Help!: Problem with TCP connection to server after client crush/incorrect exit

[zubaziga]

I'm supposed to connect to embedded server through TCP sockets (custom protocol).

Just for sanity check, I've done sample which do following steps:

1. TCP Connect (IPaddress, port);
2. Send Test IP packet (server init command);
3. Receive Responce;
--> 4. TCP Close.

This sequence works without glitch (yet).

Problem:
If client exits just one time without 4th step (TCP Close), then:
1. Next time it goes through steps 1-2 and on 3 never get any responce from server.
2. After that if I restart client, it breaks just on step 1 with "server actively refused connection". And MAINTAINs to refuse connections on that (address,port) for very long time >6hrs . Besides, http connection to same address (from brouser) is ok.


Can anybody shed some light on the situation ? Isn't server supposed to handle that kind of situations ?

[xander_tan]

I'm supposed to connect to embedded server through TCP sockets (custom protocol).

Just for sanity check, I've done sample which do following steps:

1. TCP Connect (IPaddress, port);
2. Send Test IP packet (server init command);
3. Receive Responce;
--> 4. TCP Close.

This sequence works without glitch (yet).

Problem:
If client exits just one time without 4th step (TCP Close), then:
1. Next time it goes through steps 1-2 and on 3 never get any responce from server.
2. After that if I restart client, it breaks just on step 1 with "server actively refused connection". And MAINTAINs to refuse connections on that (address,port) for very long time >6hrs . Besides, http connection to same address (from brouser) is ok.


Can anybody shed some light on the situation ? Isn't server supposed to handle that kind of situations ?

Question: what if you restart the embedded server? Will it recover?

My guess is that the server has timeout issue. It may wait for TCP close for a long time, i.e. 6 hours. Are you developing the embedded server firmware? If you are, you should check the timeout in the server.

The fact that the web browser can connect to the embedded server, it means that the server does not hang. It can still do some calculation, it's just your particular module that doesn't work.

Another question: does the server allow multiple connection? Can you connect two clients to the embedded server (not the web server) concurrently?