Perl-how to exit if recv() stalls?

Question

Somewhat new to perl, but trying to create an ntp monitor and getting confused by how to exit if the recv() command doesn't get a message within some amount of time (e.g. 5 seconds)

berger · Accepted Answer

Sorry if anyone was looking for the answer, I re-wrote and the script itself seems to work. This is the script:

#!/usr/bin/perl

# ntpman.pl

# Script is meant to monitor an ntp server. It will query the server for the ntp and recieve the ntp back from the ntp server.

# If the script either fails to send a query or fails to recieve the ntp after 10 seconds, the script will print the "Statistic: 2" down

# code and exit.

#

# Script was partially re-written from Tim Hogard's ntpdate.pl, which is housed in the public domain.

print "Starting ntpman.pl";

use IO::Select;

use Socket;

$HOST="157.142.34.100"; #NTP Server

socket($SOCKET, PF_INET, SOCK_DGRAM, getprotobyname("udp"));

$select = IO::Select->new();

$select->add($SOCKET);

$ipaddr   = inet_aton($HOST);

$portaddr = sockaddr_in(123, $ipaddr);

$MSG="\010"."\0"x47;

@ready = $select->can_write(10);

foreach $SOCKET(@ready) {

send($SOCKET, $MSG, 0, $portaddr);

print "NTP query has been sent
";

}

@ready = $select->can_read(10);

foreach $SOCKET (@ready) {

recv($SOCKET, $MSG, 48, 0);

print "NTP has been recieved
";

print "
Statistic: 0";

exit 0;

}

print "Statistic: 2";

exit 1;