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[p5sagit/p5-mst-13.2.git] / lib / Net / hostent.pm

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<netdb.h>;
namely name, aliases, addrtype, length, and addresses.  The aliases and
addresses methods return array reference, the rest scalars.  The addr
method is equivalent to the zeroth element in the addresses 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<h_>.  Thus, C<$host_obj-E<gt>name()> corresponds to
$h_name if you import the fields.  Array references are available as
regular array variables, so for example C<@{ $host_obj-E<gt>aliases()
}> would be simply @h_aliases.

The gethost() funtion 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<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 C<CORE::> 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