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# Net::Domain.pm |
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# |
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# Copyright (c) 1995-1998 Graham Barr <gbarr@pobox.com>. All rights reserved. |
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# This program is free software; you can redistribute it and/or |
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# modify it under the same terms as Perl itself. |
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|
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package Net::Domain; |
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|
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require Exporter; |
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|
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use Carp; |
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use strict; |
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use vars qw($VERSION @ISA @EXPORT_OK); |
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use Net::Config; |
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|
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@ISA = qw(Exporter); |
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@EXPORT_OK = qw(hostname hostdomain hostfqdn domainname); |
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|
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$VERSION = "2.19"; # $Id: //depot/libnet/Net/Domain.pm#21 $ |
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|
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my($host,$domain,$fqdn) = (undef,undef,undef); |
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|
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# Try every conceivable way to get hostname. |
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|
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sub _hostname { |
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|
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# we already know it |
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return $host |
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if(defined $host); |
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|
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if ($^O eq 'MSWin32') { |
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require Socket; |
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my ($name,$alias,$type,$len,@addr) = gethostbyname($ENV{'COMPUTERNAME'}||'localhost'); |
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while (@addr) |
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{ |
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my $a = shift(@addr); |
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$host = gethostbyaddr($a,Socket::AF_INET()); |
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last if defined $host; |
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} |
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if (defined($host) && index($host,'.') > 0) { |
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$fqdn = $host; |
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($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/; |
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} |
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return $host; |
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} |
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elsif ($^O eq 'MacOS') { |
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chomp ($host = `hostname`); |
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} |
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elsif ($^O eq 'VMS') { ## multiple varieties of net s/w makes this hard |
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$host = $ENV{'UCX$INET_HOST'} if defined($ENV{'UCX$INET_HOST'}); |
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$host = $ENV{'MULTINET_HOST_NAME'} if defined($ENV{'MULTINET_HOST_NAME'}); |
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if (index($host,'.') > 0) { |
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$fqdn = $host; |
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($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/; |
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} |
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return $host; |
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} |
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else { |
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local $SIG{'__DIE__'}; |
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|
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# syscall is preferred since it avoids tainting problems |
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eval { |
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my $tmp = "\0" x 256; ## preload scalar |
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eval { |
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package main; |
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require "syscall.ph"; |
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defined(&main::SYS_gethostname); |
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} |
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|| eval { |
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package main; |
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require "sys/syscall.ph"; |
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defined(&main::SYS_gethostname); |
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} |
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and $host = (syscall(&main::SYS_gethostname, $tmp, 256) == 0) |
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? $tmp |
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: undef; |
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} |
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|
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# POSIX |
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|| eval { |
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require POSIX; |
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$host = (POSIX::uname())[1]; |
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} |
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|
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# trusty old hostname command |
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|| eval { |
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chop($host = `(hostname) 2>/dev/null`); # BSD'ish |
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} |
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|
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# sysV/POSIX uname command (may truncate) |
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|| eval { |
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chop($host = `uname -n 2>/dev/null`); ## SYSV'ish && POSIX'ish |
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} |
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|
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# Apollo pre-SR10 |
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|| eval { |
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$host = (split(/[:\. ]/,`/com/host`,6))[0]; |
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} |
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|
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|| eval { |
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$host = ""; |
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}; |
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} |
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|
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# remove garbage |
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$host =~ s/[\0\r\n]+//go; |
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$host =~ s/(\A\.+|\.+\Z)//go; |
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$host =~ s/\.\.+/\./go; |
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|
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$host; |
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} |
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|
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sub _hostdomain { |
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|
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# we already know it |
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return $domain |
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if(defined $domain); |
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|
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local $SIG{'__DIE__'}; |
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|
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return $domain = $NetConfig{'inet_domain'} |
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if defined $NetConfig{'inet_domain'}; |
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|
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# try looking in /etc/resolv.conf |
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# putting this here and assuming that it is correct, eliminates |
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# calls to gethostbyname, and therefore DNS lookups. This helps |
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# those on dialup systems. |
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|
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local *RES; |
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local($_); |
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|
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if(open(RES,"/etc/resolv.conf")) { |
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while(<RES>) { |
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$domain = $1 |
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if(/\A\s*(?:domain|search)\s+(\S+)/); |
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} |
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close(RES); |
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|
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return $domain |
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if(defined $domain); |
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} |
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|
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# just try hostname and system calls |
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|
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my $host = _hostname(); |
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my(@hosts); |
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|
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@hosts = ($host,"localhost"); |
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|
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unless (defined($host) && $host =~ /\./) { |
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my $dom = undef; |
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eval { |
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my $tmp = "\0" x 256; ## preload scalar |
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eval { |
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package main; |
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require "syscall.ph"; |
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} |
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|| eval { |
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package main; |
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require "sys/syscall.ph"; |
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} |
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and $dom = (syscall(&main::SYS_getdomainname, $tmp, 256) == 0) |
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? $tmp |
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: undef; |
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}; |
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|
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if ( $^O eq 'VMS' ) { |
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$dom ||= $ENV{'TCPIP$INET_DOMAIN'} |
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|| $ENV{'UCX$INET_DOMAIN'}; |
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} |
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|
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chop($dom = `domainname 2>/dev/null`) |
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unless(defined $dom || $^O =~ /^(?:cygwin|MSWin32)/); |
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|
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if(defined $dom) { |
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my @h = (); |
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$dom =~ s/^\.+//; |
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while(length($dom)) { |
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push(@h, "$host.$dom"); |
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$dom =~ s/^[^.]+.+// or last; |
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} |
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unshift(@hosts,@h); |
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} |
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} |
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|
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# Attempt to locate FQDN |
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|
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foreach (grep {defined $_} @hosts) { |
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my @info = gethostbyname($_); |
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|
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next unless @info; |
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|
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# look at real name & aliases |
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my $site; |
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foreach $site ($info[0], split(/ /,$info[1])) { |
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if(rindex($site,".") > 0) { |
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|
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# Extract domain from FQDN |
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|
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($domain = $site) =~ s/\A[^\.]+\.//; |
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return $domain; |
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} |
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} |
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} |
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|
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# Look for environment variable |
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|
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$domain ||= $ENV{LOCALDOMAIN} || $ENV{DOMAIN}; |
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|
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if(defined $domain) { |
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$domain =~ s/[\r\n\0]+//g; |
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$domain =~ s/(\A\.+|\.+\Z)//g; |
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$domain =~ s/\.\.+/\./g; |
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} |
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|
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$domain; |
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} |
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|
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sub domainname { |
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|
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return $fqdn |
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if(defined $fqdn); |
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|
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_hostname(); |
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_hostdomain(); |
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|
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# Assumption: If the host name does not contain a period |
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# and the domain name does, then assume that they are correct |
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# this helps to eliminate calls to gethostbyname, and therefore |
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# eleminate DNS lookups |
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|
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return $fqdn = $host . "." . $domain |
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if(defined $host and defined $domain |
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and $host !~ /\./ and $domain =~ /\./); |
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|
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# For hosts that have no name, just an IP address |
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return $fqdn = $host if defined $host and $host =~ /^\d+(\.\d+){3}$/; |
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|
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my @host = defined $host ? split(/\./, $host) : ('localhost'); |
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my @domain = defined $domain ? split(/\./, $domain) : (); |
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my @fqdn = (); |
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|
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# Determine from @host & @domain the FQDN |
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|
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my @d = @domain; |
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|
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LOOP: |
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while(1) { |
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my @h = @host; |
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while(@h) { |
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my $tmp = join(".",@h,@d); |
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if((gethostbyname($tmp))[0]) { |
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@fqdn = (@h,@d); |
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$fqdn = $tmp; |
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last LOOP; |
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} |
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pop @h; |
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} |
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last unless shift @d; |
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} |
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|
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if(@fqdn) { |
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$host = shift @fqdn; |
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until((gethostbyname($host))[0]) { |
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$host .= "." . shift @fqdn; |
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} |
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$domain = join(".", @fqdn); |
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} |
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else { |
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undef $host; |
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undef $domain; |
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undef $fqdn; |
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} |
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|
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$fqdn; |
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} |
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|
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sub hostfqdn { domainname() } |
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|
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sub hostname { |
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domainname() |
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unless(defined $host); |
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return $host; |
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} |
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|
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sub hostdomain { |
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domainname() |
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unless(defined $domain); |
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return $domain; |
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} |
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|
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1; # Keep require happy |
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|
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__END__ |
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|
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=head1 NAME |
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|
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Net::Domain - Attempt to evaluate the current host's internet name and domain |
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|
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=head1 SYNOPSIS |
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|
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use Net::Domain qw(hostname hostfqdn hostdomain); |
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|
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=head1 DESCRIPTION |
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|
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Using various methods B<attempt> to find the Fully Qualified Domain Name (FQDN) |
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of the current host. From this determine the host-name and the host-domain. |
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|
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Each of the functions will return I<undef> if the FQDN cannot be determined. |
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|
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=over 4 |
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|
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=item hostfqdn () |
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|
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Identify and return the FQDN of the current host. |
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|
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=item hostname () |
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|
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Returns the smallest part of the FQDN which can be used to identify the host. |
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|
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=item hostdomain () |
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|
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Returns the remainder of the FQDN after the I<hostname> has been removed. |
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|
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=back |
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|
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=head1 AUTHOR |
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|
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Graham Barr <gbarr@pobox.com>. |
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Adapted from Sys::Hostname by David Sundstrom <sunds@asictest.sc.ti.com> |
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|
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=head1 COPYRIGHT |
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|
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Copyright (c) 1995-1998 Graham Barr. All rights reserved. |
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This program is free software; you can redistribute it and/or modify |
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it under the same terms as Perl itself. |
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|
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=for html <hr> |
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|
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I<$Id: //depot/libnet/Net/Domain.pm#21 $> |
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|
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=cut |
