I actually worked with dhcp.conf back in '98 or so. We were converting extensive BOOTP tables to a dhcp.conf. I don't remember the spec any, though. ok, enough reminescing. :)

You could use Parse::RecDescent. A start would be: 

my $grammar = <<'__END_OF_GRAMMAR__';

   {
      use strict;
      use warnings;
   }

   parse       : item(s?) /\Z/ { $item[1] }

   item        : subnet
               | option

   subnet      : SUBNET IP_ADDR NETMASK IP_ADDR subnet_blk
                 { [ @item[0,2,4,5] ] }
        
   subnet_blk  : option(s?)

   option      : OPTION option_list
                 { [ $item[0], @{$item[2]} ] }

   option_list : ...


   # Reserved Words
   # ==============

   #SUBNET      : IDENT { $item[1] eq 'subnet'  ? $item[1] : undef }
   #NETMASK     : IDENT { $item[1] eq 'netmask' ? $item[1] : undef }
   #OPTION      : IDENT { $item[1] eq 'option'  ? $item[1] : undef }
   SUBNET      : /subnet(?![a-zA-Z-9_])/
   NETMASK     : /netmask(?![a-zA-Z-9_])/
   OPTION      : /option(?![a-zA-Z-9_])/

   # Tokens
   # ======

   IDENT       : /[a-zA-Z][a-zA-Z-9_]*/
   IP_ADDR     : /\d+\.\d+\.\d+\.\d+/

__END_OF_GRAMMAR__

[download]

Update: Optimized reserved words.

In reply to Re: Parsing Config File with Multi-line Elements by ikegami
in thread Parsing Config File with Multi-line Elements by pileofrogs

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