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# Net::Time.pm
#
# Copyright (C) 1995-2004 Graham Barr.  All rights reserved.
# Copyright (C) 2014, 2020 Steve Hay.  All rights reserved.
# This module is free software; you can redistribute it and/or modify it under
# the same terms as Perl itself, i.e. under the terms of either the GNU General
# Public License or the Artistic License, as specified in the F<LICENCE> file.
package Net::Time;
use 5.008001;
use strict;
use warnings;
use Carp;
use Exporter;
use IO::Select;
use IO::Socket;
use Net::Config;
our @ISA       = qw(Exporter);
our @EXPORT_OK = qw(inet_time inet_daytime);
our $VERSION = "3.15";
our $TIMEOUT = 120;
sub _socket {
  my ($pname, $pnum, $host, $proto, $timeout) = @_;
  $proto ||= 'udp';
  my $port = (getservbyname($pname, $proto))[2] || $pnum;
  my $hosts = defined $host ? [$host] : $NetConfig{$pname . '_hosts'};
  my $me;
  foreach my $addr (@$hosts) {
    $me = IO::Socket::INET->new(
      PeerAddr => $addr,
      PeerPort => $port,
      Proto    => $proto
      )
      and last;
  }
  return unless $me;
  $me->send("\n")
    if $proto eq 'udp';
  $timeout = $TIMEOUT
    unless defined $timeout;
  IO::Select->new($me)->can_read($timeout)
    ? $me
    : undef;
}
sub inet_time {
  my $s      = _socket('time', 37, @_) || return;
  my $buf    = '';
  my $offset = 0 | 0;
  return
    unless defined $s->recv($buf, length(pack("N", 0)));
  # unpack, we | 0 to ensure we have an unsigned
  my $time = (unpack("N", $buf))[0] | 0;
  # the time protocol return time in seconds since 1900, convert
  # it to a the required format
  if ($^O eq "MacOS") {
    # MacOS return seconds since 1904, 1900 was not a leap year.
    $offset = (4 * 31536000) | 0;
  }
  else {
    # otherwise return seconds since 1972, there were 17 leap years between
    # 1900 and 1972
    $offset = (70 * 31536000 + 17 * 86400) | 0;
  }
  $time - $offset;
}
sub inet_daytime {
  my $s   = _socket('daytime', 13, @_) || return;
  my $buf = '';
  defined($s->recv($buf, 1024))
    ? $buf
    : undef;
}
1;
__END__
HideShow 99 lines of Pod
=head1 NAME
Net::Time - time and daytime network client interface
=head1 SYNOPSIS
    use Net::Time qw(inet_time inet_daytime);
    print inet_time();          # use default host from Net::Config
    print inet_time('localhost');
    print inet_time('localhost', 'tcp');
    print inet_daytime();       # use default host from Net::Config
    print inet_daytime('localhost');
    print inet_daytime('localhost', 'tcp');
=head1 DESCRIPTION
C<Net::Time> provides subroutines that obtain the time on a remote machine.
=head2 Functions
=over 4
=item C<inet_time([$host[, $protocol[, $timeout]]])>
Obtain the time on C<$host>, or some default host if C<$host> is not given
or not defined, using the protocol as defined in RFC868. The optional
argument C<$protocol> should define the protocol to use, either C<tcp> or
C<udp>. The result will be a time value in the same units as returned
by time() or I<undef> upon failure.
=item C<inet_daytime([$host[, $protocol[, $timeout]]])>
Obtain the time on C<$host>, or some default host if C<$host> is not given
or not defined, using the protocol as defined in RFC867. The optional
argument C<$protocol> should define the protocol to use, either C<tcp> or
C<udp>. The result will be an ASCII string or I<undef> upon failure.
=back
=head1 EXPORTS
The following symbols are, or can be, exported by this module:
=over 4
=item Default Exports
I<None>.
=item Optional Exports
C<inet_time>,
C<inet_daytime>.
=item Export Tags
I<None>.
=back
=head1 KNOWN BUGS
I<None>.
=head1 AUTHOR
Graham Barr E<lt>L<gbarr@pobox.com|mailto:gbarr@pobox.com>E<gt>.
Steve Hay E<lt>L<shay@cpan.org|mailto:shay@cpan.org>E<gt> is now maintaining
libnet as of version 1.22_02.
=head1 COPYRIGHT
Copyright (C) 1995-2004 Graham Barr.  All rights reserved.
Copyright (C) 2014, 2020 Steve Hay.  All rights reserved.
=head1 LICENCE
This module is free software; you can redistribute it and/or modify it under the
same terms as Perl itself, i.e. under the terms of either the GNU General Public
License or the Artistic License, as specified in the F<LICENCE> file.
=head1 VERSION
Version 3.15
=head1 DATE
20 March 2023
=head1 HISTORY
See the F<Changes> file.
=cut