xref: /openbsd-src/gnu/usr.bin/perl/cpan/libnet/lib/Net/Time.pm (revision c90a81c56dcebd6a1b73fe4aff9b03385b8e63b3) 
1# Net::Time.pm
2#
3# Versions up to 2.10 Copyright (c) 1995-2004 Graham Barr <gbarr@pobox.com>.
4# All rights reserved.
5# Changes in Version 2.11 onwards Copyright (C) 2014 Steve Hay.  All rights
6# reserved.
7# This module is free software; you can redistribute it and/or modify it under
8# the same terms as Perl itself, i.e. under the terms of either the GNU General
9# Public License or the Artistic License, as specified in the F<LICENCE> file.
10
11package Net::Time;
12
13use 5.008001;
14
15use strict;
16use warnings;
17
18use Carp;
19use Exporter;
20use IO::Select;
21use IO::Socket;
22use Net::Config;
23
24our @ISA       = qw(Exporter);
25our @EXPORT_OK = qw(inet_time inet_daytime);
26
27our $VERSION = "3.08_01";
28
29our $TIMEOUT = 120;
30
31sub _socket {
32  my ($pname, $pnum, $host, $proto, $timeout) = @_;
33
34  $proto ||= 'udp';
35
36  my $port = (getservbyname($pname, $proto))[2] || $pnum;
37
38  my $hosts = defined $host ? [$host] : $NetConfig{$pname . '_hosts'};
39
40  my $me;
41
42  foreach my $addr (@$hosts) {
43    $me = IO::Socket::INET->new(
44      PeerAddr => $addr,
45      PeerPort => $port,
46      Proto    => $proto
47      )
48      and last;
49  }
50
51  return unless $me;
52
53  $me->send("\n")
54    if $proto eq 'udp';
55
56  $timeout = $TIMEOUT
57    unless defined $timeout;
58
59  IO::Select->new($me)->can_read($timeout)
60    ? $me
61    : undef;
62}
63
64
65sub inet_time {
66  my $s      = _socket('time', 37, @_) || return;
67  my $buf    = '';
68  my $offset = 0 | 0;
69
70  return
71    unless defined $s->recv($buf, length(pack("N", 0)));
72
73  # unpack, we | 0 to ensure we have an unsigned
74  my $time = (unpack("N", $buf))[0] | 0;
75
76  # the time protocol return time in seconds since 1900, convert
77  # it to a the required format
78
79  if ($^O eq "MacOS") {
80
81    # MacOS return seconds since 1904, 1900 was not a leap year.
82    $offset = (4 * 31536000) | 0;
83  }
84  else {
85
86    # otherwise return seconds since 1972, there were 17 leap years between
87    # 1900 and 1972
88    $offset = (70 * 31536000 + 17 * 86400) | 0;
89  }
90
91  $time - $offset;
92}
93
94
95sub inet_daytime {
96  my $s   = _socket('daytime', 13, @_) || return;
97  my $buf = '';
98
99  defined($s->recv($buf, 1024))
100    ? $buf
101    : undef;
102}
103
1041;
105
106__END__
107
108=head1 NAME
109
110Net::Time - time and daytime network client interface
111
112=head1 SYNOPSIS
113
114    use Net::Time qw(inet_time inet_daytime);
115
116    print inet_time();          # use default host from Net::Config
117    print inet_time('localhost');
118    print inet_time('localhost', 'tcp');
119
120    print inet_daytime();       # use default host from Net::Config
121    print inet_daytime('localhost');
122    print inet_daytime('localhost', 'tcp');
123
124=head1 DESCRIPTION
125
126C<Net::Time> provides subroutines that obtain the time on a remote machine.
127
128=over 4
129
130=item inet_time ( [HOST [, PROTOCOL [, TIMEOUT]]])
131
132Obtain the time on C<HOST>, or some default host if C<HOST> is not given
133or not defined, using the protocol as defined in RFC868. The optional
134argument C<PROTOCOL> should define the protocol to use, either C<tcp> or
135C<udp>. The result will be a time value in the same units as returned
136by time() or I<undef> upon failure.
137
138=item inet_daytime ( [HOST [, PROTOCOL [, TIMEOUT]]])
139
140Obtain the time on C<HOST>, or some default host if C<HOST> is not given
141or not defined, using the protocol as defined in RFC867. The optional
142argument C<PROTOCOL> should define the protocol to use, either C<tcp> or
143C<udp>. The result will be an ASCII string or I<undef> upon failure.
144
145=back
146
147=head1 AUTHOR
148
149Graham Barr E<lt>F<gbarr@pobox.com>E<gt>
150
151Steve Hay E<lt>F<shay@cpan.org>E<gt> is now maintaining libnet as of version
1521.22_02
153
154=head1 COPYRIGHT
155
156Versions up to 2.11 Copyright (c) 1995-2004 Graham Barr. All rights reserved.
157Changes in Version 2.11 onwards Copyright (C) 2014 Steve Hay.  All rights
158reserved.
159
160This module is free software; you can redistribute it and/or modify it under the
161same terms as Perl itself, i.e. under the terms of either the GNU General Public
162License or the Artistic License, as specified in the F<LICENCE> file.
163
164=cut
165