SMTP直放站愛好者

Question

我正在嘗試做一箇中繼器（作爲代理）來記錄SMTP客戶端和服務器之間的數據交換。我認爲這很容易： 傾聽客戶;

• 偵聽客戶端IP連接;
• 隨時待命，連接到服務器;
• 發回服務器消息;
• 將客戶端消息發送到服務器並將服務器反饋返回給客戶端;

但是，正如我所看到的，一些服務器，MS Exchange發送多個反饋女巫打破handshaking.Like：

• 250-SIZE 41943040
• 250流水
• 250-DSN
• 250 ENHANCEDSTATUSCODES
• 250 STARTTLS
• 250-AUTH LOGIN
• 250-8BITMIME
• 250 BINARYMIME

• 250 CHUNKING

  下面是類

  進口System.Text 進口System.Net 進口的System.Net.Sockets 進口系統。線程

  公共類SmtpProxy

  Private client As TcpClient 
  Private cltstream As NetworkStream 
  Private cltreader As System.IO.StreamReader 
  Private cltwriter As System.IO.StreamWriter 
  
  Private smtpserver As New TcpClient 
  Private srvstream As NetworkStream 
  Private srvreader As System.IO.StreamReader 
  Private srvwriter As System.IO.StreamWriter 
  
  
  Private Shared mHostSrv As String 
  Public Shared Property HostSrv() As String 
      Get 
       Return mHostSrv 
      End Get 
      Set(ByVal value As String) 
       mHostSrv = value 
      End Set 
  End Property 
  
  Private Shared mServerPort As Integer = 25 
  Public Shared Property ServerPort() As Integer 
      Get 
       Return mServerPort 
      End Get 
      Set(ByVal value As Integer 
      ) 
       mServerPort = value 
      End Set 
  End Property 
  
  Private Shared mUserNm As String 
  Public Shared Property UserNm() As String 
      Get 
       Return mUserNm 
      End Get 
      Set(ByVal value As String) 
       mUserNm = value 
      End Set 
  End Property 
  
  Private Shared mPassword As String 
  Public Shared Property Password() As String 
      Get 
       Return mPassword 
      End Get 
      Set(ByVal value As String) 
       mPassword = value 
      End Set 
  End Property 
  
  
  Public Sub New(ByVal client As TcpClient) 
      Me.client = client 
      cltstream = client.GetStream() 
      cltreader = New System.IO.StreamReader(cltstream) 
      cltwriter = New System.IO.StreamWriter(cltstream) 
      cltwriter.NewLine = vbCr & vbLf 
      cltwriter.AutoFlush = True 
  
  End Sub 
  
  
  Public Shared Sub Start() 'ByVal args As String()) 
      Dim listener As New TcpListener(IPAddress.Loopback, 2525) 
      listener.Start() 
      While True 
       Dim handler As New SmtpProxy(listener.AcceptTcpClient()) 
       Dim thread As Thread = New System.Threading.Thread(New ThreadStart(AddressOf handler.Run)) 
       thread.Start() 
      End While 
  End Sub 
  
  
  Public Sub Run() 
  
      If mHostSrv Like "*.*.*.*" Then 
       Dim IpS As IPAddress = Nothing 
       IpS = IPAddress.Parse(mHostSrv) 
       smtpserver.Connect(IpS, mServerPort) 
      Else 
       smtpserver.Connect(mHostSrv, mServerPort) 
      End If 
  
      srvstream = smtpserver.GetStream 
      srvreader = New System.IO.StreamReader(srvstream) 
      srvwriter = New System.IO.StreamWriter(srvstream) 
      srvwriter.NewLine = vbCrLf 
      srvwriter.AutoFlush = True 
  
  
      Dim srvline As String = srvreader.ReadLine 
      cltwriter.WriteLine(srvline) 
      Debug.Print("Server sent: {0}", srvline & vbCrLf) 
  
      Try 
  
       Dim line As String = cltreader.ReadLine 
       While line IsNot Nothing 
        Debug.Print("Read line {0}", line) 
        srvwriter.WriteLine(line) 
        Application.DoEvents() 
        srvline = srvreader.ReadLine() 
        Debug.Print("Server sent: {0}", srvline) 
        cltwriter.WriteLine(srvline.Replace("-", " ")) 
        Application.DoEvents() 
        line = cltreader.ReadLine() 
       End While 
      Catch ex As Exception 
       client.Close() 
       smtpserver.Close() 
      End Try 
  
  End Sub 
  

  末級

我試過一次，但在此期間，客戶端返回值和錯誤讀取多個服務器產品線，如果我全送回到服務器產品線...

Private Function ReadSrvLines() As String 

    Dim strRet As String = "" 
    Do 
     If strRet Like "220*" OrElse srvreader.EndOfStream Then Exit Do 
     Dim strTmp As String = srvreader.ReadLine 
     If strTmp Is Nothing Then Exit Do 
     strRet &= strTmp.Replace("-", " ") & vbCrLf 
     cltwriter.WriteLine(strTmp.Replace("-", " ")) 
     Debug.Print("Server sent: {0}", strTmp.Replace("-", " ") & vbCrLf) 
    Loop 

    Return strRet 
End Function 

那麼是否有人有任何解決方案提出？

謝謝大家！

弗蘭克

Answer 1

您需要同時執行多個異步讀取/客戶端和服務器之間的寫作，使這項工作正常。 SMTP響應可以包含任意數量的行，並且客戶端或服務器可以在不需要命令的情況下返回消息（例如說再見）。解析數據對於實現基本日誌也是不必要的。

編輯：如果有幫助，如果3位數的消息號後面跟一個（減號）而不是一個（空格），這意味着還有另一條線。