1package Net::hostent; 2use strict; 3 4use 5.006_001; 5our $VERSION = '1.01'; 6our(@EXPORT, @EXPORT_OK, %EXPORT_TAGS); 7BEGIN { 8 use Exporter (); 9 @EXPORT = qw(gethostbyname gethostbyaddr gethost); 10 @EXPORT_OK = qw( 11 $h_name @h_aliases 12 $h_addrtype $h_length 13 @h_addr_list $h_addr 14 ); 15 %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); 16} 17use vars @EXPORT_OK; 18 19# Class::Struct forbids use of @ISA 20sub import { goto &Exporter::import } 21 22use Class::Struct qw(struct); 23struct 'Net::hostent' => [ 24 name => '$', 25 aliases => '@', 26 addrtype => '$', 27 'length' => '$', 28 addr_list => '@', 29]; 30 31sub addr { shift->addr_list->[0] } 32 33sub populate (@) { 34 return unless @_; 35 my $hob = new(); 36 $h_name = $hob->[0] = $_[0]; 37 @h_aliases = @{ $hob->[1] } = split ' ', $_[1]; 38 $h_addrtype = $hob->[2] = $_[2]; 39 $h_length = $hob->[3] = $_[3]; 40 $h_addr = $_[4]; 41 @h_addr_list = @{ $hob->[4] } = @_[ (4 .. $#_) ]; 42 return $hob; 43} 44 45sub gethostbyname ($) { populate(CORE::gethostbyname(shift)) } 46 47sub gethostbyaddr ($;$) { 48 my ($addr, $addrtype); 49 $addr = shift; 50 require Socket unless @_; 51 $addrtype = @_ ? shift : Socket::AF_INET(); 52 populate(CORE::gethostbyaddr($addr, $addrtype)) 53} 54 55sub gethost($) { 56 if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { 57 require Socket; 58 &gethostbyaddr(Socket::inet_aton(shift)); 59 } else { 60 &gethostbyname; 61 } 62} 63 641; 65__END__ 66 67=head1 NAME 68 69Net::hostent - by-name interface to Perl's built-in gethost*() functions 70 71=head1 SYNOPSIS 72 73 use Net::hostent; 74 75=head1 DESCRIPTION 76 77This module's default exports override the core gethostbyname() and 78gethostbyaddr() functions, replacing them with versions that return 79"Net::hostent" objects. This object has methods that return the similarly 80named structure field name from the C's hostent structure from F<netdb.h>; 81namely name, aliases, addrtype, length, and addr_list. The aliases and 82addr_list methods return array reference, the rest scalars. The addr 83method is equivalent to the zeroth element in the addr_list array 84reference. 85 86You may also import all the structure fields directly into your namespace 87as regular variables using the :FIELDS import tag. (Note that this still 88overrides your core functions.) Access these fields as variables named 89with a preceding C<h_>. Thus, C<$host_obj-E<gt>name()> corresponds to 90$h_name if you import the fields. Array references are available as 91regular array variables, so for example C<@{ $host_obj-E<gt>aliases() 92}> would be simply @h_aliases. 93 94The gethost() function is a simple front-end that forwards a numeric 95argument to gethostbyaddr() by way of Socket::inet_aton, and the rest 96to gethostbyname(). 97 98To access this functionality without the core overrides, 99pass the C<use> an empty import list, and then access 100function functions with their full qualified names. 101On the other hand, the built-ins are still available 102via the C<CORE::> pseudo-package. 103 104=head1 EXAMPLES 105 106 use Net::hostent; 107 use Socket; 108 109 @ARGV = ('netscape.com') unless @ARGV; 110 111 for $host ( @ARGV ) { 112 113 unless ($h = gethost($host)) { 114 warn "$0: no such host: $host\n"; 115 next; 116 } 117 118 printf "\n%s is %s%s\n", 119 $host, 120 lc($h->name) eq lc($host) ? "" : "*really* ", 121 $h->name; 122 123 print "\taliases are ", join(", ", @{$h->aliases}), "\n" 124 if @{$h->aliases}; 125 126 if ( @{$h->addr_list} > 1 ) { 127 my $i; 128 for $addr ( @{$h->addr_list} ) { 129 printf "\taddr #%d is [%s]\n", $i++, inet_ntoa($addr); 130 } 131 } else { 132 printf "\taddress is [%s]\n", inet_ntoa($h->addr); 133 } 134 135 if ($h = gethostbyaddr($h->addr)) { 136 if (lc($h->name) ne lc($host)) { 137 printf "\tThat addr reverses to host %s!\n", $h->name; 138 $host = $h->name; 139 redo; 140 } 141 } 142 } 143 144=head1 NOTE 145 146While this class is currently implemented using the Class::Struct 147module to build a struct-like class, you shouldn't rely upon this. 148 149=head1 AUTHOR 150 151Tom Christiansen 152