Add support for ignored certificate chain errors (Self signed)

Frameworks/MQTTnet.NetFramework/Implementations/MqttTcpChannel.cs

@@ -37,6 +37,7 @@ namespace MQTTnet.Implementations
         {
             _socket = socket ?? throw new ArgumentNullException(nameof(socket));
             _sslStream = sslStream;
+
             CreateStreams(socket, sslStream);
         }
 
@@ -55,8 +56,7 @@ namespace MQTTnet.Implementations
 
             if (_options.TlsOptions.UseTls)
             {
-                _sslStream = new SslStream(new NetworkStream(_socket, true));
-                
+                _sslStream = new SslStream(new NetworkStream(_socket, true), false, UserCertificateValidationCallback);
                 await _sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(_options), SslProtocols.Tls12, _options.TlsOptions.CheckCertificateRevocation).ConfigureAwait(false);
             }
 
@@ -97,6 +97,16 @@ namespace MQTTnet.Implementations
             ReceiveStream = new BufferedStream(RawReceiveStream, BufferSize);
         }
 
+        private bool UserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateChainErrors) != 0)
+            {
+                return _options.TlsOptions.IgnoreCertificateChainErrors;
+            }
+
+            return false;
+        }
+
         private static X509CertificateCollection LoadCertificates(MqttClientOptions options)
         {
             var certificates = new X509CertificateCollection();

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs

@@ -51,7 +51,7 @@ namespace MQTTnet.Implementations
 
             if (_options.TlsOptions.UseTls)
             {
-                _sslStream = new SslStream(new NetworkStream(_socket, true));
+                _sslStream = new SslStream(new NetworkStream(_socket, true), false, UserCertificateValidationCallback);
                 ReceiveStream = _sslStream;
                 await _sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(_options), SslProtocols.Tls12, _options.TlsOptions.CheckCertificateRevocation).ConfigureAwait(false);
             }
@@ -76,6 +76,16 @@ namespace MQTTnet.Implementations
             _sslStream = null;
         }
 
+        private bool UserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateChainErrors) != 0)
+            {
+                return _options.TlsOptions.IgnoreCertificateChainErrors;
+            }
+
+            return false;
+        }
+
         private static X509CertificateCollection LoadCertificates(MqttClientOptions options)
         {
             var certificates = new X509CertificateCollection();

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttTcpChannel.cs

@@ -24,6 +24,7 @@ namespace MQTTnet.Implementations
         public MqttTcpChannel(StreamSocket socket)
         {
             _socket = socket ?? throw new ArgumentNullException(nameof(socket));
+
             CreateStreams();
         }
 
@@ -48,8 +49,13 @@ namespace MQTTnet.Implementations
 
                 if (!_options.TlsOptions.CheckCertificateRevocation)
                 {
-                    _socket.Control.IgnorableServerCertificateErrors.Add(ChainValidationResult.IncompleteChain);
                     _socket.Control.IgnorableServerCertificateErrors.Add(ChainValidationResult.RevocationInformationMissing);
+                    _socket.Control.IgnorableServerCertificateErrors.Add(ChainValidationResult.Revoked);
+                }
+
+                if (_options.TlsOptions.IgnoreCertificateChainErrors)
+                {
+                    _socket.Control.IgnorableServerCertificateErrors.Add(ChainValidationResult.IncompleteChain);
                 }
 
                 await _socket.ConnectAsync(new HostName(_options.Server), _options.GetPort().ToString(), SocketProtectionLevel.Tls12);

MQTTnet.Core/Client/MqttClientTlsOptions.cs

@@ -8,6 +8,8 @@ namespace MQTTnet.Core.Client
 
         public bool CheckCertificateRevocation { get; set; }
 
+        public bool IgnoreCertificateChainErrors { get; set; }
+
         public List<byte[]> Certificates { get; set; }
     }
 }