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