b)
 437                 {
 438                         char c = Char.ToUpper ((char) b);
 439                         if (c >= '0' && c <= '9')
 440                                 return c - '0';
 441
 442                         if (c < 'A' || c > 'F')
 443                                 return 0;
 444
 445                         return (c - 'A' + 10);
 446                 }
 447
 448                 private static char GetChar (byte [] bytes, int offset, int length)
 449                 {
 450                         int value = 0;
 451                         int end = length + offset;
 452                         for (int i = offset; i < end; i++)
 453                                 value = (value << 4) + GetInt (bytes [i]);
 454
 455                         return (char) value;
 456                 }
 457
 458                 public static string UrlDecode (byte [] bytes, int offset, int count, Encoding e)
 459                 {
 460                         if (bytes == null)
 461                                 return null;
 462                         if (count == 0)
 463                                 return String.Empty;
 464
 465                         if (bytes == null)
 466                                 throw new ArgumentNullException ("bytes");
 467
 468                         if (offset < 0 || offset > bytes.Length)
 469                                 throw new ArgumentOutOfRangeException ("offset");
 470
 471                         if (count < 0 || offset + count > bytes.Length)
 472                                 throw new ArgumentOutOfRangeException ("count");
 473
 474                         StringBuilder output = new StringBuilder ();
 475                         MemoryStream acc = new MemoryStream ();
 476
 477                         int end = count + offset;
 478                         for (int i = offset; i < end; i++) {
 479                                 if (bytes [i] == '%' && i + 2 < count) {
 480                                         if (bytes [i + 1] == (byte) 'u' && i + 5 < end) {
 481                                                 if (acc.Length > 0) {
 482                                                         output.Append (GetChars (acc, e));
 483                                                         acc.SetLength (0);
 484                                                 }
 485                                                 output.Append (GetChar (bytes, i + 2, 4));
 486                                                 i += 5;
 487                                         } else {
 488                                                 acc.WriteByte ((byte) GetChar (bytes, i + 1, 2));
 489                                                 i += 2;
 490                                         }
 491                                         continue;
 492                                 }
 493
 494                                 if (acc.Length > 0) {
 495                                         output.Append (GetChars (acc, e));
 496                                         acc.SetLength (0);
 497                                 }
 498
 499                                 if (bytes [i] == '+') {
 500                                         output.Append (' ');
 501                                 } else {
 502                                         output.Append ((char) bytes [i]);
 503                                 }
 504                         }
 505
 506                         if (acc.Length > 0) {
 507                                 output.Append (GetChars (acc, e));
 508                         }
 509
 510                         acc = null;
 511                         return output.ToString ();
 512                 }
 513
 514                 public static byte [] UrlDecodeToBytes (byte [] bytes)
 515                 {
 516                         if (bytes == null)
 517                                 return null;
 518
 519                         return UrlDecodeToBytes (bytes, 0, bytes.Length);
 520                 }
 521
 522                 public static byte [] UrlDecodeToBytes (string str)
 523                 {
 524                         return UrlDecodeToBytes (str, Encoding.UTF8);
 525                 }
 526
 527                 public static byte [] UrlDecodeToBytes (string str, Encoding e)
 528                 {
 529                         if (str == null)
 530                                 return null;
 531
 532                         if (e == null)
 533                                 throw new ArgumentNullException ("e");
 534
 535                         return UrlDecodeToBytes (e.GetBytes (str));
 536                 }
 537
 538                 public static byte [] UrlDecodeToBytes (byte [] bytes, int offset, int count)
 539                 {
 540                         if (bytes == null)
 541                                 return null;
 542                         if (count == 0)
 543                                 return new byte [0];
 544
 545                         int len = bytes.Length;
 546                         if (offset < 0 || offset >= len)
 547                                 throw new ArgumentOutOfRangeException("offset");
 548
 549                         if (count < 0 || offset > len - count)
 550                                 throw new ArgumentOutOfRangeException("count");
 551
 552                         MemoryStream result = new MemoryStream ();
 553                         int end = offset + count;
 554                         for (int i = offset; i < end; i++){
 555                                 char c = (char) bytes [i];
 556                                 if (c == '+')
 557                                         c = ' ';
 558                                 else if (c == '%' && i < end - 2) {
 559                                         c = GetChar (bytes, i + 1, 2);
 560                                         i += 2;
 561                                 }
 562                                 result.WriteByte ((byte) c);
 563                         }
 564
 565                         return result.ToArray ();
 566                 }
 567
 568                 public static string UrlEncode(string str)
 569                 {
 570                         return UrlEncode(str, Encoding.UTF8);
 571                 }
 572
 573                 public static string UrlEncode (string s, Encoding Enc)
 574                 {
 575                         if (s == null)
 576                                 return null;
 577
 578                         if (s == "")
 579                                 return "";
 580
 581                         byte [] bytes = Enc.GetBytes (s);
 582                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 583                 }
 584
 585                 public static string UrlEncode (byte [] bytes)
 586                 {
 587                         if (bytes == null)
 588                                 return null;
 589
 590                         if (bytes.Length == 0)
 591                                 return "";
 592
 593                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, 0, bytes.Length));
 594                 }
 595
 596                 public static string UrlEncode (byte [] bytes, int offset, int count)
 597                 {
 598                         if (bytes == null)
 599                                 return null;
 600
 601                         if (bytes.Length == 0)
 602                                 return "";
 603
 604                         return Encoding.ASCII.GetString (UrlEncodeToBytes (bytes, offset, count));
 605                 }
 606
 607                 public static byte [] UrlEncodeToBytes (string str)
 608                 {
 609                         return UrlEncodeToBytes (str, Encoding.UTF8);
 610                 }
 611
 612                 public static byte [] UrlEncodeToBytes (string str, Encoding e)
 613                 {
 614                         if (str == null)
 615                                 return null;
 616
 617                         if (str == "")
 618                                 return new byte [0];
 619
 620                         byte [] bytes = e.GetBytes (str);
 621                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 622                 }
 623
 624                 public static byte [] UrlEncodeToBytes (byte [] bytes)
 625                 {
 626                         if (bytes == null)
 627                                 return null;
 628
 629                         if (bytes.Length == 0)
 630                                 return new byte [0];
 631
 632                         return UrlEncodeToBytes (bytes, 0, bytes.Length);
 633                 }
 634
 635                 static char [] hexChars = "0123456789abcdef".ToCharArray ();
 636
 637                 public static byte [] UrlEncodeToBytes (byte [] bytes, int offset, int count)
 638                 {
 639                         if (bytes == null)
 640                                 return null;
 641
 642                         int len = bytes.Length;
 643                         if (len == 0)
 644                                 return new byte [0];
 645
 646                         if (offset < 0 || offset >= len)
 647                                 throw new ArgumentOutOfRangeException("offset");
 648
 649                         if (count < 0 || count > len - offset)
 650                                 throw new ArgumentOutOfRangeException("count");
 651
 652                         MemoryStream result = new MemoryStream ();
 653                         int end = offset + count;
 654                         for (int i = offset; i < end; i++) {
 655                                 char c = (char) bytes [i];
 656                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 657                                     (c < 'A' && c > '9') ||
 658                                     (c > 'Z' && c < 'a' && c != '_') ||
 659                                     (c > 'z')) {
 660                                         result.WriteByte ((byte) '%');
 661                                         int idx = ((int) c) >> 4;
 662                                         result.WriteByte ((byte) hexChars [idx]);
 663                                         idx = ((int) c) & 0x0F;
 664                                         result.WriteByte ((byte) hexChars [idx]);
 665                                 } else {
 666                                         result.WriteByte ((byte) c);
 667                                 }
 668                         }
 669
 670                         return result.ToArray ();
 671                 }
 672
 673                 public static string UrlEncodeUnicode (string str)
 674                 {
 675                         if (str == null)
 676                                 return null;
 677
 678                         StringBuilder result = new StringBuilder ();
 679                         int end = str.Length;
 680                         for (int i = 0; i < end; i++) {
 681                                 int idx;
 682                                 char c = str [i];
 683                                 if (c > 255) {
 684                                         result.Append ("%u");
 685                                         idx = ((int) c) >> 24;
 686                                         result.Append (hexChars [idx]);
 687                                         idx = (((int) c) >> 16) & 0x0F;
 688                                         result.Append (hexChars [idx]);
 689                                         idx = (((int) c) >> 8) & 0x0F;
 690                                         result.Append (hexChars [idx]);
 691                                         idx = ((int) c) & 0x0F;
 692                                         result.Append (hexChars [idx]);
 693                                         continue;
 694                                 }
 695
 696                                 if ((c == ' ') || (c < '0' && c != '-' && c != '.') ||
 697                                     (c < 'A' && c > '9') ||
 698                                     (c > 'Z' && c < 'a' && c != '_') ||
 699                                     (c > 'z')) {
 700                                         result.Append ('%');
 701                                         idx = ((int) c) >> 4;
 702                                         result.Append (hexChars [idx]);
 703                                         idx = ((int) c) & 0x0F;
 704                                         result.Append (hexChars [idx]);
 705                                         continue;
 706                                 }
 707
 708                                 result.Append (c);
 709                         }
 710
 711                         return result.ToString ();
 712                 }
 713
 714                 public static byte [] UrlEncodeUnicodeToBytes (string str)
 715                 {
 716                         if (str == null)
 717                                 return null;
 718
 719                         if (str == "")
 720                                 return new byte [0];
 721
 722                         return Encoding.ASCII.GetBytes (UrlEncodeUnicode (str));
 723                 }
 724
 725                 /// <summary>
 726                 /// Decodes an HTML-encoded string and returns the decoded string.
 727                 /// </summary>
 728                 /// <param name="s">The HTML string to decode. </param>
 729                 /// <returns>The decoded text.</returns>
 730                 public static string HtmlDecode (string s)
 731                 {
 732                         if (s == null)
 733                                 throw new ArgumentNullException ("s");
 734
 735                         if (s.IndexOf ('&') == -1)
 736                                 return s;
 737
 738                         StringBuilder entity = new StringBuilder ();
 739                         StringBuilder output = new StringBuilder ();
 740                         int len = s.Length;
 741                         // 0 -> nothing,
 742                         // 1 -> right after '&'
 743                         // 2 -> between '&' and ';' but no '#'
 744                         // 3 -> '#' found after '&' and getting numbers
 745                         int state = 0;
 746                         int number = 0;
 747                         bool have_trailing_digits = false;
 748
 749                         for (int i = 0; i < len; i++) {
 750                                 char c = s [i];
 751                                 if (state == 0) {
 752                                         if (c == '&') {
 753                                                 entity.Append (c);
 754                                                 state = 1;
 755                                         } else {
 756                                                 output.Append (c);
 757                                         }
 758                                         continue;
 759                                 }
 760
 761                                 if (c == '&') {
 762                                         state = 1;
 763                                         if (have_trailing_digits) {
 764                                                 entity.Append (number.ToString (CultureInfo.InvariantCulture));
 765                                                 have_trailing_digits = false;
 766                                         }
 767
 768                                         output.Append (entity.ToString ());
 769                                         entity.Length = 0;
 770                                         entity.Append ('&');
 771                                         continue;
 772                                 }
 773
 774                                 if (state == 1) {
 775                                         if (c == ';') {
 776                                                 state = 0;
 777                                                 output.Append (entity.ToString ());
 778                                                 output.Append (c);
 779                                                 entity.Length = 0;
 780                                         } else {
 781                                                 number = 0;
 782                                                 if (c != '#') {
 783                                                         state = 2;
 784                                                 } else {
 785                                                         state = 3;
 786                                                 }
 787                                                 entity.Append (c);
 788                                         }
 789                                 } else if (state == 2) {
 790                                         entity.Append (c);
 791                                         if (c == ';') {
 792                                                 string key = entity.ToString ();
 793                                                 if (key.Length > 1 && Entities.ContainsKey (key.Substring (1, key.Length - 2)))
 794                                                         key = Entities [key.Substring (1, key.Length - 2)].ToString ();
 795
 796                                                 output.Append (key);
 797                                                 state = 0;
 798                                                 entity.Length = 0;
 799                                         }
 800                                 } else if (state == 3) {
 801                                         if (c == ';') {
 802                                                 if (number > 65535) {
 803                                                         output.Append ("&#");
 804                                                         output.Append (number.ToString (CultureInfo.InvariantCulture));
 805                                                         output.Append (";");
 806                                                 } else {
 807                                                         output.Append ((char) number);
 808                                                 }
 809                                                 state = 0;
 810                                                 entity.Length = 0;
 811                                                 have_trailing_digits = false;
 812                                         } else if (Char.IsDigit (c)) {
 813                                                 number = number * 10 + ((int) c - '0');
 814                                                 have_trailing_digits = true;
 815                                         } else {
 816                                                 state = 2;
 817                                                 if (have_trailing_digits) {
 818                                                         entity.Append (number.ToString (CultureInfo.InvariantCulture));
 819                                                         have_trailing_digits = false;
 820                                                 }
 821                                                 entity.Append (c);
 822                                         }
 823                                 }
 824                         }
 825
 826                         if (entity.Length > 0) {
 827                                 output.Append (entity.ToString ());
 828                         } else if (have_trailing_digits) {
 829                                 output.Append (number.ToString (CultureInfo.InvariantCulture));
 830                         }
 831                         return output.ToString ();
 832                 }
 833
 834                 /// <summary>
 835                 /// Decodes an HTML-encoded string and sends the resulting output to a TextWriter output stream.
 836                 /// </summary>
 837                 /// <param name="s">The HTML string to decode</param>
 838                 /// <param name="output">The TextWriter output stream containing the decoded string. </param>
 839                 public static void HtmlDecode(string s, TextWriter output)
 840                 {
 841                         if (s != null)
 842                                 output.Write (HtmlDecode (s));
 843                 }
 844
 845                 /// <summary>
 846                 /// HTML-encodes a string and returns the encoded string.
 847                 /// </summary>
 848                 /// <param name="s">The text string to encode. </param>
 849                 /// <returns>The HTML-encoded text.</returns>
 850                 public static string HtmlEncode (string s)
 851                 {
 852                         if (s == null)
 853                                 return null;
 854
 855                         StringBuilder output = new StringBuilder ();
 856
 857                         foreach (char c in s)
 858                                 switch (c) {
 859                                 case '&' :
 860                                         output.Append ("&amp;");
 861                                         break;
 862                                 case '>' :
 863                                         output.Append ("&gt;");
 864                                         break;
 865                                 case '<' :
 866                                         output.Append ("&lt;");
 867                                         break;
 868                                 case '"' :
 869                                         output.Append ("&quot;");
 870                                         break;
 871                                 default:
 872                                         // MS starts encoding with &# from 160 and stops at 255.
 873                                         // We don't do that. One reason is the 65308/65310 unicode
 874                                         // characters that look like '<' and '>'.
 875                                         if (c > 159) {
 876                                                 output.Append ("&#");
 877                                                 output.Append (((int) c).ToString (CultureInfo.InvariantCulture));
 878                                                 output.Append (";");
 879                                         } else {
 880                                                 output.Append (c);
 881                                         }
 882                                         break;
 883                                 }
 884                         return output.ToString ();
 885                 }
 886
 887                 /// <summary>
 888                 /// HTML-encodes a string and sends the resulting output to a TextWriter output stream.
 889                 /// </summary>
 890                 /// <param name="s">The string to encode. </param>
 891                 /// <param name="output">The TextWriter output stream containing the encoded string. </param>
 892                 public static void HtmlEncode(string s, TextWriter output)
 893                 {
 894                         if (s != null)
 895                                 output.Write (HtmlEncode (s));
 896                 }
 897
 898 #if NET_1_1
 899                 public static string UrlPathEncode (string s)
 900                 {
 901                         if (s == null)
 902                                 return null;
 903
 904                         int idx = s.IndexOf ("?");
 905                         string s2 = null;
 906                         if (idx != -1) {
 907                                 s2 = s.Substring (0, idx-1);
 908                                 s2 = UrlEncode (s2) + s.Substring (idx);
 909                         } else {
 910                                 s2 = UrlEncode (s);
 911                         }
 912
 913                         return s2;
 914                 }
 915 #endif
 916
 917 #if NET_2_0
 918                 [MonoTODO]
 919                 public static NameValueCollection ParseQueryString (string query)
 920                 {
 921                         // LAMESPEC: default encoding not specified
 922                         throw new NotImplementedException ();
 923                 }
 924
 925                 [MonoTODO]
 926                 public static NameValueCollection ParseQueryString (string query, Encoding encoding)
 927                 {
 928                         throw new NotImplementedException ();
 929                 }
 930 #endif
 931                 #endregion // Methods
 932         }
 933 }
 934