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