mcs/class/corlib/Mono.Security/Uri.cs

   1 //
   2 // Mono.Security.Uri
   3 //      Adapted from System.Uri (in System.dll assembly) for its use in corlib
   4 //
   5 // Authors:
   6 //    Lawrence Pit (loz@cable.a2000.nl)
   7 //    Garrett Rooney (rooneg@electricjellyfish.net)
   8 //    Ian MacLean (ianm@activestate.com)
   9 //    Ben Maurer (bmaurer@users.sourceforge.net)
  10 //    Atsushi Enomoto (atsushi@ximian.com)
  11 //
  12 // (C) 2001 Garrett Rooney
  13 // (C) 2003 Ian MacLean
  14 // (C) 2003 Ben Maurer
  15 // (C) 2003 Novell inc.
  16 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  17 //
  18 // Permission is hereby granted, free of charge, to any person obtaining
  19 // a copy of this software and associated documentation files (the
  20 // "Software"), to deal in the Software without restriction, including
  21 // without limitation the rights to use, copy, modify, merge, publish,
  22 // distribute, sublicense, and/or sell copies of the Software, and to
  23 // permit persons to whom the Software is furnished to do so, subject to
  24 // the following conditions:
  25 //
  26 // The above copyright notice and this permission notice shall be
  27 // included in all copies or substantial portions of the Software.
  28 //
  29 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  30 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  31 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  32 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  33 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  34 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  35 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  36 //
  37
  38 using System;
  39 using System.IO;
  40 using System.Text;
  41 using System.Collections;
  42 using System.Globalization;
  43
  44 // See RFC 2396 for more info on URI's.
  45
  46 // TODO: optimize by parsing host string only once
  47
  48 namespace Mono.Security {
  49
  50 #if INSIDE_CORLIB
  51         internal
  52 #else
  53         public
  54 #endif
  55         enum UriPartial {
  56                 Scheme = 0,
  57                 Authority = 1,
  58                 Path = 2,
  59         }
  60
  61 #if INSIDE_CORLIB
  62         internal
  63 #else
  64         public
  65 #endif
  66         class Uri {
  67
  68                 // NOTES:
  69                 // o  scheme excludes the scheme delimiter
  70                 // o  port is -1 to indicate no port is defined
  71                 // o  path is empty or starts with / when scheme delimiter == "://"
  72                 // o  query is empty or starts with ? char, escaped.
  73                 // o  fragment is empty or starts with # char, unescaped.
  74                 // o  all class variables are in escaped format when they are escapable,
  75                 //    except cachedToString.
  76                 // o  UNC is supported, as starts with "\\" for windows,
  77                 //    or "//" with unix.
  78
  79                 private bool isUnixFilePath = false;
  80                 private string source;
  81                 private string scheme = String.Empty;
  82                 private string host = String.Empty;
  83                 private int port = -1;
  84                 private string path = String.Empty;
  85                 private string query = String.Empty;
  86                 private string fragment = String.Empty;
  87                 private string userinfo = String.Empty;
  88                 private bool isUnc = false;
  89                 private bool isOpaquePart = false;
  90
  91                 private string [] segments;
  92
  93                 private bool userEscaped = false;
  94                 private string cachedAbsoluteUri = null;
  95                 private string cachedToString = null;
  96                 private string cachedLocalPath = null;
  97                 private int cachedHashCode = 0;
  98                 private bool reduce = true;
  99
 100                 private static readonly string hexUpperChars = "0123456789ABCDEF";
 101
 102                 // Fields
 103
 104                 public static readonly string SchemeDelimiter = "://";
 105                 public static readonly string UriSchemeFile = "file";
 106                 public static readonly string UriSchemeFtp = "ftp";
 107                 public static readonly string UriSchemeGopher = "gopher";
 108                 public static readonly string UriSchemeHttp = "http";
 109                 public static readonly string UriSchemeHttps = "https";
 110                 public static readonly string UriSchemeMailto = "mailto";
 111                 public static readonly string UriSchemeNews = "news";
 112                 public static readonly string UriSchemeNntp = "nntp";
 113
 114                 // Constructors
 115
 116                 public Uri (string uriString) : this (uriString, false)
 117                 {
 118                 }
 119
 120                 public Uri (string uriString, bool dontEscape)
 121                 {
 122                         userEscaped = dontEscape;
 123                         source = uriString;
 124                         Parse ();
 125                 }
 126
 127                 public Uri (string uriString, bool dontEscape, bool reduce)
 128                 {
 129                         userEscaped = dontEscape;
 130                         source = uriString;
 131                         this.reduce = reduce;
 132                         Parse ();
 133                 }
 134
 135                 public Uri (Uri baseUri, string relativeUri)
 136                         : this (baseUri, relativeUri, false)
 137                 {
 138                 }
 139
 140                 public Uri (Uri baseUri, string relativeUri, bool dontEscape)
 141                 {
 142                         if (baseUri == null)
 143                                 throw new NullReferenceException ("baseUri");
 144
 145                         // See RFC 2396 Par 5.2 and Appendix C
 146
 147                         userEscaped = dontEscape;
 148
 149                         if (relativeUri == null)
 150                                 throw new NullReferenceException ("relativeUri");
 151
 152                         // Check Windows UNC (for // it is scheme/host separator)
 153                         if (relativeUri.StartsWith ("\\\\")) {
 154                                 source = relativeUri;
 155                                 Parse ();
 156                                 return;
 157                         }
 158
 159                         int pos = relativeUri.IndexOf (':');
 160                         if (pos != -1) {
 161
 162                                 int pos2 = relativeUri.IndexOfAny (new char [] {'/', '\\', '?'});
 163
 164                                 // pos2 < 0 ... e.g. mailto
 165                                 // pos2 > pos ... to block ':' in query part
 166                                 if (pos2 > pos || pos2 < 0) {
 167                                         // equivalent to new Uri (relativeUri, dontEscape)
 168                                         source = relativeUri;
 169                                         Parse ();
 170
 171                                         return;
 172                                 }
 173                         }
 174
 175                         this.scheme = baseUri.scheme;
 176                         this.host = baseUri.host;
 177                         this.port = baseUri.port;
 178                         this.userinfo = baseUri.userinfo;
 179                         this.isUnc = baseUri.isUnc;
 180                         this.isUnixFilePath = baseUri.isUnixFilePath;
 181                         this.isOpaquePart = baseUri.isOpaquePart;
 182
 183                         if (relativeUri == String.Empty) {
 184                                 this.path = baseUri.path;
 185                                 this.query = baseUri.query;
 186                                 this.fragment = baseUri.fragment;
 187                                 return;
 188                         }
 189
 190                         // 8 fragment
 191                         // Note that in relative constructor, file URI cannot handle '#' as a filename character, but just regarded as a fragment identifier.
 192                         pos = relativeUri.IndexOf ('#');
 193                         if (pos != -1) {
 194                                 fragment = relativeUri.Substring (pos);
 195                                 // fragment is not escaped.
 196                                 relativeUri = relativeUri.Substring (0, pos);
 197                         }
 198
 199                         // 6 query
 200                         pos = relativeUri.IndexOf ('?');
 201                         if (pos != -1) {
 202                                 query = relativeUri.Substring (pos);
 203                                 if (!userEscaped)
 204                                         query = EscapeString (query);
 205                                 relativeUri = relativeUri.Substring (0, pos);
 206                         }
 207
 208                         if (relativeUri.Length > 0 && relativeUri [0] == '/') {
 209                                 if (relativeUri.Length > 1 && relativeUri [1] == '/') {
 210                                         source = scheme + ':' + relativeUri;
 211                                         Parse ();
 212                                         return;
 213                                 } else {
 214                                         path = relativeUri;
 215                                         if (!userEscaped)
 216                                                 path = EscapeString (path);
 217                                         return;
 218                                 }
 219                         }
 220
 221                         // par 5.2 step 6 a)
 222                         path = baseUri.path;
 223                         if (relativeUri.Length > 0 || query.Length > 0) {
 224                                 pos = path.LastIndexOf ('/');
 225                                 if (pos >= 0)
 226                                         path = path.Substring (0, pos + 1);
 227                         }
 228
 229                         if(relativeUri.Length == 0)
 230                                 return;
 231
 232                         // 6 b)
 233                         path += relativeUri;
 234
 235                         // 6 c)
 236                         int startIndex = 0;
 237                         while (true) {
 238                                 pos = path.IndexOf ("./", startIndex);
 239                                 if (pos == -1)
 240                                         break;
 241                                 if (pos == 0)
 242                                         path = path.Remove (0, 2);
 243                                 else if (path [pos - 1] != '.')
 244                                         path = path.Remove (pos, 2);
 245                                 else
 246                                         startIndex = pos + 1;
 247                         }
 248
 249                         // 6 d)
 250                         if (path.Length > 1 &&
 251                             path [path.Length - 1] == '.' &&
 252                             path [path.Length - 2] == '/')
 253                                 path = path.Remove (path.Length - 1, 1);
 254
 255                         // 6 e)
 256                         startIndex = 0;
 257                         while (true) {
 258                                 pos = path.IndexOf ("/../", startIndex);
 259                                 if (pos == -1)
 260                                         break;
 261                                 if (pos == 0) {
 262                                         startIndex = 3;
 263                                         continue;
 264                                 }
 265                                 int pos2 = path.LastIndexOf ('/', pos - 1);
 266                                 if (pos2 == -1) {
 267                                         startIndex = pos + 1;
 268                                 } else {
 269                                         if (path.Substring (pos2 + 1, pos - pos2 - 1) != "..")
 270                                                 path = path.Remove (pos2 + 1, pos - pos2 + 3);
 271                                         else
 272                                                 startIndex = pos + 1;
 273                                 }
 274                         }
 275
 276                         // 6 f)
 277                         if (path.Length > 3 && path.EndsWith ("/..")) {
 278                                 pos = path.LastIndexOf ('/', path.Length - 4);
 279                                 if (pos != -1)
 280                                         if (path.Substring (pos + 1, path.Length - pos - 4) != "..")
 281                                                 path = path.Remove (pos + 1, path.Length - pos - 1);
 282                         }
 283
 284                         if (!userEscaped)
 285                                 path = EscapeString (path);
 286                 }
 287
 288                 // Properties
 289
 290                 public string AbsolutePath {
 291                         get { return path; }
 292                 }
 293
 294                 public string AbsoluteUri {
 295                         get {
 296                                 if (cachedAbsoluteUri == null) {
 297                                         cachedAbsoluteUri = GetLeftPart (UriPartial.Path) + query + fragment;
 298                                 }
 299                                 return cachedAbsoluteUri;
 300                         }
 301                 }
 302
 303                 public string Authority {
 304                         get {
 305                                 return (GetDefaultPort (scheme) == port)
 306                                      ? host : host + ":" + port;
 307                         }
 308                 }
 309
 310                 public string Fragment {
 311                         get { return fragment; }
 312                 }
 313
 314                 public string Host {
 315                         get { return host; }
 316                 }
 317
 318 /*              public UriHostNameType HostNameType {
 319                         get {
 320                                 UriHostNameType ret = CheckHostName (host);
 321                                 if (ret != UriHostNameType.Unknown)
 322                                         return ret;
 323
 324                                 // looks it always returns Basic...
 325                                 return UriHostNameType.Basic; //.Unknown;
 326                         }
 327                 }*/
 328
 329                 public bool IsDefaultPort {
 330                         get { return GetDefaultPort (scheme) == port; }
 331                 }
 332
 333                 public bool IsFile {
 334                         get { return (scheme == UriSchemeFile); }
 335                 }
 336
 337                 public bool IsLoopback {
 338                         get {
 339                                 if (host == String.Empty)
 340                                         return false;
 341
 342                                 if (host == "loopback" || host == "localhost")
 343                                         return true;
 344 /*
 345                                 try {
 346                                         if (IPAddress.Loopback.Equals (IPAddress.Parse (host)))
 347                                                 return true;
 348                                 } catch (FormatException) {}
 349
 350                                 try {
 351                                         return IPv6Address.IsLoopback (IPv6Address.Parse (host));
 352                                 } catch (FormatException) {}
 353 */
 354                                 return false;
 355                         }
 356                 }
 357
 358                 public bool IsUnc {
 359                         // rule: This should be true only if
 360                         //   - uri string starts from "\\", or
 361                         //   - uri string starts from "//" (Samba way)
 362                         get { return isUnc; }
 363                 }
 364
 365                 public string LocalPath {
 366                         get {
 367                                 if (cachedLocalPath != null)
 368                                         return cachedLocalPath;
 369                                 if (!IsFile)
 370                                         return AbsolutePath;
 371
 372                                 bool windows = (path.Length > 3 && path [1] == ':' &&
 373                                                 (path [2] == '\\' || path [2] == '/'));
 374
 375                                 if (!IsUnc) {
 376                                         string p = Unescape (path);
 377                                         if (System.IO.Path.DirectorySeparatorChar == '\\' || windows)
 378                                                 cachedLocalPath = p.Replace ('/', '\\');
 379                                         else
 380                                                 cachedLocalPath = p;
 381                                 } else {
 382                                         // support *nix and W32 styles
 383                                         if (path.Length > 1 && path [1] == ':')
 384                                                 cachedLocalPath = Unescape (path.Replace (Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar));
 385
 386                                         // LAMESPEC: ok, now we cannot determine
 387                                         // if such URI like "file://foo/bar" is
 388                                         // Windows UNC or unix file path, so
 389                                         // they should be handled differently.
 390                                         else if (System.IO.Path.DirectorySeparatorChar == '\\')
 391                                                 cachedLocalPath = "\\\\" + Unescape (host + path.Replace ('/', '\\'));
 392                                         else
 393                                                 cachedLocalPath = Unescape (path);
 394                                 }
 395                                 if (cachedLocalPath == String.Empty)
 396                                         cachedLocalPath = Path.DirectorySeparatorChar.ToString ();
 397                                 return cachedLocalPath;
 398                         }
 399                 }
 400
 401                 public string PathAndQuery {
 402                         get { return path + query; }
 403                 }
 404
 405                 public int Port {
 406                         get { return port; }
 407                 }
 408
 409                 public string Query {
 410                         get { return query; }
 411                 }
 412
 413                 public string Scheme {
 414                         get { return scheme; }
 415                 }
 416
 417                 public string [] Segments {
 418                         get {
 419                                 if (segments != null)
 420                                         return segments;
 421
 422                                 if (path == "") {
 423                                         segments = new string [0];
 424                                         return segments;
 425                                 }
 426
 427                                 string [] parts = path.Split ('/');
 428                                 segments = parts;
 429                                 bool endSlash = path.EndsWith ("/");
 430                                 if (parts.Length > 0 && endSlash) {
 431                                         string [] newParts = new string [parts.Length - 1];
 432                                         Array.Copy (parts, 0, newParts, 0, parts.Length - 1);
 433                                         parts = newParts;
 434                                 }
 435
 436                                 int i = 0;
 437                                 if (IsFile && path.Length > 1 && path [1] == ':') {
 438                                         string [] newParts = new string [parts.Length + 1];
 439                                         Array.Copy (parts, 1, newParts, 2, parts.Length - 1);
 440                                         parts = newParts;
 441                                         parts [0] = path.Substring (0, 2);
 442                                         parts [1] = "";
 443                                         i++;
 444                                 }
 445
 446                                 int end = parts.Length;
 447                                 for (; i < end; i++)
 448                                         if (i != end - 1 || endSlash)
 449                                                 parts [i] += '/';
 450
 451                                 segments = parts;
 452                                 return segments;
 453                         }
 454                 }
 455
 456                 public bool UserEscaped {
 457                         get { return userEscaped; }
 458                 }
 459
 460                 public string UserInfo {
 461                         get { return userinfo; }
 462                 }
 463
 464
 465                 // Methods
 466
 467 /*              public static UriHostNameType CheckHostName (string name)
 468                 {
 469                         if (name == null || name.Length == 0)
 470                                 return UriHostNameType.Unknown;
 471
 472                         if (IsIPv4Address (name))
 473                                 return UriHostNameType.IPv4;
 474
 475                         if (IsDomainAddress (name))
 476                                 return UriHostNameType.Dns;
 477
 478                         try {
 479                                 IPv6Address.Parse (name);
 480                                 return UriHostNameType.IPv6;
 481                         } catch (FormatException) {}
 482
 483                         return UriHostNameType.Unknown;
 484                 }*/
 485
 486                 internal static bool IsIPv4Address (string name)
 487                 {
 488                         string [] captures = name.Split (new char [] {'.'});
 489                         if (captures.Length != 4)
 490                                 return false;
 491                         for (int i = 0; i < 4; i++) {
 492                                 try {
 493                                         int d = Int32.Parse (captures [i], CultureInfo.InvariantCulture);
 494                                         if (d < 0 || d > 255)
 495                                                 return false;
 496                                 } catch (Exception) {
 497                                         return false;
 498                                 }
 499                         }
 500                         return true;
 501                 }
 502
 503                 internal static bool IsDomainAddress (string name)
 504                 {
 505                         int len = name.Length;
 506
 507                         if (name [len - 1] == '.')
 508                                 return false;
 509
 510                         int count = 0;
 511                         for (int i = 0; i < len; i++) {
 512                                 char c = name [i];
 513                                 if (count == 0) {
 514                                         if (!Char.IsLetterOrDigit (c))
 515                                                 return false;
 516                                 } else if (c == '.') {
 517                                         count = 0;
 518                                 } else if (!Char.IsLetterOrDigit (c) && c != '-' && c != '_') {
 519                                         return false;
 520                                 }
 521                                 if (++count == 64)
 522                                         return false;
 523                         }
 524
 525                         return true;
 526                 }
 527
 528 /*              [MonoTODO ("Find out what this should do")]
 529                 protected virtual void Canonicalize ()
 530                 {
 531                 }*/
 532
 533                 public static bool CheckSchemeName (string schemeName)
 534                 {
 535                         if (schemeName == null || schemeName.Length == 0)
 536                                 return false;
 537
 538                         if (!Char.IsLetter (schemeName [0]))
 539                                 return false;
 540
 541                         int len = schemeName.Length;
 542                         for (int i = 1; i < len; i++) {
 543                                 char c = schemeName [i];
 544                                 if (!Char.IsLetterOrDigit (c) && c != '.' && c != '+' && c != '-')
 545                                         return false;
 546                         }
 547
 548                         return true;
 549                 }
 550
 551 /*              [MonoTODO ("Find out what this should do")]
 552                 protected virtual void CheckSecurity ()
 553                 {
 554                 }*/
 555
 556                 public override bool Equals (object comparant)
 557                 {
 558                         if (comparant == null)
 559                                 return false;
 560
 561                         Uri uri = comparant as Uri;
 562                         if (uri == null) {
 563                                 string s = comparant as String;
 564                                 if (s == null)
 565                                         return false;
 566                                 uri = new Uri (s);
 567                         }
 568
 569                         CultureInfo inv = CultureInfo.InvariantCulture;
 570                         return ((this.scheme.ToLower (inv) == uri.scheme.ToLower (inv)) &&
 571                                 (this.userinfo.ToLower (inv) == uri.userinfo.ToLower (inv)) &&
 572                                 (this.host.ToLower (inv) == uri.host.ToLower (inv)) &&
 573                                 (this.port == uri.port) &&
 574                                 (this.path == uri.path) &&
 575                                 (this.query.ToLower (inv) == uri.query.ToLower (inv)));
 576                 }
 577
 578                 public override int GetHashCode ()
 579                 {
 580                         if (cachedHashCode == 0)
 581                                 cachedHashCode = scheme.GetHashCode ()
 582                                                + userinfo.GetHashCode ()
 583                                                + host.GetHashCode ()
 584                                                + port
 585                                                + path.GetHashCode ()
 586                                                + query.GetHashCode ();
 587                         return cachedHashCode;
 588                 }
 589
 590                 public string GetLeftPart (UriPartial part)
 591                 {
 592                         int defaultPort;
 593                         switch (part) {
 594                         case UriPartial.Scheme :
 595                                 return scheme + GetOpaqueWiseSchemeDelimiter ();
 596                         case UriPartial.Authority :
 597                                 if (host == String.Empty ||
 598                                     scheme == Uri.UriSchemeMailto ||
 599                                     scheme == Uri.UriSchemeNews)
 600                                         return String.Empty;
 601
 602                                 StringBuilder s = new StringBuilder ();
 603                                 s.Append (scheme);
 604                                 s.Append (GetOpaqueWiseSchemeDelimiter ());
 605                                 if (path.Length > 1 && path [1] == ':' && (Uri.UriSchemeFile == scheme))
 606                                         s.Append ('/');  // win32 file
 607                                 if (userinfo.Length > 0)
 608                                         s.Append (userinfo).Append ('@');
 609                                 s.Append (host);
 610                                 defaultPort = GetDefaultPort (scheme);
 611                                 if ((port != -1) && (port != defaultPort))
 612                                         s.Append (':').Append (port);
 613                                 return s.ToString ();
 614                         case UriPartial.Path :
 615                                 StringBuilder sb = new StringBuilder ();
 616                                 sb.Append (scheme);
 617                                 sb.Append (GetOpaqueWiseSchemeDelimiter ());
 618                                 if (path.Length > 1 && path [1] == ':' && (Uri.UriSchemeFile == scheme))
 619                                         sb.Append ('/');  // win32 file
 620                                 if (userinfo.Length > 0)
 621                                         sb.Append (userinfo).Append ('@');
 622                                 sb.Append (host);
 623                                 defaultPort = GetDefaultPort (scheme);
 624                                 if ((port != -1) && (port != defaultPort))
 625                                         sb.Append (':').Append (port);
 626                                 sb.Append (path);
 627                                 return sb.ToString ();
 628                         }
 629                         return null;
 630                 }
 631
 632                 public static int FromHex (char digit)
 633                 {
 634                         if ('0' <= digit && digit <= '9') {
 635                                 return (int) (digit - '0');
 636                         }
 637
 638                         if ('a' <= digit && digit <= 'f')
 639                                 return (int) (digit - 'a' + 10);
 640
 641                         if ('A' <= digit && digit <= 'F')
 642                                 return (int) (digit - 'A' + 10);
 643
 644                         throw new ArgumentException ("digit");
 645                 }
 646
 647                 public static string HexEscape (char character)
 648                 {
 649                         if (character > 255) {
 650                                 throw new ArgumentOutOfRangeException ("character");
 651                         }
 652
 653                         return "%" + hexUpperChars [((character & 0xf0) >> 4)]
 654                                    + hexUpperChars [((character & 0x0f))];
 655                 }
 656
 657                 public static char HexUnescape (string pattern, ref int index)
 658                 {
 659                         if (pattern == null)
 660                                 throw new ArgumentException ("pattern");
 661
 662                         if (index < 0 || index >= pattern.Length)
 663                                 throw new ArgumentOutOfRangeException ("index");
 664
 665                         int stage = 0;
 666                         int c = 0;
 667                         do {
 668                                 if (((index + 3) > pattern.Length) ||
 669                                     (pattern [index] != '%') ||
 670                                     !IsHexDigit (pattern [index + 1]) ||
 671                                     !IsHexDigit (pattern [index + 2]))
 672                                 {
 673                                         if (stage == 0)
 674                                                 return pattern [index++];
 675                                         break;
 676                                 }
 677
 678                                 index++;
 679                                 int msb = FromHex (pattern [index++]);
 680                                 int lsb = FromHex (pattern [index++]);
 681                                 int b = (msb << 4) + lsb;
 682
 683                                 if (stage == 0) {
 684                                         if (b < 0xc0)
 685                                                 return (char) b;
 686                                         else if (b < 0xE0) {
 687                                                 c = b - 0xc0;
 688                                                 stage = 2;
 689                                         } else if (b < 0xF0) {
 690                                                 c = b - 0xe0;
 691                                                 stage = 3;
 692                                         } else if (b < 0xF8) {
 693                                                 c = b - 0xf0;
 694                                                 stage = 4;
 695                                         } else if (b < 0xFB) {
 696                                                 c = b - 0xf8;
 697                                                 stage = 5;
 698                                         } else if (b < 0xFE) {
 699                                                 c = b - 0xfc;
 700                                                 stage = 6;
 701                                         }
 702                                         c <<= (stage - 1) * 6;
 703                                 }
 704                                 else
 705                                         c += (b - 0x80) << ((stage - 1) * 6);
 706 //Console.WriteLine ("stage {0}: {5:X04} <-- {1:X02}|{2:X01},{3:X01} {4}", new object [] {stage, b, msb, lsb, pattern.Substring (index), c});
 707                                 stage--;
 708                         } while (stage > 0);
 709
 710                         return (char) c;
 711                 }
 712
 713                 public static bool IsHexDigit (char digit)
 714                 {
 715                         return (('0' <= digit && digit <= '9') ||
 716                                 ('a' <= digit && digit <= 'f') ||
 717                                 ('A' <= digit && digit <= 'F'));
 718                 }
 719
 720                 public static bool IsHexEncoding (string pattern, int index)
 721                 {
 722                         if ((index + 3) > pattern.Length)
 723                                 return false;
 724
 725                         return ((pattern [index++] == '%') &&
 726                                 IsHexDigit (pattern [index++]) &&
 727                                 IsHexDigit (pattern [index]));
 728                 }
 729
 730                 public string MakeRelative (Uri toUri)
 731                 {
 732                         if ((this.Scheme != toUri.Scheme) ||
 733                             (this.Authority != toUri.Authority))
 734                                 return toUri.ToString ();
 735
 736                         if (this.path == toUri.path)
 737                                 return String.Empty;
 738
 739                         string [] segments = this.Segments;
 740                         string [] segments2 = toUri.Segments;
 741
 742                         int k = 0;
 743                         int max = System.Math.Min (segments.Length, segments2.Length);
 744                         for (; k < max; k++)
 745                                 if (segments [k] != segments2 [k])
 746                                         break;
 747
 748                         string result = String.Empty;
 749                         for (int i = k + 1; i < segments.Length; i++)
 750                                 result += "../";
 751                         for (int i = k; i < segments2.Length; i++)
 752                                 result += segments2 [i];
 753
 754                         return result;
 755                 }
 756
 757                 public override string ToString ()
 758                 {
 759                         if (cachedToString != null)
 760                                 return cachedToString;
 761                         string q = query.StartsWith ("?") ? '?' + Unescape (query.Substring (1)) : Unescape (query);
 762                         cachedToString = Unescape (GetLeftPart (UriPartial.Path), true) + q + fragment;
 763                         return cachedToString;
 764                 }
 765
 766 /*              void ISerializable.GetObjectData (SerializationInfo info,
 767                                           StreamingContext context)
 768                 {
 769                         info.AddValue ("AbsoluteUri", this.AbsoluteUri);
 770                 }*/
 771
 772
 773                 // Internal Methods
 774
 775                 protected void Escape ()
 776                 {
 777                         path = EscapeString (path);
 778                 }
 779
 780                 protected static string EscapeString (string str)
 781                 {
 782                         return EscapeString (str, false, true, true);
 783                 }
 784
 785                 internal static string EscapeString (string str, bool escapeReserved, bool escapeHex, bool escapeBrackets)
 786                 {
 787                         if (str == null)
 788                                 return String.Empty;
 789
 790                         byte [] data = Encoding.UTF8.GetBytes (str.ToCharArray ());
 791                         StringBuilder s = new StringBuilder ();
 792                         int len = data.Length;
 793                         for (int i = 0; i < len; i++) {
 794                                 char c = (char) data [i];
 795                                 // reserved    = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" | "$" | ","
 796                                 // mark        = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
 797                                 // control     = <US-ASCII coded characters 00-1F and 7F hexadecimal>
 798                                 // space       = <US-ASCII coded character 20 hexadecimal>
 799                                 // delims      = "<" | ">" | "#" | "%" | <">
 800                                 // unwise      = "{" | "}" | "|" | "\" | "^" | "[" | "]" | "`"
 801
 802                                 // check for escape code already placed in str,
 803                                 // i.e. for encoding that follows the pattern
 804                 // "%hexhex" in a string, where "hex" is a digit from 0-9
 805                                 // or a letter from A-F (case-insensitive).
 806                                 if('%'.Equals(c) && IsHexEncoding(str,i))
 807                                 {
 808                                         // if ,yes , copy it as is
 809                                         s.Append(c);
 810                                         s.Append(str[++i]);
 811                                         s.Append(str[++i]);
 812                                         continue;
 813                                 }
 814
 815                                 if ((c <= 0x20) || (c >= 0x7f) ||
 816                                     ("<>%\"{}|\\^`".IndexOf (c) != -1) ||
 817                                     (escapeHex && (c == '#')) ||
 818                                     (escapeBrackets && (c == '[' || c == ']')) ||
 819                                     (escapeReserved && (";/?:@&=+$,".IndexOf (c) != -1))) {
 820                                         s.Append (HexEscape (c));
 821                                         continue;
 822                                 }
 823
 824
 825                                 s.Append (c);
 826                         }
 827
 828                         return s.ToString ();
 829                 }
 830
 831                 // This method is called from .ctor(). When overriden, we can
 832                 // avoid the "absolute uri" constraints of the .ctor() by
 833                 // overriding with custom code.
 834                 protected void Parse ()
 835                 {
 836                         Parse (source);
 837
 838                         if (userEscaped)
 839                                 return;
 840
 841                         host = EscapeString (host, false, true, false);
 842                         path = EscapeString (path);
 843                 }
 844
 845                 protected string Unescape (string str)
 846                 {
 847                         return Unescape (str, false);
 848                 }
 849
 850                 internal string Unescape (string str, bool excludeSharp)
 851                 {
 852                         if (str == null)
 853                                 return String.Empty;
 854                         StringBuilder s = new StringBuilder ();
 855                         int len = str.Length;
 856                         for (int i = 0; i < len; i++) {
 857                                 char c = str [i];
 858                                 if (c == '%') {
 859                                         char x = HexUnescape (str, ref i);
 860                                         if (excludeSharp && x == '#')
 861                                                 s.Append ("%23");
 862                                         else
 863                                                 s.Append (x);
 864                                         i--;
 865                                 } else
 866                                         s.Append (c);
 867                         }
 868                         return s.ToString ();
 869                 }
 870
 871
 872                 // Private Methods
 873
 874                 private void ParseAsWindowsUNC (string uriString)
 875                 {
 876                         scheme = UriSchemeFile;
 877                         port = -1;
 878                         fragment = String.Empty;
 879                         query = String.Empty;
 880                         isUnc = true;
 881
 882                         uriString = uriString.TrimStart (new char [] {'\\'});
 883                         int pos = uriString.IndexOf ('\\');
 884                         if (pos > 0) {
 885                                 path = uriString.Substring (pos);
 886                                 host = uriString.Substring (0, pos);
 887                         } else { // "\\\\server"
 888                                 host = uriString;
 889                                 path = String.Empty;
 890                         }
 891                         path = path.Replace ("\\", "/");
 892                 }
 893
 894                 private void ParseAsWindowsAbsoluteFilePath (string uriString)
 895                 {
 896                         if (uriString.Length > 2 && uriString [2] != '\\'
 897                                         && uriString [2] != '/')
 898                                 throw new FormatException ("Relative file path is not allowed.");
 899                         scheme = UriSchemeFile;
 900                         host = String.Empty;
 901                         port = -1;
 902                         path = uriString.Replace ("\\", "/");
 903                         fragment = String.Empty;
 904                         query = String.Empty;
 905                 }
 906
 907                 private void ParseAsUnixAbsoluteFilePath (string uriString)
 908                 {
 909                         isUnixFilePath = true;
 910                         scheme = UriSchemeFile;
 911                         port = -1;
 912                         fragment = String.Empty;
 913                         query = String.Empty;
 914                         host = String.Empty;
 915                         path = null;
 916
 917                         if (uriString.StartsWith ("//")) {
 918                                 uriString = uriString.TrimStart (new char [] {'/'});
 919                                 // Now we don't regard //foo/bar as "foo" host.
 920                                 /*
 921                                 int pos = uriString.IndexOf ('/');
 922                                 if (pos > 0) {
 923                                         path = '/' + uriString.Substring (pos + 1);
 924                                         host = uriString.Substring (0, pos);
 925                                 } else { // "///server"
 926                                         host = uriString;
 927                                         path = String.Empty;
 928                                 }
 929                                 */
 930                                 path = '/' + uriString;
 931                         }
 932                         if (path == null)
 933                                 path = uriString;
 934                 }
 935
 936                 // this parse method is as relaxed as possible about the format
 937                 // it will hardly ever throw a UriFormatException
 938                 private void Parse (string uriString)
 939                 {
 940                         //
 941                         // From RFC 2396 :
 942                         //
 943                         //      ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
 944                         //       12            3  4          5       6  7        8 9
 945                         //
 946
 947                         if (uriString == null)
 948                                 throw new ArgumentNullException ("uriString");
 949
 950                         int len = uriString.Length;
 951                         if (len <= 1)
 952                                 throw new FormatException ();
 953
 954                         int pos = 0;
 955
 956                         // 1, 2
 957                         // Identify Windows path, unix path, or standard URI.
 958                         pos = uriString.IndexOf (':');
 959                         if (pos < 0) {
 960                                 // It must be Unix file path or Windows UNC
 961                                 if (uriString [0] == '/')
 962                                         ParseAsUnixAbsoluteFilePath (uriString);
 963                                 else if (uriString.StartsWith ("\\\\"))
 964                                         ParseAsWindowsUNC (uriString);
 965                                 else
 966                                         throw new FormatException ("URI scheme was not recognized, nor input string is not recognized as an absolute file path.");
 967                                 return;
 968                         }
 969                         else if (pos == 1) {
 970                                 if (!Char.IsLetter (uriString [0]))
 971                                         throw new FormatException ("URI scheme must start with alphabet character.");
 972                                 // This means 'a:' == windows full path.
 973                                 ParseAsWindowsAbsoluteFilePath (uriString);
 974                                 return;
 975                         }
 976
 977                         // scheme
 978                         scheme = uriString.Substring (0, pos).ToLower (CultureInfo.InvariantCulture);
 979                         // Check scheme name characters as specified in RFC2396.
 980                         if (!Char.IsLetter (scheme [0]))
 981                                         throw new FormatException ("URI scheme must start with alphabet character.");
 982                         for (int i = 1; i < scheme.Length; i++) {
 983                                 if (!Char.IsLetterOrDigit (scheme, i)) {
 984                                         switch (scheme [i]) {
 985                                         case '+':
 986                                         case '-':
 987                                         case '.':
 988                                                 break;
 989                                         default:
 990                                                 throw new FormatException ("URI scheme must consist of one of alphabet, digits, '+', '-' or '.' character.");
 991                                         }
 992                                 }
 993                         }
 994                         uriString = uriString.Substring (pos + 1);
 995
 996                         // 8 fragment
 997                         pos = uriString.IndexOf ('#');
 998                         if (!IsUnc && pos != -1) {
 999                                 fragment = uriString.Substring (pos);
1000                                 uriString = uriString.Substring (0, pos);
1001                         }
1002
1003                         // 6 query
1004                         pos = uriString.IndexOf ('?');
1005                         if (pos != -1) {
1006                                 query = uriString.Substring (pos);
1007                                 uriString = uriString.Substring (0, pos);
1008                                 if (!userEscaped)
1009                                         query = EscapeString (query);
1010                         }
1011
1012                         // 3
1013                         bool unixAbsPath = scheme == UriSchemeFile && uriString.StartsWith ("///");
1014                         if (uriString.StartsWith ("//")) {
1015                                 if (uriString.StartsWith ("////"))
1016                                         unixAbsPath = false;
1017                                 uriString = uriString.TrimStart (new char [] {'/'});
1018                                 if (uriString.Length > 1 && uriString [1] == ':')
1019                                         unixAbsPath = false;
1020                         } else if (!IsPredefinedScheme (scheme)) {
1021                                 path = uriString;
1022                                 isOpaquePart = true;
1023                                 return;
1024                         }
1025
1026                         // 5 path
1027                         pos = uriString.IndexOfAny (new char[] {'/'});
1028                         if (unixAbsPath)
1029                                 pos = -1;
1030                         if (pos == -1) {
1031                                 if ((scheme != Uri.UriSchemeMailto) &&
1032                                     (scheme != Uri.UriSchemeNews) &&
1033                                         (scheme != Uri.UriSchemeFile))
1034                                         path = "/";
1035                         } else {
1036                                 path = uriString.Substring (pos);
1037                                 uriString = uriString.Substring (0, pos);
1038                         }
1039
1040                         // 4.a user info
1041                         pos = uriString.IndexOf ("@");
1042                         if (pos != -1) {
1043                                 userinfo = uriString.Substring (0, pos);
1044                                 uriString = uriString.Remove (0, pos + 1);
1045                         }
1046
1047                         // 4.b port
1048                         port = -1;
1049                         pos = uriString.LastIndexOf (":");
1050                         if (unixAbsPath)
1051                                 pos = -1;
1052                         if (pos != -1 && pos != (uriString.Length - 1)) {
1053                                 string portStr = uriString.Remove (0, pos + 1);
1054                                 if (portStr.Length > 1 && portStr [portStr.Length - 1] != ']') {
1055                                         try {
1056                                                 port = (int) UInt32.Parse (portStr, CultureInfo.InvariantCulture);
1057                                                 uriString = uriString.Substring (0, pos);
1058                                         } catch (Exception) {
1059                                                 throw new FormatException ("Invalid URI: invalid port number");
1060                                         }
1061                                 }
1062                         }
1063                         if (port == -1) {
1064                                 port = GetDefaultPort (scheme);
1065                         }
1066
1067                         // 4 authority
1068                         host = uriString;
1069 /*                      if (host.Length > 1 && host [0] == '[' && host [host.Length - 1] == ']') {
1070                                 try {
1071                                         host = "[" + IPv6Address.Parse (host).ToString () + "]";
1072                                 } catch (Exception) {
1073                                         throw new FormatException ("Invalid URI: The hostname could not be parsed");
1074                                 }
1075                         }*/
1076
1077                         if (unixAbsPath) {
1078                                 path = '/' + uriString;
1079                                 host = String.Empty;
1080                         } else if (host.Length == 2 && host [1] == ':') {
1081                                 // windows filepath
1082                                 path = host + path;
1083                                 host = String.Empty;
1084                         } else if (isUnixFilePath) {
1085                                 uriString = "//" + uriString;
1086                                 host = String.Empty;
1087                         } else if (host.Length == 0) {
1088                                 throw new FormatException ("Invalid URI: The hostname could not be parsed");
1089                         } else if (scheme == UriSchemeFile) {
1090                                 isUnc = true;
1091                         }
1092
1093                         if ((scheme != Uri.UriSchemeMailto) &&
1094                                         (scheme != Uri.UriSchemeNews) &&
1095                                         (scheme != Uri.UriSchemeFile))
1096
1097                         if (reduce)
1098                                 path = Reduce (path);
1099                 }
1100
1101                 private static string Reduce (string path)
1102                 {
1103                         path = path.Replace ('\\','/');
1104                         string [] parts = path.Split ('/');
1105                         ArrayList result = new ArrayList ();
1106
1107                         int end = parts.Length;
1108                         for (int i = 0; i < end; i++) {
1109                                 string current = parts [i];
1110                                 if (current == "" || current == "." )
1111                                         continue;
1112
1113                                 if (current == "..") {
1114                                         if (result.Count == 0) {
1115                                                 if (i == 1) // see bug 52599
1116                                                         continue;
1117                                                 throw new Exception ("Invalid path.");
1118                                         }
1119
1120                                         result.RemoveAt (result.Count - 1);
1121                                         continue;
1122                                 }
1123
1124                                 result.Add (current);
1125                         }
1126
1127                         if (result.Count == 0)
1128                                 return "/";
1129
1130                         result.Insert (0, "");
1131
1132                         string res = String.Join ("/", (string []) result.ToArray (typeof (string)));
1133                         if (path.EndsWith ("/"))
1134                                 res += '/';
1135
1136                         return res;
1137                 }
1138
1139                 private struct UriScheme
1140                 {
1141                         public string scheme;
1142                         public string delimiter;
1143                         public int defaultPort;
1144
1145                         public UriScheme (string s, string d, int p)
1146                         {
1147                                 scheme = s;
1148                                 delimiter = d;
1149                                 defaultPort = p;
1150                         }
1151                 };
1152
1153                 static UriScheme [] schemes = new UriScheme [] {
1154                         new UriScheme (UriSchemeHttp, SchemeDelimiter, 80),
1155                         new UriScheme (UriSchemeHttps, SchemeDelimiter, 443),
1156                         new UriScheme (UriSchemeFtp, SchemeDelimiter, 21),
1157                         new UriScheme (UriSchemeFile, SchemeDelimiter, -1),
1158                         new UriScheme (UriSchemeMailto, ":", 25),
1159                         new UriScheme (UriSchemeNews, ":", -1),
1160                         new UriScheme (UriSchemeNntp, SchemeDelimiter, 119),
1161                         new UriScheme (UriSchemeGopher, SchemeDelimiter, 70),
1162                 };
1163
1164                 internal static string GetSchemeDelimiter (string scheme)
1165                 {
1166                         for (int i = 0; i < schemes.Length; i++)
1167                                 if (schemes [i].scheme == scheme)
1168                                         return schemes [i].delimiter;
1169                         return Uri.SchemeDelimiter;
1170                 }
1171
1172                 internal static int GetDefaultPort (string scheme)
1173                 {
1174                         for (int i = 0; i < schemes.Length; i++)
1175                                 if (schemes [i].scheme == scheme)
1176                                         return schemes [i].defaultPort;
1177                         return -1;
1178                 }
1179
1180                 private string GetOpaqueWiseSchemeDelimiter ()
1181                 {
1182                         if (isOpaquePart)
1183                                 return ":";
1184                         else
1185                                 return GetSchemeDelimiter (scheme);
1186                 }
1187
1188                 protected bool IsBadFileSystemCharacter (char ch)
1189                 {
1190                         // It does not always overlap with InvalidPathChars.
1191                         int chInt = (int) ch;
1192                         if (chInt < 32 || (chInt < 64 && chInt > 57))
1193                                 return true;
1194                         switch (chInt) {
1195                         case 0:
1196                         case 34: // "
1197                         case 38: // &
1198                         case 42: // *
1199                         case 44: // ,
1200                         case 47: // /
1201                         case 92: // \
1202                         case 94: // ^
1203                         case 124: // |
1204                                 return true;
1205                         }
1206
1207                         return false;
1208                 }
1209
1210
1211                 protected static bool IsExcludedCharacter (char ch)
1212                 {
1213                         if (ch <= 32 || ch >= 127)
1214                                 return true;
1215
1216                         if (ch == '"' || ch == '#' || ch == '%' || ch == '<' ||
1217                             ch == '>' || ch == '[' || ch == '\\' || ch == ']' ||
1218                             ch == '^' || ch == '`' || ch == '{' || ch == '|' ||
1219                             ch == '}')
1220                                 return true;
1221                         return false;
1222                 }
1223
1224                 private static bool IsPredefinedScheme (string scheme)
1225                 {
1226                         switch (scheme) {
1227                         case "http":
1228                         case "https":
1229                         case "file":
1230                         case "ftp":
1231                         case "nntp":
1232                         case "gopher":
1233                         case "mailto":
1234                         case "news":
1235                                 return true;
1236                         default:
1237                                 return false;
1238                         }
1239                 }
1240
1241                 protected bool IsReservedCharacter (char ch)
1242                 {
1243                         if (ch == '$' || ch == '&' || ch == '+' || ch == ',' ||
1244                             ch == '/' || ch == ':' || ch == ';' || ch == '=' ||
1245                             ch == '@')
1246                                 return true;
1247                         return false;
1248                 }
1249         }
1250 }