Eigenen HTTP-Proxy-Server programmieren

Imports System
Imports System.Text
Imports System.IO
Imports System.Net
Imports System.Net.Sockets
Imports System.Threading

Namespace WebProxy2
    Class WebProxy2
        Private clientSocket As Socket
        Private read() As [Byte] = New Byte(1024) {}
        Private Buffer As [Byte]() = Nothing
        Private ASCII As Encoding = Encoding.ASCII
        Private HTTP_VERSION As String = "HTTP/1.0"  
        Private CRLF As String = ControlChars.Cr + ControlChars.Lf
        Private RecvBytes(4096) As [Byte]

        Public Sub New(ByVal socket As Socket)
            Me.clientSocket = socket
        End Sub

        Public Sub run()
            Dim clientmessage As [String] = " "  
            Dim sURL As [String] = " "  
            Dim bytes As Integer = readmessage(read, clientSocket, clientmessage)
            If bytes = 0 Then
                Return
            End If
            Dim index1 As Integer = clientmessage.IndexOf(" "c)  
            Dim index2 As Integer = clientmessage.IndexOf(" "c, index1 + 1)  
            If index1 = -1 Or index2 = -1 Then
                Throw New IOException
            End If
            Console.WriteLine("Connecting to Site: {0}", clientmessage.Substring(index1 + 1, index2 - index1))  
            Console.WriteLine("Connection from {0}", clientSocket.RemoteEndPoint)  
            Dim part1 As String = clientmessage.Substring(index1 + 1, index2 - index1)
            Dim index3 As Integer = part1.IndexOf("/"c, index1 + 8)  
            Dim index4 As Integer = part1.IndexOf(" "c, index1 + 8)  
            Dim index5 As Integer = index4 - index3
            sURL = part1.Substring(index1 + 4, part1.Length - index5 - 8)
            Try
                Dim IPHost As IPHostEntry = Dns.Resolve(sURL)
                Console.WriteLine("Request resolved: ", IPHost.HostName)  
                Dim aliases As String() = IPHost.Aliases
                Dim address As IPAddress() = IPHost.AddressList
                Console.WriteLine(address(0))
                Dim sEndpoint As New IPEndPoint(address(0), 80)
                Dim IPsocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
                IPsocket.Connect(sEndpoint)
                If IPsocket.Connected Then
                    Console.WriteLine("Socket connect OK")  
                End If
                Dim [GET] As String = clientmessage
                Dim ByteGet As [Byte]() = ASCII.GetBytes([GET])
                IPsocket.Send(ByteGet, ByteGet.Length, 0)
                Dim rBytes As Int32 = IPsocket.Receive(RecvBytes, RecvBytes.Length, 0)
                Console.WriteLine("Recieved {0}", +rBytes)  
                'Buffer = RecvBytes;  
                Dim strRetPage As [String] = Nothing
                strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, rBytes)
                While rBytes > 0
                    rBytes = IPsocket.Receive(RecvBytes, RecvBytes.Length, 0)
                    strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, rBytes)
                End While
                IPsocket.Shutdown(SocketShutdown.Both)
                IPsocket.Close()
                sendmessage(clientSocket, strRetPage)
            Catch exc2 As Exception
                Console.WriteLine(exc2.ToString())
            End Try
        End Sub

        Private Function readmessage(ByVal ByteArray() As Byte, ByRef s As Socket, ByRef clientmessage As [String]) As Integer
            Dim bytes As Integer = s.Receive(ByteArray, 1024, 0)
            Dim messagefromclient As String = Encoding.ASCII.GetString(ByteArray)
            clientmessage = CType(messagefromclient, [String])
            Return bytes
        End Function

        Private Sub sendmessage(ByVal s As Socket, ByVal message As String)
            Buffer = New [Byte](message.Length + 1) {}
            Dim length As Integer = ASCII.GetBytes(message, 0, message.Length, Buffer, 0)
            s.Send(Buffer, length, 0)
        End Sub


        Public Overloads Shared Sub Main()
            Main(System.Environment.GetCommandLineArgs())
        End Sub

        Overloads Shared Sub Main(ByVal args() As String)
            Const port As Integer = 8889
            Dim tcplistener As New TcpListener(port)
            Console.WriteLine("Listening on port {0}", +port)  
            tcplistener.Start()
            While True
                Dim socket As Socket = tcplistener.AcceptSocket()
                Dim webproxy As New WebProxy2(socket)
                Dim thread As New Thread(New ThreadStart(AddressOf webproxy.run))
                thread.Start()
            End While
        End Sub 'Main  
    End Class 'WebProxy2  
End Namespace 'WebProxy2  


Class WebProxy
    Private clientSocket As Socket
    Private read() As [Byte] = New Byte(1023) {}
    Private Buffer As [Byte]() = Nothing
    Private ASCII As Text.Encoding = System.Text.Encoding.ASCII
    Private Const HTTP_VERSION As String = "HTTP/1.0"  
    Private Const CRLF As String = vbCr + vbLf
    Private RecvBytes(4095) As [Byte]
    Const port As Integer = 8088

    Shared Sub Main(ByVal args() As String)
        Dim tcplistener As New TcpListener(port)
        tcplistener.Start()
        Console.WriteLine("Listening on port {0}", +port)  
        'WriteToLog("log.txt", "Listening on port " & port)  

        While True
            Dim socket As Socket = tcplistener.AcceptSocket()
            Dim webproxy As New WebProxy(socket)
            Dim thread As New Thread(New ThreadStart(AddressOf webproxy.run))
            thread.Start()
        End While
    End Sub

    Public Sub New(ByVal socket As Socket)
        Me.clientSocket = socket
    End Sub

    Public Sub run()
        Dim clientmessage As String = " "  
        Dim sURL As String = " "  
        Dim bytes As Integer = readmessage(read, clientSocket, clientmessage)
        If bytes = 0 Then
            Return
        End If

        Dim index1 As Integer = clientmessage.IndexOf(" "c)  
        Dim index2 As Integer = clientmessage.IndexOf(" "c, index1 + 1)  
        If index1 = -1 OrElse index2 = -1 Then
            Throw New IOException()
        End If
        Console.WriteLine("Connecting to Site: {0}", clientmessage.Substring(index1 + 1, index2 - index1))  
        Console.WriteLine("Connection from {0}", clientSocket.RemoteEndPoint)  
        'WriteToLog("log.txt", DirectCast("Connecting to Site: {0}" & clientmessage.Substring(index1 + 1, index2 - index1), String))  
        'WriteToLog("log.txt", "Connection from : {0}")  
        Dim part1 As String = clientmessage.Substring(index1 + 1, index2 - index1) 'Könnte die Datei sein, ist keine Datei angegeben /  
        Dim index3 As Integer = part1.IndexOf("/"c, index1 + 8)  
        Dim index4 As Integer = part1.IndexOf(" "c, index1 + 8)  
        Dim index5 As Integer = index4 - index3
        sURL = part1.Substring(index1 + 4, part1.Length - index5 - 8)

        Try
            Dim IPHost As IPHostEntry = Dns.Resolve(sURL)
            Console.WriteLine("Request resolved: ", IPHost.HostName)  
            'WriteToLog("log.txt", "Request resolved: " & IPHost.HostName.ToString)  
            Dim aliases As String() = IPHost.Aliases
            Dim address As IPAddress() = IPHost.AddressList
            Console.WriteLine(address(0))
            'WriteToLog("log.txt", address(0).ToString)  
            Dim sEndpoint As New IPEndPoint(address(0), 80)
            Dim IPsocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
            IPsocket.Connect(sEndpoint)
            If IPsocket.Connected Then
                Console.WriteLine("Socket connect OK")  
                'WriteToLog("log.txt", "Socket connect OK")  
            End If
            Dim [GET] As String = clientmessage
            Dim ByteGet As [Byte]() = ASCII.GetBytes([GET])
            IPsocket.Send(ByteGet, ByteGet.Length, 0)
            Dim rBytes As Int32 = IPsocket.Receive(RecvBytes, RecvBytes.Length, 0)
            Console.WriteLine("Recieved {0}", +rBytes)  
            'WriteToLog("log.txt", "Recieved {0}" & CStr(+rBytes))  
            'Buffer = RecvBytes; 'War schon ausgeklammert  
            Dim strRetPage As String = Nothing
            strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, rBytes)
            While rBytes > 0
                rBytes = IPsocket.Receive(RecvBytes, RecvBytes.Length, 0)
                strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, rBytes) '****THIS SHOULD RETURN THE PAGE IF IM NOT MISTAKEN*********  
            End While
            IPsocket.Shutdown(SocketShutdown.Both)
            IPsocket.Close()
            sendmessage(clientSocket, strRetPage) 'Then we actualy send it...?  
        Catch exc2 As Exception
            Console.WriteLine(exc2.ToString())
            'WriteToLog("log.txt", exc2.ToString)  
        End Try
    End Sub

    Private Function readmessage(ByVal ByteArray() As Byte, ByRef s As Socket, ByRef clientmessage As String) As Integer
        Dim bytes As Integer = s.Receive(ByteArray, 1024, 0)
        Dim messagefromclient As String = System.Text.Encoding.ASCII.GetString(ByteArray)
        clientmessage = CStr(messagefromclient)
        Return bytes
    End Function

    Private Sub sendmessage(ByVal s As Socket, ByVal message As String)
        Buffer = New [Byte](message.Length + 1) {}
        Dim length As Integer = ASCII.GetBytes(message, 0, message.Length, Buffer, 0)
        s.Send(Buffer, length, 0)
    End Sub

End Class

CONNECT tss.t.shop.nintendowifi.net:443 HTTP/1.0
User-Agent: Opera/9.50 (Nintendo; Opera/154; U; Nintendo DS; en)
Host: tss.t.shop.nintendowifi.net:443