Npgsql.NpgsqlConnector.DefaultProvideClientCertificatesCallback C# (CSharp) Method

        internal void DefaultProvideClientCertificatesCallback(X509CertificateCollection certificates)
        {
            if (ProvideClientCertificatesCallback != null)
            {
                ProvideClientCertificatesCallback(certificates);
            }
        }

        public override void Open(NpgsqlConnector context, Int32 timeout)
        {
            try
            {
                NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Open");

                IAsyncResult result;
                // Keep track of time remaining; Even though there may be multiple timeout-able calls,
                // this allows us to still respect the caller's timeout expectation.
                DateTime attemptStart;

                attemptStart = DateTime.Now;

                result = Dns.BeginGetHostAddresses(context.Host, null, null);

                if (!result.AsyncWaitHandle.WaitOne(timeout, true))
                {
                    // Timeout was used up attempting the Dns lookup
                    throw new TimeoutException(resman.GetString("Exception_DnsLookupTimeout"));
                }

                timeout -= Convert.ToInt32((DateTime.Now - attemptStart).TotalMilliseconds);

                IPAddress[] ips    = Dns.EndGetHostAddresses(result);
                Socket      socket = null;
                Exception   lastSocketException = null;

                // try every ip address of the given hostname, use the first reachable one
                // make sure not to exceed the caller's timeout expectation by splitting the
                // time we have left between all the remaining ip's in the list.
                for (int i = 0; i < ips.Length; i++)
                {
                    NpgsqlEventLog.LogMsg(resman, "Log_ConnectingTo", LogLevel.Debug, ips[i]);

                    IPEndPoint ep = new IPEndPoint(ips[i], context.Port);
                    socket = new Socket(ep.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

                    attemptStart = DateTime.Now;

                    try
                    {
                        result = socket.BeginConnect(ep, null, null);

                        if (!result.AsyncWaitHandle.WaitOne(timeout / (ips.Length - i), true))
                        {
                            throw new TimeoutException(resman.GetString("Exception_ConnectionTimeout"));
                        }

                        socket.EndConnect(result);

                        // connect was successful, leave the loop
                        break;
                    }
                    catch (Exception e)
                    {
                        NpgsqlEventLog.LogMsg(resman, "Log_FailedConnection", LogLevel.Normal, ips[i]);

                        timeout            -= Convert.ToInt32((DateTime.Now - attemptStart).TotalMilliseconds);
                        lastSocketException = e;

                        socket.Close();
                        socket = null;
                    }
                }

                if (socket == null)
                {
                    throw lastSocketException;
                }

                NpgsqlNetworkStream baseStream = new NpgsqlNetworkStream(socket, true);
                Stream sslStream = null;

                // If the PostgreSQL server has SSL connectors enabled Open SslClientStream if (response == 'S') {
                if (context.SSL || (context.SslMode == SslMode.Require) || (context.SslMode == SslMode.Prefer))
                {
                    baseStream
                    .WriteInt32(8)
                    .WriteInt32(80877103);

                    // Receive response
                    Char response = (Char)baseStream.ReadByte();

                    if (response == 'S')
                    {
                        //create empty collection
                        X509CertificateCollection clientCertificates = new X509CertificateCollection();

                        //trigger the callback to fetch some certificates
                        context.DefaultProvideClientCertificatesCallback(clientCertificates);

                        //if (context.UseMonoSsl)
                        if (!NpgsqlConnector.UseSslStream)
                        {
                            SslClientStream sslStreamPriv;

                            sslStreamPriv = new SslClientStream(
                                baseStream,
                                context.Host,
                                true,
                                SecurityProtocolType.Default,
                                clientCertificates);

                            sslStreamPriv.ClientCertSelectionDelegate =
                                new CertificateSelectionCallback(context.DefaultCertificateSelectionCallback);
                            sslStreamPriv.ServerCertValidationDelegate =
                                new CertificateValidationCallback(context.DefaultCertificateValidationCallback);
                            sslStreamPriv.PrivateKeyCertSelectionDelegate =
                                new PrivateKeySelectionCallback(context.DefaultPrivateKeySelectionCallback);
                            sslStream = sslStreamPriv;
                        }
                        else
                        {
                            SslStream sslStreamPriv;

                            sslStreamPriv = new SslStream(baseStream, true, context.DefaultValidateRemoteCertificateCallback);

                            sslStreamPriv.AuthenticateAsClient(context.Host, clientCertificates, System.Security.Authentication.SslProtocols.Default, false);
                            sslStream = sslStreamPriv;
                        }
                    }
                    else if (context.SslMode == SslMode.Require)
                    {
                        throw new InvalidOperationException(resman.GetString("Exception_Ssl_RequestError"));
                    }
                }

                context.Socket     = socket;
                context.BaseStream = baseStream;
                context.Stream     = new BufferedStream(sslStream == null ? baseStream : sslStream, 8192);

                NpgsqlEventLog.LogMsg(resman, "Log_ConnectedTo", LogLevel.Normal, context.Host, context.Port);
                ChangeState(context, NpgsqlConnectedState.Instance);
            }
            catch (Exception e)
            {
                throw new NpgsqlException(string.Format(resman.GetString("Exception_FailedConnection"), context.Host), e);
            }
        }