mcs/class/System/System.Net/DnsPermission.cs

   1 //\r
   2 // System.Net.DnsPermission.cs\r
   3 //\r
   4 // Authors:\r
   5 //      Lawrence Pit (loz@cable.a2000.nl)\r
   6 //      Sebastien Pouliot  <sebastien@ximian.com>\r
   7 //\r
   8 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)\r
   9 //\r
  10 // Permission is hereby granted, free of charge, to any person obtaining\r
  11 // a copy of this software and associated documentation files (the\r
  12 // "Software"), to deal in the Software without restriction, including\r
  13 // without limitation the rights to use, copy, modify, merge, publish,\r
  14 // distribute, sublicense, and/or sell copies of the Software, and to\r
  15 // permit persons to whom the Software is furnished to do so, subject to\r
  16 // the following conditions:\r
  17 // \r
  18 // The above copyright notice and this permission notice shall be\r
  19 // included in all copies or substantial portions of the Software.\r
  20 // \r
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,\r
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF\r
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND\r
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE\r
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION\r
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION\r
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\r
  28 //\r
  29 \r
  30 using System.Collections;\r
  31 using System.Security;\r
  32 using System.Security.Permissions;\r
  33 \r
  34 namespace System.Net {\r
  35 \r
  36         [Serializable]\r
  37         public sealed class DnsPermission : CodeAccessPermission, IUnrestrictedPermission {\r
  38 \r
  39                 private const int version = 1;\r
  40 \r
  41                 // Fields\r
  42                 bool m_noRestriction;\r
  43                 \r
  44                 // Constructors\r
  45                 public DnsPermission (PermissionState state)\r
  46                         : base () \r
  47                 {                                               \r
  48                         m_noRestriction = (state == PermissionState.Unrestricted);\r
  49                 }\r
  50                 \r
  51                 // Methods\r
  52                                 \r
  53                 public override IPermission Copy ()\r
  54                 {\r
  55                         return new DnsPermission (m_noRestriction ? PermissionState.Unrestricted : PermissionState.None);               \r
  56                 }\r
  57                 \r
  58                 public override IPermission Intersect (IPermission target)\r
  59                 {\r
  60                         DnsPermission dp = Cast (target);\r
  61                         if (dp == null)\r
  62                                 return null;\r
  63                         if (IsUnrestricted () && dp.IsUnrestricted ())\r
  64                                 return new DnsPermission (PermissionState.Unrestricted);\r
  65                         return null;\r
  66                 }\r
  67                 \r
  68                 public override bool IsSubsetOf (IPermission target) \r
  69                 {\r
  70                         DnsPermission dp = Cast (target);\r
  71                         if (dp == null)\r
  72                                 return IsEmpty ();\r
  73 \r
  74                         return (dp.IsUnrestricted () || (m_noRestriction == dp.m_noRestriction));\r
  75                 }\r
  76 \r
  77                 public bool IsUnrestricted () \r
  78                 {\r
  79                         return this.m_noRestriction;\r
  80                 }\r
  81 \r
  82                 public override SecurityElement ToXml ()\r
  83                 {\r
  84                         SecurityElement se = PermissionHelper.Element (typeof (DnsPermission), version);\r
  85                         if (m_noRestriction)\r
  86                                 se.AddAttribute ("Unrestricted", "true");                               \r
  87                         return se;\r
  88                 }\r
  89                 \r
  90                 public override void FromXml (SecurityElement securityElement)\r
  91                 {\r
  92                         PermissionHelper.CheckSecurityElement (securityElement, "securityElement", version, version);\r
  93                 \r
  94                         // LAMESPEC: it says to throw an ArgumentNullException in this case                             \r
  95                         if (securityElement.Tag != "IPermission")\r
  96                                 throw new ArgumentException ("securityElement");\r
  97                                 \r
  98                         this.m_noRestriction = PermissionHelper.IsUnrestricted (securityElement);\r
  99                 }               \r
 100                 \r
 101                 public override IPermission Union (IPermission target) \r
 102                 {\r
 103                         DnsPermission dp = Cast (target);\r
 104                         if (dp == null)\r
 105                                 return Copy ();\r
 106                         if (IsUnrestricted () || dp.IsUnrestricted ())\r
 107                                 return new DnsPermission (PermissionState.Unrestricted);\r
 108                         else\r
 109                                 return new DnsPermission (PermissionState.None);\r
 110                 }\r
 111 \r
 112                 // Internal helpers methods\r
 113 \r
 114                 private bool IsEmpty ()\r
 115                 {\r
 116                         return !m_noRestriction;\r
 117                 }\r
 118 \r
 119                 private DnsPermission Cast (IPermission target)\r
 120                 {\r
 121                         if (target == null)\r
 122                                 return null;\r
 123 \r
 124                         DnsPermission dp = (target as DnsPermission);\r
 125                         if (dp == null) {\r
 126                                 PermissionHelper.ThrowInvalidPermission (target, typeof (DnsPermission));\r
 127                         }\r
 128 \r
 129                         return dp;\r
 130                 }\r
 131         }\r
 132 }\r