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

I tried several solutions. But is it possible to use Net::Netmask to do this:

(This is just demo code to illustrate my point) 

%maskcount = ( "/25"  =>  "128",
             "/26"  =>  "64",
             "/27"  =>  "32",
             "/28"  =>  "16");

# loop POPs
while($line=<STDIN>) {
  chomp($line);
  next unless ($line=~/^\d/);

  ($ipbase,$mask)=split(/;/,$line);

  @ip=split(/\./,$ipbase);
  $areacode =~ s/^0//;
  print "$areacode: $ipbase/$mask\n";

  # do not load first (=network) and second (=gateway) ip addressess
  $startip=2;

  # do not load last (=broadcast) ip address
  $endip=$maskcount{$mask}-1;
  print $endip;

  for ($cnt=$startip;$cnt<$endip;$cnt++) {
    $ipend[0]=$ip[0];
    $ipend[1]=$ip[1];
    $ipend[2]=$ip[2];
    $ipend[3]=$ip[3]+$cnt;
    if ($ipend[3]>255) { $ipend[2]=$ip[2]+1; $ipend[3]=$ip[3]-255; }
    $ipend = join(".",@ipend);

    print "$ipend\n";
  }
}

[download]
I just want to generate a list of IP's. I know the start ip and the network mask and want to generate the whole list of IP's from that range. I tried this approach, but there , must be a cleaner way to do this...

--
My opinions may have changed,
but not the fact that I am right

Replies are listed 'Best First'.
Re: IP troubles
by jwest (Friar) on Dec 18, 2001 at 02:07 UTC
    Does this fit the bill?

    use strict;
use warnings;
use Net::Netmask;

while (<>) {
  chomp;
  s/;/:/;
  my $block = new Net::Netmask($_);
  if (not $block) {
    warn "Bad CIDR specification";
    next;
  }
  my @ip    = $block->enumerate();

  # Remove the network and gateway addresses.
  shift(@ip);
  shift(@ip);

  # Remove the broadcast address.
  pop(@ip);

  for my $ip (@ip) {
    print $ip, "\n";
  }
}

    [download]

    --jwest

    -><- -><- -><- -><- -><-
All things are Perfect
    To every last Flaw
    And bound in accord
         With Eris's Law
 - HBT; The Book of Advice, 1:7
[reply]
[d/l]
      How should the data look as input?

      --
      My opinions may have changed,
      but not the fact that I am right

[reply]
        Sorry - I should have specified that. As per your example, you can enter it as:

        192.168.1.0;255.255.255.0

        Or, since we're using Net::Netmask:

        192.168.1.0/24
        192.168.1.0:255.255.255.0
        192.168.1 - which assumes a /24 block
        192.168 - which assumes a /16 block
        192 - which assumes a /8 block
        192.168.1/24
        192.168/16
        etc.

        Net::Netmask is particularly smart about parsing these things, so it's a nice tool to leverage for this type of work.

        --jwest

        -><- -><- -><- -><- -><-
All things are Perfect
    To every last Flaw
    And bound in accord
         With Eris's Law
 - HBT; The Book of Advice, 1:7
[reply]
Re: IP troubles
by atcroft (Abbot) on Dec 18, 2001 at 11:38 UTC

    Here is my own code (derived from Re: Checking IP's with an IP/mask) to generate the list, without using Net::Netmask. It also seems to work for supernetted blocks through at least a /8 (just finished that test-16,777,216 addresses and code feels fine). Included is my test code for a block (in this case, 192.168.1.32/28). The code also makes allowances for if you want to generate the list with/without the network, gateway, and/or broadcast addresses included.

    (Might could use some clean-up by way of making sure that $nonetwork, $nogateway, and $nobroadcast are only set either 0 or 1.) 

    #!/usr/bin/perl -w --

use strict;

#
# Set to 1 to remove from generated list, 0 to leave in
#
my $nonetwork = 1;
my $nogateway = 1;
my $nobroadcast = 1;

my $block = '192.168.1.32';
my $cidr = 28;

my $machines = 2**(32 - $cidr);
my $lip = unpack("N", pack("C4", split(/\D/, $block, 4)));

#
# Assumes gateway is at beginning, not end, of block
#
for (my $i = ($nonetwork + $nogateway); 
        $i < ($machines - $nobroadcast); 
        $i++)
    my $res = $lip + $i;
    print(join('.', unpack("C4", pack("N", $res))), "\n");
}

    [download]

    Comments? Questions? Hope this helps.

    Update: Noted in several of the posts afterwards that the input format was discussed. In my code above, I believe significate modification would likely be required to use netmask rather than CIDR notation.

[reply]
[d/l]

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