use strict;
use warnings;

use Fcntl;
use Errno;
use Socket;
use IO::Select;

my $socket;
my $flags;
my $port = 80;
my $ip = '1.1.1.1';

# create socket
socket($socket, PF_INET, SOCK_STREAM, getprotobyname('tcp')) || die("socket: $!");

# set the socket to non-blocking mode
$flags = fcntl($socket, F_GETFL, $flags) || die("fcntl: $!");
fcntl($socket, F_SETFL, $flags | O_NONBLOCK) || die("fcntl: $!");

if (! connect($socket, sockaddr_in($port, inet_aton($ip))) {
    if ($!{EINPROGRESS}) {
        ...
        run a select loop or do something else here
        installing a callback handler is a good bet
        ...
        return;
    }
    else {
        die("connect: $!");
    }
}
else {
    handle_successful_connect();
}

sub callback_handler
{
    my $socket = shift;

    # check the error condition on the socket
    my $option = getsockopt($socket, SOL_SOCKET, SO_ERROR);

    if (! defined($option)) {
        die("getsockopt: $!");
    }
 
    if (0 != ($! = unpack('i', $option))) {
        die("connect: $!");
    }

    handle_successful_connect();
}

sub handle_successful_connect
{
}