1package Net::hostent; 2use strict; 3 4BEGIN { 5 use Exporter (); 6 use vars qw(@EXPORT @EXPORT_OK %EXPORT_TAGS); 7 @EXPORT = qw(gethostbyname gethostbyaddr gethost); 8 @EXPORT_OK = qw( 9 $h_name @h_aliases 10 $h_addrtype $h_length 11 @h_addr_list $h_addr 12 ); 13 %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); 14} 15use vars @EXPORT_OK; 16 17# Class::Struct forbids use of @ISA 18sub import { goto &Exporter::import } 19 20use Class::Struct qw(struct); 21struct 'Net::hostent' => [ 22 name => '$', 23 aliases => '@', 24 addrtype => '$', 25 'length' => '$', 26 addr_list => '@', 27]; 28 29sub addr { shift->addr_list->[0] } 30 31sub populate (@) { 32 return unless @_; 33 my $hob = new(); 34 $h_name = $hob->[0] = $_[0]; 35 @h_aliases = @{ $hob->[1] } = split ' ', $_[1]; 36 $h_addrtype = $hob->[2] = $_[2]; 37 $h_length = $hob->[3] = $_[3]; 38 $h_addr = $_[4]; 39 @h_addr_list = @{ $hob->[4] } = @_[ (4 .. $#_) ]; 40 return $hob; 41} 42 43sub gethostbyname ($) { populate(CORE::gethostbyname(shift)) } 44 45sub gethostbyaddr ($;$) { 46 my ($addr, $addrtype); 47 $addr = shift; 48 require Socket unless @_; 49 $addrtype = @_ ? shift : Socket::AF_INET(); 50 populate(CORE::gethostbyaddr($addr, $addrtype)) 51} 52 53sub gethost($) { 54 if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { 55 require Socket; 56 &gethostbyaddr(Socket::inet_aton(shift)); 57 } else { 58 &gethostbyname; 59 } 60} 61 621; 63__END__ 64 65=head1 NAME 66 67Net::hostent - by-name interface to Perl's built-in gethost*() functions 68 69=head1 SYNOPSIS 70 71 use Net::hostnet; 72 73=head1 DESCRIPTION 74 75This module's default exports override the core gethostbyname() and 76gethostbyaddr() functions, replacing them with versions that return 77"Net::hostent" objects. This object has methods that return the similarly 78named structure field name from the C's hostent structure from F<netdb.h>; 79namely name, aliases, addrtype, length, and addr_list. The aliases and 80addr_list methods return array reference, the rest scalars. The addr 81method is equivalent to the zeroth element in the addr_list array 82reference. 83 84You may also import all the structure fields directly into your namespace 85as regular variables using the :FIELDS import tag. (Note that this still 86overrides your core functions.) Access these fields as variables named 87with a preceding C<h_>. Thus, C<$host_obj-E<gt>name()> corresponds to 88$h_name if you import the fields. Array references are available as 89regular array variables, so for example C<@{ $host_obj-E<gt>aliases() 90}> would be simply @h_aliases. 91 92The gethost() funtion is a simple front-end that forwards a numeric 93argument to gethostbyaddr() by way of Socket::inet_aton, and the rest 94to gethostbyname(). 95 96To access this functionality without the core overrides, 97pass the C<use> an empty import list, and then access 98function functions with their full qualified names. 99On the other hand, the built-ins are still available 100via the C<CORE::> pseudo-package. 101 102=head1 EXAMPLES 103 104 use Net::hostent; 105 use Socket; 106 107 @ARGV = ('netscape.com') unless @ARGV; 108 109 for $host ( @ARGV ) { 110 111 unless ($h = gethost($host)) { 112 warn "$0: no such host: $host\n"; 113 next; 114 } 115 116 printf "\n%s is %s%s\n", 117 $host, 118 lc($h->name) eq lc($host) ? "" : "*really* ", 119 $h->name; 120 121 print "\taliases are ", join(", ", @{$h->aliases}), "\n" 122 if @{$h->aliases}; 123 124 if ( @{$h->addr_list} > 1 ) { 125 my $i; 126 for $addr ( @{$h->addr_list} ) { 127 printf "\taddr #%d is [%s]\n", $i++, inet_ntoa($addr); 128 } 129 } else { 130 printf "\taddress is [%s]\n", inet_ntoa($h->addr); 131 } 132 133 if ($h = gethostbyaddr($h->addr)) { 134 if (lc($h->name) ne lc($host)) { 135 printf "\tThat addr reverses to host %s!\n", $h->name; 136 $host = $h->name; 137 redo; 138 } 139 } 140 } 141 142=head1 NOTE 143 144While this class is currently implemented using the Class::Struct 145module to build a struct-like class, you shouldn't rely upon this. 146 147=head1 AUTHOR 148 149Tom Christiansen 150