#! /usr/bin/perl -w
use strict;
my $DEBUG = 0;

my ($if) = @ARGV;
print STDERR "Detecting network for $if ...";

while (<STDIN>) {
    chomp;
    my ($alias, $cmd, @arg) = split ' ', $_;
    my ($label) = ($alias);
    $label =~ s/.*[-:;]//;
    if ($cmd eq 'ping') {
        my ($from, $mask, $gw) = @arg;
        system('ifconfig', $if, '0.0.0.0', 'down');
        system('ifconfig', $if, $from, 'netmask', $mask, 'up');
        local $_ = qx(traceroute -n -r -i $if -I -w 3 -m 1 $gw 2>&1);
        print STDERR "\n",$_,"\n" if $DEBUG;
        system('ifconfig', $if, '0.0.0.0', 'down');
        if (/\*|\!H/) {
            print STDERR " !$label";
            next;
        } else {
            print STDERR " $label";
            print STDOUT $alias;
            last;
        }
    } elsif ($cmd eq 'fallback') {
        print STDERR " $label";
        print STDOUT $alias;
        last;
    }
}
print STDERR "\n";
exit;