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1 | package Net::netent; |
2 | use strict; |
3 | |
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4 | use 5.005_64; |
5 | our(@EXPORT, @EXPORT_OK, %EXPORT_TAGS); |
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6 | BEGIN { |
7 | use Exporter (); |
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8 | @EXPORT = qw(getnetbyname getnetbyaddr getnet); |
9 | @EXPORT_OK = qw( |
10 | $n_name @n_aliases |
11 | $n_addrtype $n_net |
12 | ); |
13 | %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); |
14 | } |
15 | use vars @EXPORT_OK; |
16 | |
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17 | # Class::Struct forbids use of @ISA |
18 | sub import { goto &Exporter::import } |
19 | |
20 | use Class::Struct qw(struct); |
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21 | struct 'Net::netent' => [ |
22 | name => '$', |
23 | aliases => '@', |
24 | addrtype => '$', |
25 | net => '$', |
26 | ]; |
27 | |
28 | sub populate (@) { |
29 | return unless @_; |
30 | my $nob = new(); |
31 | $n_name = $nob->[0] = $_[0]; |
32 | @n_aliases = @{ $nob->[1] } = split ' ', $_[1]; |
33 | $n_addrtype = $nob->[2] = $_[2]; |
34 | $n_net = $nob->[3] = $_[3]; |
35 | return $nob; |
36 | } |
37 | |
38 | sub getnetbyname ($) { populate(CORE::getnetbyname(shift)) } |
39 | |
40 | sub getnetbyaddr ($;$) { |
41 | my ($net, $addrtype); |
42 | $net = shift; |
43 | require Socket if @_; |
44 | $addrtype = @_ ? shift : Socket::AF_INET(); |
45 | populate(CORE::getnetbyaddr($net, $addrtype)) |
46 | } |
47 | |
48 | sub getnet($) { |
49 | if ($_[0] =~ /^\d+(?:\.\d+(?:\.\d+(?:\.\d+)?)?)?$/) { |
50 | require Socket; |
51 | &getnetbyaddr(Socket::inet_aton(shift)); |
52 | } else { |
53 | &getnetbyname; |
54 | } |
55 | } |
56 | |
57 | 1; |
58 | __END__ |
59 | |
60 | =head1 NAME |
61 | |
62 | Net::netent - by-name interface to Perl's built-in getnet*() functions |
63 | |
64 | =head1 SYNOPSIS |
65 | |
66 | use Net::netent qw(:FIELDS); |
67 | getnetbyname("loopback") or die "bad net"; |
68 | printf "%s is %08X\n", $n_name, $n_net; |
69 | |
70 | use Net::netent; |
71 | |
72 | $n = getnetbyname("loopback") or die "bad net"; |
73 | { # there's gotta be a better way, eh? |
74 | @bytes = unpack("C4", pack("N", $n->net)); |
75 | shift @bytes while @bytes && $bytes[0] == 0; |
76 | } |
77 | printf "%s is %08X [%d.%d.%d.%d]\n", $n->name, $n->net, @bytes; |
78 | |
79 | =head1 DESCRIPTION |
80 | |
81 | This module's default exports override the core getnetbyname() and |
82 | getnetbyaddr() functions, replacing them with versions that return |
83 | "Net::netent" objects. This object has methods that return the similarly |
84 | named structure field name from the C's netent structure from F<netdb.h>; |
85 | namely name, aliases, addrtype, and net. The aliases |
86 | method returns an array reference, the rest scalars. |
87 | |
88 | You may also import all the structure fields directly into your namespace |
89 | as regular variables using the :FIELDS import tag. (Note that this still |
90 | overrides your core functions.) Access these fields as variables named |
91 | with a preceding C<n_>. Thus, C<$net_obj-E<gt>name()> corresponds to |
92 | $n_name if you import the fields. Array references are available as |
93 | regular array variables, so for example C<@{ $net_obj-E<gt>aliases() |
94 | }> would be simply @n_aliases. |
95 | |
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96 | The getnet() function is a simple front-end that forwards a numeric |
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97 | argument to getnetbyaddr(), and the rest |
98 | to getnetbyname(). |
99 | |
100 | To access this functionality without the core overrides, |
101 | pass the C<use> an empty import list, and then access |
102 | function functions with their full qualified names. |
103 | On the other hand, the built-ins are still available |
104 | via the C<CORE::> pseudo-package. |
105 | |
106 | =head1 EXAMPLES |
107 | |
108 | The getnet() functions do this in the Perl core: |
109 | |
110 | sv_setiv(sv, (I32)nent->n_net); |
111 | |
112 | The gethost() functions do this in the Perl core: |
113 | |
114 | sv_setpvn(sv, hent->h_addr, len); |
115 | |
116 | That means that the address comes back in binary for the |
117 | host functions, and as a regular perl integer for the net ones. |
118 | This seems a bug, but here's how to deal with it: |
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119 | |
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120 | use strict; |
121 | use Socket; |
122 | use Net::netent; |
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123 | |
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124 | @ARGV = ('loopback') unless @ARGV; |
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125 | |
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126 | my($n, $net); |
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127 | |
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128 | for $net ( @ARGV ) { |
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129 | |
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130 | unless ($n = getnetbyname($net)) { |
131 | warn "$0: no such net: $net\n"; |
132 | next; |
133 | } |
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134 | |
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135 | printf "\n%s is %s%s\n", |
136 | $net, |
137 | lc($n->name) eq lc($net) ? "" : "*really* ", |
138 | $n->name; |
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139 | |
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140 | print "\taliases are ", join(", ", @{$n->aliases}), "\n" |
141 | if @{$n->aliases}; |
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142 | |
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143 | # this is stupid; first, why is this not in binary? |
144 | # second, why am i going through these convolutions |
145 | # to make it looks right |
146 | { |
147 | my @a = unpack("C4", pack("N", $n->net)); |
148 | shift @a while @a && $a[0] == 0; |
149 | printf "\taddr is %s [%d.%d.%d.%d]\n", $n->net, @a; |
150 | } |
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151 | |
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152 | if ($n = getnetbyaddr($n->net)) { |
153 | if (lc($n->name) ne lc($net)) { |
154 | printf "\tThat addr reverses to net %s!\n", $n->name; |
155 | $net = $n->name; |
156 | redo; |
157 | } |
158 | } |
159 | } |
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160 | |
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161 | =head1 NOTE |
162 | |
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163 | While this class is currently implemented using the Class::Struct |
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164 | module to build a struct-like class, you shouldn't rely upon this. |
165 | |
166 | =head1 AUTHOR |
167 | |
168 | Tom Christiansen |