1package Sys::Hostname;
2
3use strict;
4
5use Carp;
6
7require Exporter;
8
9our @ISA     = qw/ Exporter /;
10our @EXPORT  = qw/ hostname /;
11
12our $VERSION;
13
14our $host;
15
16BEGIN {
17    $VERSION = '1.18';
18    {
19	local $SIG{__DIE__};
20	eval {
21	    require XSLoader;
22	    XSLoader::load();
23	};
24	warn $@ if $@;
25    }
26}
27
28
29sub hostname {
30
31  # method 1 - we already know it
32  return $host if defined $host;
33
34  # method 1' - try to ask the system
35  $host = ghname() if defined &ghname;
36  return $host if defined $host;
37
38  if ($^O eq 'VMS') {
39
40    # method 2 - no sockets ==> return DECnet node name
41    eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] };
42    if ($@) { return $host = $ENV{'SYS$NODE'}; }
43
44    # method 3 - has someone else done the job already?  It's common for the
45    #    TCP/IP stack to advertise the hostname via a logical name.  (Are
46    #    there any other logicals which TCP/IP stacks use for the host name?)
47    $host = $ENV{'ARPANET_HOST_NAME'}  || $ENV{'INTERNET_HOST_NAME'} ||
48            $ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'}      ||
49            $ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'};
50    return $host if $host;
51
52    # method 4 - does hostname happen to work?
53    my($rslt) = `hostname`;
54    if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; }
55    return $host if $host;
56
57    # rats!
58    $host = '';
59    croak "Cannot get host name of local machine";
60
61  }
62  elsif ($^O eq 'MSWin32') {
63    ($host) = gethostbyname('localhost');
64    chomp($host = `hostname 2> NUL`) unless defined $host;
65    return $host;
66  }
67  else {  # Unix
68    # is anyone going to make it here?
69
70    local $ENV{PATH} = '/usr/bin:/bin:/usr/sbin:/sbin'; # Paranoia.
71
72    # method 2 - syscall is preferred since it avoids tainting problems
73    # XXX: is it such a good idea to return hostname untainted?
74    eval {
75	local $SIG{__DIE__};
76	require "syscall.ph";
77	$host = "\0" x 65; ## preload scalar
78	syscall(&SYS_gethostname, $host, 65) == 0;
79    }
80
81    # method 2a - syscall using systeminfo instead of gethostname
82    #           -- needed on systems like Solaris
83    || eval {
84	local $SIG{__DIE__};
85	require "sys/syscall.ph";
86	require "sys/systeminfo.ph";
87	$host = "\0" x 65; ## preload scalar
88	syscall(&SYS_systeminfo, &SI_HOSTNAME, $host, 65) != -1;
89    }
90
91    # method 3 - trusty old hostname command
92    || eval {
93	local $SIG{__DIE__};
94	local $SIG{CHLD};
95	$host = `(hostname) 2>/dev/null`; # BSDish
96    }
97
98    # method 4 - use POSIX::uname(), which strictly can't be expected to be
99    # correct
100    || eval {
101	local $SIG{__DIE__};
102	require POSIX;
103	$host = (POSIX::uname())[1];
104    }
105
106    # method 5 - sysV uname command (may truncate)
107    || eval {
108	local $SIG{__DIE__};
109	$host = `uname -n 2>/dev/null`; ## sysVish
110    }
111
112    # bummer
113    || croak "Cannot get host name of local machine";
114
115    # remove garbage
116    $host =~ tr/\0\r\n//d;
117    $host;
118  }
119}
120
1211;
122
123__END__
124
125=head1 NAME
126
127Sys::Hostname - Try every conceivable way to get hostname
128
129=head1 SYNOPSIS
130
131    use Sys::Hostname;
132    $host = hostname;
133
134=head1 DESCRIPTION
135
136Attempts several methods of getting the system hostname and
137then caches the result.  It tries the first available of the C
138library's gethostname(), C<`$Config{aphostname}`>, uname(2),
139C<syscall(SYS_gethostname)>, C<`hostname`>, C<`uname -n`>,
140and the file F</com/host>.  If all that fails it C<croak>s.
141
142All NULs, returns, and newlines are removed from the result.
143
144=head1 AUTHOR
145
146David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
147
148Texas Instruments
149
150XS code added by Greg Bacon E<lt>F<gbacon@cs.uah.edu>E<gt>
151
152=cut
153
154