mcs/class/Mono.Security/Mono.Security.Protocol.Tls/ClientSessionCache.cs

   1 //
   2 // ClientSessionCache.cs: Client-side cache for re-using sessions
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //
   7 // Copyright (C) 2006 Novell (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Collections;
  31
  32 namespace Mono.Security.Protocol.Tls {
  33
  34         internal class ClientSessionInfo : IDisposable {
  35
  36                 // we keep this item valid for 3 minutes (if unused)
  37                 private const int ValidityInterval = 3 * 60;
  38
  39                 private bool disposed;
  40                 private DateTime validuntil;
  41                 private string host;
  42
  43                 // see RFC2246 - Section 7
  44                 private byte[] sid;
  45                 private byte[] masterSecret;
  46
  47                 public ClientSessionInfo (string hostname, byte[] id)
  48                 {
  49                         host = hostname;
  50                         sid = id;
  51                         KeepAlive ();
  52                 }
  53
  54                 ~ClientSessionInfo ()
  55                 {
  56                         Dispose (false);
  57                 }
  58
  59
  60                 public string HostName {
  61                         get { return host; }
  62                 }
  63
  64                 public byte[] Id {
  65                         get { return sid; }
  66                 }
  67
  68                 public bool Valid {
  69                         get { return (validuntil > DateTime.UtcNow); }
  70                 }
  71
  72
  73                 public void GetContext (Context context)
  74                 {
  75                         CheckDisposed ();
  76                         masterSecret = (byte[]) context.MasterSecret.Clone ();
  77                 }
  78
  79                 public void SetContext (Context context)
  80                 {
  81                         CheckDisposed ();
  82                         context.MasterSecret = (byte[]) masterSecret.Clone ();
  83                 }
  84
  85                 public void KeepAlive ()
  86                 {
  87                         CheckDisposed ();
  88                         validuntil = DateTime.UtcNow.AddSeconds (ValidityInterval);
  89                 }
  90
  91                 public void Dispose ()
  92                 {
  93                         Dispose (true);
  94                         GC.SuppressFinalize (this);
  95                 }
  96
  97                 private void Dispose (bool disposing)
  98                 {
  99                         if (!disposed) {
 100                                 validuntil = DateTime.MinValue;
 101                                 host = null;
 102                                 sid = null;
 103
 104                                 if (masterSecret != null) {
 105                                         Array.Clear (masterSecret, 0, masterSecret.Length);
 106                                         masterSecret = null;
 107                                 }
 108                         }
 109                         disposed = true;
 110                 }
 111
 112                 private void CheckDisposed ()
 113                 {
 114                         if (disposed) {
 115                                 string msg = Locale.GetText ("Cache session information were disposed.");
 116                                 throw new ObjectDisposedException (msg);
 117                         }
 118                 }
 119         }
 120
 121         // note: locking is aggressive but isn't used often (and we gain much more :)
 122         internal class ClientSessionCache {
 123
 124                 static Hashtable cache;
 125                 static object locker;
 126
 127                 static ClientSessionCache ()
 128                 {
 129                         cache = new Hashtable ();
 130                         locker = new object ();
 131                 }
 132
 133                 // note: we may have multiple connections with a host, so
 134                 // possibly multiple entries per host (each with a different
 135                 // id), so we do not use the host as the hashtable key
 136                 static public void Add (string host, byte[] id)
 137                 {
 138                         lock (locker) {
 139                                 string uid = BitConverter.ToString (id);
 140                                 ClientSessionInfo si = (ClientSessionInfo) cache[uid];
 141                                 if (si == null) {
 142                                         cache.Add (uid, new ClientSessionInfo (host, id));
 143                                 } else if (si.HostName == host) {
 144                                         // we already have this and it's still valid
 145                                         // on the server, so we'll keep it a little longer
 146                                         si.KeepAlive ();
 147                                 } else {
 148                                         // it's very unlikely but the same session id
 149                                         // could be used by more than one host. In this
 150                                         // case we replace the older one with the new one
 151                                         si.Dispose ();
 152                                         cache.Remove (uid);
 153                                         cache.Add (uid, new ClientSessionInfo (host, id));
 154                                 }
 155                         }
 156                 }
 157
 158                 // return the first session us
 159                 static public byte[] FromHost (string host)
 160                 {
 161                         lock (locker) {
 162                                 foreach (ClientSessionInfo si in cache.Values) {
 163                                         if (si.HostName == host) {
 164                                                 if (si.Valid) {
 165                                                         // ensure it's still valid when we really need it
 166                                                         si.KeepAlive ();
 167                                                         return si.Id;
 168                                                 }
 169                                         }
 170                                 }
 171                                 return null;
 172                         }
 173                 }
 174
 175                 // only called inside the lock
 176                 static private ClientSessionInfo FromContext (Context context)
 177                 {
 178                         if (context == null)
 179                                 return null;
 180
 181                         byte[] id = context.SessionId;
 182                         if ((id == null) || (id.Length == 0))
 183                                 return null;
 184
 185                         // do we have a session cached for this host ?
 186                         string uid = BitConverter.ToString (id);
 187
 188                         ClientSessionInfo si = (ClientSessionInfo) cache[uid];
 189                         if (si == null)
 190                                 return null;
 191
 192                         // In the unlikely case of multiple hosts using the same
 193                         // session id, we just act like we do not know about it
 194                         if (context.ClientSettings.TargetHost != si.HostName)
 195                                 return null;
 196
 197                         // yes, so what's its status ?
 198                         if (!si.Valid) {
 199                                 si.Dispose ();
 200                                 cache.Remove (uid);
 201                                 return null;
 202                         }
 203
 204                         // ok, it make sense
 205                         return si;
 206                 }
 207
 208                 static public bool SetContextInCache (Context context)
 209                 {
 210                         lock (locker) {
 211                                 ClientSessionInfo csi = FromContext (context);
 212                                 if (csi == null)
 213                                         return false;
 214
 215                                 csi.GetContext (context);
 216                                 csi.KeepAlive ();
 217                                 return true;
 218                         }
 219                 }
 220
 221                 static public bool SetContextFromCache (Context context)
 222                 {
 223                         lock (locker) {
 224                                 ClientSessionInfo csi = FromContext (context);
 225                                 if (csi == null)
 226                                         return false;
 227
 228                                 csi.SetContext (context);
 229                                 csi.KeepAlive ();
 230                                 return true;
 231                         }
 232                 }
 233         }
 234 }