在 c 编程中处理客户端 - 服务器套接字中的 ctrl+c

Question

I wrote a telnet server in C programing language. Clients connect to the server using this command :

telnet *IP_Address*

I want when a client presses ctrl+c in its teminal, server closes the client connection but the server socket remains open. To to that put this command in first line of main function :

signal(SIGINT, CtrlC_Handler);

and this is CtrlC_Handler function :

void CtrlC_Handler(int sig) {

     close(_c->_client_socket);
}

the problem is when client press ctrl-c in its terminal connection doesn't close and commandline terminal doesn't response to client :

But when the server socket is closed, client can types in terminal again. server and client are in different servers. can anybody help how can i caught ctrl+c signal in this case ?

Answer 1

Your server handles the interrupt signal, which the process will receive when the terminal running the server gets a Ctrl-C. It has nothing to do with Ctrl-C being pressed in telnet .

telnet reacts to Ctrl-C by sending two control sequences:

• FF F4 ( IAC IP , Interrupt Process)
• FF FD 06 ( IAC DO TIMING-MARK )

You can react to receiving these sequences (specifically, the first one in your case; reacting to the second one should be obligatory by the telnet protocol, but it's a moot point if you break the connection :P ).