I am writing a script that randomly chooses an IP from an array, then tries to make an IO::Socket connection to it. I want to wrap the socket connection in alarm() to keep it from hanging forever if something goes wrong. I don't want the whole script to die from the SIGALRM, so I'm writing a signal handler for it.

The problem is, I want the handler to use some variables from outside the handler. I can't pass them as arguments, and I don't want to make them globals. (The reason for no globals is that I want this sub to eventually be a fully-encapsulated object method.)

One solution I had thought of was making the handler local inside the sub (a nested sub). Is this the best way, or is there a better way to accomplish this task?

Here's my code so far (which is currently broken): 
#!/usr/bin/perl

use strict;
use warnings;

$|++;

use Carp;

my $info = $ARGV[0] || 'string_of_data';
print outer($info);

sub outer {

    use IO::Socket;
    
    my @ips = ('xxx.xxx.xxx.xx0','xxx.xxx.xxx.xx1','xxx.xxx.xxx.xx2');
    my $port = xxxx;
    ### $SIG{INT} = \&buh_bye; ### per ikegami
    ### $SIG{ALRM} = \&fallback; ### per ikegami
    local $SIG{INT} = \&buh_bye;
    local $SIG{ALRM} = \&fallback;

    ### srand; ### woops, thanks again ikegami
    my $index = int(rand(scalar @ips));
    
    alarm(5);
    my $sock = IO::Socket::INET->new($ips[$index].':'.$port);
    $index = fallback() unless ($sock);
    alarm(0);
    
    die "$! ($ips[$index])\n" unless ($sock);
    
    print $sock "$info$/";
    sysread $sock, my ($text), 10000;
    close($sock);
    
    print "ok ($ips[$index])\n";

    return $text;
    
}


sub fallback {

    my $signame = shift;

    print +($signame) ? "Caught SIG$signame! " : "$! ";

    print "($ips[$index])\nTrying fallback host ";
    $index -= 1;
    print "($ips[$index])\n";
    $sock = IO::Socket::INET->new($ips[$index].':'.$port);
    return $index;

}


sub buh_bye {

    my $signame = shift;
    die "\nCaught SIG${signame}!\nIP: $ips[$index]\n";

}

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It's all fine and dandy until someone has to look at the code.

In reply to Signal handlers and scoped variables, or Nested subs? by kwaping

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