1package Net::netent 1.02; 2use v5.38; 3 4our ( 5 $n_name, @n_aliases, 6 $n_addrtype, $n_net 7); 8 9use Exporter 'import'; 10our @EXPORT = qw(getnetbyname getnetbyaddr getnet); 11our @EXPORT_OK = qw( 12 $n_name @n_aliases 13 $n_addrtype $n_net 14 ); 15our %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); 16 17use Class::Struct qw(struct); 18struct 'Net::netent' => [ 19 name => '$', 20 aliases => '@', 21 addrtype => '$', 22 net => '$', 23]; 24 25sub populate { 26 return unless @_; 27 my $nob = new(); 28 $n_name = $nob->[0] = $_[0]; 29 @n_aliases = @{ $nob->[1] } = split ' ', $_[1]; 30 $n_addrtype = $nob->[2] = $_[2]; 31 $n_net = $nob->[3] = $_[3]; 32 return $nob; 33} 34 35sub getnetbyname :prototype($) { populate(CORE::getnetbyname(shift)) } 36 37sub getnetbyaddr :prototype($;$) { 38 my ($net, $addrtype); 39 $net = shift; 40 require Socket if @_; 41 $addrtype = @_ ? shift : Socket::AF_INET(); 42 populate(CORE::getnetbyaddr($net, $addrtype)) 43} 44 45sub getnet :prototype($) { 46 if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { 47 require Socket; 48 &getnetbyaddr(Socket::inet_aton(shift)); 49 } else { 50 &getnetbyname; 51 } 52} 53 54__END__ 55 56=head1 NAME 57 58Net::netent - by-name interface to Perl's built-in getnet*() functions 59 60=head1 SYNOPSIS 61 62 use Net::netent qw(:FIELDS); 63 getnetbyname("loopback") or die "bad net"; 64 printf "%s is %08X\n", $n_name, $n_net; 65 66 use Net::netent; 67 68 $n = getnetbyname("loopback") or die "bad net"; 69 { # there's gotta be a better way, eh? 70 @bytes = unpack("C4", pack("N", $n->net)); 71 shift @bytes while @bytes && $bytes[0] == 0; 72 } 73 printf "%s is %08X [%d.%d.%d.%d]\n", $n->name, $n->net, @bytes; 74 75=head1 DESCRIPTION 76 77This module's default exports override the core getnetbyname() and 78getnetbyaddr() functions, replacing them with versions that return 79"Net::netent" objects. This object has methods that return the similarly 80named structure field name from the C's netent structure from F<netdb.h>; 81namely name, aliases, addrtype, and net. The aliases 82method returns an array reference, the rest scalars. 83 84You may also import all the structure fields directly into your namespace 85as regular variables using the :FIELDS import tag. (Note that this still 86overrides your core functions.) Access these fields as variables named 87with a preceding C<n_>. Thus, C<$net_obj-E<gt>name()> corresponds to 88$n_name if you import the fields. Array references are available as 89regular array variables, so for example C<@{ $net_obj-E<gt>aliases() 90}> would be simply @n_aliases. 91 92The getnet() function is a simple front-end that forwards a numeric 93argument to getnetbyaddr(), and the rest 94to getnetbyname(). 95 96To access this functionality without the core overrides, 97pass the C<use> an empty import list, and then access 98function functions with their full qualified names. 99On the other hand, the built-ins are still available 100via the C<CORE::> pseudo-package. 101 102=head1 EXAMPLES 103 104The getnet() functions do this in the Perl core: 105 106 sv_setiv(sv, (I32)nent->n_net); 107 108The gethost() functions do this in the Perl core: 109 110 sv_setpvn(sv, hent->h_addr, len); 111 112That means that the address comes back in binary for the 113host functions, and as a regular perl integer for the net ones. 114This seems a bug, but here's how to deal with it: 115 116 use strict; 117 use Socket; 118 use Net::netent; 119 120 @ARGV = ('loopback') unless @ARGV; 121 122 my($n, $net); 123 124 for $net ( @ARGV ) { 125 126 unless ($n = getnetbyname($net)) { 127 warn "$0: no such net: $net\n"; 128 next; 129 } 130 131 printf "\n%s is %s%s\n", 132 $net, 133 lc($n->name) eq lc($net) ? "" : "*really* ", 134 $n->name; 135 136 print "\taliases are ", join(", ", @{$n->aliases}), "\n" 137 if @{$n->aliases}; 138 139 # this is stupid; first, why is this not in binary? 140 # second, why am i going through these convolutions 141 # to make it looks right 142 { 143 my @a = unpack("C4", pack("N", $n->net)); 144 shift @a while @a && $a[0] == 0; 145 printf "\taddr is %s [%d.%d.%d.%d]\n", $n->net, @a; 146 } 147 148 if ($n = getnetbyaddr($n->net)) { 149 if (lc($n->name) ne lc($net)) { 150 printf "\tThat addr reverses to net %s!\n", $n->name; 151 $net = $n->name; 152 redo; 153 } 154 } 155 } 156 157=head1 NOTE 158 159While this class is currently implemented using the Class::Struct 160module to build a struct-like class, you shouldn't rely upon this. 161 162=head1 AUTHOR 163 164Tom Christiansen 165