package Net::hostent; use strict; BEGIN { use Exporter (); use vars qw(@EXPORT @EXPORT_OK %EXPORT_TAGS); @EXPORT = qw(gethostbyname gethostbyaddr gethost); @EXPORT_OK = qw( $h_name @h_aliases $h_addrtype $h_length @h_addr_list $h_addr ); %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); } use vars @EXPORT_OK; # Class::Struct forbids use of @ISA sub import { goto &Exporter::import } use Class::Struct qw(struct); struct 'Net::hostent' => [ name => '$', aliases => '@', addrtype => '$', 'length' => '$', addr_list => '@', ]; sub addr { shift->addr_list->[0] } sub populate (@) { return unless @_; my $hob = new(); $h_name = $hob->[0] = $_[0]; @h_aliases = @{ $hob->[1] } = split ' ', $_[1]; $h_addrtype = $hob->[2] = $_[2]; $h_length = $hob->[3] = $_[3]; $h_addr = $_[4]; @h_addr_list = @{ $hob->[4] } = @_[ (4 .. $#_) ]; return $hob; } sub gethostbyname ($) { populate(CORE::gethostbyname(shift)) } sub gethostbyaddr ($;$) { my ($addr, $addrtype); $addr = shift; require Socket unless @_; $addrtype = @_ ? shift : Socket::AF_INET(); populate(CORE::gethostbyaddr($addr, $addrtype)) } sub gethost($) { if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { require Socket; &gethostbyaddr(Socket::inet_aton(shift)); } else { &gethostbyname; } } 1; __END__ =head1 NAME Net::hostent - by-name interface to Perl's built-in gethost*() functions =head1 SYNOPSIS use Net::hostnet; =head1 DESCRIPTION This module's default exports override the core gethostbyname() and gethostbyaddr() 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 F; 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 C. Thus, C<$host_obj-Ename()> corresponds to $h_name if you import the fields. Array references are available as regular array variables, so for example C<@{ $host_obj-Ealiases() }> would be simply @h_aliases. The gethost() function is a simple front-end that forwards a numeric argument to gethostbyaddr() by way of Socket::inet_aton, and the rest to gethostbyname(). To access this functionality without the core overrides, pass the C 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 C pseudo-package. =head1 EXAMPLES 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; } } } =head1 NOTE While this class is currently implemented using the Class::Struct module to build a struct-like class, you shouldn't rely upon this. =head1 AUTHOR Tom Christiansen