Added MqttClientTlsOptions to control RevocationMode for clients with limited...

Added MqttClientTlsOptions to control RevocationMode for clients with limited Internet access (defaults to Online) (#1396)
Co-authored-by: NAndres Olivares <andres.olivares@ncr.com>

Source/MQTTnet/Client/Options/MqttClientTlsOptions.cs

@@ -21,6 +21,8 @@ namespace MQTTnet.Client
 
         public bool AllowUntrustedCertificates { get; set; }
 
+        public X509RevocationMode RevocationMode { get; set; } = X509RevocationMode.Online;
+
 #if WINDOWS_UWP
         public List<byte[]> Certificates { get; set; }
 #else

Source/MQTTnet/Implementations/MqttTcpChannel.cs

@@ -103,7 +103,7 @@ namespace MQTTnet.Implementations
                             ApplicationProtocols = _tcpOptions.TlsOptions.ApplicationProtocols,
                             ClientCertificates = LoadCertificates(),
                             EnabledSslProtocols = _tcpOptions.TlsOptions.SslProtocol,
-                            CertificateRevocationCheckMode = _tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors ? X509RevocationMode.NoCheck : X509RevocationMode.Online,
+                            CertificateRevocationCheckMode = _tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors ? X509RevocationMode.NoCheck : _tcpOptions.TlsOptions.RevocationMode,
                             TargetHost = _tcpOptions.Server,
                             CipherSuitesPolicy = _tcpOptions.TlsOptions.CipherSuitesPolicy
                         };