mcs/class/corlib/System.Security.Policy/HashMembershipCondition.cs

   1 //
   2 // System.Security.Policy.HashMembershipCondition
   3 //
   4 // Author(s):
   5 //  Jackson Harper (Jackson@LatitudeGeo.com)
   6 //
   7 // (C) 2002 Jackson Harper, All rights reserved
   8 //
   9
  10 //
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System.Text;
  34 using System.Reflection;
  35 using System.Security.Cryptography;
  36
  37 namespace System.Security.Policy {
  38
  39         [Serializable]
  40         public sealed class HashMembershipCondition : IMembershipCondition,
  41                 ISecurityEncodable, ISecurityPolicyEncodable {
  42
  43                 private static readonly string XmlTag = "IMembershipCondition";
  44
  45                 private HashAlgorithm hash_algorithm;
  46                 private byte[] hash_value;
  47
  48                 public HashMembershipCondition (HashAlgorithm hash_algorithm,
  49                         byte[] hash_value)
  50                 {
  51                         if (hash_algorithm == null || hash_value == null)
  52                                 throw new ArgumentNullException ();
  53
  54                         this.hash_algorithm = hash_algorithm;
  55                         this.hash_value = hash_value;
  56                 }
  57
  58                 //
  59                 // Public Properties
  60                 //
  61
  62                 public HashAlgorithm HashAlgorithm {
  63                         get { return hash_algorithm; }
  64                         set {
  65                                 if (value == null)
  66                                         throw new ArgumentNullException ();
  67                                 hash_algorithm = value;
  68                         }
  69                 }
  70
  71                 public byte[] HashValue {
  72                         get { return hash_value; }
  73                         set {
  74                                 if (value == null)
  75                                         throw new ArgumentNullException ();
  76                                 hash_value = value;
  77                         }
  78                 }
  79
  80                 //
  81                 // Public Methods
  82                 //
  83
  84                 public bool Check (Evidence evidence)
  85                 {
  86                         if (evidence == null)
  87                                 throw new ArgumentNullException ();
  88
  89                         // Loop through evidence finding the first Hash object
  90                         foreach (object obj in evidence) {
  91                                 Hash hash = obj as Hash;
  92                                 if (hash == null)
  93                                         continue;
  94                                 if (EqualsHashValue (hash.GenerateHash (hash_algorithm)))
  95                                         return true;
  96                                 break;
  97                         }
  98                         return false;
  99                 }
 100
 101                 public IMembershipCondition Copy ()
 102                 {
 103                         return new HashMembershipCondition (hash_algorithm, hash_value);
 104                 }
 105
 106                 public override bool Equals (object o)
 107                 {
 108                         HashMembershipCondition other;
 109                         if (!(o is HashMembershipCondition))
 110                                 return false;
 111
 112                         other = (HashMembershipCondition)o;
 113
 114                         return (other.HashAlgorithm == hash_algorithm &&
 115                                 other.HashValue == hash_value);
 116                 }
 117
 118                 public SecurityElement ToXml()
 119                 {
 120                         return ToXml (null);
 121                 }
 122
 123                 public SecurityElement ToXml (PolicyLevel level)
 124                 {
 125                         SecurityElement se = new SecurityElement (XmlTag);
 126                         Type type = this.GetType ();
 127                         string classString = type.FullName + ", " + type.Assembly;
 128                         se.AddAttribute ("class", classString);
 129                         se.AddAttribute ("version", "1");
 130                         se.AddAttribute ("HashValue", Encoding.Default.GetString (hash_value));
 131                         se.AddAttribute ("HashAlgorithm", hash_algorithm.GetType ().FullName);
 132                         return se;
 133                 }
 134
 135                 public void FromXml (SecurityElement element)
 136                 {
 137                         FromXml (element, null);
 138                 }
 139
 140                 public void FromXml (SecurityElement e,
 141                         PolicyLevel level)
 142                 {
 143                         if (e == null)
 144                                 throw new ArgumentNullException ();
 145                         if (e.Tag != XmlTag)
 146                                 throw new ArgumentException(
 147                                         "e","The Tag of SecurityElement must be " + XmlTag);
 148
 149                         string value = (string)e.Attributes["HashValue"];
 150                         string algorithm = (string)e.Attributes["HashAlgorithm"];
 151
 152                         if (value == null || algorithm == null )
 153                                 throw new ArgumentException ();
 154
 155                         hash_value = Encoding.Default.GetBytes (value);
 156                         hash_algorithm = (HashAlgorithm)Assembly.GetExecutingAssembly ().CreateInstance (algorithm);
 157
 158                 }
 159
 160                 [MonoTODO("This is not right")]
 161                 public override int GetHashCode ()
 162                 {
 163                         return hash_value.GetHashCode ();
 164                 }
 165
 166                 public override string ToString ()
 167                 {
 168                         StringBuilder builder = new StringBuilder ();
 169                         Type alg_type = hash_algorithm.GetType ();
 170
 171                         builder.Append ("Hash -");
 172                         builder.AppendFormat ("{0} {1}", alg_type.FullName,
 173                                 alg_type.Assembly);
 174                         builder.AppendFormat (" = ",  Encoding.Default.GetString (hash_value));
 175
 176                         return builder.ToString ();
 177                 }
 178
 179                 //
 180                 // Private Methods
 181                 //
 182
 183                 private bool EqualsHashValue (byte[] value)
 184                 {
 185                         int len;
 186
 187                         if (value.Length != hash_value.Length)
 188                                 return false;
 189
 190                         len = value.Length;
 191                         for (int i=0; i<len; i++ ) {
 192                                 if (value[i] != hash_value[i])
 193                                         return false;
 194                         }
 195
 196                         return true;
 197                 }
 198         }
 199 }
 200