SMTP Repeater loger

Question

我正在尝试使用转发器（作为代理）来记录SMTP客户端和服务器之间的数据交换。我认为这很简单： 倾听客户的意见;

• 侦听客户端IP连接;
• 通话时，连接服务器;
• 发回服务器消息;
• 将客户端消息发送到服务器并将服务器反馈返回给客户端;

但是，正如我所看到的，一些服务器作为MS交换发送了多个反馈，正在打破握手。喜欢：

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

• 250 CHUNKING

  这是班级

  导入System.Text 进口System.Net 导入System.Net.Sockets 进口System.Threading

  Public Class 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
  

  结束班

我尝试一次读取多个服务器行，但同时客户端返回错误，如果我发送整个返回的服务器行...

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

那么有人提出任何解决方案吗？

谢谢大家!!

谢

Answer 1

您需要在客户端和服务器之间同时执行异步读/写操作才能使其正常工作。 SMTP响应可以包含任意数量的行，客户端或服务器可以返回消息而无需命令（例如再见）。解析数据对于实现基本日志也是不必要的。

编辑：如果有帮助，如果3位数的消息编号后跟一个（减号）而不是一个（空格），则表示还有另一条线要跟随。