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1 | package Net::netent; |
2 | use strict; |
3 | |
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4 | use 5.006_001; |
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5 | our $VERSION = '1.00'; |
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6 | our(@EXPORT, @EXPORT_OK, %EXPORT_TAGS); |
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7 | BEGIN { |
8 | use Exporter (); |
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9 | @EXPORT = qw(getnetbyname getnetbyaddr getnet); |
10 | @EXPORT_OK = qw( |
11 | $n_name @n_aliases |
12 | $n_addrtype $n_net |
13 | ); |
14 | %EXPORT_TAGS = ( FIELDS => [ @EXPORT_OK, @EXPORT ] ); |
15 | } |
16 | use vars @EXPORT_OK; |
17 | |
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18 | # Class::Struct forbids use of @ISA |
19 | sub import { goto &Exporter::import } |
20 | |
21 | use Class::Struct qw(struct); |
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22 | struct 'Net::netent' => [ |
23 | name => '$', |
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<@{ $net_obj-E<gt>aliases() |
95 | }> would be simply @n_aliases. |
96 | |
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97 | The getnet() function is a simple front-end that forwards a numeric |
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98 | argument to getnetbyaddr(), and the rest |
99 | to getnetbyname(). |
100 | |
101 | To access this functionality without the core overrides, |
102 | pass the C<use> an empty import list, and then access |
103 | function functions with their full qualified names. |
104 | On the other hand, the built-ins are still available |
105 | via the C<CORE::> pseudo-package. |
106 | |
107 | =head1 EXAMPLES |
108 | |
109 | The getnet() functions do this in the Perl core: |
110 | |
111 | sv_setiv(sv, (I32)nent->n_net); |
112 | |
113 | The gethost() functions do this in the Perl core: |
114 | |
115 | sv_setpvn(sv, hent->h_addr, len); |
116 | |
117 | That means that the address comes back in binary for the |
118 | host functions, and as a regular perl integer for the net ones. |
119 | This seems a bug, but here's how to deal with it: |
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120 | |
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121 | use strict; |
122 | use Socket; |
123 | use Net::netent; |
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124 | |
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125 | @ARGV = ('loopback') unless @ARGV; |
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126 | |
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127 | my($n, $net); |
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128 | |
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129 | for $net ( @ARGV ) { |
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130 | |
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131 | unless ($n = getnetbyname($net)) { |
132 | warn "$0: no such net: $net\n"; |
133 | next; |
134 | } |
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135 | |
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136 | printf "\n%s is %s%s\n", |
137 | $net, |
138 | lc($n->name) eq lc($net) ? "" : "*really* ", |
139 | $n->name; |
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140 | |
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141 | print "\taliases are ", join(", ", @{$n->aliases}), "\n" |
142 | if @{$n->aliases}; |
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143 | |
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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", $n->net, @a; |
151 | } |
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152 | |
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153 | if ($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 | } |
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161 | |
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162 | =head1 NOTE |
163 | |
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164 | While this class is currently implemented using the Class::Struct |
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165 | module to build a struct-like class, you shouldn't rely upon this. |
166 | |
167 | =head1 AUTHOR |
168 | |
169 | Tom Christiansen |