mcs/class/System/System/Uri.cs

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