# Net::Time.pm

#

# Copyright (C) 1995-2004 Graham Barr.  All rights reserved.

# Copyright (C) 2014 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 = "3.11";

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__

=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.

=over 4

=item 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 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 AUTHOR

Graham Barr E<lt>F<gbarr@pobox.com>E<gt>.

Steve Hay E<lt>F<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 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.

=cut