1package Sys::Hostname;
2
3use strict;
4
5use Carp;
6
7require Exporter;
8require AutoLoader;
9
10our @ISA     = qw/ Exporter AutoLoader /;
11our @EXPORT  = qw/ hostname /;
12
13our $VERSION;
14
15our $host;
16
17BEGIN {
18    $VERSION = '1.11';
19    {
20	local $SIG{__DIE__};
21	eval {
22	    require XSLoader;
23	    XSLoader::load('Sys::Hostname', $VERSION);
24	};
25	warn $@ if $@;
26    }
27}
28
29
30sub hostname {
31
32  # method 1 - we already know it
33  return $host if defined $host;
34
35  # method 1' - try to ask the system
36  $host = ghname() if defined &ghname;
37  return $host if defined $host;
38
39  if ($^O eq 'VMS') {
40
41    # method 2 - no sockets ==> return DECnet node name
42    eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] };
43    if ($@) { return $host = $ENV{'SYS$NODE'}; }
44
45    # method 3 - has someone else done the job already?  It's common for the
46    #    TCP/IP stack to advertise the hostname via a logical name.  (Are
47    #    there any other logicals which TCP/IP stacks use for the host name?)
48    $host = $ENV{'ARPANET_HOST_NAME'}  || $ENV{'INTERNET_HOST_NAME'} ||
49            $ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'}      ||
50            $ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'};
51    return $host if $host;
52
53    # method 4 - does hostname happen to work?
54    my($rslt) = `hostname`;
55    if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; }
56    return $host if $host;
57
58    # rats!
59    $host = '';
60    croak "Cannot get host name of local machine";
61
62  }
63  elsif ($^O eq 'MSWin32') {
64    ($host) = gethostbyname('localhost');
65    chomp($host = `hostname 2> NUL`) unless defined $host;
66    return $host;
67  }
68  elsif ($^O eq 'epoc') {
69    $host = 'localhost';
70    return $host;
71  }
72  else {  # Unix
73    # is anyone going to make it here?
74
75    local $ENV{PATH} = '/usr/bin:/bin:/usr/sbin:/sbin'; # Paranoia.
76
77    # method 2 - syscall is preferred since it avoids tainting problems
78    # XXX: is it such a good idea to return hostname untainted?
79    eval {
80	local $SIG{__DIE__};
81	require "syscall.ph";
82	$host = "\0" x 65; ## preload scalar
83	syscall(&SYS_gethostname, $host, 65) == 0;
84    }
85
86    # method 2a - syscall using systeminfo instead of gethostname
87    #           -- needed on systems like Solaris
88    || eval {
89	local $SIG{__DIE__};
90	require "sys/syscall.ph";
91	require "sys/systeminfo.ph";
92	$host = "\0" x 65; ## preload scalar
93	syscall(&SYS_systeminfo, &SI_HOSTNAME, $host, 65) != -1;
94    }
95
96    # method 3 - trusty old hostname command
97    || eval {
98	local $SIG{__DIE__};
99	local $SIG{CHLD};
100	$host = `(hostname) 2>/dev/null`; # bsdish
101    }
102
103    # method 4 - use POSIX::uname(), which strictly can't be expected to be
104    # correct
105    || eval {
106	local $SIG{__DIE__};
107	require POSIX;
108	$host = (POSIX::uname())[1];
109    }
110
111    # method 5 - sysV uname command (may truncate)
112    || eval {
113	local $SIG{__DIE__};
114	$host = `uname -n 2>/dev/null`; ## sysVish
115    }
116
117    # method 6 - Apollo pre-SR10
118    || eval {
119	local $SIG{__DIE__};
120        my($a,$b,$c,$d);
121	($host,$a,$b,$c,$d)=split(/[:\. ]/,`/com/host`,6);
122    }
123
124    # bummer
125    || croak "Cannot get host name of local machine";
126
127    # remove garbage
128    $host =~ tr/\0\r\n//d;
129    $host;
130  }
131}
132
1331;
134
135__END__
136
137=head1 NAME
138
139Sys::Hostname - Try every conceivable way to get hostname
140
141=head1 SYNOPSIS
142
143    use Sys::Hostname;
144    $host = hostname;
145
146=head1 DESCRIPTION
147
148Attempts several methods of getting the system hostname and
149then caches the result.  It tries the first available of the C
150library's gethostname(), C<`$Config{aphostname}`>, uname(2),
151C<syscall(SYS_gethostname)>, C<`hostname`>, C<`uname -n`>,
152and the file F</com/host>.  If all that fails it C<croak>s.
153
154All NULs, returns, and newlines are removed from the result.
155
156=head1 AUTHOR
157
158David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
159
160Texas Instruments
161
162XS code added by Greg Bacon E<lt>F<gbacon@cs.uah.edu>E<gt>
163
164=cut
165
166