claree0 has asked for the wisdom of the Perl Monks concerning the following question:

As a part of a project, I need to manipulate an IP address and network mask, both in dotted notation, to give a network address in slash notation (i.e. 192.168.1.5 255.255.255.0 becomes 192.168.1.0/24)

I've written the sub shown below, but I don't know if my method for finding the number of bits in the netmask is the best way to do it....... 

sub nets {
        # takes 2 args - IP address and network mask
        my $ip = $_[0];
        my $mask = $_[1];
        my $nets = inet_ntoa ((inet_aton($ip)) & (inet_aton($mask)));
        my $binmask = unpack ("B32", pack ("C4", split(/\./, $mask)));
        $binmask =~ /(10)/;
        my $bits = $-[1]+1;
        my $network = "$nets\/$bits";
        return $network;
}

[download]

Replies are listed 'Best First'.
Re: Manipulating IPs and masks
by rob_au (Abbot) on Sep 03, 2001 at 18:27 UTC
    There are two modules which I think you should have a look at - Net::CIDR and more importantly, Net::Netmask. The latter of these modules incorporates a number of functions for exactly what you are requiring. eg.
     
    use Net::Netmask;

my ($block) = new Net::Netmask ("192.168.1.5", "255.255.255.0");
print $block->base(), "/", $block->bits(), "\n";

    [download]

     

     
    Ooohhh, Rob no beer function well without!
[reply]
[d/l]

Back to Seekers of Perl Wisdom