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1 | # Net::Domain.pm |
2 | # |
3 | # Copyright (c) 1995-1998 Graham Barr <gbarr@pobox.com>. All rights reserved. |
4 | # This program is free software; you can redistribute it and/or |
5 | # modify it under the same terms as Perl itself. |
6 | |
7 | package Net::Domain; |
8 | |
9 | require Exporter; |
10 | |
11 | use Carp; |
12 | use strict; |
13 | use vars qw($VERSION @ISA @EXPORT_OK); |
14 | use Net::Config; |
15 | |
16 | @ISA = qw(Exporter); |
17 | @EXPORT_OK = qw(hostname hostdomain hostfqdn domainname); |
18 | |
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19 | $VERSION = "2.16"; # $Id: //depot/libnet/Net/Domain.pm#17 $ |
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20 | |
21 | my($host,$domain,$fqdn) = (undef,undef,undef); |
22 | |
23 | # Try every conceivable way to get hostname. |
24 | |
25 | sub _hostname { |
26 | |
27 | # we already know it |
28 | return $host |
29 | if(defined $host); |
30 | |
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31 | if ($^O eq 'MSWin32') { |
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32 | require Socket; |
33 | my ($name,$alias,$type,$len,@addr) = gethostbyname($ENV{'COMPUTERNAME'}||'localhost'); |
34 | while (@addr) |
35 | { |
36 | my $a = shift(@addr); |
37 | $host = gethostbyaddr($a,Socket::AF_INET()); |
38 | last if defined $host; |
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39 | } |
40 | if (index($host,'.') > 0) { |
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41 | $fqdn = $host; |
42 | ($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/; |
43 | } |
44 | return $host; |
45 | } |
46 | elsif ($^O eq 'MacOS') { |
47 | chomp ($host = `hostname`); |
48 | } |
49 | elsif ($^O eq 'VMS') { ## multiple varieties of net s/w makes this hard |
50 | $host = $ENV{'UCX$INET_HOST'} if defined($ENV{'UCX$INET_HOST'}); |
51 | $host = $ENV{'MULTINET_HOST_NAME'} if defined($ENV{'MULTINET_HOST_NAME'}); |
52 | if (index($host,'.') > 0) { |
53 | $fqdn = $host; |
54 | ($host,$domain) = $fqdn =~ /^([^\.]+)\.(.*)$/; |
55 | } |
56 | return $host; |
57 | } |
58 | else { |
59 | local $SIG{'__DIE__'}; |
60 | |
61 | # syscall is preferred since it avoids tainting problems |
62 | eval { |
63 | my $tmp = "\0" x 256; ## preload scalar |
64 | eval { |
65 | package main; |
66 | require "syscall.ph"; |
67 | defined(&main::SYS_gethostname); |
68 | } |
69 | || eval { |
70 | package main; |
71 | require "sys/syscall.ph"; |
72 | defined(&main::SYS_gethostname); |
73 | } |
74 | and $host = (syscall(&main::SYS_gethostname, $tmp, 256) == 0) |
75 | ? $tmp |
76 | : undef; |
77 | } |
78 | |
79 | # POSIX |
80 | || eval { |
81 | require POSIX; |
82 | $host = (POSIX::uname())[1]; |
83 | } |
84 | |
85 | # trusty old hostname command |
86 | || eval { |
87 | chop($host = `(hostname) 2>/dev/null`); # BSD'ish |
88 | } |
89 | |
90 | # sysV/POSIX uname command (may truncate) |
91 | || eval { |
92 | chop($host = `uname -n 2>/dev/null`); ## SYSV'ish && POSIX'ish |
93 | } |
94 | |
95 | # Apollo pre-SR10 |
96 | || eval { |
97 | $host = (split(/[:\. ]/,`/com/host`,6))[0]; |
98 | } |
99 | |
100 | || eval { |
101 | $host = ""; |
102 | }; |
103 | } |
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104 | |
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105 | # remove garbage |
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106 | $host =~ s/[\0\r\n]+//go; |
107 | $host =~ s/(\A\.+|\.+\Z)//go; |
108 | $host =~ s/\.\.+/\./go; |
109 | |
110 | $host; |
111 | } |
112 | |
113 | sub _hostdomain { |
114 | |
115 | # we already know it |
116 | return $domain |
117 | if(defined $domain); |
118 | |
119 | local $SIG{'__DIE__'}; |
120 | |
121 | return $domain = $NetConfig{'inet_domain'} |
122 | if defined $NetConfig{'inet_domain'}; |
123 | |
124 | # try looking in /etc/resolv.conf |
125 | # putting this here and assuming that it is correct, eliminates |
126 | # calls to gethostbyname, and therefore DNS lookups. This helps |
127 | # those on dialup systems. |
128 | |
129 | local *RES; |
130 | |
131 | if(open(RES,"/etc/resolv.conf")) { |
132 | while(<RES>) { |
133 | $domain = $1 |
134 | if(/\A\s*(?:domain|search)\s+(\S+)/); |
135 | } |
136 | close(RES); |
137 | |
138 | return $domain |
139 | if(defined $domain); |
140 | } |
141 | |
142 | # just try hostname and system calls |
143 | |
144 | my $host = _hostname(); |
145 | my(@hosts); |
146 | local($_); |
147 | |
148 | @hosts = ($host,"localhost"); |
149 | |
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150 | unless($host =~ /\./) { |
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151 | my $dom = undef; |
152 | eval { |
153 | my $tmp = "\0" x 256; ## preload scalar |
154 | eval { |
155 | package main; |
156 | require "syscall.ph"; |
157 | } |
158 | || eval { |
159 | package main; |
160 | require "sys/syscall.ph"; |
161 | } |
162 | and $dom = (syscall(&main::SYS_getdomainname, $tmp, 256) == 0) |
163 | ? $tmp |
164 | : undef; |
165 | }; |
166 | |
167 | chop($dom = `domainname 2>/dev/null`) |
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168 | unless(defined $dom || $^O =~ /^(?:cygwin|MSWin32)/); |
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169 | |
170 | if(defined $dom) { |
171 | my @h = (); |
172 | while(length($dom)) { |
173 | push(@h, "$host.$dom"); |
174 | $dom =~ s/^[^.]+.//; |
175 | } |
176 | unshift(@hosts,@h); |
177 | } |
178 | } |
179 | |
180 | # Attempt to locate FQDN |
181 | |
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182 | foreach (@hosts) { |
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183 | my @info = gethostbyname($_); |
184 | |
185 | next unless @info; |
186 | |
187 | # look at real name & aliases |
188 | my $site; |
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189 | foreach $site ($info[0], split(/ /,$info[1])) { |
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190 | if(rindex($site,".") > 0) { |
191 | |
192 | # Extract domain from FQDN |
193 | |
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194 | ($domain = $site) =~ s/\A[^\.]+\.//; |
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195 | return $domain; |
196 | } |
197 | } |
198 | } |
199 | |
200 | # Look for environment variable |
201 | |
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202 | $domain ||= $ENV{LOCALDOMAIN} || $ENV{DOMAIN}; |
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203 | |
204 | if(defined $domain) { |
205 | $domain =~ s/[\r\n\0]+//g; |
206 | $domain =~ s/(\A\.+|\.+\Z)//g; |
207 | $domain =~ s/\.\.+/\./g; |
208 | } |
209 | |
210 | $domain; |
211 | } |
212 | |
213 | sub domainname { |
214 | |
215 | return $fqdn |
216 | if(defined $fqdn); |
217 | |
218 | _hostname(); |
219 | _hostdomain(); |
220 | |
221 | # Assumption: If the host name does not contain a period |
222 | # and the domain name does, then assume that they are correct |
223 | # this helps to eliminate calls to gethostbyname, and therefore |
224 | # eleminate DNS lookups |
225 | |
226 | return $fqdn = $host . "." . $domain |
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227 | if(defined $host and defined $domain |
228 | and $host !~ /\./ and $domain =~ /\./); |
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229 | |
230 | # For hosts that have no name, just an IP address |
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231 | return $fqdn = $host if defined $host and $host =~ /^\d+(\.\d+){3}$/; |
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232 | |
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233 | my @host = defined $host ? split(/\./, $host) : ('localhost'); |
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234 | my @domain = defined $domain ? split(/\./, $domain) : (''); |
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235 | my @fqdn = (); |
236 | |
237 | # Determine from @host & @domain the FQDN |
238 | |
239 | my @d = @domain; |
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240 | |
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241 | LOOP: |
242 | while(1) { |
243 | my @h = @host; |
244 | while(@h) { |
245 | my $tmp = join(".",@h,@d); |
246 | if((gethostbyname($tmp))[0]) { |
247 | @fqdn = (@h,@d); |
248 | $fqdn = $tmp; |
249 | last LOOP; |
250 | } |
251 | pop @h; |
252 | } |
253 | last unless shift @d; |
254 | } |
255 | |
256 | if(@fqdn) { |
257 | $host = shift @fqdn; |
258 | until((gethostbyname($host))[0]) { |
259 | $host .= "." . shift @fqdn; |
260 | } |
261 | $domain = join(".", @fqdn); |
262 | } |
263 | else { |
264 | undef $host; |
265 | undef $domain; |
266 | undef $fqdn; |
267 | } |
268 | |
269 | $fqdn; |
270 | } |
271 | |
272 | sub hostfqdn { domainname() } |
273 | |
274 | sub hostname { |
275 | domainname() |
276 | unless(defined $host); |
277 | return $host; |
278 | } |
279 | |
280 | sub hostdomain { |
281 | domainname() |
282 | unless(defined $domain); |
283 | return $domain; |
284 | } |
285 | |
286 | 1; # Keep require happy |
287 | |
288 | __END__ |
289 | |
290 | =head1 NAME |
291 | |
292 | Net::Domain - Attempt to evaluate the current host's internet name and domain |
293 | |
294 | =head1 SYNOPSIS |
295 | |
296 | use Net::Domain qw(hostname hostfqdn hostdomain); |
297 | |
298 | =head1 DESCRIPTION |
299 | |
300 | Using various methods B<attempt> to find the Fully Qualified Domain Name (FQDN) |
301 | of the current host. From this determine the host-name and the host-domain. |
302 | |
303 | Each of the functions will return I<undef> if the FQDN cannot be determined. |
304 | |
305 | =over 4 |
306 | |
307 | =item hostfqdn () |
308 | |
309 | Identify and return the FQDN of the current host. |
310 | |
311 | =item hostname () |
312 | |
313 | Returns the smallest part of the FQDN which can be used to identify the host. |
314 | |
315 | =item hostdomain () |
316 | |
317 | Returns the remainder of the FQDN after the I<hostname> has been removed. |
318 | |
319 | =back |
320 | |
321 | =head1 AUTHOR |
322 | |
323 | Graham Barr <gbarr@pobox.com>. |
324 | Adapted from Sys::Hostname by David Sundstrom <sunds@asictest.sc.ti.com> |
325 | |
326 | =head1 COPYRIGHT |
327 | |
328 | Copyright (c) 1995-1998 Graham Barr. All rights reserved. |
329 | This program is free software; you can redistribute it and/or modify |
330 | it under the same terms as Perl itself. |
331 | |
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332 | =for html <hr> |
333 | |
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334 | I<$Id: //depot/libnet/Net/Domain.pm#17 $> |
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335 | |
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336 | =cut |