' 导入命名空间
Imports System.Collections
Imports System.Net
Imports System.Net.Sockets
Imports System.Net.Security
Imports System.Security.Authentication
Imports System.Text
Imports System.Security.Cryptography.X509Certificates
Imports System.IO

Namespace Examples.System.Net
    Public NotInheritable Class SslTcpServer
        Shared serverCertificate As X509Certificate = Nothing

        ' The certificate parameter specifies the name of the file 
        ' containing the machine certificate.
        Public Shared Sub RunServer(certificate As String)
            serverCertificate = X509Certificate.CreateFromCertFile(certificate)
            ' Create a TCP/IP (IPv4) socket And listen for incoming connections.
            Dim listener = New TcpListener(IPAddress.Any, 8080)
            listener.Start()

            While True
                Console.WriteLine("Waiting for a client to connect...")
                ' Application blocks while waiting for an incoming connection.
                ' Type CNTL-C to terminate the server.
                Dim client As TcpClient = listener.AcceptTcpClient()
                ProcessClient(client)
            End While
        End Sub
        Private Shared Sub ProcessClient(client As TcpClient)
            ' A client has connected. Create the 
            ' SslStream using the client's network stream.
            Dim sslStream = New SslStream(client.GetStream(), False)

            Try

                sslStream.AuthenticateAsServer(serverCertificate, clientCertificateRequired:=False, checkCertificateRevocation:=True)
                ' Display the properties And settings for the authenticated stream.
                DisplaySecurityLevel(sslStream)
                DisplaySecurityServices(sslStream)
                DisplayCertificateInformation(sslStream)
                DisplayStreamProperties(sslStream)

                ' Set timeouts for the read and write to 5 seconds.
                sslStream.ReadTimeout = 5000
                sslStream.WriteTimeout = 5000

                ' Read a message from the client.   
                Console.WriteLine("Waiting for client message...")
                Dim messageData As String = ReadMessage(sslStream)
                Console.WriteLine("Received: {0}", messageData)

                ' Write a message to the client.
                Dim message As Byte() = Encoding.UTF8.GetBytes("Hello from the server.<EOF>")
                Console.WriteLine("Sending hello message.")
                sslStream.Write(message)
            Catch e As AuthenticationException
                Console.WriteLine("Exception: {0}", e.Message)

                If e.InnerException IsNot Nothing Then
                    Console.WriteLine("Inner exception: {0}", e.InnerException.Message)
                End If

                Console.WriteLine("Authentication failed - closing the connection.")
                sslStream.Close()
                client.Close()
                Return
            Finally
                ' The client stream will be closed with the sslStream
                ' because we specified this behavior when creating
                ' the sslStream.
                sslStream.Close()
                client.Close()
            End Try
        End Sub

        Private Shared Function ReadMessage(sslStream As SslStream) As String

            ' Read the  message sent by the client.
            ' The client signals the end of the message using the
            ' "<EOF>" marker.
            Dim buffer As Byte() = New Byte(2048) {}
            Dim messageData As StringBuilder = New StringBuilder()
            Dim bytes As Integer = -1

            Do
                ' Read the client's test message.
                bytes = sslStream.Read(buffer, 0, buffer.Length)

                ' Use decoder class to convert from bytes to UTF8
                ' in case a character spans two buffers.
                Dim decoder As Decoder = Encoding.UTF8.GetDecoder()
                Dim chars As Char() = New Char(decoder.GetCharCount(buffer, 0, bytes) - 1) {}
                decoder.GetChars(buffer, 0, bytes, chars, 0)
                messageData.Append(chars)

                ' Check for EOF or an empty message.
                If messageData.ToString().IndexOf("<EOF>") <> -1 Then
                    Exit Do
                End If
            Loop While bytes <> 0

            Return messageData.ToString()
        End Function

        Private Shared Sub DisplaySecurityLevel(stream As SslStream)
            Console.WriteLine("Cipher: {0} strength {1}", stream.CipherAlgorithm, stream.CipherStrength)
            Console.WriteLine("Hash: {0} strength {1}", stream.HashAlgorithm, stream.HashStrength)
            Console.WriteLine("Key exchange: {0} strength {1}", stream.KeyExchangeAlgorithm, stream.KeyExchangeStrength)
            Console.WriteLine("Protocol: {0}", stream.SslProtocol)
        End Sub

        Private Shared Sub DisplaySecurityServices(stream As SslStream)
            Console.WriteLine("Is authenticated: {0} as server? {1}", stream.IsAuthenticated, stream.IsServer)
            Console.WriteLine("IsSigned: {0}", stream.IsSigned)
            Console.WriteLine("Is Encrypted: {0}", stream.IsEncrypted)
        End Sub

        Private Shared Sub DisplayStreamProperties(stream As SslStream)
            Console.WriteLine("Can read: {0}, write {1}", stream.CanRead, stream.CanWrite)
            Console.WriteLine("Can timeout: {0}", stream.CanTimeout)
        End Sub

        Private Shared Sub DisplayCertificateInformation(stream As SslStream)
            Console.WriteLine("Certificate revocation list checked: {0}", stream.CheckCertRevocationStatus)
            Dim localCertificate As X509Certificate = stream.LocalCertificate

            If stream.LocalCertificate IsNot Nothing Then
                Console.WriteLine("Local cert was issued to {0} and is valid from {1} until {2}.", localCertificate.Subject, localCertificate.GetEffectiveDateString(), localCertificate.GetExpirationDateString())
            Else
                Console.WriteLine("Local certificate is null.")
            End If

            ' Display the properties of the client's certificate.
            Dim remoteCertificate As X509Certificate = stream.RemoteCertificate

            If stream.RemoteCertificate IsNot Nothing Then
                Console.WriteLine("Remote cert was issued to {0} and is valid from {1} until {2}.", remoteCertificate.Subject, remoteCertificate.GetEffectiveDateString(), remoteCertificate.GetExpirationDateString())
            Else
                Console.WriteLine("Remote certificate is null.")
            End If
        End Sub

        Private Shared Sub DisplayUsage()
            Console.WriteLine("To start the server specify:")
            Console.WriteLine("serverSync certificateFile.cer")
            Environment.[Exit](1)
        End Sub

        Public Shared Function Main(ByVal args As String()) As Integer
            Dim certificate As String

            If args Is Nothing OrElse args.Length < 1 Then
                DisplayUsage()
            End If

            certificate = args(0)
            RunServer(certificate)
            Return 0
        End Function
    End Class
End Namespace

' 导入命名空间
Imports System.Collections
Imports System.Net
Imports System.Net.Security
Imports System.Net.Sockets
Imports System.Security.Authentication
Imports System.Text
Imports System.Security.Cryptography.X509Certificates
Imports System.IO

Namespace Examples.System.Net

    Public Class SslTcpClient
        
        ' The following method is invoked by the RemoteCertificateValidationDelegate.
        Public Shared Function ValidateServerCertificate(
            sender As Object, 
            certificate As X509Certificate, 
            chain As X509Chain, 
            sslPolicyErrors As SslPolicyErrors) As Boolean
            
            If sslPolicyErrors = SslPolicyErrors.None Then Return True

            Console.WriteLine("Certificate error: {0}", sslPolicyErrors)

            ' Do not allow this client to communicate with unauthenticated servers.
            Return False
        End Function
        Public Shared Sub RunClient(machineName As String, serverName As String)

            ' Create a TCP/IP client socket.
            ' machineName is the host running the server application.
            Dim client = New TcpClient(machineName, 443)
            Console.WriteLine("Client connected.")

            ' Create an SSL stream that will close the client's stream.
            Dim sslStream = New SslStream(
                client.GetStream(), False, 
                New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate), Nothing)

            ' The server name must match the name on the server certificate.
            Try
                sslStream.AuthenticateAsClient(serverName)
            Catch e As AuthenticationException
                Console.WriteLine("Exception: {0}", e.Message)

                If e.InnerException IsNot Nothing Then
                    Console.WriteLine("Inner exception: {0}", e.InnerException.Message)
                End If

                Console.WriteLine("Authentication failed - closing the connection.")
                client.Close()
                Return
            End Try
            
            ' Encode a test message into a byte array.
            ' Signal the end of the message using the "<EOF>".
            Dim messsage As Byte() = Encoding.UTF8.GetBytes("Hello from the client.<EOF>")
            
            ' Send hello message to the server.
            sslStream.Write(messsage)
            sslStream.Flush()
            ' Read message from the server.
            Dim serverMessage = ReadMessage(sslStream)
            Console.WriteLine("Server says: {0}", serverMessage)

            ' Close the client connection
            client.Close()
            Console.WriteLine("Client closed.")
        End Sub
        
        Private Shared Function ReadMessage(sslStream As SslStream) As String

            ' Read the  message sent by the server.
            ' The end of the message is signaled using the "<EOF>" marker.
            Dim buffer = New Byte(2048) {}
            Dim messageData = New StringBuilder()
            Dim bytes As Integer

            Do
                bytes = sslStream.Read(buffer, 0, buffer.Length)

                ' Use Decoder class to convert from bytes to UTF8
                ' in case a character spans two buffers.        
                Dim decoder As Decoder = Encoding.UTF8.GetDecoder()
                Dim chars = New Char(decoder.GetCharCount(buffer, 0, bytes) - 1) {}
                decoder.GetChars(buffer, 0, bytes, chars, 0)
                messageData.Append(chars)

                ' Check for EOF.
                If messageData.ToString().IndexOf("<EOF>") <> -1 Then Exit Do
                
            Loop While bytes <> 0

            Return messageData.ToString()

        End Function

        Private Shared Sub DisplayUsage()

            Console.WriteLine("To start the client specify:")
            Console.WriteLine("clientSync machineName [serverName]")
            Environment.[Exit](1)

        End Sub

        Public Shared Function Main(args As String()) As Integer

            Dim serverCertificateName As String
            Dim machineName As String

            If args Is Nothing OrElse args.Length < 1 Then
                DisplayUsage()
            End If

            ' User can specify the machine name and server name.
            ' Server name must match the name on the server's certificate. 
            machineName = args(0)

            If args.Length < 2 Then
                serverCertificateName = machineName
            Else
                serverCertificateName = args(1)
            End If

            SslTcpClient.RunClient(machineName, serverCertificateName)

            Return 0

        End Function

    End Class

End Namespace