1 | # Net::Domain.pm
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2 | #
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3 | # Copyright (c) 1995-1998 Graham Barr <[email protected]>. All rights reserved.
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4 | # This program is free software; you can redistribute it and/or
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5 | # modify it under the same terms as Perl itself.
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6 |
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7 | package Net::Domain;
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8 |
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9 | require Exporter;
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10 |
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11 | use Carp;
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12 | use strict;
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13 | use vars qw($VERSION @ISA @EXPORT_OK);
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14 | use Net::Config;
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15 |
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16 | @ISA = qw(Exporter);
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17 | @EXPORT_OK = qw(hostname hostdomain hostfqdn domainname);
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18 |
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19 | $VERSION = "2.19"; # $Id: //depot/libnet/Net/Domain.pm#21 $
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20 |
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21 | my($host,$domain,$fqdn) = (undef,undef,undef);
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22 |
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23 | # Try every conceivable way to get hostname.
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24 |
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25 | sub _hostname {
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26 |
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27 | # we already know it
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28 | return $host
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29 | if(defined $host);
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30 |
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31 | if ($^O eq 'MSWin32') {
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32 | require Socket;
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33 | my ($name,$alias,$type,$len,@addr) = gethostbyname($ENV{'COMPUTERNAME'}||'localhost');
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34 | while (@addr)
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35 | {
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36 | my $a = shift(@addr);
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37 | $host = gethostbyaddr($a,Socket::AF_INET());
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38 | last if defined $host;
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39 | }
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40 | if (defined($host) && index($host,'.') > 0) {
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41 | $fqdn = $host;
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42 | ($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/;
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43 | }
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44 | return $host;
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45 | }
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46 | elsif ($^O eq 'MacOS') {
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47 | chomp ($host = `hostname`);
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48 | }
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49 | elsif ($^O eq 'VMS') { ## multiple varieties of net s/w makes this hard
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50 | $host = $ENV{'UCX$INET_HOST'} if defined($ENV{'UCX$INET_HOST'});
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51 | $host = $ENV{'MULTINET_HOST_NAME'} if defined($ENV{'MULTINET_HOST_NAME'});
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52 | if (index($host,'.') > 0) {
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53 | $fqdn = $host;
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54 | ($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/;
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55 | }
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56 | return $host;
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57 | }
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58 | else {
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59 | local $SIG{'__DIE__'};
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60 |
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61 | # syscall is preferred since it avoids tainting problems
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62 | eval {
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63 | my $tmp = "\0" x 256; ## preload scalar
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64 | eval {
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65 | package main;
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66 | require "syscall.ph";
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67 | defined(&main::SYS_gethostname);
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68 | }
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69 | || eval {
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70 | package main;
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71 | require "sys/syscall.ph";
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72 | defined(&main::SYS_gethostname);
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73 | }
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74 | and $host = (syscall(&main::SYS_gethostname, $tmp, 256) == 0)
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75 | ? $tmp
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76 | : undef;
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77 | }
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78 |
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79 | # POSIX
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80 | || eval {
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81 | require POSIX;
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82 | $host = (POSIX::uname())[1];
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83 | }
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84 |
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85 | # trusty old hostname command
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86 | || eval {
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87 | chop($host = `(hostname) 2>/dev/null`); # BSD'ish
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88 | }
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89 |
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90 | # sysV/POSIX uname command (may truncate)
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91 | || eval {
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92 | chop($host = `uname -n 2>/dev/null`); ## SYSV'ish && POSIX'ish
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93 | }
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94 |
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95 | # Apollo pre-SR10
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96 | || eval {
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97 | $host = (split(/[:\. ]/,`/com/host`,6))[0];
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98 | }
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99 |
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100 | || eval {
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101 | $host = "";
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102 | };
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103 | }
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104 |
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105 | # remove garbage
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106 | $host =~ s/[\0\r\n]+//go;
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107 | $host =~ s/(\A\.+|\.+\Z)//go;
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108 | $host =~ s/\.\.+/\./go;
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109 |
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110 | $host;
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111 | }
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112 |
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113 | sub _hostdomain {
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114 |
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115 | # we already know it
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116 | return $domain
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117 | if(defined $domain);
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118 |
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119 | local $SIG{'__DIE__'};
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120 |
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121 | return $domain = $NetConfig{'inet_domain'}
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122 | if defined $NetConfig{'inet_domain'};
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123 |
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124 | # try looking in /etc/resolv.conf
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125 | # putting this here and assuming that it is correct, eliminates
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126 | # calls to gethostbyname, and therefore DNS lookups. This helps
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127 | # those on dialup systems.
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128 |
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129 | local *RES;
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130 | local($_);
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131 |
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132 | if(open(RES,"/etc/resolv.conf")) {
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133 | while(<RES>) {
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134 | $domain = $1
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135 | if(/\A\s*(?:domain|search)\s+(\S+)/);
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136 | }
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137 | close(RES);
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138 |
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139 | return $domain
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140 | if(defined $domain);
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141 | }
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142 |
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143 | # just try hostname and system calls
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144 |
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145 | my $host = _hostname();
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146 | my(@hosts);
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147 |
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148 | @hosts = ($host,"localhost");
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149 |
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150 | unless (defined($host) && $host =~ /\./) {
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151 | my $dom = undef;
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152 | eval {
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153 | my $tmp = "\0" x 256; ## preload scalar
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154 | eval {
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155 | package main;
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156 | require "syscall.ph";
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157 | }
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158 | || eval {
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159 | package main;
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160 | require "sys/syscall.ph";
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161 | }
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162 | and $dom = (syscall(&main::SYS_getdomainname, $tmp, 256) == 0)
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163 | ? $tmp
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164 | : undef;
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165 | };
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166 |
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167 | if ( $^O eq 'VMS' ) {
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168 | $dom ||= $ENV{'TCPIP$INET_DOMAIN'}
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169 | || $ENV{'UCX$INET_DOMAIN'};
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170 | }
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171 |
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172 | chop($dom = `domainname 2>/dev/null`)
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173 | unless(defined $dom || $^O =~ /^(?:cygwin|MSWin32)/);
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174 |
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175 | if(defined $dom) {
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176 | my @h = ();
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177 | $dom =~ s/^\.+//;
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178 | while(length($dom)) {
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179 | push(@h, "$host.$dom");
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180 | $dom =~ s/^[^.]+.+// or last;
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181 | }
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182 | unshift(@hosts,@h);
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183 | }
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184 | }
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185 |
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186 | # Attempt to locate FQDN
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187 |
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188 | foreach (grep {defined $_} @hosts) {
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189 | my @info = gethostbyname($_);
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190 |
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191 | next unless @info;
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192 |
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193 | # look at real name & aliases
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194 | my $site;
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195 | foreach $site ($info[0], split(/ /,$info[1])) {
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196 | if(rindex($site,".") > 0) {
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197 |
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198 | # Extract domain from FQDN
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199 |
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200 | ($domain = $site) =~ s/\A[^\.]+\.//;
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201 | return $domain;
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202 | }
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203 | }
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204 | }
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205 |
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206 | # Look for environment variable
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207 |
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208 | $domain ||= $ENV{LOCALDOMAIN} || $ENV{DOMAIN};
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209 |
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210 | if(defined $domain) {
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211 | $domain =~ s/[\r\n\0]+//g;
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212 | $domain =~ s/(\A\.+|\.+\Z)//g;
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213 | $domain =~ s/\.\.+/\./g;
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214 | }
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215 |
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216 | $domain;
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217 | }
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218 |
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219 | sub domainname {
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220 |
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221 | return $fqdn
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222 | if(defined $fqdn);
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223 |
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224 | _hostname();
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225 | _hostdomain();
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226 |
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227 | # Assumption: If the host name does not contain a period
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228 | # and the domain name does, then assume that they are correct
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229 | # this helps to eliminate calls to gethostbyname, and therefore
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230 | # eleminate DNS lookups
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231 |
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232 | return $fqdn = $host . "." . $domain
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233 | if(defined $host and defined $domain
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234 | and $host !~ /\./ and $domain =~ /\./);
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235 |
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236 | # For hosts that have no name, just an IP address
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237 | return $fqdn = $host if defined $host and $host =~ /^\d+(\.\d+){3}$/;
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238 |
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239 | my @host = defined $host ? split(/\./, $host) : ('localhost');
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240 | my @domain = defined $domain ? split(/\./, $domain) : ();
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241 | my @fqdn = ();
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242 |
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243 | # Determine from @host & @domain the FQDN
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244 |
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245 | my @d = @domain;
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246 |
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247 | LOOP:
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248 | while(1) {
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249 | my @h = @host;
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250 | while(@h) {
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251 | my $tmp = join(".",@h,@d);
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252 | if((gethostbyname($tmp))[0]) {
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253 | @fqdn = (@h,@d);
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254 | $fqdn = $tmp;
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255 | last LOOP;
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256 | }
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257 | pop @h;
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258 | }
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259 | last unless shift @d;
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260 | }
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261 |
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262 | if(@fqdn) {
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263 | $host = shift @fqdn;
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264 | until((gethostbyname($host))[0]) {
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265 | $host .= "." . shift @fqdn;
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266 | }
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267 | $domain = join(".", @fqdn);
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268 | }
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269 | else {
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270 | undef $host;
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271 | undef $domain;
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272 | undef $fqdn;
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273 | }
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274 |
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275 | $fqdn;
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276 | }
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277 |
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278 | sub hostfqdn { domainname() }
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279 |
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280 | sub hostname {
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281 | domainname()
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282 | unless(defined $host);
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283 | return $host;
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284 | }
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285 |
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286 | sub hostdomain {
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287 | domainname()
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288 | unless(defined $domain);
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289 | return $domain;
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290 | }
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291 |
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292 | 1; # Keep require happy
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293 |
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294 | __END__
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295 |
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296 | =head1 NAME
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297 |
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298 | Net::Domain - Attempt to evaluate the current host's internet name and domain
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299 |
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300 | =head1 SYNOPSIS
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301 |
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302 | use Net::Domain qw(hostname hostfqdn hostdomain);
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303 |
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304 | =head1 DESCRIPTION
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305 |
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306 | Using various methods B<attempt> to find the Fully Qualified Domain Name (FQDN)
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307 | of the current host. From this determine the host-name and the host-domain.
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308 |
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309 | Each of the functions will return I<undef> if the FQDN cannot be determined.
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310 |
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311 | =over 4
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312 |
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313 | =item hostfqdn ()
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314 |
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315 | Identify and return the FQDN of the current host.
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316 |
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317 | =item hostname ()
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318 |
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319 | Returns the smallest part of the FQDN which can be used to identify the host.
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320 |
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321 | =item hostdomain ()
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322 |
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323 | Returns the remainder of the FQDN after the I<hostname> has been removed.
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324 |
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325 | =back
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326 |
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327 | =head1 AUTHOR
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328 |
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329 | Graham Barr <[email protected]>.
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330 | Adapted from Sys::Hostname by David Sundstrom <[email protected]>
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331 |
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332 | =head1 COPYRIGHT
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333 |
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334 | Copyright (c) 1995-1998 Graham Barr. All rights reserved.
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335 | This program is free software; you can redistribute it and/or modify
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336 | it under the same terms as Perl itself.
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337 |
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338 | =for html <hr>
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339 |
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340 | I<$Id: //depot/libnet/Net/Domain.pm#21 $>
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341 |
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342 | =cut
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