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 //    Sebastien Pouliot  <sebastien@ximian.com>
  11 //    Stephane Delcroix  <stephane@delcroix.org>
  12 //
  13 // (C) 2001 Garrett Rooney
  14 // (C) 2003 Ian MacLean
  15 // (C) 2003 Ben Maurer
  16 // Copyright (C) 2003,2009 Novell, Inc (http://www.novell.com)
  17 // Copyright (c) 2009 Stephane Delcroix
  18 //
  19 // Permission is hereby granted, free of charge, to any person obtaining
  20 // a copy of this software and associated documentation files (the
  21 // "Software"), to deal in the Software without restriction, including
  22 // without limitation the rights to use, copy, modify, merge, publish,
  23 // distribute, sublicense, and/or sell copies of the Software, and to
  24 // permit persons to whom the Software is furnished to do so, subject to
  25 // the following conditions:
  26 //
  27 // The above copyright notice and this permission notice shall be
  28 // included in all copies or substantial portions of the Software.
  29 //
  30 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  31 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  32 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  33 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  34 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  35 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  36 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  37 //
  38 // See RFC 2396 for more info on URI's.
  39 //
  40 // TODO: optimize by parsing host string only once
  41 //
  42 using System.ComponentModel;
  43 using System.IO;
  44 using System.Net;
  45 using System.Runtime.Serialization;
  46 using System.Text;
  47 using System.Collections;
  48 using System.Collections.Generic;
  49 using System.Globalization;
  50
  51 //
  52 // Disable warnings on Obsolete methods being used
  53 //
  54 #pragma warning disable 612
  55
  56 namespace System {
  57
  58         [Serializable]
  59         [TypeConverter (typeof (UriTypeConverter))]
  60         public class Uri : ISerializable {
  61                 // NOTES:
  62                 // o  scheme excludes the scheme delimiter
  63                 // o  port is -1 to indicate no port is defined
  64                 // o  path is empty or starts with / when scheme delimiter == "://"
  65                 // o  query is empty or starts with ? char, escaped.
  66                 // o  fragment is empty or starts with # char, unescaped.
  67                 // o  all class variables are in escaped format when they are escapable,
  68                 //    except cachedToString.
  69                 // o  UNC is supported, as starts with "\\" for windows,
  70                 //    or "//" with unix.
  71
  72                 private string source;
  73                 private string scheme = String.Empty;
  74                 private string host = String.Empty;
  75                 private int port = -1;
  76                 private string path = String.Empty;
  77                 private string query = String.Empty;
  78                 private string fragment = String.Empty;
  79                 private string userinfo;
  80                 private bool isUnc;
  81                 private bool isAbsoluteUri = true;
  82                 private long scope_id;
  83
  84                 private List<string> segments;
  85
  86                 private bool userEscaped;
  87                 private string cachedAbsoluteUri;
  88                 private string cachedToString;
  89                 private string cachedLocalPath;
  90                 private int cachedHashCode;
  91
  92                 private static bool s_IriParsing;
  93
  94                 internal static bool IriParsing {
  95                         get { return s_IriParsing; }
  96                         set { s_IriParsing = value; }
  97                 }
  98
  99 #if BOOTSTRAP_BASIC
 100                 private static readonly string hexUpperChars = "0123456789ABCDEF";
 101                 private static readonly string [] Empty = new string [0];
 102                 private static bool isWin32 = (Path.DirectorySeparatorChar == '\\');
 103 #else
 104                 static readonly char[] hexUpperChars = new [] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
 105 #endif
 106
 107                 // Fields
 108
 109                 public static readonly string SchemeDelimiter = "://";
 110                 public static readonly string UriSchemeFile = "file";
 111                 public static readonly string UriSchemeFtp = "ftp";
 112                 public static readonly string UriSchemeGopher = "gopher";
 113                 public static readonly string UriSchemeHttp = "http";
 114                 public static readonly string UriSchemeHttps = "https";
 115                 public static readonly string UriSchemeMailto = "mailto";
 116                 public static readonly string UriSchemeNews = "news";
 117                 public static readonly string UriSchemeNntp = "nntp";
 118                 public static readonly string UriSchemeNetPipe = "net.pipe";
 119                 public static readonly string UriSchemeNetTcp = "net.tcp";
 120
 121                 internal static readonly string UriSchemeTelnet = "telnet";
 122                 internal static readonly string UriSchemeLdap = "ldap";
 123                 internal static readonly string UriSchemeUuid = "uuid";
 124
 125                 private static readonly string [] knownUriSchemes =
 126                 {
 127                         UriSchemeFile,
 128                         UriSchemeFtp,
 129                         UriSchemeGopher,
 130                         UriSchemeHttp,
 131                         UriSchemeHttps,
 132                         UriSchemeMailto,
 133                         UriSchemeNews,
 134                         UriSchemeNntp,
 135                         UriSchemeNetPipe,
 136                         UriSchemeNetTcp
 137                 };
 138
 139                 // Constructors
 140
 141                 static Uri ()
 142                 {
 143 #if NET_4_5
 144                         IriParsing = true;
 145 #endif
 146
 147                         var iriparsingVar = Environment.GetEnvironmentVariable ("MONO_URI_IRIPARSING");
 148                         if (iriparsingVar == "true")
 149                                 IriParsing = true;
 150                         else if (iriparsingVar == "false")
 151                                 IriParsing = false;
 152                 }
 153
 154                 public Uri (string uriString) : this (uriString, false)
 155                 {
 156                 }
 157
 158                 protected Uri (SerializationInfo serializationInfo, StreamingContext streamingContext)
 159                 {
 160                         string uri = serializationInfo.GetString ("AbsoluteUri");
 161                         if (uri.Length > 0) {
 162                                 source = uri;
 163                                 ParseUri (UriKind.Absolute);
 164                         } else {
 165                                 uri = serializationInfo.GetString ("RelativeUri");
 166                                 if (uri.Length > 0) {
 167                                         source = uri;
 168                                         ParseUri (UriKind.Relative);
 169                                 } else {
 170                                         throw new ArgumentException ("Uri string was null or empty.");
 171                                 }
 172                         }
 173                 }
 174
 175                 public Uri (string uriString, UriKind uriKind)
 176                 {
 177                         source = uriString;
 178                         ParseUri (uriKind);
 179
 180                         switch (uriKind) {
 181                         case UriKind.Absolute:
 182                                 if (!IsAbsoluteUri)
 183                                         throw new UriFormatException ("Invalid URI: The format of the URI could not be "
 184                                                 + "determined.");
 185                                 break;
 186                         case UriKind.Relative:
 187                                 if (IsAbsoluteUri)
 188                                         throw new UriFormatException ("Invalid URI: The format of the URI could not be "
 189                                                 + "determined because the parameter 'uriString' represents an absolute URI.");
 190                                 break;
 191                         case UriKind.RelativeOrAbsolute:
 192                                 break;
 193                         default:
 194                                 string msg = Locale.GetText ("Invalid UriKind value '{0}'.", uriKind);
 195                                 throw new ArgumentException (msg);
 196                         }
 197                 }
 198
 199                 //
 200                 // An exception-less constructor, returns success
 201                 // condition on the out parameter `success'.
 202                 //
 203                 Uri (string uriString, UriKind uriKind, out bool success)
 204                 {
 205                         if (uriString == null) {
 206                                 success = false;
 207                                 return;
 208                         }
 209
 210                         if (uriKind != UriKind.RelativeOrAbsolute &&
 211                                 uriKind != UriKind.Absolute &&
 212                                 uriKind != UriKind.Relative) {
 213                                 string msg = Locale.GetText ("Invalid UriKind value '{0}'.", uriKind);
 214                                 throw new ArgumentException (msg);
 215                         }
 216
 217                         source = uriString;
 218                         if (ParseNoExceptions (uriKind, uriString) != null)
 219                                 success = false;
 220                         else {
 221                                 success = true;
 222
 223                                 switch (uriKind) {
 224                                 case UriKind.Absolute:
 225                                         if (!IsAbsoluteUri)
 226                                                 success = false;
 227                                         break;
 228                                 case UriKind.Relative:
 229                                         if (IsAbsoluteUri)
 230                                                 success = false;
 231                                         break;
 232                                 case UriKind.RelativeOrAbsolute:
 233                                         break;
 234                                 default:
 235                                         success = false;
 236                                         break;
 237                                 }
 238                         }
 239                 }
 240
 241                 public Uri (Uri baseUri, Uri relativeUri)
 242                 {
 243                         Merge (baseUri, relativeUri == null ? String.Empty : relativeUri.OriginalString);
 244                         // FIXME: this should call UriParser.Resolve
 245                 }
 246
 247                 // note: doc says that dontEscape is always false but tests show otherwise
 248                 [Obsolete]
 249                 public Uri (string uriString, bool dontEscape)
 250                 {
 251                         userEscaped = dontEscape;
 252                         source = uriString;
 253                         ParseUri (UriKind.Absolute);
 254                         if (!isAbsoluteUri)
 255                                 throw new UriFormatException ("Invalid URI: The format of the URI could not be "
 256                                         + "determined: " + uriString);
 257                 }
 258
 259                 public Uri (Uri baseUri, string relativeUri)
 260                 {
 261                         Merge (baseUri, relativeUri);
 262                         // FIXME: this should call UriParser.Resolve
 263                 }
 264
 265                 [Obsolete ("dontEscape is always false")]
 266                 public Uri (Uri baseUri, string relativeUri, bool dontEscape)
 267                 {
 268                         userEscaped = dontEscape;
 269                         Merge (baseUri, relativeUri);
 270                 }
 271
 272                 private void Merge (Uri baseUri, string relativeUri)
 273                 {
 274                         if (baseUri == null)
 275                                 throw new ArgumentNullException ("baseUri");
 276                         if (!baseUri.IsAbsoluteUri)
 277                                 throw new ArgumentOutOfRangeException ("baseUri");
 278                         if (string.IsNullOrEmpty (relativeUri)) {
 279                                 source = baseUri.OriginalString;
 280                                 ParseUri (UriKind.Absolute);
 281                                 return;
 282                         }
 283
 284                         string error;
 285                         bool startsWithSlash = false;
 286
 287                         UriElements baseEl;
 288                         if (!UriParseComponents.TryParseComponents (baseUri.OriginalString, UriKind.Absolute, out baseEl, out error))
 289                                 throw new UriFormatException (error);
 290
 291                         if (relativeUri.StartsWith (baseEl.scheme + ":", StringComparison.Ordinal))
 292                                 relativeUri = relativeUri.Substring (baseEl.scheme.Length + 1);
 293
 294                         if (relativeUri.Length >= 1 && relativeUri [0] == '/') {
 295                                 if (relativeUri.Length >= 2 && relativeUri [1] == '/') {
 296                                         source = baseEl.scheme + ":" + relativeUri;
 297                                         ParseUri (UriKind.Absolute);
 298                                         return;
 299                                 }
 300
 301                                 relativeUri = relativeUri.Substring (1);
 302                                 startsWithSlash = true;
 303                         }
 304
 305                         UriElements relativeEl;
 306                         if (!UriParseComponents.TryParseComponents (relativeUri, UriKind.RelativeOrAbsolute, out relativeEl, out error))
 307                                 throw new UriFormatException (error);
 308
 309                         if (relativeEl.isAbsoluteUri) {
 310                                 source = relativeUri;
 311                                 ParseUri (UriKind.Absolute);
 312                                 return;
 313                         }
 314
 315                         source = baseEl.scheme + baseEl.delimiter;
 316
 317                         if (baseEl.user != null)
 318                                 source += baseEl.user + "@";
 319
 320                         source += baseEl.host;
 321
 322                         if (baseEl.port >= 0)
 323                                 source += ":" + baseEl.port.ToString (CultureInfo.InvariantCulture);
 324
 325                         var canUseBase = true;
 326
 327                         string path;
 328                         if (!string.IsNullOrEmpty (relativeEl.path) || startsWithSlash) {
 329                                 canUseBase = false;
 330                                 path = relativeEl.path;
 331                                 if (startsWithSlash)
 332                                         path = relativeEl.path;
 333                                 else {
 334                                         var pathEnd = baseEl.path.LastIndexOf ('/');
 335                                         path = (pathEnd > 0)? baseEl.path.Substring (0, pathEnd+1) : "";
 336                                         path += relativeEl.path;
 337                                 }
 338                         } else {
 339                                 path = baseEl.path;
 340 #if !NET_4_0
 341                                 if (relativeEl.query != null) {
 342                                         var pathEnd = path.LastIndexOf ('/');
 343                                         path = (pathEnd > 0)? path.Substring (0, pathEnd+1) : "";
 344                                 }
 345 #endif
 346                         }
 347
 348                         if ((path.Length == 0 || path [0] != '/') && baseEl.delimiter == SchemeDelimiter)
 349                                 path = "/" + path;
 350
 351                         source += UriHelper.Reduce (path, true);
 352
 353                         if (relativeEl.query != null) {
 354                                 canUseBase = false;
 355                                 source += "?" + relativeEl.query;
 356                         } else if (canUseBase && baseEl.query != null)
 357                                 source += "?" + baseEl.query;
 358
 359                         if (relativeEl.fragment != null)
 360                                 source += "#" + relativeEl.fragment;
 361                         else if (canUseBase && baseEl.fragment != null)
 362                                 source += "#" + baseEl.fragment;
 363
 364                         ParseUri (UriKind.Absolute);
 365
 366                         return;
 367                 }
 368
 369                 // Properties
 370
 371                 public string AbsolutePath {
 372                         get {
 373                                 EnsureAbsoluteUri ();
 374                                 if (scheme == "mailto" || scheme == "file")
 375                                         // faster (mailto) and special (file) cases
 376                                         return path;
 377
 378                                 if (path.Length == 0) {
 379                                         string start = scheme + SchemeDelimiter;
 380                                         if (path.StartsWith (start, StringComparison.Ordinal))
 381                                                 return "/";
 382                                         else
 383                                                 return String.Empty;
 384                                 }
 385                                 return path;
 386                         }
 387                 }
 388
 389                 public string AbsoluteUri {
 390                         get {
 391                                 EnsureAbsoluteUri ();
 392
 393                                 if (cachedAbsoluteUri == null)
 394                                         cachedAbsoluteUri = GetComponents (UriComponents.AbsoluteUri, UriFormat.UriEscaped);
 395
 396                                 return cachedAbsoluteUri;
 397                         }
 398                 }
 399
 400                 public string Authority {
 401                         get {
 402                                 EnsureAbsoluteUri ();
 403                                 return (GetDefaultPort (Scheme) == port)
 404                                      ? host : host + ":" + port;
 405                         }
 406                 }
 407
 408                 public string Fragment {
 409                         get {
 410                                 EnsureAbsoluteUri ();
 411                                 return fragment;
 412                         }
 413                 }
 414
 415                 public string Host {
 416                         get {
 417                                 EnsureAbsoluteUri ();
 418                                 return host;
 419                         }
 420                 }
 421
 422                 public UriHostNameType HostNameType {
 423                         get {
 424                                 EnsureAbsoluteUri ();
 425                                 UriHostNameType ret = CheckHostName (Host);
 426                                 if (ret != UriHostNameType.Unknown)
 427                                         return ret;
 428
 429                                 if (scheme == "mailto")
 430                                         return UriHostNameType.Basic;
 431                                 return (IsFile) ? UriHostNameType.Basic : ret;
 432                         }
 433                 }
 434
 435                 public bool IsDefaultPort {
 436                         get {
 437                                 EnsureAbsoluteUri ();
 438                                 return GetDefaultPort (Scheme) == port;
 439                         }
 440                 }
 441
 442                 public bool IsFile {
 443                         get {
 444                                 EnsureAbsoluteUri ();
 445                                 return (Scheme == UriSchemeFile);
 446                         }
 447                 }
 448
 449                 public bool IsLoopback {
 450                         get {
 451                                 EnsureAbsoluteUri ();
 452
 453                                 if (Host.Length == 0) {
 454                                         return IsFile;
 455                                 }
 456
 457                                 if (host == "loopback" || host == "localhost")
 458                                         return true;
 459
 460                                 IPAddress result;
 461                                 if (IPAddress.TryParse (host, out result))
 462                                         if (IPAddress.Loopback.Equals (result))
 463                                                 return true;
 464
 465                                 IPv6Address result6;
 466                                 if (IPv6Address.TryParse (host, out result6)){
 467                                         if (IPv6Address.IsLoopback (result6))
 468                                                 return true;
 469                                 }
 470
 471                                 return false;
 472                         }
 473                 }
 474
 475                 public bool IsUnc {
 476                         // rule: This should be true only if
 477                         //   - uri string starts from "\\", or
 478                         //   - uri string starts from "//" (Samba way)
 479                         get {
 480                                 EnsureAbsoluteUri ();
 481                                 return isUnc;
 482                         }
 483                 }
 484
 485                 private bool IsLocalIdenticalToAbsolutePath ()
 486                 {
 487                         if (IsFile)
 488                                 return false;
 489
 490                         if ((scheme == Uri.UriSchemeNews) || (scheme == Uri.UriSchemeNntp) || (scheme == Uri.UriSchemeFtp))
 491                                 return false;
 492
 493                         return IsWellFormedOriginalString ();
 494                 }
 495
 496                 public string LocalPath {
 497                         get {
 498                                 EnsureAbsoluteUri ();
 499                                 if (cachedLocalPath != null)
 500                                         return cachedLocalPath;
 501
 502                                 var formatFlags = UriHelper.FormatFlags.NoSlashReplace;
 503
 504                                 if (userEscaped)
 505                                         formatFlags |= UriHelper.FormatFlags.UserEscaped;
 506
 507                                 string unescapedPath = UriHelper.FormatAbsolute (path, scheme,
 508                                         UriComponents.Path, UriFormat.Unescaped, formatFlags);
 509
 510                                 if (path.StartsWith ("/", StringComparison.Ordinal) &&
 511                                         !unescapedPath.StartsWith ("/", StringComparison.Ordinal))
 512                                         unescapedPath = "/" + unescapedPath;
 513
 514                                 if (IsLocalIdenticalToAbsolutePath ()) {
 515                                         cachedLocalPath = unescapedPath;
 516                                         return cachedLocalPath;
 517                                 }
 518
 519                                 if (!IsUnc) {
 520                                         bool windows = (path.Length > 3 && path [1] == ':' &&
 521                                                 (path [2] == '\\' || path [2] == '/'));
 522
 523                                         if (windows)
 524                                                 cachedLocalPath = unescapedPath.Replace ('/', '\\');
 525                                         else
 526                                                 cachedLocalPath = unescapedPath;
 527                                 } else {
 528                                         // support *nix and W32 styles
 529                                         if (path.Length > 1 && path [1] == ':')
 530                                                 cachedLocalPath = unescapedPath.Replace (Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
 531
 532                                         // LAMESPEC: ok, now we cannot determine
 533                                         // if such URI like "file://foo/bar" is
 534                                         // Windows UNC or unix file path, so
 535                                         // they should be handled differently.
 536                                         else if (System.IO.Path.DirectorySeparatorChar == '\\') {
 537                                                 string h = host;
 538                                                 if (path.Length > 0) {
 539                                                         if ((path.Length > 1) || (path[0] != '/')) {
 540                                                                 h += unescapedPath.Replace ('/', '\\');
 541                                                         }
 542                                                 }
 543                                                 cachedLocalPath = "\\\\" + h;
 544                                         }  else
 545                                                 cachedLocalPath = unescapedPath;
 546                                 }
 547                                 if (cachedLocalPath.Length == 0)
 548                                         cachedLocalPath = Path.DirectorySeparatorChar.ToString ();
 549                                 return cachedLocalPath;
 550                         }
 551                 }
 552
 553                 public string PathAndQuery {
 554                         get {
 555                                 EnsureAbsoluteUri ();
 556                                 return path + Query;
 557                         }
 558                 }
 559
 560                 public int Port {
 561                         get {
 562                                 EnsureAbsoluteUri ();
 563                                 return port;
 564                         }
 565                 }
 566
 567                 public string Query {
 568                         get {
 569                                 EnsureAbsoluteUri ();
 570                                 return query;
 571                         }
 572                 }
 573
 574                 public string Scheme {
 575                         get {
 576                                 EnsureAbsoluteUri ();
 577                                 return scheme;
 578                         }
 579                 }
 580
 581                 public string [] Segments {
 582                         get {
 583                                 EnsureAbsoluteUri ();
 584
 585                                 // return a (pre-allocated) empty array
 586                                 if (path.Length == 0)
 587 #if BOOTSTRAP_BASIC
 588                                         return Empty;
 589 #else
 590                                         return EmptyArray<string>.Value;
 591 #endif
 592                                 // do not return the original array (since items can be changed)
 593                                 if (segments != null)
 594                                         return segments.ToArray ();
 595
 596                                 List<string> list = new List<string> ();
 597                                 StringBuilder current = new StringBuilder ();
 598                                 for (int i = 0; i < path.Length; i++) {
 599                                         switch (path [i]) {
 600                                         case '/':
 601                                         case '\\':
 602                                                 current.Append (path [i]);
 603                                                 list.Add (current.ToString ());
 604                                                 current.Length = 0;
 605                                                 break;
 606                                         case '%':
 607                                                 if ((i < path.Length - 2) && (path [i + 1] == '5' && path [i + 2] == 'C')) {
 608                                                         current.Append ("%5C");
 609                                                         list.Add (current.ToString ());
 610                                                         current.Length = 0;
 611                                                         i += 2;
 612                                                 } else {
 613                                                         current.Append ('%');
 614                                                 }
 615                                                 break;
 616                                         default:
 617                                                 current.Append (path [i]);
 618                                                 break;
 619                                         }
 620                                 }
 621
 622                                 if (current.Length > 0)
 623                                         list.Add (current.ToString ());
 624
 625                                 if (IsFile && (list.Count > 0)) {
 626                                         string first = list [0];
 627                                         if ((first.Length > 1) && (first [1] == ':')) {
 628                                                 list.Insert (0, "/");
 629                                         }
 630                                 }
 631                                 segments = list;
 632                                 return segments.ToArray ();
 633                         }
 634                 }
 635
 636                 public bool UserEscaped {
 637                         get { return userEscaped; }
 638                 }
 639
 640                 public string UserInfo {
 641                         get {
 642                                 EnsureAbsoluteUri ();
 643                                 return userinfo == null ? String.Empty : userinfo;
 644                         }
 645                 }
 646
 647                 public string DnsSafeHost {
 648                         get {
 649                                 EnsureAbsoluteUri ();
 650                                 string host = Host;
 651                                 if (HostNameType == UriHostNameType.IPv6) {
 652                                         host = Host.Substring (1, Host.Length - 2);
 653                                         if (scope_id != 0)
 654                                                 host += "%" + scope_id.ToString ();
 655                                 }
 656                                 return Unescape (host);
 657                         }
 658                 }
 659
 660                 public bool IsAbsoluteUri {
 661                         get { return isAbsoluteUri; }
 662                 }
 663
 664                 public string OriginalString {
 665                         get { return source; }
 666                 }
 667
 668                 // Methods
 669
 670                 public static UriHostNameType CheckHostName (string name)
 671                 {
 672                         if (name == null || name.Length == 0)
 673                                 return UriHostNameType.Unknown;
 674
 675                         if (IsIPv4Address (name))
 676                                 return UriHostNameType.IPv4;
 677
 678                         if (IsDomainAddress (name))
 679                                 return UriHostNameType.Dns;
 680
 681                         IPv6Address addr;
 682                         if (IPv6Address.TryParse (name, out addr))
 683                                 return UriHostNameType.IPv6;
 684
 685                         return UriHostNameType.Unknown;
 686                 }
 687
 688                 internal static bool IsIPv4Address (string name)
 689                 {
 690                         string [] captures = name.Split (new char [] {'.'});
 691                         if (captures.Length != 4)
 692                                 return false;
 693
 694                         for (int i = 0; i < 4; i++) {
 695                                 int length;
 696
 697                                 length = captures [i].Length;
 698                                 if (length == 0)
 699                                         return false;
 700                                 uint number;
 701                                 if (!UInt32.TryParse (captures [i], out number))
 702                                         return false;
 703                                 if (number > 255)
 704                                         return false;
 705                         }
 706                         return true;
 707                 }
 708
 709                 internal static bool IsDomainAddress (string name)
 710                 {
 711                         int len = name.Length;
 712
 713                         int count = 0;
 714                         for (int i = 0; i < len; i++) {
 715                                 char c = name [i];
 716                                 if (count == 0) {
 717                                         if (!Char.IsLetterOrDigit (c))
 718                                                 return false;
 719                                 } else if (c == '.') {
 720                                         // www..host.com is bad
 721                                         if (i + 1 < len && name [i + 1] == '.')
 722                                                 return false;
 723                                         count = 0;
 724                                         continue;
 725                                 } else if (!Char.IsLetterOrDigit (c) && c != '-' && c != '_') {
 726                                         return false;
 727                                 }
 728                                 if (++count == 64)
 729                                         return false;
 730                         }
 731
 732                         return true;
 733                 }
 734 #if !NET_2_1
 735
 736                 [Obsolete ("This method does nothing, it has been obsoleted")]
 737                 protected virtual void Canonicalize ()
 738                 {
 739                         //
 740                         // This is flagged in the Microsoft documentation as used
 741                         // internally, no longer in use, and Obsolete.
 742                         //
 743                 }
 744
 745                 [MonoTODO ("Find out what this should do")]
 746                 [Obsolete]
 747                 protected virtual void CheckSecurity ()
 748                 {
 749                 }
 750
 751 #endif // NET_2_1
 752
 753                 // defined in RFC3986 as = ALPHA *( ALPHA / DIGIT / "+" / "-" / ".")
 754                 public static bool CheckSchemeName (string schemeName)
 755                 {
 756                         if (schemeName == null || schemeName.Length == 0)
 757                                 return false;
 758
 759                         if (!IsAlpha (schemeName [0]))
 760                                 return false;
 761
 762                         int len = schemeName.Length;
 763                         for (int i = 1; i < len; i++) {
 764                                 char c = schemeName [i];
 765                                 if (!Char.IsDigit (c) && !IsAlpha (c) && c != '.' && c != '+' && c != '-')
 766                                         return false;
 767                         }
 768
 769                         return true;
 770                 }
 771
 772                 private static bool IsAlpha (char c)
 773                 {
 774                         // as defined in rfc2234
 775                         // %x41-5A / %x61-7A (A-Z / a-z)
 776                         int i = (int) c;
 777                         return (((i >= 0x41) && (i <= 0x5A)) || ((i >= 0x61) && (i <= 0x7A)));
 778                 }
 779
 780                 public override bool Equals (object comparand)
 781                 {
 782                         if (comparand == null)
 783                                 return false;
 784
 785                         Uri uri = comparand as Uri;
 786                         if ((object) uri == null) {
 787                                 string s = comparand as String;
 788                                 if (s == null)
 789                                         return false;
 790
 791                                 if (!TryCreate (s, UriKind.RelativeOrAbsolute, out uri))
 792                                         return false;
 793                         }
 794
 795                         return InternalEquals (uri);
 796                 }
 797
 798                 // Assumes: uri != null
 799                 bool InternalEquals (Uri uri)
 800                 {
 801                         if (this.isAbsoluteUri != uri.isAbsoluteUri)
 802                                 return false;
 803                         if (!this.isAbsoluteUri)
 804                                 return this.source == uri.source;
 805
 806                         CultureInfo inv = CultureInfo.InvariantCulture;
 807                         return this.scheme.ToLower (inv) == uri.scheme.ToLower (inv)
 808                                 && this.host.ToLower (inv) == uri.host.ToLower (inv)
 809                                 && this.port == uri.port
 810                                 && this.query == uri.query
 811                                 && this.path == uri.path;
 812                 }
 813
 814                 public static bool operator == (Uri uri1, Uri uri2)
 815                 {
 816                         return object.Equals (uri1, uri2);
 817                 }
 818
 819                 public static bool operator != (Uri uri1, Uri uri2)
 820                 {
 821                         return !(uri1 == uri2);
 822                 }
 823
 824                 public override int GetHashCode ()
 825                 {
 826                         if (cachedHashCode == 0) {
 827                                 CultureInfo inv = CultureInfo.InvariantCulture;
 828                                 if (isAbsoluteUri) {
 829                                         cachedHashCode = scheme.ToLower (inv).GetHashCode ()
 830                                                 ^ host.ToLower (inv).GetHashCode ()
 831                                                 ^ port
 832                                                 ^ query.GetHashCode ()
 833                                                 ^ path.GetHashCode ();
 834                                 }
 835                                 else {
 836                                         cachedHashCode = source.GetHashCode ();
 837                                 }
 838                         }
 839                         return cachedHashCode;
 840                 }
 841
 842                 public string GetLeftPart (UriPartial part)
 843                 {
 844                         EnsureAbsoluteUri ();
 845                         int defaultPort;
 846                         switch (part) {
 847                         case UriPartial.Scheme :
 848                                 return scheme + GetOpaqueWiseSchemeDelimiter ();
 849                         case UriPartial.Authority :
 850                                 if ((scheme == Uri.UriSchemeMailto) || (scheme == Uri.UriSchemeNews))
 851                                         return String.Empty;
 852
 853                                 StringBuilder s = new StringBuilder ();
 854                                 s.Append (scheme);
 855                                 s.Append (GetOpaqueWiseSchemeDelimiter ());
 856                                 if (path.Length > 1 && path [1] == ':' && (Uri.UriSchemeFile == scheme))
 857                                         s.Append ('/');  // win32 file
 858                                 if (userinfo != null)
 859                                         s.Append (userinfo).Append ('@');
 860                                 s.Append (host);
 861                                 defaultPort = GetDefaultPort (scheme);
 862                                 if ((port != -1) && (port != defaultPort))
 863                                         s.Append (':').Append (port);
 864                                 return s.ToString ();
 865                         case UriPartial.Path :
 866                                 StringBuilder sb = new StringBuilder ();
 867                                 sb.Append (scheme);
 868                                 sb.Append (GetOpaqueWiseSchemeDelimiter ());
 869                                 if (path.Length > 1 && path [1] == ':' && (Uri.UriSchemeFile == scheme))
 870                                         sb.Append ('/');  // win32 file
 871                                 if (userinfo != null)
 872                                         sb.Append (userinfo).Append ('@');
 873                                 sb.Append (host);
 874                                 defaultPort = GetDefaultPort (scheme);
 875                                 if ((port != -1) && (port != defaultPort))
 876                                         sb.Append (':').Append (port);
 877
 878                                 if (path.Length > 0) {
 879                                         if (scheme == "mailto" || scheme == "news")
 880                                                 sb.Append (path);
 881                                         else
 882                                                 sb.Append (Reduce (path, CompactEscaped (scheme)));
 883                                 }
 884                                 return sb.ToString ();
 885                         }
 886                         return null;
 887                 }
 888
 889                 public static int FromHex (char digit)
 890                 {
 891                         if ('0' <= digit && digit <= '9') {
 892                                 return (int) (digit - '0');
 893                         }
 894
 895                         if ('a' <= digit && digit <= 'f')
 896                                 return (int) (digit - 'a' + 10);
 897
 898                         if ('A' <= digit && digit <= 'F')
 899                                 return (int) (digit - 'A' + 10);
 900
 901                         throw new ArgumentException ("digit");
 902                 }
 903
 904                 public static string HexEscape (char character)
 905                 {
 906                         if (character > 255) {
 907                                 throw new ArgumentOutOfRangeException ("character");
 908                         }
 909
 910                         return "%" + hexUpperChars [((character & 0xf0) >> 4)]
 911                                    + hexUpperChars [((character & 0x0f))];
 912                 }
 913
 914                 public static char HexUnescape (string pattern, ref int index)
 915                 {
 916                         if (pattern == null)
 917                                 throw new ArgumentException ("pattern");
 918
 919                         if (index < 0 || index >= pattern.Length)
 920                                 throw new ArgumentOutOfRangeException ("index");
 921
 922                         if (!IsHexEncoding (pattern, index))
 923                                 return pattern [index++];
 924
 925                         index++;
 926                         int msb = FromHex (pattern [index++]);
 927                         int lsb = FromHex (pattern [index++]);
 928                         return (char) ((msb << 4) | lsb);
 929                 }
 930
 931                 public static bool IsHexDigit (char character)
 932                 {
 933                         return (('0' <= character && character <= '9') ||
 934                                 ('a' <= character && character <= 'f') ||
 935                                 ('A' <= character && character <= 'F'));
 936                 }
 937
 938                 public static bool IsHexEncoding (string pattern, int index)
 939                 {
 940                         if ((index + 3) > pattern.Length)
 941                                 return false;
 942
 943                         return ((pattern [index++] == '%') &&
 944                                 IsHexDigit (pattern [index++]) &&
 945                                 IsHexDigit (pattern [index]));
 946                 }
 947
 948                 //
 949                 // Implemented by copying most of the MakeRelative code
 950                 //
 951                 public Uri MakeRelativeUri (Uri uri)
 952                 {
 953 #if NET_4_0
 954                         if (uri == null)
 955                                 throw new ArgumentNullException ("uri");
 956 #endif
 957                         if (Host != uri.Host || Scheme != uri.Scheme)
 958                                 return uri;
 959
 960                         string result = String.Empty;
 961                         if (this.path != uri.path){
 962                                 string [] segments = this.Segments;
 963                                 string [] segments2 = uri.Segments;
 964
 965                                 int k = 0;
 966                                 int max = Math.Min (segments.Length, segments2.Length);
 967                                 for (; k < max; k++)
 968                                         if (segments [k] != segments2 [k])
 969                                                 break;
 970
 971                                 for (int i = k; i < segments.Length && segments [i].EndsWith ("/", StringComparison.Ordinal); i++)
 972                                         result += "../";
 973                                 for (int i = k; i < segments2.Length; i++)
 974                                         result += segments2 [i];
 975
 976                                 if (result == string.Empty)
 977                                         result = "./";
 978                         }
 979                         uri.AppendQueryAndFragment (ref result);
 980
 981                         return new Uri (result, UriKind.Relative);
 982                 }
 983
 984                 [Obsolete ("Use MakeRelativeUri(Uri uri) instead.")]
 985                 public string MakeRelative (Uri toUri)
 986                 {
 987                         if ((this.Scheme != toUri.Scheme) ||
 988                             (this.Authority != toUri.Authority))
 989                                 return toUri.ToString ();
 990
 991                         string result = String.Empty;
 992                         if (this.path != toUri.path){
 993                                 string [] segments = this.Segments;
 994                                 string [] segments2 = toUri.Segments;
 995                                 int k = 0;
 996                                 int max = Math.Min (segments.Length, segments2.Length);
 997                                 for (; k < max; k++)
 998                                         if (segments [k] != segments2 [k])
 999                                                 break;
1000
1001                                 for (int i = k + 1; i < segments.Length; i++)
1002                                         result += "../";
1003                                 for (int i = k; i < segments2.Length; i++)
1004                                         result += segments2 [i];
1005                         }
1006
1007                         // Important: MakeRelative does not append fragment or query.
1008
1009                         return result;
1010                 }
1011
1012                 void AppendQueryAndFragment (ref string result)
1013                 {
1014                         if (query.Length > 0) {
1015                                 string q = query [0] == '?' ? '?' + Unescape (query.Substring (1), true, false) : Unescape (query, false);
1016                                 result += q;
1017                         }
1018                         if (fragment.Length > 0)
1019                                 result += Unescape (fragment, true, false);
1020                 }
1021
1022                 public override string ToString ()
1023                 {
1024                         if (cachedToString != null)
1025                                 return cachedToString;
1026
1027                         if (isAbsoluteUri) {
1028                                 if (Parser is DefaultUriParser)
1029                                         cachedToString = Parser.GetComponentsHelper (this, UriComponents.AbsoluteUri, UriHelper.ToStringUnescape);
1030                                 else
1031                                         cachedToString = Parser.GetComponents (this, UriComponents.AbsoluteUri, UriFormat.SafeUnescaped);
1032                         } else
1033                                 cachedToString = UriHelper.FormatRelative (source, scheme, UriHelper.ToStringUnescape);
1034
1035                         return cachedToString;
1036                 }
1037
1038                 protected void GetObjectData (SerializationInfo serializationInfo, StreamingContext streamingContext)
1039                 {
1040                         if (this.isAbsoluteUri) {
1041                                 serializationInfo.AddValue ("AbsoluteUri", this.AbsoluteUri);
1042                         } else {
1043                                 serializationInfo.AddValue ("AbsoluteUri", String.Empty);
1044                                 serializationInfo.AddValue ("RelativeUri", this.OriginalString);
1045                         }
1046                 }
1047
1048                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
1049                 {
1050                         GetObjectData (info, context);
1051                 }
1052
1053
1054                 // Internal Methods
1055
1056                 [Obsolete]
1057                 protected virtual void Escape ()
1058                 {
1059                         path = EscapeString (path);
1060                 }
1061
1062                 [Obsolete]
1063                 protected static string EscapeString (string str)
1064                 {
1065                         return EscapeString (str, Uri.EscapeCommonHexBrackets);
1066                 }
1067
1068                 private const string EscapeCommon = "<>%\"{}|\\^`";
1069                 private const string EscapeReserved = ";/?:@&=+$,";
1070                 private const string EscapeFragment = "#";
1071                 private const string EscapeBrackets = "[]";
1072
1073                 private const string EscapeNews = EscapeCommon + EscapeBrackets + "?";
1074                 private const string EscapeCommonHex = EscapeCommon + EscapeFragment;
1075                 private const string EscapeCommonBrackets = EscapeCommon + EscapeBrackets;
1076                 internal const string EscapeCommonHexBrackets = EscapeCommon + EscapeFragment + EscapeBrackets;
1077                 internal const string EscapeCommonHexBracketsQuery = EscapeCommonHexBrackets + "?";
1078
1079                 internal static string EscapeString (string str, string escape)
1080                 {
1081                         return EscapeString (str, escape, true);
1082                 }
1083
1084                 internal static string EscapeString (string str, string escape, bool nonAsciiEscape)
1085                 {
1086                         if (String.IsNullOrEmpty (str))
1087                                 return String.Empty;
1088
1089                         StringBuilder s = new StringBuilder ();
1090                         int len = str.Length;
1091                         for (int i = 0; i < len; i++) {
1092                                 // reserved    = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" | "$" | ","
1093                                 // mark        = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
1094                                 // control     = <US-ASCII coded characters 00-1F and 7F hexadecimal>
1095                                 // space       = <US-ASCII coded character 20 hexadecimal>
1096                                 // delims      = "<" | ">" | "#" | "%" | <">
1097                                 // unwise      = "{" | "}" | "|" | "\" | "^" | "[" | "]" | "`"
1098
1099                                 // check for escape code already placed in str,
1100                                 // i.e. for encoding that follows the pattern
1101                                 // "%hexhex" in a string, where "hex" is a digit from 0-9
1102                                 // or a letter from A-F (case-insensitive).
1103                                 if (IsHexEncoding (str,i)) {
1104                                         // if ,yes , copy it as is
1105                                         s.Append (str.Substring (i, 3));
1106                                         i += 2;
1107                                         continue;
1108                                 }
1109
1110                                 char c = str [i];
1111                                 bool outside_limited_ascii = ((c <= 0x20) || (c >= 0x7f));
1112                                 bool needs_escape = (escape.IndexOf (c) != -1);
1113                                 if (nonAsciiEscape && outside_limited_ascii) {
1114                                         byte [] data = Encoding.UTF8.GetBytes (new char [] { c });
1115                                         int length = data.Length;
1116                                         for (int j = 0; j < length; j++) {
1117                                                 c = (char) data [j];
1118                                                 if (needs_escape || nonAsciiEscape)
1119                                                         s.Append (HexEscape (c));
1120                                                 else
1121                                                         s.Append (c);
1122                                         }
1123                                 } else if (needs_escape) {
1124                                         s.Append (HexEscape (c));
1125                                 } else {
1126                                         s.Append (c);
1127                                 }
1128                         }
1129
1130                         return s.ToString ();
1131                 }
1132
1133                 // On .NET 1.x, this method is called from .ctor(). When overriden, we
1134                 // can avoid the "absolute uri" constraints of the .ctor() by
1135                 // overriding with custom code.
1136                 [Obsolete("The method has been deprecated. It is not used by the system.")]
1137                 protected virtual void Parse ()
1138                 {
1139                 }
1140
1141                 private void ParseUri (UriKind kind)
1142                 {
1143                         Parse (kind, source);
1144
1145                         if (userEscaped)
1146                                 return;
1147
1148                         if (host.Length > 1 && host [0] != '[' && host [host.Length - 1] != ']') {
1149                                 // host name present (but not an IPv6 address)
1150                                 host = host.ToLower (CultureInfo.InvariantCulture);
1151                         }
1152                 }
1153
1154                 [Obsolete]
1155                 protected virtual string Unescape (string path)
1156                 {
1157                         var formatFlags = UriHelper.FormatFlags.NoSlashReplace | UriHelper.FormatFlags.NoReduce;
1158                         return UriHelper.FormatAbsolute (path, scheme, UriComponents.Path, UriFormat.Unescaped, formatFlags);
1159                 }
1160
1161                 internal static string Unescape (string str, bool excludeSpecial)
1162                 {
1163                         return Unescape (str, excludeSpecial, excludeSpecial);
1164                 }
1165
1166                 internal static string Unescape (string str, bool excludeSpecial, bool excludeBackslash)
1167                 {
1168                         if (String.IsNullOrEmpty (str))
1169                                 return String.Empty;
1170
1171                         StringBuilder s = new StringBuilder ();
1172                         int len = str.Length;
1173                         for (int i = 0; i < len; i++) {
1174                                 char c = str [i];
1175                                 if (c == '%') {
1176                                         char surrogate;
1177                                         char x = HexUnescapeMultiByte (str, ref i, out surrogate);
1178                                         if (excludeSpecial && x == '#')
1179                                                 s.Append ("%23");
1180                                         else if (excludeSpecial && x == '%')
1181                                                 s.Append ("%25");
1182                                         else if (excludeSpecial && x == '?')
1183                                                 s.Append ("%3F");
1184                                         else if (excludeBackslash && x == '\\')
1185                                                 s.Append ("%5C");
1186                                         else {
1187                                                 s.Append (x);
1188                                                 if (surrogate != char.MinValue)
1189                                                         s.Append (surrogate);
1190                                         }
1191                                         i--;
1192                                 } else
1193                                         s.Append (c);
1194                         }
1195                         return s.ToString ();
1196                 }
1197
1198
1199                 // Private Methods
1200
1201                 private void ParseAsWindowsUNC (string uriString)
1202                 {
1203                         scheme = UriSchemeFile;
1204                         port = -1;
1205                         fragment = String.Empty;
1206                         query = String.Empty;
1207                         isUnc = true;
1208
1209                         uriString = uriString.TrimStart (new char [] {'\\'});
1210                         int pos = uriString.IndexOf ('\\');
1211                         if (pos > 0) {
1212                                 path = uriString.Substring (pos);
1213                                 host = uriString.Substring (0, pos);
1214                         } else { // "\\\\server"
1215                                 host = uriString;
1216                                 path = String.Empty;
1217                         }
1218                         path = path.Replace ("\\", "/");
1219                 }
1220
1221                 //
1222                 // Returns null on success, string with error on failure
1223                 //
1224                 private string ParseAsWindowsAbsoluteFilePath (string uriString)
1225                 {
1226                         if (uriString.Length > 2 && uriString [2] != '\\' && uriString [2] != '/')
1227                                 return "Relative file path is not allowed.";
1228                         scheme = UriSchemeFile;
1229                         host = String.Empty;
1230                         port = -1;
1231                         path = uriString.Replace ("\\", "/");
1232                         fragment = String.Empty;
1233                         query = String.Empty;
1234
1235                         return null;
1236                 }
1237
1238                 private void ParseAsUnixAbsoluteFilePath (string uriString)
1239                 {
1240                         scheme = UriSchemeFile;
1241                         port = -1;
1242                         fragment = String.Empty;
1243                         query = String.Empty;
1244                         host = String.Empty;
1245                         path = null;
1246
1247                         if (uriString.Length >= 2 && uriString [0] == '/' && uriString [1] == '/') {
1248                                 uriString = uriString.TrimStart (new char [] {'/'});
1249                                 // Now we don't regard //foo/bar as "foo" host.
1250                                 /*
1251                                 int pos = uriString.IndexOf ('/');
1252                                 if (pos > 0) {
1253                                         path = '/' + uriString.Substring (pos + 1);
1254                                         host = uriString.Substring (0, pos);
1255                                 } else { // "///server"
1256                                         host = uriString;
1257                                         path = String.Empty;
1258                                 }
1259                                 */
1260                                 path = '/' + uriString;
1261                         }
1262                         if (path == null)
1263                                 path = uriString;
1264                 }
1265
1266                 //
1267                 // This parse method will throw exceptions on failure
1268                 //
1269                 private void Parse (UriKind kind, string uriString)
1270                 {
1271                         if (uriString == null)
1272                                 throw new ArgumentNullException ("uriString");
1273
1274                         string s = ParseNoExceptions (kind, uriString);
1275                         if (s != null)
1276                                 throw new UriFormatException (s);
1277                 }
1278
1279                 private bool SupportsQuery ()
1280                 {
1281                         return UriHelper.SupportsQuery (scheme);
1282                 }
1283
1284
1285                 private string ParseNoExceptions (UriKind kind, string uriString)
1286                 {
1287                         UriElements elements;
1288                         string error;
1289                         if (!UriParseComponents.TryParseComponents (source, kind, out elements, out error))
1290                                 return error;
1291
1292                         scheme = elements.scheme;
1293                         var parser = UriParser.GetParser (scheme);
1294                         if (parser != null && !(parser is DefaultUriParser)) {
1295                                 userinfo = Parser.GetComponents (this, UriComponents.UserInfo, UriFormat.UriEscaped);
1296                                 host = Parser.GetComponents (this, UriComponents.Host, UriFormat.UriEscaped);
1297
1298                                 var portStr = Parser.GetComponents (this, UriComponents.StrongPort, UriFormat.UriEscaped);
1299                                 if (!string.IsNullOrEmpty (portStr))
1300                                         port = int.Parse (portStr);
1301
1302                                 path = Parser.GetComponents (this, UriComponents.Path | UriComponents.KeepDelimiter, UriFormat.UriEscaped);
1303                                 query = Parser.GetComponents (this, UriComponents.Query, UriFormat.UriEscaped);
1304                                 fragment = Parser.GetComponents (this, UriComponents.StrongPort, UriFormat.UriEscaped);
1305
1306                                 return null;
1307                         }
1308
1309                         var formatFlags = UriHelper.FormatFlags.None;
1310                         if (UriHelper.HasCharactersToNormalize (uriString))
1311                                 formatFlags |= UriHelper.FormatFlags.HasUriCharactersToNormalize;
1312
1313                         if (userEscaped)
1314                                 formatFlags |= UriHelper.FormatFlags.UserEscaped;
1315
1316                         if (elements.host != null)
1317                                 formatFlags |= UriHelper.FormatFlags.HasHost;
1318
1319                         userinfo = elements.user;
1320
1321                         if (elements.host != null) {
1322                                 host = UriHelper.FormatAbsolute (elements.host, scheme,
1323                                         UriComponents.Host, UriFormat.UriEscaped, formatFlags);
1324                         }
1325
1326                         port = elements.port;
1327
1328                         if (port == -1)
1329                                 port = GetDefaultPort (scheme);
1330
1331                         if (elements.path != null) {
1332                                 path = UriHelper.FormatAbsolute (elements.path, scheme,
1333                                         UriComponents.Path, UriFormat.UriEscaped, formatFlags);
1334                                 if (elements.delimiter == SchemeDelimiter && string.IsNullOrEmpty (path))
1335                                         path = "/";
1336                         }
1337
1338                         if (elements.query != null) {
1339                                 query = "?" + UriHelper.FormatAbsolute (elements.query, scheme,
1340                                         UriComponents.Query, UriFormat.UriEscaped, formatFlags);
1341                         }
1342
1343                         if (elements.fragment != null) {
1344                                 fragment = "#" + UriHelper.FormatAbsolute (elements.fragment, scheme,
1345                                         UriComponents.Fragment, UriFormat.UriEscaped, formatFlags);
1346                         }
1347
1348                         isAbsoluteUri = elements.isAbsoluteUri;
1349                         isUnc = elements.isUnc;
1350                         scope_id = elements.scopeId;
1351
1352                         return null;
1353                 }
1354
1355                 private static string TryGetKnownUriSchemeInstance (string scheme)
1356                 {
1357                         foreach (string knownScheme in knownUriSchemes) {
1358                                 if (knownScheme == scheme)
1359                                         return knownScheme;
1360                         }
1361
1362                         return scheme;
1363                 }
1364
1365                 private static bool CompactEscaped (string scheme)
1366                 {
1367                         if (scheme == null || scheme.Length < 4)
1368                                 return false;
1369
1370                         char first = scheme [0];
1371                         if (first == 'h'){
1372                                 return scheme == "http" || scheme == "https";
1373                         } else if (first == 'f' && scheme == "file"){
1374                                 return true;
1375                         } else if (first == 'n')
1376                                 return scheme == "net.pipe" || scheme == "net.tcp";
1377
1378                         return false;
1379                 }
1380
1381                 // replace '\', %5C ('\') and %2f ('/') into '/'
1382                 // replace %2e ('.') into '.'
1383                 private static string NormalizePath (string path)
1384                 {
1385                         StringBuilder res = new StringBuilder ();
1386                         for (int i = 0; i < path.Length; i++) {
1387                                 char c = path [i];
1388                                 switch (c) {
1389                                 case '\\':
1390                                         c = '/';
1391                                         break;
1392                                 case '%':
1393                                         if (i < path.Length - 2) {
1394                                                 char c1 = path [i + 1];
1395                                                 char c2 = Char.ToUpper (path [i + 2]);
1396                                                 if ((c1 == '2') && (c2 == 'E')) {
1397                                                         c = '.';
1398                                                         i += 2;
1399                                                 } else if (((c1 == '2') && (c2 == 'F')) || ((c1 == '5') && (c2 == 'C'))) {
1400                                                         c = '/';
1401                                                         i += 2;
1402                                                 }
1403                                         }
1404                                         break;
1405                                 }
1406                                 res.Append (c);
1407                         }
1408                         return res.ToString ();
1409                 }
1410
1411                 // This is called "compacting" in the MSDN documentation
1412                 private static string Reduce (string path, bool compact_escaped)
1413                 {
1414                         // quick out, allocation-free, for a common case
1415                         if (path == "/")
1416                                 return path;
1417
1418                         if (compact_escaped && (path.IndexOf ('%') != -1)) {
1419                                 // replace '\', %2f, %5c with '/' and replace %2e with '.'
1420                                 // other escaped values seems to survive this step
1421                                 path = NormalizePath (path);
1422                         } else {
1423                                 // (always) replace '\' with '/'
1424                                 path = path.Replace ('\\', '/');
1425                         }
1426
1427                         List<string> result = new List<string> ();
1428
1429                         bool begin = true;
1430                         for (int startpos = 0; startpos < path.Length; ) {
1431                                 int endpos = path.IndexOf ('/', startpos);
1432                                 if (endpos == -1)
1433                                         endpos = path.Length;
1434                                 string current = path.Substring (startpos, endpos-startpos);
1435                                 startpos = endpos + 1;
1436                                 if ((begin && current.Length == 0) || current == "." ) {
1437                                         begin = false;
1438                                         continue;
1439                                 }
1440
1441                                 begin = false;
1442                                 if (current == "..") {
1443                                         int resultCount = result.Count;
1444                                         // in 2.0 profile, skip leading ".." parts
1445                                         if (resultCount == 0) {
1446                                                 continue;
1447                                         }
1448
1449                                         result.RemoveAt (resultCount - 1);
1450                                         continue;
1451                                 }
1452
1453                                 result.Add (current);
1454                         }
1455
1456                         if (result.Count == 0)
1457                                 return "/";
1458
1459                         StringBuilder res = new StringBuilder ();
1460
1461                         if (path [0] == '/')
1462                                 res.Append ('/');
1463
1464                         bool first = true;
1465                         foreach (string part in result) {
1466                                 if (first) {
1467                                         first = false;
1468                                 } else {
1469                                         res.Append ('/');
1470                                 }
1471                                 res.Append (part);
1472                         }
1473
1474                         if (path [path.Length - 1] == '/')
1475                                 res.Append ('/');
1476
1477                         return res.ToString ();
1478                 }
1479
1480                 // A variant of HexUnescape() which can decode multi-byte escaped
1481                 // sequences such as (e.g.) %E3%81%8B into a single character
1482                 internal static char HexUnescapeMultiByte (string pattern, ref int index, out char surrogate)
1483                 {
1484                         bool invalidEscape;
1485                         return HexUnescapeMultiByte (pattern, ref index, out surrogate, out invalidEscape);
1486                 }
1487
1488                 internal static char HexUnescapeMultiByte (string pattern, ref int index, out char surrogate, out bool invalidEscape)
1489                 {
1490                         surrogate = char.MinValue;
1491                         invalidEscape = false;
1492
1493                         if (pattern == null)
1494                                 throw new ArgumentException ("pattern");
1495
1496                         if (index < 0 || index >= pattern.Length)
1497                                 throw new ArgumentOutOfRangeException ("index");
1498
1499                         if (!IsHexEncoding (pattern, index))
1500                                 return pattern [index++];
1501
1502                         int orig_index = index++;
1503                         int msb = FromHex (pattern [index++]);
1504                         int lsb = FromHex (pattern [index++]);
1505
1506                         // We might be dealing with a multi-byte character:
1507                         // The number of ones at the top-end of the first byte will tell us
1508                         // how many bytes will make up this character.
1509                         int msb_copy = msb;
1510                         int num_bytes = 0;
1511                         while ((msb_copy & 0x8) == 0x8) {
1512                                 num_bytes++;
1513                                 msb_copy <<= 1;
1514                         }
1515
1516                         // We might be dealing with a single-byte character:
1517                         // If there was only 0 or 1 leading ones then we're not dealing
1518                         // with a multi-byte character.
1519                         if (num_bytes <= 1) {
1520                                 var c = (char) ((msb << 4) | lsb);
1521                                 invalidEscape = c > 0x7F;
1522                                 return c;
1523                         }
1524
1525                         // Now that we know how many bytes *should* follow, we'll check them
1526                         // to ensure we are dealing with a valid multi-byte character.
1527                         byte [] chars = new byte [num_bytes];
1528                         bool all_invalid = false;
1529                         chars[0] = (byte) ((msb << 4) | lsb);
1530
1531                         for (int i = 1; i < num_bytes; i++) {
1532                                 if (!IsHexEncoding (pattern, index++)) {
1533                                         all_invalid = true;
1534                                         break;
1535                                 }
1536
1537                                 // All following bytes must be in the form 10xxxxxx
1538                                 int cur_msb = FromHex (pattern [index++]);
1539                                 if ((cur_msb & 0xc) != 0x8) {
1540                                         all_invalid = true;
1541                                         break;
1542                                 }
1543
1544                                 int cur_lsb = FromHex (pattern [index++]);
1545                                 chars[i] = (byte) ((cur_msb << 4) | cur_lsb);
1546                         }
1547
1548                         // If what looked like a multi-byte character is invalid, then we'll
1549                         // just return the first byte as a single byte character.
1550                         if (all_invalid) {
1551                                 invalidEscape = true;
1552                                 index = orig_index + 3;
1553                                 return (char) chars[0];
1554                         }
1555
1556                         // Otherwise, we're dealing with a valid multi-byte character.
1557                         // We need to ignore the leading ones from the first byte:
1558                         byte mask = (byte) 0xFF;
1559                         mask >>= (num_bytes + 1);
1560                         int result = chars[0] & mask;
1561
1562                         // The result will now be built up from the following bytes.
1563                         for (int i = 1; i < num_bytes; i++) {
1564                                 // Ignore upper two bits
1565                                 result <<= 6;
1566                                 result |= (chars[i] & 0x3F);
1567                         }
1568
1569                         if (result <= 0xFFFF) {
1570                                 return (char) result;
1571                         } else {
1572                                 // We need to handle this as a UTF16 surrogate (i.e. return
1573                                 // two characters)
1574                                 result -= 0x10000;
1575                                 surrogate = (char) ((result & 0x3FF) | 0xDC00);
1576                                 return (char) ((result >> 10) | 0xD800);
1577                         }
1578                 }
1579
1580                 private struct UriScheme
1581                 {
1582                         public string scheme;
1583                         public string delimiter;
1584                         public int defaultPort;
1585
1586                         public UriScheme (string s, string d, int p)
1587                         {
1588                                 scheme = s;
1589                                 delimiter = d;
1590                                 defaultPort = p;
1591                         }
1592                 };
1593
1594                 static UriScheme [] schemes = new UriScheme [] {
1595                         new UriScheme (UriSchemeHttp, SchemeDelimiter, 80),
1596                         new UriScheme (UriSchemeHttps, SchemeDelimiter, 443),
1597                         new UriScheme (UriSchemeFtp, SchemeDelimiter, 21),
1598                         new UriScheme (UriSchemeFile, SchemeDelimiter, -1),
1599                         new UriScheme (UriSchemeMailto, ":", 25),
1600                         new UriScheme (UriSchemeNews, ":", 119),
1601                         new UriScheme (UriSchemeUuid, ":", -1),
1602                         new UriScheme (UriSchemeNntp, SchemeDelimiter, 119),
1603                         new UriScheme (UriSchemeGopher, SchemeDelimiter, 70),
1604                 };
1605
1606                 internal static string GetSchemeDelimiter (string scheme)
1607                 {
1608                         for (int i = 0; i < schemes.Length; i++)
1609                                 if (schemes [i].scheme == scheme)
1610                                         return schemes [i].delimiter;
1611                         return Uri.SchemeDelimiter;
1612                 }
1613
1614                 internal static int GetDefaultPort (string scheme)
1615                 {
1616                         UriParser parser = UriParser.GetParser (scheme);
1617                         if (parser == null)
1618                                 return -1;
1619                         return parser.DefaultPort;
1620                 }
1621
1622                 private string GetOpaqueWiseSchemeDelimiter ()
1623                 {
1624                         return GetSchemeDelimiter (scheme);
1625                 }
1626
1627                 [Obsolete]
1628                 protected virtual bool IsBadFileSystemCharacter (char character)
1629                 {
1630                         // It does not always overlap with InvalidPathChars.
1631                         int chInt = (int) character;
1632                         if (chInt < 32 || (chInt < 64 && chInt > 57))
1633                                 return true;
1634                         switch (chInt) {
1635                         case 0:
1636                         case 34: // "
1637                         case 38: // &
1638                         case 42: // *
1639                         case 44: // ,
1640                         case 47: // /
1641                         case 92: // \
1642                         case 94: // ^
1643                         case 124: // |
1644                                 return true;
1645                         }
1646
1647                         return false;
1648                 }
1649
1650                 [Obsolete]
1651                 protected static bool IsExcludedCharacter (char character)
1652                 {
1653                         if (character <= 32 || character >= 127)
1654                                 return true;
1655
1656                         if (character == '"' || character == '#' || character == '%' || character == '<' ||
1657                             character == '>' || character == '[' || character == '\\' || character == ']' ||
1658                             character == '^' || character == '`' || character == '{' || character == '|' ||
1659                             character == '}')
1660                                 return true;
1661                         return false;
1662                 }
1663
1664                 internal static bool MaybeUri (string s)
1665                 {
1666                         int p = s.IndexOf (':');
1667                         if (p == -1)
1668                                 return false;
1669
1670                         if (p >= 10)
1671                                 return false;
1672
1673                         return IsPredefinedScheme (s.Substring (0, p));
1674                 }
1675
1676                 //
1677                 // Using a simple block of if's is twice as slow as the compiler generated
1678                 // switch statement.   But using this tuned code is faster than the
1679                 // compiler generated code, with a million loops on x86-64:
1680                 //
1681                 // With "http": .10 vs .51 (first check)
1682                 // with "https": .16 vs .51 (second check)
1683                 // with "foo": .22 vs .31 (never found)
1684                 // with "mailto": .12 vs .51  (last check)
1685                 //
1686                 //
1687                 private static bool IsPredefinedScheme (string scheme)
1688                 {
1689                         if (scheme == null || scheme.Length < 3)
1690                                 return false;
1691
1692                         char c = scheme [0];
1693                         if (c == 'h')
1694                                 return (scheme == "http" || scheme == "https");
1695                         if (c == 'f')
1696                                 return (scheme == "file" || scheme == "ftp");
1697
1698                         if (c == 'n'){
1699                                 c = scheme [1];
1700                                 if (c == 'e')
1701                                         return (scheme == "news" || scheme == "net.pipe" || scheme == "net.tcp");
1702                                 if (scheme == "nntp")
1703                                         return true;
1704                                 return false;
1705                         }
1706                         if ((c == 'g' && scheme == "gopher") || (c == 'm' && scheme == "mailto"))
1707                                 return true;
1708
1709                         return false;
1710                 }
1711
1712                 [Obsolete]
1713                 protected virtual bool IsReservedCharacter (char character)
1714                 {
1715                         if (character == '$' || character == '&' || character == '+' || character == ',' ||
1716                             character == '/' || character == ':' || character == ';' || character == '=' ||
1717                             character == '@')
1718                                 return true;
1719                         return false;
1720                 }
1721
1722                 [NonSerialized]
1723                 private UriParser parser;
1724
1725                 private UriParser Parser {
1726                         get {
1727                                 if (parser == null) {
1728                                         parser = UriParser.GetParser (scheme);
1729                                         // no specific parser ? then use a default one
1730                                         if (parser == null)
1731                                                 parser = new DefaultUriParser ("*");
1732                                 }
1733                                 return parser;
1734                         }
1735                         set { parser = value; }
1736                 }
1737
1738                 public string GetComponents (UriComponents components, UriFormat format)
1739                 {
1740                         if ((components & UriComponents.SerializationInfoString) == 0)
1741                                 EnsureAbsoluteUri ();
1742
1743                         return Parser.GetComponents (this, components, format);
1744                 }
1745
1746                 public bool IsBaseOf (Uri uri)
1747                 {
1748 #if NET_4_0
1749                         if (uri == null)
1750                                 throw new ArgumentNullException ("uri");
1751 #endif
1752                         return Parser.IsBaseOf (this, uri);
1753                 }
1754
1755                 public bool IsWellFormedOriginalString ()
1756                 {
1757                         // funny, but it does not use the Parser's IsWellFormedOriginalString().
1758                         // Also, it seems we need to *not* escape hex.
1759                         return EscapeString (OriginalString, EscapeCommonBrackets) == OriginalString;
1760                 }
1761
1762                 // static methods
1763
1764                 private const int MaxUriLength = 32766;
1765
1766                 public static int Compare (Uri uri1, Uri uri2, UriComponents partsToCompare, UriFormat compareFormat, StringComparison comparisonType)
1767                 {
1768                         if ((comparisonType < StringComparison.CurrentCulture) || (comparisonType > StringComparison.OrdinalIgnoreCase)) {
1769                                 string msg = Locale.GetText ("Invalid StringComparison value '{0}'", comparisonType);
1770                                 throw new ArgumentException ("comparisonType", msg);
1771                         }
1772
1773                         if ((uri1 == null) && (uri2 == null))
1774                                 return 0;
1775                         if (uri1 == null)
1776                                 return -1;
1777                         if (uri2 == null)
1778                                 return 1;
1779
1780                         string s1 = uri1.GetComponents (partsToCompare, compareFormat);
1781                         string s2 = uri2.GetComponents (partsToCompare, compareFormat);
1782                         return String.Compare (s1, s2, comparisonType);
1783                 }
1784
1785                 //
1786                 // The rules for EscapeDataString
1787                 //
1788                 static bool NeedToEscapeDataChar (char b)
1789                 {
1790                         if ((b >= 'A' && b <= 'Z') ||
1791                                 (b >= 'a' && b <= 'z') ||
1792                                 (b >= '0' && b <= '9'))
1793                                 return false;
1794
1795                         switch (b) {
1796                         case '-':
1797                         case '.':
1798                         case '_':
1799                         case '~':
1800                                 return false;
1801                         }
1802
1803 #if !NET_4_5
1804                         switch (b) {
1805                         case '!':
1806                         case '\'':
1807                         case '(':
1808                         case ')':
1809                         case '*':
1810                         case '-':
1811                         case '.':
1812                                 return false;
1813                         }
1814 #endif
1815
1816                         return true;
1817                 }
1818
1819                 public static string EscapeDataString (string stringToEscape)
1820                 {
1821                         if (stringToEscape == null)
1822                                 throw new ArgumentNullException ("stringToEscape");
1823
1824                         if (stringToEscape.Length > MaxUriLength) {
1825                                 throw new UriFormatException (string.Format ("Uri is longer than the maximum {0} characters.", MaxUriLength));
1826                         }
1827
1828                         bool escape = false;
1829                         foreach (char c in stringToEscape){
1830                                 if (NeedToEscapeDataChar (c)){
1831                                         escape = true;
1832                                         break;
1833                                 }
1834                         }
1835                         if (!escape){
1836                                 return stringToEscape;
1837                         }
1838
1839                         StringBuilder sb = new StringBuilder ();
1840                         byte [] bytes = Encoding.UTF8.GetBytes (stringToEscape);
1841                         foreach (byte b in bytes){
1842                                 if (NeedToEscapeDataChar ((char) b))
1843                                         sb.Append (HexEscape ((char) b));
1844                                 else
1845                                         sb.Append ((char) b);
1846                         }
1847                         return sb.ToString ();
1848                 }
1849
1850                 //
1851                 // The rules for EscapeUriString
1852                 //
1853                 static bool NeedToEscapeUriChar (char b)
1854                 {
1855                         if ((b >= 'A' && b <= 'Z') || (b >= 'a' && b <= 'z') || (b >= '&' && b <= ';'))
1856                                 return false;
1857
1858                         switch (b) {
1859                         case '!':
1860                         case '#':
1861                         case '$':
1862                         case '=':
1863                         case '?':
1864                         case '@':
1865                         case '_':
1866                         case '~':
1867                                 return false;
1868 #if NET_4_5
1869                         case '[':
1870                         case ']':
1871                                 return false;
1872 #endif
1873                         }
1874
1875                         return true;
1876                 }
1877
1878                 public static string EscapeUriString (string stringToEscape)
1879                 {
1880                         if (stringToEscape == null)
1881                                 throw new ArgumentNullException ("stringToEscape");
1882
1883                         if (stringToEscape.Length > MaxUriLength) {
1884                                 throw new UriFormatException (string.Format ("Uri is longer than the maximum {0} characters.", MaxUriLength));
1885                         }
1886
1887                         bool escape = false;
1888                         foreach (char c in stringToEscape){
1889                                 if (NeedToEscapeUriChar (c)){
1890                                         escape = true;
1891                                         break;
1892                                 }
1893                         }
1894                         if (!escape)
1895                                 return stringToEscape;
1896
1897                         StringBuilder sb = new StringBuilder ();
1898                         byte [] bytes = Encoding.UTF8.GetBytes (stringToEscape);
1899                         foreach (byte b in bytes){
1900                                 if (NeedToEscapeUriChar ((char) b))
1901                                         sb.Append (HexEscape ((char) b));
1902                                 else
1903                                         sb.Append ((char) b);
1904                         }
1905                         return sb.ToString ();
1906                 }
1907
1908                 public static bool IsWellFormedUriString (string uriString, UriKind uriKind)
1909                 {
1910                         if (uriString == null)
1911                                 return false;
1912
1913                         Uri uri;
1914                         if (Uri.TryCreate (uriString, uriKind, out uri))
1915                                 return uri.IsWellFormedOriginalString ();
1916                         return false;
1917                 }
1918
1919                 public static bool TryCreate (string uriString, UriKind uriKind, out Uri result)
1920                 {
1921                         bool success;
1922
1923                         Uri r = new Uri (uriString, uriKind, out success);
1924                         if (success) {
1925                                 result = r;
1926                                 return true;
1927                         }
1928                         result = null;
1929                         return false;
1930                 }
1931
1932                 // [MonoTODO ("rework code to avoid exception catching")]
1933                 public static bool TryCreate (Uri baseUri, string relativeUri, out Uri result)
1934                 {
1935                         result = null;
1936                         if (relativeUri == null)
1937                                 return false;
1938
1939                         try {
1940                                 Uri relative = new Uri (relativeUri, UriKind.RelativeOrAbsolute);
1941                                 if ((baseUri != null) && baseUri.IsAbsoluteUri) {
1942                                         // FIXME: this should call UriParser.Resolve
1943                                         result = new Uri (baseUri, relative);
1944                                 } else if (relative.IsAbsoluteUri) {
1945                                         // special case - see unit tests
1946                                         result = relative;
1947                                 }
1948                                 return (result != null);
1949                         } catch (UriFormatException) {
1950                                 return false;
1951                         }
1952                 }
1953
1954                 //[MonoTODO ("rework code to avoid exception catching")]
1955                 public static bool TryCreate (Uri baseUri, Uri relativeUri, out Uri result)
1956                 {
1957                         result = null;
1958                         if ((baseUri == null) || !baseUri.IsAbsoluteUri)
1959                                 return false;
1960 #if NET_4_0
1961                         if (relativeUri == null)
1962                                 return false;
1963 #endif
1964                         try {
1965                                 // FIXME: this should call UriParser.Resolve
1966                                 result = new Uri (baseUri, relativeUri.OriginalString);
1967                                 return true;
1968                         } catch (UriFormatException) {
1969                                 return false;
1970                         }
1971                 }
1972
1973                 public static string UnescapeDataString (string stringToUnescape)
1974                 {
1975                         return UnescapeDataString (stringToUnescape, false);
1976                 }
1977
1978                 internal static string UnescapeDataString (string stringToUnescape, bool safe)
1979                 {
1980                         if (stringToUnescape == null)
1981                                 throw new ArgumentNullException ("stringToUnescape");
1982
1983                         if (stringToUnescape.IndexOf ('%') == -1 && stringToUnescape.IndexOf ('+') == -1)
1984                                 return stringToUnescape;
1985
1986                         StringBuilder output = new StringBuilder ();
1987                         long len = stringToUnescape.Length;
1988                         MemoryStream bytes = new MemoryStream ();
1989                         int xchar;
1990
1991                         for (int i = 0; i < len; i++) {
1992                                 if (stringToUnescape [i] == '%' && i + 2 < len && stringToUnescape [i + 1] != '%') {
1993                                         if (stringToUnescape [i + 1] == 'u' && i + 5 < len) {
1994                                                 if (bytes.Length > 0) {
1995                                                         output.Append (GetChars (bytes, Encoding.UTF8));
1996                                                         bytes.SetLength (0);
1997                                                 }
1998
1999                                                 xchar = GetChar (stringToUnescape, i + 2, 4, safe);
2000                                                 if (xchar != -1) {
2001                                                         output.Append ((char) xchar);
2002                                                         i += 5;
2003                                                 }
2004                                                 else {
2005                                                         output.Append ('%');
2006                                                 }
2007                                         }
2008                                         else if ((xchar = GetChar (stringToUnescape, i + 1, 2, safe)) != -1) {
2009                                                 bytes.WriteByte ((byte) xchar);
2010                                                 i += 2;
2011                                         }
2012                                         else {
2013                                                 output.Append ('%');
2014                                         }
2015                                         continue;
2016                                 }
2017
2018                                 if (bytes.Length > 0) {
2019                                         output.Append (GetChars (bytes, Encoding.UTF8));
2020                                         bytes.SetLength (0);
2021                                 }
2022
2023                                 output.Append (stringToUnescape [i]);
2024                         }
2025
2026                         if (bytes.Length > 0) {
2027                                 output.Append (GetChars (bytes, Encoding.UTF8));
2028                         }
2029
2030                         bytes = null;
2031                         return output.ToString ();
2032                 }
2033
2034                 private static int GetInt (byte b)
2035                 {
2036                         char c = (char) b;
2037                         if (c >= '0' && c <= '9')
2038                                 return c - '0';
2039
2040                         if (c >= 'a' && c <= 'f')
2041                                 return c - 'a' + 10;
2042
2043                         if (c >= 'A' && c <= 'F')
2044                                 return c - 'A' + 10;
2045
2046                         return -1;
2047                 }
2048
2049                 private static int GetChar (string str, int offset, int length, bool safe)
2050                 {
2051                         int val = 0;
2052                         int end = length + offset;
2053                         for (int i = offset; i < end; i++) {
2054                                 char c = str [i];
2055                                 if (c > 127)
2056                                         return -1;
2057
2058                                 int current = GetInt ((byte) c);
2059                                 if (current == -1)
2060                                         return -1;
2061                                 val = (val << 4) + current;
2062                         }
2063
2064                         if (!safe)
2065                                 return val;
2066
2067                         switch ((char) val) {
2068                         case '%':
2069                         case '#':
2070                         case '?':
2071                         case '/':
2072                         case '\\':
2073                         case '@':
2074                         case '&': // not documented
2075                                 return -1;
2076                         default:
2077                                 return val;
2078                         }
2079                 }
2080
2081                 private static char [] GetChars (MemoryStream b, Encoding e)
2082                 {
2083                         return e.GetChars (b.GetBuffer (), 0, (int) b.Length);
2084                 }
2085
2086
2087                 private void EnsureAbsoluteUri ()
2088                 {
2089                         if (!IsAbsoluteUri)
2090                                 throw new InvalidOperationException ("This operation is not supported for a relative URI.");
2091                 }
2092         }
2093 }