Net::hostent(3p) Perl Programmers Reference Guide Net::hostent(3p) #

Net::hostent(3p) Perl Programmers Reference Guide Net::hostent(3p)

NNAAMMEE #

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

SSYYNNOOPPSSIISS #

  use Net::hostent;

DDEESSCCRRIIPPTTIIOONN #

 This module's default exports override the core ggeetthhoossttbbyynnaammee(()) and
 ggeetthhoossttbbyyaaddddrr(()) functions, replacing them with versions that return
 "Net::hostent" objects.  This object has methods that return the
 similarly named structure field name from the C's hostent structure from
 _n_e_t_d_b_._h; namely name, aliases, addrtype, length, and addr_list.  The
 aliases and addr_list methods return array reference, the rest scalars.
 The addr method is equivalent to the zeroth element in the addr_list
 array reference.

 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 "h_".  Thus, "$host_obj->name()" corresponds to $h_name
 if you import the fields.  Array references are available as regular
 array variables, so for example "@{ $host_obj->aliases() }" would be
 simply @h_aliases.

 The ggeetthhoosstt(()) function is a simple front-end that forwards a numeric
 argument to ggeetthhoossttbbyyaaddddrr(()) by way of Socket::inet_aton, and the rest to
 ggeetthhoossttbbyynnaammee(()).

 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.

EEXXAAMMPPLLEESS #

  use Net::hostent;
  use Socket;

  @ARGV = ('netscape.com') unless @ARGV;

  for $host ( @ARGV ) {

     unless ($h = gethost($host)) {
         warn "$0: no such host: $host\n";
         next;
     }

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

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

     if ( @{$h->addr_list} > 1 ) {
         my $i;
         for $addr ( @{$h->addr_list} ) {
             printf "\taddr #%d is [%s]\n", $i++, inet_ntoa($addr);
         }
     } else {
         printf "\taddress is [%s]\n", inet_ntoa($h->addr);
     }

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

NNOOTTEE #

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

AAUUTTHHOORR #

 Tom Christiansen

perl v5.36.3 2023-02-15 Net::hostent(3p)