sent RST after got FIN

Question

・What am I doing: A TCP server and A UDP “server” simultaneously ・What I have done in my code: when I want to close the TCP socket or got a FIN if the socket status is SOCK_ESTABLISHED then DICONN otherwise CLOSE ・What happend: got FIN sent ACK sent RST ・Then I changed my code as this: when I want to close the TCP socket or got FIN if the socket status is SOCK_LISTEN then CLOSE if the socket status is SOCK_ESTABLISHED or SOCK_CLOSE_WAIT then DICONN ・What happend then: got FIN sent ACK, FIN got ACK sent RST What am I asking: What shold I do when I want to close the TCP socket or got a FIN? For some reason I can not reconstruct the code. Only this one function I can touch. ・Further question: ①Are these the all status that available in TCP server? SOCK_INIT SOCK_LISTEN SOCK_ESTABLISHED SOCK_CLOSE_WAIT SOCK_SYNSENT SOCK_SYNRECV SOCK_FIN_WAIT SOCK_FIN_WAIT SOCK_CLOSING SOCK_TIME_WAIT SOCK_LAST_ACK SOCK_ARP_0 SOCK_ARP_1 SOCK_ARP_2 ②Is the SOCK_CLOSE_WAIT the only available status when got a FIN? ③When I want to close the TCP socket, what should I do when the the CHIP is in each status in ①? ④Are these the all status that available in UDP “server”? SOCK_INIT SOCK_UDP SOCK_ARP_0 SOCK_ARP_1 SOCK_ARP_2 ⑤When I want to close the UDP socket, what should I do when the the CHIP is in each status in ④? Thank you.

becky · Answer

The status to be managed while using the tcp server is as follows. This is because the rest of the status is a brief moment or does not occur on the TCP server. image754×690 203 KB Yes, when FIN is received, W5100 becomes SOCK_CLOSE_WAIT state. Transmit DISCONNECT or CLOSE Command. CLOSE is recommended for INIT and LISTEN, CLOSE or DISCONNECT for ESTABLISHED, and DISCONNECT for CLOSE_WAIT. Like the tcp server, the status to be managed while using the udp is as follows. image686×585 191 KB Please send a close command

becky · Answer

That is possible.