Convert ISC dhcpd.leases file to JSON

isc-leases-to-json.pl

#!/usr/bin/perl

use strict;
use warnings;
use JSON;
use experimental qw(switch);

my %leases;
my %current_lease;
my $current_lease_ip;

sub save_lease {
        if ($current_lease_ip) {
                $leases{$current_lease_ip} = { %current_lease };
                %current_lease = ();
                $current_lease_ip = undef;
        }                        
}

foreach (<>) {
        chomp; # eat the newlines
        when (/^lease ([0-9.]+) {$/) {
                save_lease();
                $current_lease_ip = $1;
        }
        save_lease() when (/^}$/);
        $current_lease{"starts"} = $1 when (/^ +starts (.+);$/);
        $current_lease{"ends"} = $1 when (/^ +ends (.+);$/);
        $current_lease{"tstp"} = $1 when (/^ +tstp (.+);$/);
        $current_lease{"cltt"} = $1 when (/^ +cltt (.+);$/);
        $current_lease{"binding state"} = $1 when (/^ +binding state (.+);$/);
        $current_lease{"next binding state"} = $1 when (/^ +next binding state (.+);$/);
        $current_lease{"rewind binding state"} = $1 when (/^ +rewind binding state (.+);$/);
        $current_lease{"hardware ethernet"} = $1 when (/^ +hardware ethernet (.+);$/);
        $current_lease{"uid"} = $1 when (/^ +uid "(.+)";$/);
        $current_lease{"ddns-rev-name"} = $1 when (/^ +set ddns-rev-name = "(.+)";$/);
        $current_lease{"ddns-txt"} = $1 when (/^ +set ddns-txt = "(.+)";$/);
        $current_lease{"ddns-fwd-name"} = $1 when (/^ +set ddns-fwd-name = "(.+)";$/);
        $current_lease{"client-hostname"} = $1 when (/^ +client-hostname "(.+)";$/);
        next when (/^server-duid "(.*)";$/);
        next when (/^ *#/); # comment
        next when (/^ *$/); # blank lines
        default { print "Unrecognized line '$_'\n"; }
}

my $json = JSON->new->utf8->pretty->encode(\%leases);

print $json;