CODEWITHSUNDEEP
ctcpnetwork-programming
user138126
user138126

Reputation: 1003

how to kill a tcp connection in a tcp server program if no FIN/ACK or RST received

I wrote a tcp server program(linux c) and run it on host B

if host A establishes a TCP connection with host B

then A shutdown without sending FIN/ACK

how do I write source codes inside tcp server to kill this tcp connection?

use raw socket to craft s fake RST?

or other ways?

thanks!

Upvotes: 0

Views: 2706

Answers (2)

Artem
Artem

Reputation: 117

I'm not sure in this case, but if you create a binary file with all the open connections:

FILE *ptr_myfile;
ptr_myfile=fopen("test.bin","wb"); //opened sockets
//.. your code ..
sockfd[k] = socket(AF_INET, SOCK_STREAM, 0);
fwrite(&sockfd[k], sizeof(sockfd[k]), 1, ptr_myfile_soc);
//.. your code ..
close(ptr_myfile);

and if host A shuts down without sending FIN/ACK, in another executable you will read from that file and close the related sockets:

fread(&sockfd[k],sizeof(sockfd[k]),1,ptr_myfile_soc);
printf("closing %d \n",k );
close(sockfd[k]);

Upvotes: 0

Remy Lebeau
Remy Lebeau

Reputation: 595782

Just close() the server's end of the socket once it has determined that the connection is no longer available. Eventually, the socket will time out internally and start reporting errors to read/write operations, at which time you can then close it. If you do not want to wait that long then implement a timeout in your own code, either as a keepalive/ping command in your protocol, or just as a simple timer that keeps track of the last time the client exchanged any data with the server. If the timeout period expires, close the socket regardless of its actual state.

Upvotes: 1

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