delphi - 如何使用 TIdTCPServer 断开不活动客户端的连接？

Question

我正在尝试断开连接到 TIdTCPServer 的非事件客户端的连接，无论这些客户端是与 Internet 断开连接还是在一段非事件时间内。

我尝试在 OnConnect 事件中设置超时，如下所示:

procedure TservForm.TcpServerConnect(AContext: TIdContext);
begin
  AContext.Connection.IOHandler.ReadTimeout := 26000;
  AContext.Binding.SetSockOpt(Id_SOL_SOCKET, Id_SO_SNDTIMEO, 15000);
end; 

但客户端连接丢失后似乎不会触发断开连接。

我尝试使用SetKeepAliveValues()，但断开不活动客户端的连接需要花费太多时间。

是否有更有用的方法来断开不活动的客户端？那么如果客户端没有接收或发送任何东西，比如30秒内，服务器就会断开连接？

执行事件

procedure TservForm.TcpServerExecute(AContext: TIdContext);
var
  Connection: TConnection;
  cmd: String;
  Cache, OutboundCmds: TStringList;
  MS: TMemoryStream;
  I: integer;
  S: String;
begin
  Connection := AContext as TConnection;

  // check for pending outbound commands...
  OutboundCmds := nil;
  try
    Cache := Connection.OutboundCache.Lock;
    try
      if Cache.Count > 0 then
      begin
        OutboundCmds := TStringList.Create;
        OutboundCmds.Assign(Cache);
        Cache.Clear;
      end;
    finally
      Connection.OutboundCache.Unlock;
    end;

    if OutboundCmds <> nil then
    begin
      for I := 0 to OutboundCmds.Count - 1 do
      begin
        AContext.Connection.IOHandler.Writeln(OutboundCmds.Strings[I],
          IndyTextEncoding_UTF8);
        MS := TMemoryStream(OutboundCmds.Objects[I]);
        if MS <> nil then
        begin
          AContext.Connection.IOHandler.DefStringEncoding := IndyTextEncoding_UTF8;
          AContext.Connection.IOHandler.LargeStream := true;
          AContext.Connection.IOHandler.Write(MS, 0, true);
        end;
      end;
    end;
  finally
    if OutboundCmds <> nil then
    begin
      for I := 0 to OutboundCmds.Count - 1 do
        OutboundCmds.Objects[I].Free;
    end;
    OutboundCmds.Free;
  end;

  // check for a pending inbound command...
  if AContext.Connection.IOHandler.InputBufferIsEmpty then
  begin
    AContext.Connection.IOHandler.CheckForDataOnSource(100);
    AContext.Connection.IOHandler.CheckForDisconnect;
    if AContext.Connection.IOHandler.InputBufferIsEmpty then
    begin
    Exit;
    end;
  end;

  cmd := AContext.Connection.Socket.ReadLn(IndyTextEncoding_UTF8);

  ...............
  ...............

Answer 1

客户端不会断开连接，因为在空闲时间内未达到 ReadLn()，因此 ReadTimeout 不起作用，并且如果您发送的数据不多的命令，则套接字缓冲区未填满，因此 SO_SNDTIMEO 也不起作用。

由于您已经进行了一些手动超时处理，因此您也可以对其进行扩展以处理空闲超时，例如:

type
  TConnection = class(TIdServerContext)
    ...
  public
    LastSendRecv: LongWord;
    ...
  end;

...

procedure TservForm.TcpServerConnect(AContext: TIdContext);
var
  Connection: TConnection;
begin
  Connection := AContext as TConnection;
  AContext.Connection.IOHandler.DefStringEncoding := IndyTextEncoding_UTF8;
  AContext.Connection.IOHandler.LargeStream := True;
  AContext.Connection.IOHandler.ReadTimeout := 30000;
  AContext.Binding.SetSockOpt(Id_SOL_SOCKET, Id_SO_SNDTIMEO, 15000);
  Connection.LastSendRecv := Ticks;
end; 

procedure TservForm.TcpServerExecute(AContext: TIdContext);
var
  Connection: TConnection;
  cmd: String;
  Cache, OutboundCmds: TStringList;
  MS: TMemoryStream;
  I: integer;
  S: String;
begin
  Connection := AContext as TConnection;

  // check for pending outbound commands...
  OutboundCmds := nil;
  try
    Cache := Connection.OutboundCache.Lock;
    try
      if Cache.Count > 0 then
      begin
        OutboundCmds := TStringList.Create;
        OutboundCmds.Assign(Cache);
        Cache.Clear;
      end;
    finally
      Connection.OutboundCache.Unlock;
    end;

    if OutboundCmds <> nil then
    begin
      for I := 0 to OutboundCmds.Count - 1 do
      begin
        AContext.Connection.IOHandler.WriteLn(OutboundCmds.Strings[I]);
        MS := TMemoryStream(OutboundCmds.Objects[I]);
        if MS <> nil then               
          AContext.Connection.IOHandler.Write(MS, 0, true);    
      end;
      Connection.LastSendRecv := Ticks;
    end;
  finally
    if OutboundCmds <> nil then
    begin
      for I := 0 to OutboundCmds.Count - 1 do
        OutboundCmds.Objects[I].Free;
    end;
    OutboundCmds.Free;
  end;

  // check for a pending inbound command...
  if AContext.Connection.IOHandler.InputBufferIsEmpty then
  begin
    AContext.Connection.IOHandler.CheckForDataOnSource(100);
    AContext.Connection.IOHandler.CheckForDisconnect;
    if AContext.Connection.IOHandler.InputBufferIsEmpty then
    begin
      if GetTickDiff(Connection.LastSendRecv, Ticks) >= 30000 then
        AContext.Connection.Disconnect;
      Exit;
    end;
  end;

  cmd := AContext.Connection.Socket.ReadLn;    
  Connection.LastSendRecv := Ticks;

  ...
end;