Merge pull request #472 from MelanieT/spmanager_fix
[mono.git] / mcs / class / System / System.Net / ServicePointManager.cs
index 22926e35fc97fc77cef0b2dae6819009377d8e8c..21de4e04e02fbe8f6e7bb1d3726c3c957e180929 100644 (file)
@@ -1,8 +1,11 @@
 //
 // System.Net.ServicePointManager
 //
-// Author:
+// Authors:
 //   Lawrence Pit (loz@cable.a2000.nl)
+//   Gonzalo Paniagua Javier (gonzalo@novell.com)
+//
+// Copyright (c) 2003-2010 Novell, Inc (http://www.novell.com)
 //
 
 //
@@ -33,8 +36,15 @@ using System.Configuration;
 using System.Net.Configuration;
 using System.Security.Cryptography.X509Certificates;
 
-#if NET_2_0
+using System.Globalization;
 using System.Net.Security;
+#if SECURITY_DEP
+using System.Text.RegularExpressions;
+using Mono.Security;
+using Mono.Security.Cryptography;
+using Mono.Security.X509.Extensions;
+using Mono.Security.Protocol.Tls;
+using MSX = Mono.Security.X509;
 #endif
 
 //
@@ -57,8 +67,11 @@ using System.Net.Security;
 
 namespace System.Net 
 {
-       public class ServicePointManager
-       {
+#if MOONLIGHT
+       internal class ServicePointManager {
+#else
+       public class ServicePointManager {
+#endif
                class SPKey {
                        Uri uri; // schema/host/port
                        bool use_connect;
@@ -101,29 +114,35 @@ namespace System.Net
                private static bool _checkCRL = false;
                private static SecurityProtocolType _securityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;
 
-#if NET_1_1
 #if TARGET_JVM
                static bool expectContinue = false;
 #else
                static bool expectContinue = true;
 #endif
                static bool useNagle;
-#endif
-#if NET_2_0
                static RemoteCertificateValidationCallback server_cert_cb;
-#endif
+               static bool tcp_keepalive;
+               static int tcp_keepalive_time;
+               static int tcp_keepalive_interval;
 
                // Fields
                
                public const int DefaultNonPersistentConnectionLimit = 4;
+#if MONOTOUCH
+               public const int DefaultPersistentConnectionLimit = 10;
+#else
                public const int DefaultPersistentConnectionLimit = 2;
+#endif
 
+#if !NET_2_1
                const string configKey = "system.net/connectionManagement";
                static ConnectionManagementData manager;
+#endif
                
                static ServicePointManager ()
                {
-#if NET_2_0 && CONFIGURATION_DEP
+#if !NET_2_1
+#if CONFIGURATION_DEP
                        object cfg = ConfigurationManager.GetSection (configKey);
                        ConnectionManagementSection s = cfg as ConnectionManagementSection;
                        if (s != null) {
@@ -139,6 +158,7 @@ namespace System.Net
                        if (manager != null) {
                                defaultConnectionLimit = (int) manager.GetMaxConnections ("*");                         
                        }
+#endif
                }
 
                // Constructors
@@ -148,23 +168,14 @@ namespace System.Net
                
                // Properties
                
-#if NET_2_0
-               [Obsolete ("Use ServerCertificateValidationCallback instead",
-                          false)]
-#endif
+               [Obsolete ("Use ServerCertificateValidationCallback instead", false)]
                public static ICertificatePolicy CertificatePolicy {
                        get { return policy; }
                        set { policy = value; }
                }
 
-#if NET_1_0
-               // we need it for SslClientStream
-               internal
-#else
                [MonoTODO("CRL checks not implemented")]
-               public
-#endif
-               static bool CheckCertificateRevocationList {
+               public static bool CheckCertificateRevocationList {
                        get { return _checkCRL; }
                        set { _checkCRL = false; }      // TODO - don't yet accept true
                }
@@ -176,10 +187,11 @@ namespace System.Net
                                        throw new ArgumentOutOfRangeException ("value");
 
                                defaultConnectionLimit = value; 
+                if (manager != null)
+                                       manager.Add ("*", defaultConnectionLimit);
                        }
                }
 
-#if NET_2_0
                static Exception GetMustImplement ()
                {
                        return new NotImplementedException ();
@@ -206,7 +218,6 @@ namespace System.Net
                                throw GetMustImplement ();
                        }
                }
-#endif
                
                public static int MaxServicePointIdleTime {
                        get { 
@@ -243,7 +254,6 @@ namespace System.Net
                        set { _securityProtocol = value; }
                }
 
-#if NET_2_0
                public static RemoteCertificateValidationCallback ServerCertificateValidationCallback
                {
                        get {
@@ -253,9 +263,7 @@ namespace System.Net
                                server_cert_cb = value;
                        }
                }
-#endif
 
-#if NET_1_1
                public static bool Expect100Continue {
                        get { return expectContinue; }
                        set { expectContinue = value; }
@@ -265,9 +273,22 @@ namespace System.Net
                        get { return useNagle; }
                        set { useNagle = value; }
                }
-#endif
+
                // Methods
-               
+               public static void SetTcpKeepAlive (bool enabled, int keepAliveTime, int keepAliveInterval)
+               {
+                       if (enabled) {
+                               if (keepAliveTime <= 0)
+                                       throw new ArgumentOutOfRangeException ("keepAliveTime", "Must be greater than 0");
+                               if (keepAliveInterval <= 0)
+                                       throw new ArgumentOutOfRangeException ("keepAliveInterval", "Must be greater than 0");
+                       }
+
+                       tcp_keepalive = enabled;
+                       tcp_keepalive_time = keepAliveTime;
+                       tcp_keepalive_interval = keepAliveInterval;
+               }
+
                public static ServicePoint FindServicePoint (Uri address) 
                {
                        return FindServicePoint (address, GlobalProxySelection.Select);
@@ -284,6 +305,8 @@ namespace System.Net
                                throw new ArgumentNullException ("address");
 
                        RecycleServicePoints ();
+
+                       var origAddress = new Uri (address.Scheme + "://" + address.Authority);
                        
                        bool usesProxy = false;
                        bool useConnect = false;
@@ -302,7 +325,7 @@ namespace System.Net
                        
                        ServicePoint sp = null;
                        lock (servicePoints) {
-                               SPKey key = new SPKey (address, useConnect);
+                               SPKey key = new SPKey (origAddress, useConnect);
                                sp = servicePoints [key] as ServicePoint;
                                if (sp != null)
                                        return sp;
@@ -311,14 +334,17 @@ namespace System.Net
                                        throw new InvalidOperationException ("maximum number of service points reached");
 
                                string addr = address.ToString ();
+#if NET_2_1
+                               int limit = defaultConnectionLimit;
+#else
                                int limit = (int) manager.GetMaxConnections (addr);
+#endif
                                sp = new ServicePoint (address, limit, maxServicePointIdleTime);
-#if NET_1_1
                                sp.Expect100Continue = expectContinue;
                                sp.UseNagleAlgorithm = useNagle;
-#endif
                                sp.UsesProxy = usesProxy;
                                sp.UseConnect = useConnect;
+                               sp.SetTcpKeepAlive (tcp_keepalive, tcp_keepalive_time, tcp_keepalive_interval);
                                servicePoints.Add (key, sp);
                        }
                        
@@ -361,5 +387,396 @@ namespace System.Net
                                        servicePoints.Remove (list.GetByIndex (i));
                        }
                }
+#if MOONLIGHT && SECURITY_DEP
+               internal class ChainValidationHelper {
+                       object sender;
+
+                       public ChainValidationHelper (object sender)
+                       {
+                               this.sender = sender;
+                       }
+
+                       // no need to check certificates since we are either
+                       // (a) loading from the site of origin (and we accepted its certificate to load from it)
+                       // (b) loading from a cross-domain site and we downloaded the policy file using the browser stack
+                       //     i.e. the certificate was accepted (or the policy would not be valid)
+                       internal ValidationResult ValidateChain (Mono.Security.X509.X509CertificateCollection certs)
+                       {
+                               return new ValidationResult (true, false, 0);
+                       }
+               }
+#elif SECURITY_DEP
+               internal class ChainValidationHelper {
+                       object sender;
+                       string host;
+                       static bool is_macosx = System.IO.File.Exists (MSX.OSX509Certificates.SecurityLibrary);
+                       static X509RevocationMode revocation_mode;
+
+                       static ChainValidationHelper ()
+                       {
+#if !MONOTOUCH
+                               revocation_mode = X509RevocationMode.NoCheck;
+                               try {
+                                       string str = Environment.GetEnvironmentVariable ("MONO_X509_REVOCATION_MODE");
+                                       if (String.IsNullOrEmpty (str))
+                                               return;
+                                       revocation_mode = (X509RevocationMode) Enum.Parse (typeof (X509RevocationMode), str, true);
+                               } catch {
+                               }
+#endif
+                       }
+
+                       public ChainValidationHelper (object sender)
+                       {
+                               this.sender = sender;
+                       }
+
+                       public string Host {
+                               get {
+                                       if (host == null && sender is HttpWebRequest)
+                                               host = ((HttpWebRequest) sender).Address.Host;
+                                       return host;
+                               }
+
+                               set { host = value; }
+                       }
+
+                       // Used when the obsolete ICertificatePolicy is set to DefaultCertificatePolicy
+                       // and the new ServerCertificateValidationCallback is not null
+                       internal ValidationResult ValidateChain (Mono.Security.X509.X509CertificateCollection certs)
+                       {
+                               // user_denied is true if the user callback is called and returns false
+                               bool user_denied = false;
+                               if (certs == null || certs.Count == 0)
+                                       return null;
+
+                               ICertificatePolicy policy = ServicePointManager.CertificatePolicy;
+                               RemoteCertificateValidationCallback cb = ServicePointManager.ServerCertificateValidationCallback;
+
+                               X509Certificate2 leaf = new X509Certificate2 (certs [0].RawData);
+                               int status11 = 0; // Error code passed to the obsolete ICertificatePolicy callback
+                               SslPolicyErrors errors = 0;
+                               X509Chain chain = null;
+                               bool result = false;
+#if MONOTOUCH
+                               // The X509Chain is not really usable with MonoTouch (since the decision is not based on this data)
+                               // However if someone wants to override the results (good or bad) from iOS then they will want all
+                               // the certificates that the server provided (which generally does not include the root) so, only  
+                               // if there's a user callback, we'll create the X509Chain but won't build it
+                               // ref: https://bugzilla.xamarin.com/show_bug.cgi?id=7245
+                               if (cb != null) {
+#endif
+                               chain = new X509Chain ();
+                               chain.ChainPolicy = new X509ChainPolicy ();
+                               chain.ChainPolicy.RevocationMode = revocation_mode;
+                               for (int i = 1; i < certs.Count; i++) {
+                                       X509Certificate2 c2 = new X509Certificate2 (certs [i].RawData);
+                                       chain.ChainPolicy.ExtraStore.Add (c2);
+                               }
+#if MONOTOUCH
+                               }
+#else
+                               try {
+                                       if (!chain.Build (leaf))
+                                               errors |= GetErrorsFromChain (chain);
+                               } catch (Exception e) {
+                                       Console.Error.WriteLine ("ERROR building certificate chain: {0}", e);
+                                       Console.Error.WriteLine ("Please, report this problem to the Mono team");
+                                       errors |= SslPolicyErrors.RemoteCertificateChainErrors;
+                               }
+
+                               // for OSX and iOS we're using the native API to check for the SSL server policy and host names
+                               if (!is_macosx) {
+                                       if (!CheckCertificateUsage (leaf)) {
+                                               errors |= SslPolicyErrors.RemoteCertificateChainErrors;
+                                               status11 = -2146762490; //CERT_E_PURPOSE 0x800B0106
+                                       }
+
+                                       if (!CheckServerIdentity (certs [0], Host)) {
+                                               errors |= SslPolicyErrors.RemoteCertificateNameMismatch;
+                                               status11 = -2146762481; // CERT_E_CN_NO_MATCH 0x800B010F
+                                       }
+                               } else {
+#endif
+                                       // Attempt to use OSX certificates
+                                       // Ideally we should return the SecTrustResult
+                                       MSX.OSX509Certificates.SecTrustResult trustResult = MSX.OSX509Certificates.SecTrustResult.Deny;
+                                       try {
+                                               trustResult = MSX.OSX509Certificates.TrustEvaluateSsl (certs, Host);
+                                               // We could use the other values of trustResult to pass this extra information
+                                               // to the .NET 2 callback for values like SecTrustResult.Confirm
+                                               result = (trustResult == MSX.OSX509Certificates.SecTrustResult.Proceed ||
+                                                                 trustResult == MSX.OSX509Certificates.SecTrustResult.Unspecified);
+                                       } catch {
+                                               // Ignore
+                                       }
+                                       
+                                       if (result) {
+                                               // TrustEvaluateSsl was successful so there's no trust error
+                                               // IOW we discard our own chain (since we trust OSX one instead)
+                                               errors = 0;
+                                       } else {
+                                               // callback and DefaultCertificatePolicy needs this since 'result' is not specified
+                                               status11 = (int) trustResult;
+                                               errors |= SslPolicyErrors.RemoteCertificateChainErrors;
+                                       }
+#if !MONOTOUCH
+                               }
+#endif
+
+#if MONODROID
+                               result = AndroidPlatform.TrustEvaluateSsl (certs, sender, leaf, chain, errors);
+                               if (result) {
+                                       // chain.Build() + GetErrorsFromChain() (above) will ALWAYS fail on
+                                       // Android (there are no mozroots or preinstalled root certificates),
+                                       // thus `errors` will ALWAYS have RemoteCertificateChainErrors.
+                                       // Android just verified the chain; clear RemoteCertificateChainErrors.
+                                       errors  &= ~SslPolicyErrors.RemoteCertificateChainErrors;
+                               }
+#endif
+
+                               if (policy != null && (!(policy is DefaultCertificatePolicy) || cb == null)) {
+                                       ServicePoint sp = null;
+                                       HttpWebRequest req = sender as HttpWebRequest;
+                                       if (req != null)
+                                               sp = req.ServicePointNoLock;
+                                       if (status11 == 0 && errors != 0)
+                                               status11 = GetStatusFromChain (chain);
+
+                                       // pre 2.0 callback
+                                       result = policy.CheckValidationResult (sp, leaf, req, status11);
+                                       user_denied = !result && !(policy is DefaultCertificatePolicy);
+                               }
+                               // If there's a 2.0 callback, it takes precedence
+                               if (cb != null) {
+                                       result = cb (sender, leaf, chain, errors);
+                                       user_denied = !result;
+                               }
+                               return new ValidationResult (result, user_denied, status11);
+                       }
+
+                       static int GetStatusFromChain (X509Chain chain)
+                       {
+                               long result = 0;
+                               foreach (var status in chain.ChainStatus) {
+                                       X509ChainStatusFlags flags = status.Status;
+                                       if (flags == X509ChainStatusFlags.NoError)
+                                               continue;
+
+                                       // CERT_E_EXPIRED
+                                       if ((flags & X509ChainStatusFlags.NotTimeValid) != 0) result = 0x800B0101;
+                                       // CERT_E_VALIDITYPERIODNESTING
+                                       else if ((flags & X509ChainStatusFlags.NotTimeNested) != 0) result = 0x800B0102;
+                                       // CERT_E_REVOKED
+                                       else if ((flags & X509ChainStatusFlags.Revoked) != 0) result = 0x800B010C;
+                                       // TRUST_E_CERT_SIGNATURE
+                                       else if ((flags & X509ChainStatusFlags.NotSignatureValid) != 0) result = 0x80096004;
+                                       // CERT_E_WRONG_USAGE
+                                       else if ((flags & X509ChainStatusFlags.NotValidForUsage) != 0) result = 0x800B0110;
+                                       // CERT_E_UNTRUSTEDROOT
+                                       else if ((flags & X509ChainStatusFlags.UntrustedRoot) != 0) result = 0x800B0109;
+                                       // CRYPT_E_NO_REVOCATION_CHECK
+                                       else if ((flags & X509ChainStatusFlags.RevocationStatusUnknown) != 0) result = 0x80092012;
+                                       // CERT_E_CHAINING
+                                       else if ((flags & X509ChainStatusFlags.Cyclic) != 0) result = 0x800B010A;
+                                       // TRUST_E_FAIL - generic
+                                       else if ((flags & X509ChainStatusFlags.InvalidExtension) != 0) result = 0x800B010B;
+                                       // CERT_E_UNTRUSTEDROOT
+                                       else if ((flags & X509ChainStatusFlags.InvalidPolicyConstraints) != 0) result = 0x800B010D;
+                                       // TRUST_E_BASIC_CONSTRAINTS
+                                       else if ((flags & X509ChainStatusFlags.InvalidBasicConstraints) != 0) result = 0x80096019;
+                                       // CERT_E_INVALID_NAME
+                                       else if ((flags & X509ChainStatusFlags.InvalidNameConstraints) != 0) result = 0x800B0114;
+                                       // CERT_E_INVALID_NAME
+                                       else if ((flags & X509ChainStatusFlags.HasNotSupportedNameConstraint) != 0) result = 0x800B0114;
+                                       // CERT_E_INVALID_NAME
+                                       else if ((flags & X509ChainStatusFlags.HasNotDefinedNameConstraint) != 0) result = 0x800B0114;
+                                       // CERT_E_INVALID_NAME
+                                       else if ((flags & X509ChainStatusFlags.HasNotPermittedNameConstraint) != 0) result = 0x800B0114;
+                                       // CERT_E_INVALID_NAME
+                                       else if ((flags & X509ChainStatusFlags.HasExcludedNameConstraint) != 0) result = 0x800B0114;
+                                       // CERT_E_CHAINING
+                                       else if ((flags & X509ChainStatusFlags.PartialChain) != 0) result = 0x800B010A;
+                                       // CERT_E_EXPIRED
+                                       else if ((flags & X509ChainStatusFlags.CtlNotTimeValid) != 0) result = 0x800B0101;
+                                       // TRUST_E_CERT_SIGNATURE
+                                       else if ((flags & X509ChainStatusFlags.CtlNotSignatureValid) != 0) result = 0x80096004;
+                                       // CERT_E_WRONG_USAGE
+                                       else if ((flags & X509ChainStatusFlags.CtlNotValidForUsage) != 0) result = 0x800B0110;
+                                       // CRYPT_E_NO_REVOCATION_CHECK
+                                       else if ((flags & X509ChainStatusFlags.OfflineRevocation) != 0) result = 0x80092012;
+                                       // CERT_E_ISSUERCHAINING
+                                       else if ((flags & X509ChainStatusFlags.NoIssuanceChainPolicy) != 0) result = 0x800B0107;
+                                       else result = 0x800B010B; // TRUST_E_FAIL - generic
+
+                                       break; // Exit the loop on the first error
+                               }
+                               return (int) result;
+                       }
+#if !MONOTOUCH
+                       static SslPolicyErrors GetErrorsFromChain (X509Chain chain)
+                       {
+                               SslPolicyErrors errors = SslPolicyErrors.None;
+                               foreach (var status in chain.ChainStatus) {
+                                       if (status.Status == X509ChainStatusFlags.NoError)
+                                               continue;
+                                       errors |= SslPolicyErrors.RemoteCertificateChainErrors;
+                                       break;
+                               }
+                               return errors;
+                       }
+
+                       static X509KeyUsageFlags s_flags = X509KeyUsageFlags.DigitalSignature  | 
+                                                       X509KeyUsageFlags.KeyAgreement |
+                                                       X509KeyUsageFlags.KeyEncipherment;
+                       // Adapted to System 2.0+ from TlsServerCertificate.cs
+                       //------------------------------
+                       // Note: this method only works for RSA certificates
+                       // DH certificates requires some changes - does anyone use one ?
+                       static bool CheckCertificateUsage (X509Certificate2 cert) 
+                       {
+                               try {
+                                       // certificate extensions are required for this
+                                       // we "must" accept older certificates without proofs
+                                       if (cert.Version < 3)
+                                               return true;
+
+                                       X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
+                                       X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
+                                       if (kux != null && eku != null) {
+                                               // RFC3280 states that when both KeyUsageExtension and 
+                                               // ExtendedKeyUsageExtension are present then BOTH should
+                                               // be valid
+                                               if ((kux.KeyUsages & s_flags) == 0)
+                                                       return false;
+                                               return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
+                                                       eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
+                                       } else if (kux != null) {
+                                               return ((kux.KeyUsages & s_flags) != 0);
+                                       } else if (eku != null) {
+                                               // Server Authentication (1.3.6.1.5.5.7.3.1) or
+                                               // Netscape Server Gated Crypto (2.16.840.1.113730.4)
+                                               return eku.EnhancedKeyUsages ["1.3.6.1.5.5.7.3.1"] != null ||
+                                                       eku.EnhancedKeyUsages ["2.16.840.1.113730.4.1"] != null;
+                                       }
+
+                                       // last chance - try with older (deprecated) Netscape extensions
+                                       X509Extension ext = cert.Extensions ["2.16.840.1.113730.1.1"];
+                                       if (ext != null) {
+                                               string text = ext.NetscapeCertType (false);
+                                               return text.IndexOf ("SSL Server Authentication", StringComparison.Ordinal) != -1;
+                                       }
+                                       return true;
+                               } catch (Exception e) {
+                                       Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
+                                       Console.Error.WriteLine ("Please, report this problem to the Mono team");
+                                       return false;
+                               }
+                       }
+
+                       // RFC2818 - HTTP Over TLS, Section 3.1
+                       // http://www.ietf.org/rfc/rfc2818.txt
+                       // 
+                       // 1.   if present MUST use subjectAltName dNSName as identity
+                       // 1.1.         if multiples entries a match of any one is acceptable
+                       // 1.2.         wildcard * is acceptable
+                       // 2.   URI may be an IP address -> subjectAltName.iPAddress
+                       // 2.1.         exact match is required
+                       // 3.   Use of the most specific Common Name (CN=) in the Subject
+                       // 3.1          Existing practice but DEPRECATED
+                       static bool CheckServerIdentity (Mono.Security.X509.X509Certificate cert, string targetHost) 
+                       {
+                               try {
+                                       Mono.Security.X509.X509Extension ext = cert.Extensions ["2.5.29.17"];
+                                       // 1. subjectAltName
+                                       if (ext != null) {
+                                               SubjectAltNameExtension subjectAltName = new SubjectAltNameExtension (ext);
+                                               // 1.1 - multiple dNSName
+                                               foreach (string dns in subjectAltName.DNSNames) {
+                                                       // 1.2 TODO - wildcard support
+                                                       if (Match (targetHost, dns))
+                                                               return true;
+                                               }
+                                               // 2. ipAddress
+                                               foreach (string ip in subjectAltName.IPAddresses) {
+                                                       // 2.1. Exact match required
+                                                       if (ip == targetHost)
+                                                               return true;
+                                               }
+                                       }
+                                       // 3. Common Name (CN=)
+                                       return CheckDomainName (cert.SubjectName, targetHost);
+                               } catch (Exception e) {
+                                       Console.Error.WriteLine ("ERROR processing certificate: {0}", e);
+                                       Console.Error.WriteLine ("Please, report this problem to the Mono team");
+                                       return false;
+                               }
+                       }
+
+                       static bool CheckDomainName (string subjectName, string targetHost)
+                       {
+                               string  domainName = String.Empty;
+                               Regex search = new Regex(@"CN\s*=\s*([^,]*)");
+                               MatchCollection elements = search.Matches(subjectName);
+                               if (elements.Count == 1) {
+                                       if (elements[0].Success)
+                                               domainName = elements[0].Groups[1].Value.ToString();
+                               }
+
+                               return Match (targetHost, domainName);
+                       }
+
+                       // ensure the pattern is valid wrt to RFC2595 and RFC2818
+                       // http://www.ietf.org/rfc/rfc2595.txt
+                       // http://www.ietf.org/rfc/rfc2818.txt
+                       static bool Match (string hostname, string pattern)
+                       {
+                               // check if this is a pattern
+                               int index = pattern.IndexOf ('*');
+                               if (index == -1) {
+                                       // not a pattern, do a direct case-insensitive comparison
+                                       return (String.Compare (hostname, pattern, true, CultureInfo.InvariantCulture) == 0);
+                               }
+
+                               // check pattern validity
+                               // A "*" wildcard character MAY be used as the left-most name component in the certificate.
+
+                               // unless this is the last char (valid)
+                               if (index != pattern.Length - 1) {
+                                       // then the next char must be a dot .'.
+                                       if (pattern [index + 1] != '.')
+                                               return false;
+                               }
+
+                               // only one (A) wildcard is supported
+                               int i2 = pattern.IndexOf ('*', index + 1);
+                               if (i2 != -1)
+                                       return false;
+
+                               // match the end of the pattern
+                               string end = pattern.Substring (index + 1);
+                               int length = hostname.Length - end.Length;
+                               // no point to check a pattern that is longer than the hostname
+                               if (length <= 0)
+                                       return false;
+
+                               if (String.Compare (hostname, length, end, 0, end.Length, true, CultureInfo.InvariantCulture) != 0)
+                                       return false;
+
+                               // special case, we start with the wildcard
+                               if (index == 0) {
+                                       // ensure we hostname non-matched part (start) doesn't contain a dot
+                                       int i3 = hostname.IndexOf ('.');
+                                       return ((i3 == -1) || (i3 >= (hostname.Length - end.Length)));
+                               }
+
+                               // match the start of the pattern
+                               string start = pattern.Substring (0, index);
+                               return (String.Compare (hostname, 0, start, 0, start.Length, true, CultureInfo.InvariantCulture) == 0);
+                       }
+#endif
+               }
+#endif
        }
 }
+