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NAME

     Net::netent - by-name interface to Perl's built-in getnet*()
     functions



SYNOPSIS
      use Net::netent qw(:FIELDS);
      getnetbyname("loopback")               or die "bad net";
      printf "%s is %08X\n", $n_name, $n_net;

      use Net::netent;

      $n = getnetbyname("loopback")          or die "bad net";
      { # there's gotta be a better way, eh?
          @bytes = unpack("C4", pack("N", $n->net));
          shift @bytes while @bytes && $bytes[0] == 0;
      }
      printf "%s is %08X [%d.%d.%d.%d]\n", $n->name, $n->net, @bytes;




DESCRIPTION
     This module's default exports override the core
     getnetbyname() and getnetbyaddr() functions, replacing them
     with versions that return "Net::netent" objects.  This
     object has methods that return the similarly named structure
     field name from the C's netent structure from netdb.h;
     namely name, aliases, addrtype, and net.  The aliases method
     returns an array reference, the rest scalars.

     You may also import all the structure fields directly into
     your namespace as regular variables using the :FIELDS import
     tag.  (Note that this still overrides your core functions.)
     Access these fields as variables named with a preceding n_.
     Thus, $net_obj->name() corresponds to $n_name if you import
     the fields.  Array references are available as regular array
     variables, so for example @{ $net_obj->aliases() } would be
     simply @n_aliases.

     The getnet() function is a simple front-end that forwards a
     numeric argument to getnetbyaddr(), and the rest to
     getnetbyname().

     To access this functionality without the core overrides,
     pass the use an empty import list, and then access function
     functions with their full qualified names.  On the other
     hand, the built-ins are still available via the CORE::
     pseudo-package.



EXAMPLES
     The getnet() functions do this in the Perl core:

         sv_setiv(sv, (I32)nent->n_net);

     The gethost() functions do this in the Perl core:

         sv_setpvn(sv, hent->h_addr, len);

     That means that the address comes back in binary for the
     host functions, and as a regular perl integer for the net
     ones.  This seems a bug, but here's how to deal with it:

      use strict;
      use Socket;
      use Net::netent;

      @ARGV = ('loopback') unless @ARGV;

      my($n, $net);

      for $net ( @ARGV ) {

          unless ($n = getnetbyname($net)) {
             warn "$0: no such net: $net\n";
             next;
          }

          printf "\n%s is %s%s\n",
                 $net,
                 lc($n->name) eq lc($net) ? "" : "*really* ",
                 $n->name;

          print "\taliases are ", join(", ", @{$n->aliases}), "\n"
                     if @{$n->aliases};

          # this is stupid; first, why is this not in binary?
          # second, why am i going through these convolutions
          # to make it looks right
          {
             my @a = unpack("C4", pack("N", $n->net));
             shift @a while @a && $a[0] == 0;
             printf "\taddr is %s [%d.%d.%d.%d]\n", $n->net, @a;
          }

          if ($n = getnetbyaddr($n->net)) {
             if (lc($n->name) ne lc($net)) {
                 printf "\tThat addr reverses to net %s!\n", $n->name;
                 $net = $n->name;
                 redo;
             }
          }
      }




NOTE
     While this class is currently implemented using the
     Class::Struct module to build a struct-like class, you
     shouldn't rely upon this.



AUTHOR
     Tom Christiansen









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