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