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>
   7 //\r
   8 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29 \r
  30 using System.Collections;\r
  31 using System.Security;\r
  32 using System.Security.Permissions;\r
  33 \r
  34 namespace System.Net {
  35 \r
  36         [Serializable]\r
  37         public sealed class DnsPermission : CodeAccessPermission, IUnrestrictedPermission {
  38
  39                 private const int version = 1;
  40 \r
  41                 // Fields\r
  42                 bool m_noRestriction;\r
  43                 \r
  44                 // Constructors\r
  45                 public DnsPermission (PermissionState state)
  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);
  61                         if (dp == null)
  62                                 return null;
  63                         if (IsUnrestricted () && dp.IsUnrestricted ())
  64                                 return new DnsPermission (PermissionState.Unrestricted);
  65                         return null;\r
  66                 }\r
  67                 \r
  68                 public override bool IsSubsetOf (IPermission target) \r
  69                 {\r
  70                         DnsPermission dp = Cast (target);
  71                         if (dp == null)
  72                                 return IsEmpty ();
  73
  74                         return (dp.IsUnrestricted () || (m_noRestriction == dp.m_noRestriction));
  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);
  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                 {
  92                         PermissionHelper.CheckSecurityElement (securityElement, "securityElement", version, version);
  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                 {
 103                         DnsPermission dp = Cast (target);
 104                         if (dp == null)
 105                                 return Copy ();
 106                         if (IsUnrestricted () || dp.IsUnrestricted ())
 107                                 return new DnsPermission (PermissionState.Unrestricted);
 108                         else
 109                                 return new DnsPermission (PermissionState.None);
 110                 }\r
 111
 112                 // Internal helpers methods
 113
 114                 private bool IsEmpty ()
 115                 {
 116                         return !m_noRestriction;
 117                 }
 118
 119                 private DnsPermission Cast (IPermission target)
 120                 {
 121                         if (target == null)
 122                                 return null;
 123
 124                         DnsPermission dp = (target as DnsPermission);
 125                         if (dp == null) {
 126                                 PermissionHelper.ThrowInvalidPermission (target, typeof (DnsPermission));
 127                         }
 128
 129                         return dp;
 130                 }
 131         }\r
 132 }\r