Added time format with only offset. Fixes #22558.
[mono.git] / mcs / class / System / System.Net / ServicePointManager.cs
1 //
2 // System.Net.ServicePointManager
3 //
4 // Authors:
5 //   Lawrence Pit (loz@cable.a2000.nl)
6 //   Gonzalo Paniagua Javier (gonzalo@novell.com)
7 //
8 // Copyright (c) 2003-2010 Novell, Inc (http://www.novell.com)
9 //
10
11 //
12 // Permission is hereby granted, free of charge, to any person obtaining
13 // a copy of this software and associated documentation files (the
14 // "Software"), to deal in the Software without restriction, including
15 // without limitation the rights to use, copy, modify, merge, publish,
16 // distribute, sublicense, and/or sell copies of the Software, and to
17 // permit persons to whom the Software is furnished to do so, subject to
18 // the following conditions:
19 // 
20 // The above copyright notice and this permission notice shall be
21 // included in all copies or substantial portions of the Software.
22 // 
23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
30 //
31
32 #if SECURITY_DEP
33
34 #if MONOTOUCH || MONODROID
35 using Mono.Security.Protocol.Tls;
36 using MSX = Mono.Security.X509;
37 using Mono.Security.X509.Extensions;
38 #else
39 extern alias MonoSecurity;
40 using MonoSecurity::Mono.Security.X509.Extensions;
41 using MonoSecurity::Mono.Security.Protocol.Tls;
42 using MSX = MonoSecurity::Mono.Security.X509;
43 #endif
44
45 using System.Text.RegularExpressions;
46 #endif
47
48 using System;
49 using System.Threading;
50 using System.Collections;
51 using System.Collections.Generic;
52 using System.Collections.Specialized;
53 using System.Configuration;
54 using System.Net.Configuration;
55 using System.Security.Cryptography.X509Certificates;
56
57 using System.Globalization;
58 using System.Net.Security;
59 using System.Diagnostics;
60
61 //
62 // notes:
63 // A service point manager manages service points (duh!).
64 // A service point maintains a list of connections (per scheme + authority).
65 // According to HttpWebRequest.ConnectionGroupName each connection group
66 // creates additional connections. therefor, a service point has a hashtable
67 // of connection groups where each value is a list of connections.
68 // 
69 // when we need to make an HttpWebRequest, we need to do the following:
70 // 1. find service point, given Uri and Proxy 
71 // 2. find connection group, given service point and group name
72 // 3. find free connection in connection group, or create one (if ok due to limits)
73 // 4. lease connection
74 // 5. execute request
75 // 6. when finished, return connection
76 //
77
78
79 namespace System.Net 
80 {
81         public partial class ServicePointManager {
82                 class SPKey {
83                         Uri uri; // schema/host/port
84                         Uri proxy;
85                         bool use_connect;
86
87                         public SPKey (Uri uri, Uri proxy, bool use_connect) {
88                                 this.uri = uri;
89                                 this.proxy = proxy;
90                                 this.use_connect = use_connect;
91                         }
92
93                         public Uri Uri {
94                                 get { return uri; }
95                         }
96
97                         public bool UseConnect {
98                                 get { return use_connect; }
99                         }
100
101                         public bool UsesProxy {
102                                 get { return proxy != null; }
103                         }
104
105                         public override int GetHashCode () {
106                                 int hash = 23;
107                                 hash = hash * 31 + ((use_connect) ? 1 : 0);
108                                 hash = hash * 31 + uri.GetHashCode ();
109                                 hash = hash * 31 + (proxy != null ? proxy.GetHashCode () : 0);
110                                 return hash;
111                         }
112
113                         public override bool Equals (object obj) {
114                                 SPKey other = obj as SPKey;
115                                 if (obj == null) {
116                                         return false;
117                                 }
118
119                                 if (!uri.Equals (other.uri))
120                                         return false;
121                                 if (use_connect != other.use_connect || UsesProxy != other.UsesProxy)
122                                         return false;
123                                 if (UsesProxy && !proxy.Equals (other.proxy))
124                                         return false;
125                                 return true;
126                         }
127                 }
128
129                 private static HybridDictionary servicePoints = new HybridDictionary ();
130                 
131                 // Static properties
132                 
133                 private static ICertificatePolicy policy = new DefaultCertificatePolicy ();
134                 private static int defaultConnectionLimit = DefaultPersistentConnectionLimit;
135                 private static int maxServicePointIdleTime = 100000; // 100 seconds
136                 private static int maxServicePoints = 0;
137                 private static bool _checkCRL = false;
138                 private static SecurityProtocolType _securityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;
139
140                 static bool expectContinue = true;
141                 static bool useNagle;
142                 static RemoteCertificateValidationCallback server_cert_cb;
143                 static bool tcp_keepalive;
144                 static int tcp_keepalive_time;
145                 static int tcp_keepalive_interval;
146
147                 // Fields
148                 
149                 public const int DefaultNonPersistentConnectionLimit = 4;
150 #if MONOTOUCH
151                 public const int DefaultPersistentConnectionLimit = 10;
152 #else
153                 public const int DefaultPersistentConnectionLimit = 2;
154 #endif
155
156 #if !NET_2_1
157                 const string configKey = "system.net/connectionManagement";
158                 static ConnectionManagementData manager;
159 #endif
160                 
161                 static ServicePointManager ()
162                 {
163 #if !NET_2_1
164 #if CONFIGURATION_DEP
165                         object cfg = ConfigurationManager.GetSection (configKey);
166                         ConnectionManagementSection s = cfg as ConnectionManagementSection;
167                         if (s != null) {
168                                 manager = new ConnectionManagementData (null);
169                                 foreach (ConnectionManagementElement e in s.ConnectionManagement)
170                                         manager.Add (e.Address, e.MaxConnection);
171
172                                 defaultConnectionLimit = (int) manager.GetMaxConnections ("*");                         
173                                 return;
174                         }
175 #endif
176                         manager = (ConnectionManagementData) ConfigurationSettings.GetConfig (configKey);
177                         if (manager != null) {
178                                 defaultConnectionLimit = (int) manager.GetMaxConnections ("*");                         
179                         }
180 #endif
181                 }
182
183                 // Constructors
184                 private ServicePointManager ()
185                 {
186                 }               
187                 
188                 // Properties
189                 
190                 [Obsolete ("Use ServerCertificateValidationCallback instead", false)]
191                 public static ICertificatePolicy CertificatePolicy {
192                         get { return policy; }
193                         set { policy = value; }
194                 }
195
196                 [MonoTODO("CRL checks not implemented")]
197                 public static bool CheckCertificateRevocationList {
198                         get { return _checkCRL; }
199                         set { _checkCRL = false; }      // TODO - don't yet accept true
200                 }
201                 
202                 public static int DefaultConnectionLimit {
203                         get { return defaultConnectionLimit; }
204                         set { 
205                                 if (value <= 0)
206                                         throw new ArgumentOutOfRangeException ("value");
207
208                                 defaultConnectionLimit = value; 
209 #if !NET_2_1
210                 if (manager != null)
211                                         manager.Add ("*", defaultConnectionLimit);
212 #endif
213                         }
214                 }
215
216                 static Exception GetMustImplement ()
217                 {
218                         return new NotImplementedException ();
219                 }
220                 
221                 [MonoTODO]
222                 public static int DnsRefreshTimeout
223                 {
224                         get {
225                                 throw GetMustImplement ();
226                         }
227                         set {
228                                 throw GetMustImplement ();
229                         }
230                 }
231                 
232                 [MonoTODO]
233                 public static bool EnableDnsRoundRobin
234                 {
235                         get {
236                                 throw GetMustImplement ();
237                         }
238                         set {
239                                 throw GetMustImplement ();
240                         }
241                 }
242                 
243                 public static int MaxServicePointIdleTime {
244                         get { 
245                                 return maxServicePointIdleTime;
246                         }
247                         set { 
248                                 if (value < -2 || value > Int32.MaxValue)
249                                         throw new ArgumentOutOfRangeException ("value");
250                                 maxServicePointIdleTime = value;
251                         }
252                 }
253                 
254                 public static int MaxServicePoints {
255                         get { 
256                                 return maxServicePoints; 
257                         }
258                         set {  
259                                 if (value < 0)
260                                         throw new ArgumentException ("value");                          
261
262                                 maxServicePoints = value;
263                         }
264                 }
265
266 #if NET_1_0
267                 // we need it for SslClientStream
268                 internal
269 #else
270                 public
271 #endif
272                 static SecurityProtocolType SecurityProtocol {
273                         get { return _securityProtocol; }
274                         set { _securityProtocol = value; }
275                 }
276
277                 public static RemoteCertificateValidationCallback ServerCertificateValidationCallback
278                 {
279                         get {
280                                 return server_cert_cb;
281                         }
282                         set {
283                                 server_cert_cb = value;
284                         }
285                 }
286
287                 public static bool Expect100Continue {
288                         get { return expectContinue; }
289                         set { expectContinue = value; }
290                 }
291
292                 public static bool UseNagleAlgorithm {
293                         get { return useNagle; }
294                         set { useNagle = value; }
295                 }
296
297                 // Methods
298                 public static void SetTcpKeepAlive (bool enabled, int keepAliveTime, int keepAliveInterval)
299                 {
300                         if (enabled) {
301                                 if (keepAliveTime <= 0)
302                                         throw new ArgumentOutOfRangeException ("keepAliveTime", "Must be greater than 0");
303                                 if (keepAliveInterval <= 0)
304                                         throw new ArgumentOutOfRangeException ("keepAliveInterval", "Must be greater than 0");
305                         }
306
307                         tcp_keepalive = enabled;
308                         tcp_keepalive_time = keepAliveTime;
309                         tcp_keepalive_interval = keepAliveInterval;
310                 }
311
312                 public static ServicePoint FindServicePoint (Uri address) 
313                 {
314                         return FindServicePoint (address, GlobalProxySelection.Select);
315                 }
316                 
317                 public static ServicePoint FindServicePoint (string uriString, IWebProxy proxy)
318                 {
319                         return FindServicePoint (new Uri(uriString), proxy);
320                 }
321
322                 public static ServicePoint FindServicePoint (Uri address, IWebProxy proxy)
323                 {
324                         if (address == null)
325                                 throw new ArgumentNullException ("address");
326
327                         var origAddress = new Uri (address.Scheme + "://" + address.Authority);
328                         
329                         bool usesProxy = false;
330                         bool useConnect = false;
331                         if (proxy != null && !proxy.IsBypassed(address)) {
332                                 usesProxy = true;
333                                 bool isSecure = address.Scheme == "https";
334                                 address = proxy.GetProxy (address);
335                                 if (address.Scheme != "http" && !isSecure)
336                                         throw new NotSupportedException ("Proxy scheme not supported.");
337
338                                 if (isSecure && address.Scheme == "http")
339                                         useConnect = true;
340                         } 
341
342                         address = new Uri (address.Scheme + "://" + address.Authority);
343                         
344                         ServicePoint sp = null;
345                         SPKey key = new SPKey (origAddress, usesProxy ? address : null, useConnect);
346                         lock (servicePoints) {
347                                 sp = servicePoints [key] as ServicePoint;
348                                 if (sp != null)
349                                         return sp;
350
351                                 if (maxServicePoints > 0 && servicePoints.Count >= maxServicePoints)
352                                         throw new InvalidOperationException ("maximum number of service points reached");
353
354                                 int limit;
355 #if NET_2_1
356                                 limit = defaultConnectionLimit;
357 #else
358                                 string addr = address.ToString ();
359                                 limit = (int) manager.GetMaxConnections (addr);
360 #endif
361                                 sp = new ServicePoint (address, limit, maxServicePointIdleTime);
362                                 sp.Expect100Continue = expectContinue;
363                                 sp.UseNagleAlgorithm = useNagle;
364                                 sp.UsesProxy = usesProxy;
365                                 sp.UseConnect = useConnect;
366                                 sp.SetTcpKeepAlive (tcp_keepalive, tcp_keepalive_time, tcp_keepalive_interval);
367                                 servicePoints.Add (key, sp);
368                         }
369                         
370                         return sp;
371                 }
372                 
373 #if SECURITY_DEP
374                 internal class ChainValidationHelper {
375                         object sender;
376                         string host;
377                         RemoteCertificateValidationCallback cb;
378
379 #if !MONOTOUCH
380                         static bool is_macosx = System.IO.File.Exists (OSX509Certificates.SecurityLibrary);
381                         static X509RevocationMode revocation_mode;
382
383                         static ChainValidationHelper ()
384                         {
385                                 revocation_mode = X509RevocationMode.NoCheck;
386                                 try {
387                                         string str = Environment.GetEnvironmentVariable ("MONO_X509_REVOCATION_MODE");
388                                         if (String.IsNullOrEmpty (str))
389                                                 return;
390                                         revocation_mode = (X509RevocationMode) Enum.Parse (typeof (X509RevocationMode), str, true);
391                                 } catch {
392                                 }
393                         }
394 #endif
395
396                         public ChainValidationHelper (object sender, string hostName)
397                         {
398                                 this.sender = sender;
399                                 host = hostName;
400                         }
401
402                         public RemoteCertificateValidationCallback ServerCertificateValidationCallback {
403                                 get {
404                                         if (cb == null)
405                                                 cb = ServicePointManager.ServerCertificateValidationCallback;
406                                         return cb;
407                                 }
408                                 set { cb = value; }
409                         }
410
411                         // Used when the obsolete ICertificatePolicy is set to DefaultCertificatePolicy
412                         // and the new ServerCertificateValidationCallback is not null
413                         internal ValidationResult ValidateChain (MSX.X509CertificateCollection certs)
414                         {
415                                 // user_denied is true if the user callback is called and returns false
416                                 bool user_denied = false;
417                                 if (certs == null || certs.Count == 0)
418                                         return null;
419
420                                 ICertificatePolicy policy = ServicePointManager.CertificatePolicy;
421
422                                 X509Certificate2 leaf = new X509Certificate2 (certs [0].RawData);
423                                 int status11 = 0; // Error code passed to the obsolete ICertificatePolicy callback
424                                 SslPolicyErrors errors = 0;
425                                 X509Chain chain = null;
426                                 bool result = false;
427 #if MONOTOUCH
428                                 // The X509Chain is not really usable with MonoTouch (since the decision is not based on this data)
429                                 // However if someone wants to override the results (good or bad) from iOS then they will want all
430                                 // the certificates that the server provided (which generally does not include the root) so, only  
431                                 // if there's a user callback, we'll create the X509Chain but won't build it
432                                 // ref: https://bugzilla.xamarin.com/show_bug.cgi?id=7245
433                                 if (ServerCertificateValidationCallback != null) {
434 #endif
435                                 chain = new X509Chain ();
436                                 chain.ChainPolicy = new X509ChainPolicy ();
437 #if !MONOTOUCH
438                                 chain.ChainPolicy.RevocationMode = revocation_mode;
439 #endif
440                                 for (int i = 1; i < certs.Count; i++) {
441                                         X509Certificate2 c2 = new X509Certificate2 (certs [i].RawData);
442                                         chain.ChainPolicy.ExtraStore.Add (c2);
443                                 }
444 #if MONOTOUCH
445                                 }
446 #else
447                                 try {
448                                         if (!chain.Build (leaf))
449                                                 errors |= GetErrorsFromChain (chain);
450                                 } catch (Exception e) {
451                                         Console.Error.WriteLine ("ERROR building certificate chain: {0}", e);
452                                         Console.Error.WriteLine ("Please, report this problem to the Mono team");
453                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
454                                 }
455
456                                 // for OSX and iOS we're using the native API to check for the SSL server policy and host names
457                                 if (!is_macosx) {
458                                         if (!CheckCertificateUsage (leaf)) {
459                                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
460                                                 status11 = -2146762490; //CERT_E_PURPOSE 0x800B0106
461                                         }
462
463                                         if (!CheckServerIdentity (certs [0], host)) {
464                                                 errors |= SslPolicyErrors.RemoteCertificateNameMismatch;
465                                                 status11 = -2146762481; // CERT_E_CN_NO_MATCH 0x800B010F
466                                         }
467                                 } else {
468 #endif
469                                         // Attempt to use OSX certificates
470                                         // Ideally we should return the SecTrustResult
471                                         OSX509Certificates.SecTrustResult trustResult = OSX509Certificates.SecTrustResult.Deny;
472                                         try {
473                                                 trustResult = OSX509Certificates.TrustEvaluateSsl (certs, host);
474                                                 // We could use the other values of trustResult to pass this extra information
475                                                 // to the .NET 2 callback for values like SecTrustResult.Confirm
476                                                 result = (trustResult == OSX509Certificates.SecTrustResult.Proceed ||
477                                                                   trustResult == OSX509Certificates.SecTrustResult.Unspecified);
478                                         } catch {
479                                                 // Ignore
480                                         }
481                                         
482                                         if (result) {
483                                                 // TrustEvaluateSsl was successful so there's no trust error
484                                                 // IOW we discard our own chain (since we trust OSX one instead)
485                                                 errors = 0;
486                                         } else {
487                                                 // callback and DefaultCertificatePolicy needs this since 'result' is not specified
488                                                 status11 = (int) trustResult;
489                                                 errors |= SslPolicyErrors.RemoteCertificateChainErrors;
490                                         }
491 #if !MONOTOUCH
492                                 }
493 #endif
494
495 #if MONODROID && SECURITY_DEP
496                                 result = AndroidPlatform.TrustEvaluateSsl (certs, sender, leaf, chain, errors);
497                                 if (result) {
498                                         // chain.Build() + GetErrorsFromChain() (above) will ALWAYS fail on
499                                         // Android (there are no mozroots or preinstalled root certificates),
500                                         // thus `errors` will ALWAYS have RemoteCertificateChainErrors.
501                                         // Android just verified the chain; clear RemoteCertificateChainErrors.
502                                         errors  &= ~SslPolicyErrors.RemoteCertificateChainErrors;
503                                 }
504 #endif
505
506                                 if (policy != null && (!(policy is DefaultCertificatePolicy) || cb == null)) {
507                                         ServicePoint sp = null;
508                                         HttpWebRequest req = sender as HttpWebRequest;
509                                         if (req != null)
510                                                 sp = req.ServicePointNoLock;
511                                         if (status11 == 0 && errors != 0)
512                                                 status11 = GetStatusFromChain (chain);
513
514                                         // pre 2.0 callback
515                                         result = policy.CheckValidationResult (sp, leaf, req, status11);
516                                         user_denied = !result && !(policy is DefaultCertificatePolicy);
517                                 }
518                                 // If there's a 2.0 callback, it takes precedence
519                                 if (ServerCertificateValidationCallback != null) {
520                                         result = ServerCertificateValidationCallback (sender, leaf, chain, errors);
521                                         user_denied = !result;
522                                 }
523                                 return new ValidationResult (result, user_denied, status11);
524                         }
525
526                         static int GetStatusFromChain (X509Chain chain)
527                         {
528                                 long result = 0;
529                                 foreach (var status in chain.ChainStatus) {
530                                         X509ChainStatusFlags flags = status.Status;
531                                         if (flags == X509ChainStatusFlags.NoError)
532                                                 continue;
533
534                                         // CERT_E_EXPIRED
535                                         if ((flags & X509ChainStatusFlags.NotTimeValid) != 0) result = 0x800B0101;
536                                         // CERT_E_VALIDITYPERIODNESTING
537                                         else if ((flags & X509ChainStatusFlags.NotTimeNested) != 0) result = 0x800B0102;
538                                         // CERT_E_REVOKED
539                                         else if ((flags & X509ChainStatusFlags.Revoked) != 0) result = 0x800B010C;
540                                         // TRUST_E_CERT_SIGNATURE
541                                         else if ((flags & X509ChainStatusFlags.NotSignatureValid) != 0) result = 0x80096004;
542                                         // CERT_E_WRONG_USAGE
543                                         else if ((flags & X509ChainStatusFlags.NotValidForUsage) != 0) result = 0x800B0110;
544                                         // CERT_E_UNTRUSTEDROOT
545                                         else if ((flags & X509ChainStatusFlags.UntrustedRoot) != 0) result = 0x800B0109;
546                                         // CRYPT_E_NO_REVOCATION_CHECK
547                                         else if ((flags & X509ChainStatusFlags.RevocationStatusUnknown) != 0) result = 0x80092012;
548                                         // CERT_E_CHAINING
549                                         else if ((flags & X509ChainStatusFlags.Cyclic) != 0) result = 0x800B010A;
550                                         // TRUST_E_FAIL - generic
551                                         else if ((flags & X509ChainStatusFlags.InvalidExtension) != 0) result = 0x800B010B;
552                                         // CERT_E_UNTRUSTEDROOT
553                                         else if ((flags & X509ChainStatusFlags.InvalidPolicyConstraints) != 0) result = 0x800B010D;
554                                         // TRUST_E_BASIC_CONSTRAINTS
555                                         else if ((flags & X509ChainStatusFlags.InvalidBasicConstraints) != 0) result = 0x80096019;
556                                         // CERT_E_INVALID_NAME
557                                         else if ((flags & X509ChainStatusFlags.InvalidNameConstraints) != 0) result = 0x800B0114;
558                                         // CERT_E_INVALID_NAME
559                                         else if ((flags & X509ChainStatusFlags.HasNotSupportedNameConstraint) != 0) result = 0x800B0114;
560                                         // CERT_E_INVALID_NAME
561                                         else if ((flags & X509ChainStatusFlags.HasNotDefinedNameConstraint) != 0) result = 0x800B0114;
562                                         // CERT_E_INVALID_NAME
563                                         else if ((flags & X509ChainStatusFlags.HasNotPermittedNameConstraint) != 0) result = 0x800B0114;
564                                         // CERT_E_INVALID_NAME
565                                         else if ((flags & X509ChainStatusFlags.HasExcludedNameConstraint) != 0) result = 0x800B0114;
566                                         // CERT_E_CHAINING
567                                         else if ((flags & X509ChainStatusFlags.PartialChain) != 0) result = 0x800B010A;
568                                         // CERT_E_EXPIRED
569                                         else if ((flags & X509ChainStatusFlags.CtlNotTimeValid) != 0) result = 0x800B0101;
570                                         // TRUST_E_CERT_SIGNATURE
571                                         else if ((flags & X509ChainStatusFlags.CtlNotSignatureValid) != 0) result = 0x80096004;
572                                         // CERT_E_WRONG_USAGE
573                                         else if ((flags & X509ChainStatusFlags.CtlNotValidForUsage) != 0) result = 0x800B0110;
574                                         // CRYPT_E_NO_REVOCATION_CHECK
575                                         else if ((flags & X509ChainStatusFlags.OfflineRevocation) != 0) result = 0x80092012;
576                                         // CERT_E_ISSUERCHAINING
577                                         else if ((flags & X509ChainStatusFlags.NoIssuanceChainPolicy) != 0) result = 0x800B0107;
578                                         else result = 0x800B010B; // TRUST_E_FAIL - generic
579
580                                         break; // Exit the loop on the first error
581                                 }
582                                 return (int) result;
583                         }
584 #if !MONOTOUCH
585                         static SslPolicyErrors GetErrorsFromChain (X509Chain chain)
586                         {
587                                 SslPolicyErrors errors = SslPolicyErrors.None;
588                                 foreach (var status in chain.ChainStatus) {
589                                         if (status.Status == X509ChainStatusFlags.NoError)
590                                                 continue;
591                                         errors |= SslPolicyErrors.RemoteCertificateChainErrors;
592                                         break;
593                                 }
594                                 return errors;
595                         }
596
597                         static X509KeyUsageFlags s_flags = X509KeyUsageFlags.DigitalSignature  | 
598                                                         X509KeyUsageFlags.KeyAgreement |
599                                                         X509KeyUsageFlags.KeyEncipherment;
600                         // Adapted to System 2.0+ from TlsServerCertificate.cs
601                         //------------------------------
602                         // Note: this method only works for RSA certificates
603                         // DH certificates requires some changes - does anyone use one ?
604                         static bool CheckCertificateUsage (X509Certificate2 cert) 
605                         {
606                                 try {
607                                         // certificate extensions are required for this
608                                         // we "must" accept older certificates without proofs
609                                         if (cert.Version < 3)
610                                                 return true;
611
612                                         X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
613                                         X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
614                                         if (kux != null && eku != null) {
615                                                 // RFC3280 states that when both KeyUsageExtension and 
616                                                 // ExtendedKeyUsageExtension are present then BOTH should
617                                                 // be valid
618                                                 if ((kux.KeyUsages & s_flags) == 0)
619                                                         return false;
620                                                 return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
621                                                         eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
622                                         } else if (kux != null) {
623                                                 return ((kux.KeyUsages & s_flags) != 0);
624                                         } else if (eku != null) {
625                                                 // Server Authentication (1.3.6.1.5.5.7.3.1) or
626                                                 // Netscape Server Gated Crypto (2.16.840.1.113730.4)
627                                                 return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
628                                                         eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
629                                         }
630
631                                         // last chance - try with older (deprecated) Netscape extensions
632                                         X509Extension ext = cert.Extensions ["2.16.840.1.113730.1.1"];
633                                         if (ext != null) {
634                                                 string text = ext.NetscapeCertType (false);
635                                                 return text.IndexOf ("SSL Server Authentication", StringComparison.Ordinal) != -1;
636                                         }
637                                         return true;
638                                 } catch (Exception e) {
639                                         Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
640                                         Console.Error.WriteLine ("Please, report this problem to the Mono team");
641                                         return false;
642                                 }
643                         }
644
645                         // RFC2818 - HTTP Over TLS, Section 3.1
646                         // http://www.ietf.org/rfc/rfc2818.txt
647                         // 
648                         // 1.   if present MUST use subjectAltName dNSName as identity
649                         // 1.1.         if multiples entries a match of any one is acceptable
650                         // 1.2.         wildcard * is acceptable
651                         // 2.   URI may be an IP address -> subjectAltName.iPAddress
652                         // 2.1.         exact match is required
653                         // 3.   Use of the most specific Common Name (CN=) in the Subject
654                         // 3.1          Existing practice but DEPRECATED
655                         static bool CheckServerIdentity (MSX.X509Certificate cert, string targetHost) 
656                         {
657                                 try {
658                                         MSX.X509Extension ext = cert.Extensions ["2.5.29.17"];
659                                         // 1. subjectAltName
660                                         if (ext != null) {
661                                                 SubjectAltNameExtension subjectAltName = new SubjectAltNameExtension (ext);
662                                                 // 1.1 - multiple dNSName
663                                                 foreach (string dns in subjectAltName.DNSNames) {
664                                                         // 1.2 TODO - wildcard support
665                                                         if (Match (targetHost, dns))
666                                                                 return true;
667                                                 }
668                                                 // 2. ipAddress
669                                                 foreach (string ip in subjectAltName.IPAddresses) {
670                                                         // 2.1. Exact match required
671                                                         if (ip == targetHost)
672                                                                 return true;
673                                                 }
674                                         }
675                                         // 3. Common Name (CN=)
676                                         return CheckDomainName (cert.SubjectName, targetHost);
677                                 } catch (Exception e) {
678                                         Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
679                                         Console.Error.WriteLine ("Please, report this problem to the Mono team");
680                                         return false;
681                                 }
682                         }
683
684                         static bool CheckDomainName (string subjectName, string targetHost)
685                         {
686                                 string  domainName = String.Empty;
687                                 Regex search = new Regex(@"CN\s*=\s*([^,]*)");
688                                 MatchCollection elements = search.Matches(subjectName);
689                                 if (elements.Count == 1) {
690                                         if (elements[0].Success)
691                                                 domainName = elements[0].Groups[1].Value.ToString();
692                                 }
693
694                                 return Match (targetHost, domainName);
695                         }
696
697                         // ensure the pattern is valid wrt to RFC2595 and RFC2818
698                         // http://www.ietf.org/rfc/rfc2595.txt
699                         // http://www.ietf.org/rfc/rfc2818.txt
700                         static bool Match (string hostname, string pattern)
701                         {
702                                 // check if this is a pattern
703                                 int index = pattern.IndexOf ('*');
704                                 if (index == -1) {
705                                         // not a pattern, do a direct case-insensitive comparison
706                                         return (String.Compare (hostname, pattern, true, CultureInfo.InvariantCulture) == 0);
707                                 }
708
709                                 // check pattern validity
710                                 // A "*" wildcard character MAY be used as the left-most name component in the certificate.
711
712                                 // unless this is the last char (valid)
713                                 if (index != pattern.Length - 1) {
714                                         // then the next char must be a dot .'.
715                                         if (pattern [index + 1] != '.')
716                                                 return false;
717                                 }
718
719                                 // only one (A) wildcard is supported
720                                 int i2 = pattern.IndexOf ('*', index + 1);
721                                 if (i2 != -1)
722                                         return false;
723
724                                 // match the end of the pattern
725                                 string end = pattern.Substring (index + 1);
726                                 int length = hostname.Length - end.Length;
727                                 // no point to check a pattern that is longer than the hostname
728                                 if (length <= 0)
729                                         return false;
730
731                                 if (String.Compare (hostname, length, end, 0, end.Length, true, CultureInfo.InvariantCulture) != 0)
732                                         return false;
733
734                                 // special case, we start with the wildcard
735                                 if (index == 0) {
736                                         // ensure we hostname non-matched part (start) doesn't contain a dot
737                                         int i3 = hostname.IndexOf ('.');
738                                         return ((i3 == -1) || (i3 >= (hostname.Length - end.Length)));
739                                 }
740
741                                 // match the start of the pattern
742                                 string start = pattern.Substring (0, index);
743                                 return (String.Compare (hostname, 0, start, 0, start.Length, true, CultureInfo.InvariantCulture) == 0);
744                         }
745 #endif
746                 }
747 #endif
748         }
749 }
750