c# - 使用 .net 的 Telnet 连接

Question

我们办公室目前使用 telnet 查询外部服务器。过程是这样的。

1. 连接 - telnet opent 128........ 25000
2. 查询 - 我们粘贴查询然后点击 alt + 019
3. 响应 - 我们在 telnet 窗口中收到文本形式的响应

所以我尝试使用 C# 应用程序自动执行此查询。我的代码如下

首先是连接。 (没有异常(exception))

    SocketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    String szIPSelected = txtIPAddress.Text;
    String szPort = txtPort.Text;
    int alPort = System.Convert.ToInt16(szPort, 10);

    System.Net.IPAddress remoteIPAddress = System.Net.IPAddress.Parse(szIPSelected);
    System.Net.IPEndPoint remoteEndPoint = new System.Net.IPEndPoint(remoteIPAddress, alPort);
    SocketClient.Connect(remoteEndPoint);

然后我发送查询(没有异常(exception))

    string data ="some query";
    byte[] byData = System.Text.Encoding.ASCII.GetBytes(data);
    SocketClient.Send(byData);

然后我尝试接收响应

    byte[] buffer = new byte[10];
    Receive(SocketClient, buffer, 0, buffer.Length, 10000);
    string str = Encoding.ASCII.GetString(buffer, 0, buffer.Length);
    txtDataRx.Text = str;

public static void Receive(Socket socket, byte[] buffer, int offset, int size, int timeout)
{
  int startTickCount = Environment.TickCount;
  int received = 0;  // how many bytes is already received
  do
  {
    if (Environment.TickCount > startTickCount + timeout)
      throw new Exception("Timeout.");
    try
    {
      received += socket.Receive(buffer, offset + received, size - received, SocketFlags.None);
    }
    catch (SocketException ex)
    {
      if (ex.SocketErrorCode == SocketError.WouldBlock ||
          ex.SocketErrorCode == SocketError.IOPending ||
          ex.SocketErrorCode == SocketError.NoBufferSpaceAvailable)
      {
        // socket buffer is probably empty, wait and try again
        Thread.Sleep(30);
      }
      else
        throw ex;  // any serious error occurr
    }
  } while (received < size);
}

每次我尝试接收响应时，如果打开 telnet 并发送相同的查询，我会立即收到响应“一个现有的连接已被远程主机强行关闭”

有什么想法或建议吗？

Answer 1

根据你我之间的评论交流，你似乎需要在查询末尾附加 Ascii 代码 19 (0x13)。