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920dae64 AT |
1 | package Net::netent; |
2 | use strict; | |
3 | ||
4 | use 5.006_001; | |
5 | our $VERSION = '1.00'; | |
6 | our(@EXPORT, @EXPORT_OK, %EXPORT_TAGS); | |
7 | BEGIN { | |
8 | use Exporter (); | |
9 | @EXPORT = qw(getnetbyname getnetbyaddr getnet); | |
10 | @EXPORT_OK = qw( | |
11 | $n_name @n_aliases | |
12 | $n_addrtype $n_net | |
13 | ); | |
14 | %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); | |
15 | } | |
16 | use vars @EXPORT_OK; | |
17 | ||
18 | # Class::Struct forbids use of @ISA | |
19 | sub import { goto &Exporter::import } | |
20 | ||
21 | use Class::Struct qw(struct); | |
22 | struct 'Net::netent' => [ | |
23 | name => '$', | |
24 | aliases => '@', | |
25 | addrtype => '$', | |
26 | net => '$', | |
27 | ]; | |
28 | ||
29 | sub populate (@) { | |
30 | return unless @_; | |
31 | my $nob = new(); | |
32 | $n_name = $nob->[0] = $_[0]; | |
33 | @n_aliases = @{ $nob->[1] } = split ' ', $_[1]; | |
34 | $n_addrtype = $nob->[2] = $_[2]; | |
35 | $n_net = $nob->[3] = $_[3]; | |
36 | return $nob; | |
37 | } | |
38 | ||
39 | sub getnetbyname ($) { populate(CORE::getnetbyname(shift)) } | |
40 | ||
41 | sub getnetbyaddr ($;$) { | |
42 | my ($net, $addrtype); | |
43 | $net = shift; | |
44 | require Socket if @_; | |
45 | $addrtype = @_ ? shift : Socket::AF_INET(); | |
46 | populate(CORE::getnetbyaddr($net, $addrtype)) | |
47 | } | |
48 | ||
49 | sub getnet($) { | |
50 | if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { | |
51 | require Socket; | |
52 | &getnetbyaddr(Socket::inet_aton(shift)); | |
53 | } else { | |
54 | &getnetbyname; | |
55 | } | |
56 | } | |
57 | ||
58 | 1; | |
59 | __END__ | |
60 | ||
61 | =head1 NAME | |
62 | ||
63 | Net::netent - by-name interface to Perl's built-in getnet*() functions | |
64 | ||
65 | =head1 SYNOPSIS | |
66 | ||
67 | use Net::netent qw(:FIELDS); | |
68 | getnetbyname("loopback") or die "bad net"; | |
69 | printf "%s is %08X\n", $n_name, $n_net; | |
70 | ||
71 | use Net::netent; | |
72 | ||
73 | $n = getnetbyname("loopback") or die "bad net"; | |
74 | { # there's gotta be a better way, eh? | |
75 | @bytes = unpack("C4", pack("N", $n->net)); | |
76 | shift @bytes while @bytes && $bytes[0] == 0; | |
77 | } | |
78 | printf "%s is %08X [%d.%d.%d.%d]\n", $n->name, $n->net, @bytes; | |
79 | ||
80 | =head1 DESCRIPTION | |
81 | ||
82 | This module's default exports override the core getnetbyname() and | |
83 | getnetbyaddr() functions, replacing them with versions that return | |
84 | "Net::netent" objects. This object has methods that return the similarly | |
85 | named structure field name from the C's netent structure from F<netdb.h>; | |
86 | namely name, aliases, addrtype, and net. The aliases | |
87 | method returns an array reference, the rest scalars. | |
88 | ||
89 | You may also import all the structure fields directly into your namespace | |
90 | as regular variables using the :FIELDS import tag. (Note that this still | |
91 | overrides your core functions.) Access these fields as variables named | |
92 | with a preceding C<n_>. Thus, C<$net_obj-E<gt>name()> corresponds to | |
93 | $n_name if you import the fields. Array references are available as | |
94 | regular array variables, so for example C<@{ $net_obj-E<gt>aliases() | |
95 | }> would be simply @n_aliases. | |
96 | ||
97 | The getnet() function is a simple front-end that forwards a numeric | |
98 | argument to getnetbyaddr(), and the rest | |
99 | to getnetbyname(). | |
100 | ||
101 | To access this functionality without the core overrides, | |
102 | pass the C<use> an empty import list, and then access | |
103 | function functions with their full qualified names. | |
104 | On the other hand, the built-ins are still available | |
105 | via the C<CORE::> pseudo-package. | |
106 | ||
107 | =head1 EXAMPLES | |
108 | ||
109 | The getnet() functions do this in the Perl core: | |
110 | ||
111 | sv_setiv(sv, (I32)nent->n_net); | |
112 | ||
113 | The gethost() functions do this in the Perl core: | |
114 | ||
115 | sv_setpvn(sv, hent->h_addr, len); | |
116 | ||
117 | That means that the address comes back in binary for the | |
118 | host functions, and as a regular perl integer for the net ones. | |
119 | This seems a bug, but here's how to deal with it: | |
120 | ||
121 | use strict; | |
122 | use Socket; | |
123 | use Net::netent; | |
124 | ||
125 | @ARGV = ('loopback') unless @ARGV; | |
126 | ||
127 | my($n, $net); | |
128 | ||
129 | for $net ( @ARGV ) { | |
130 | ||
131 | unless ($n = getnetbyname($net)) { | |
132 | warn "$0: no such net: $net\n"; | |
133 | next; | |
134 | } | |
135 | ||
136 | printf "\n%s is %s%s\n", | |
137 | $net, | |
138 | lc($n->name) eq lc($net) ? "" : "*really* ", | |
139 | $n->name; | |
140 | ||
141 | print "\taliases are ", join(", ", @{$n->aliases}), "\n" | |
142 | if @{$n->aliases}; | |
143 | ||
144 | # this is stupid; first, why is this not in binary? | |
145 | # second, why am i going through these convolutions | |
146 | # to make it looks right | |
147 | { | |
148 | my @a = unpack("C4", pack("N", $n->net)); | |
149 | shift @a while @a && $a[0] == 0; | |
150 | printf "\taddr is %s [%d.%d.%d.%d]\n", $n->net, @a; | |
151 | } | |
152 | ||
153 | if ($n = getnetbyaddr($n->net)) { | |
154 | if (lc($n->name) ne lc($net)) { | |
155 | printf "\tThat addr reverses to net %s!\n", $n->name; | |
156 | $net = $n->name; | |
157 | redo; | |
158 | } | |
159 | } | |
160 | } | |
161 | ||
162 | =head1 NOTE | |
163 | ||
164 | While this class is currently implemented using the Class::Struct | |
165 | module to build a struct-like class, you shouldn't rely upon this. | |
166 | ||
167 | =head1 AUTHOR | |
168 | ||
169 | Tom Christiansen |