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                 // (by default) we keep this item valid for 3 minutes (if unused)
  37                 private const int DefaultValidityInterval = 3 * 60;
  38                 private static readonly int ValidityInterval;
  39
  40                 private bool disposed;
  41                 private DateTime validuntil;
  42                 private string host;
  43
  44                 // see RFC2246 - Section 7
  45                 private byte[] sid;
  46                 private byte[] masterSecret;
  47
  48                 static ClientSessionInfo ()
  49                 {
  50 #if MOONLIGHT
  51                         ValidityInterval = DefaultValidityInterval;
  52 #else
  53                         string user_cache_timeout = Environment.GetEnvironmentVariable ("MONO_TLS_SESSION_CACHE_TIMEOUT");
  54                         if (user_cache_timeout == null) {
  55                                 ValidityInterval = DefaultValidityInterval;
  56                         } else {
  57                                 try {
  58                                         ValidityInterval = Int32.Parse (user_cache_timeout);
  59                                 }
  60                                 catch {
  61                                         ValidityInterval = DefaultValidityInterval;
  62                                 }
  63                         }
  64 #endif
  65                 }
  66
  67                 public ClientSessionInfo (string hostname, byte[] id)
  68                 {
  69                         host = hostname;
  70                         sid = id;
  71                         KeepAlive ();
  72                 }
  73
  74                 ~ClientSessionInfo ()
  75                 {
  76                         Dispose (false);
  77                 }
  78
  79
  80                 public string HostName {
  81                         get { return host; }
  82                 }
  83
  84                 public byte[] Id {
  85                         get { return sid; }
  86                 }
  87
  88                 public bool Valid {
  89                         get { return ((masterSecret != null) && (validuntil > DateTime.UtcNow)); }
  90                 }
  91
  92
  93                 public void GetContext (Context context)
  94                 {
  95                         CheckDisposed ();
  96                         if (context.MasterSecret != null)
  97                                 masterSecret = (byte[]) context.MasterSecret.Clone ();
  98                 }
  99
 100                 public void SetContext (Context context)
 101                 {
 102                         CheckDisposed ();
 103                         if (masterSecret != null)
 104                                 context.MasterSecret = (byte[]) masterSecret.Clone ();
 105                 }
 106
 107                 public void KeepAlive ()
 108                 {
 109                         CheckDisposed ();
 110                         validuntil = DateTime.UtcNow.AddSeconds (ValidityInterval);
 111                 }
 112
 113                 public void Dispose ()
 114                 {
 115                         Dispose (true);
 116                         GC.SuppressFinalize (this);
 117                 }
 118
 119                 private void Dispose (bool disposing)
 120                 {
 121                         if (!disposed) {
 122                                 validuntil = DateTime.MinValue;
 123                                 host = null;
 124                                 sid = null;
 125
 126                                 if (masterSecret != null) {
 127                                         Array.Clear (masterSecret, 0, masterSecret.Length);
 128                                         masterSecret = null;
 129                                 }
 130                         }
 131                         disposed = true;
 132                 }
 133
 134                 private void CheckDisposed ()
 135                 {
 136                         if (disposed) {
 137                                 string msg = Locale.GetText ("Cache session information were disposed.");
 138                                 throw new ObjectDisposedException (msg);
 139                         }
 140                 }
 141         }
 142
 143         // note: locking is aggressive but isn't used often (and we gain much more :)
 144         internal class ClientSessionCache {
 145
 146                 static Hashtable cache;
 147                 static object locker;
 148
 149                 static ClientSessionCache ()
 150                 {
 151                         cache = new Hashtable ();
 152                         locker = new object ();
 153                 }
 154
 155                 // note: we may have multiple connections with a host, so
 156                 // possibly multiple entries per host (each with a different
 157                 // id), so we do not use the host as the hashtable key
 158                 static public void Add (string host, byte[] id)
 159                 {
 160                         lock (locker) {
 161                                 string uid = BitConverter.ToString (id);
 162                                 ClientSessionInfo si = (ClientSessionInfo) cache[uid];
 163                                 if (si == null) {
 164                                         cache.Add (uid, new ClientSessionInfo (host, id));
 165                                 } else if (si.HostName == host) {
 166                                         // we already have this and it's still valid
 167                                         // on the server, so we'll keep it a little longer
 168                                         si.KeepAlive ();
 169                                 } else {
 170                                         // it's very unlikely but the same session id
 171                                         // could be used by more than one host. In this
 172                                         // case we replace the older one with the new one
 173                                         si.Dispose ();
 174                                         cache.Remove (uid);
 175                                         cache.Add (uid, new ClientSessionInfo (host, id));
 176                                 }
 177                         }
 178                 }
 179
 180                 // return the first session us
 181                 static public byte[] FromHost (string host)
 182                 {
 183                         lock (locker) {
 184                                 foreach (ClientSessionInfo si in cache.Values) {
 185                                         if (si.HostName == host) {
 186                                                 if (si.Valid) {
 187                                                         // ensure it's still valid when we really need it
 188                                                         si.KeepAlive ();
 189                                                         return si.Id;
 190                                                 }
 191                                         }
 192                                 }
 193                                 return null;
 194                         }
 195                 }
 196
 197                 // only called inside the lock
 198                 static private ClientSessionInfo FromContext (Context context, bool checkValidity)
 199                 {
 200                         if (context == null)
 201                                 return null;
 202
 203                         byte[] id = context.SessionId;
 204                         if ((id == null) || (id.Length == 0))
 205                                 return null;
 206
 207                         // do we have a session cached for this host ?
 208                         string uid = BitConverter.ToString (id);
 209
 210                         ClientSessionInfo si = (ClientSessionInfo) cache[uid];
 211                         if (si == null)
 212                                 return null;
 213
 214                         // In the unlikely case of multiple hosts using the same
 215                         // session id, we just act like we do not know about it
 216                         if (context.ClientSettings.TargetHost != si.HostName)
 217                                 return null;
 218
 219                         // yes, so what's its status ?
 220                         if (checkValidity && !si.Valid) {
 221                                 si.Dispose ();
 222                                 cache.Remove (uid);
 223                                 return null;
 224                         }
 225
 226                         // ok, it make sense
 227                         return si;
 228                 }
 229
 230                 static public bool SetContextInCache (Context context)
 231                 {
 232                         lock (locker) {
 233                                 // Don't check the validity because the masterKey of the ClientSessionInfo
 234                                 // can still be null when this is called the first time
 235                                 ClientSessionInfo csi = FromContext (context, false);
 236                                 if (csi == null)
 237                                         return false;
 238
 239                                 csi.GetContext (context);
 240                                 csi.KeepAlive ();
 241                                 return true;
 242                         }
 243                 }
 244
 245                 static public bool SetContextFromCache (Context context)
 246                 {
 247                         lock (locker) {
 248                                 ClientSessionInfo csi = FromContext (context, true);
 249                                 if (csi == null)
 250                                         return false;
 251
 252                                 csi.SetContext (context);
 253                                 csi.KeepAlive ();
 254                                 return true;
 255                         }
 256                 }
 257         }
 258 }