CODEWITHSUNDEEP
perlsockets
Fabien
Fabien

Reputation: 13406

How do you know a socket client disconnected?

I'm having a little trouble using sockets in a Perl server.

How can you know a (non-blocking) client just disconnected ? In C, I'm used to doing

if (recv(sock, buff, size, flags) == 0) {
    printf("Client disconnected\n";
}

or the equivalent in python or other languages : recv returns -1 if no data is available, 0 if client exited, a positive number if data could be read.

But perl's recv doesn't work this way, and using $data = <$sock> does not seem to give any possibility to know.

Is there any (simple) possibility ?

Upvotes: 4

Views: 2839

Answers (1)

F. Hauri - Give Up GitHub
F. Hauri - Give Up GitHub

Reputation: 70812

You have to take a look at perldoc perlio and perldoc IO::Socket.

#!/usr/bin/perl -w
use IO::Socket;

There is a lot of ways to compose with non-blocking IOs, from PIPE signal to recv you could use (depending on what you are doing):

return "Socket is closed" unless $sock->connected;

That is how I've controlled many sockets to serve them with select. When a socket is closed, I have to remove them from list (nothing else, as if disconnect, the socket doesn't exist anymore, so there is no need to close them):

unless (eval {$group{$grp}->{'socket'}->connected}) {
    delete $group{$grp}->{'socket'};
    return 0;
};

The eval prevents a bad try to a disconnected socket which will end your script with a socket io error.

Hope this helps!

Upvotes: 1

Related Questions