| 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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