[p5sagit/p5-mst-13.2.git] / lib / Net / Ping.pm

package Net::Ping;

# Authors: karrer@bernina.ethz.ch (Andreas Karrer)
#          pmarquess@bfsec.bt.co.uk (Paul Marquess)

require 5.002 ;
require Exporter;

use strict ;
use vars qw(@ISA @EXPORT $VERSION $tcp_proto $echo_port) ;

@ISA = qw(Exporter);
@EXPORT = qw(ping pingecho);
$VERSION = 1.01;

use Socket 'PF_INET', 'AF_INET', 'SOCK_STREAM';
use Carp ;

$tcp_proto = (getprotobyname('tcp'))[2];
$echo_port = (getservbyname('echo', 'tcp'))[2];

sub ping {
    croak "ping not implemented yet. Use pingecho()";
}


sub pingecho {

    croak "usage: pingecho host [timeout]" 
        unless @_ == 1 or @_ == 2 ;

    my ($host, $timeout) = @_;
    my ($saddr, $ip);
    my ($ret) ;
    local (*PINGSOCK);

    # check if $host is alive by connecting to its echo port, within $timeout
    # (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found

    $timeout = 5 unless $timeout;

    if ($host =~ /^\s*((\d+\.){3}\d+)\s*$/)
      { $ip = pack ('C4', split (/\./, $1)) }
    else
      { $ip = (gethostbyname($host))[4] }

    return 0 unless $ip;		# "no such host"

    $saddr = pack('S n a4 x8', AF_INET, $echo_port, $ip);
    $SIG{'ALRM'} = sub { die } ;
    alarm($timeout);
    
    $ret = 0;
    eval <<'EOM' ;
    return unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $tcp_proto) ;
    return unless connect(PINGSOCK, $saddr) ;
    $ret=1 ;
EOM
    alarm(0);
    close(PINGSOCK);
    $ret;
}   

1;
__END__

=cut

=head1 NAME

Net::Ping, pingecho - check a host for upness

=head1 SYNOPSIS

    use Net::Ping;
    print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ;

=head1 DESCRIPTION

This module contains routines to test for the reachability of remote hosts.
Currently the only routine implemented is pingecho(). 

pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the
remote host is reachable. This is usually adequate to tell that a remote
host is available to rsh(1), ftp(1), or telnet(1) onto.

=head2 Parameters

=over 5

=item hostname

The remote host to check, specified either as a hostname or as an IP address.

=item timeout

The timeout in seconds. If not specified it will default to 5 seconds.

=back

=head1 WARNING

pingecho() uses alarm to implement the timeout, so don't set another alarm
while you are using it.
Commit	Line	Data
a0d0e21e	1	package Net::Ping;
	2
	3	# Authors: karrer@bernina.ethz.ch (Andreas Karrer)
	4	# pmarquess@bfsec.bt.co.uk (Paul Marquess)
	5
a79c1648	6	require 5.002 ;
a0d0e21e	7	require Exporter;
a0d0e21e	8
a79c1648	9	use strict ;
	10	use vars qw(@ISA @EXPORT $VERSION $tcp_proto $echo_port) ;
	11
a0d0e21e	12	@ISA = qw(Exporter);
a0d0e21e	13	@EXPORT = qw(ping pingecho);
a79c1648	14	$VERSION = 1.01;
a0d0e21e	15
8e07c86e	16	use Socket 'PF_INET', 'AF_INET', 'SOCK_STREAM';
a79c1648	17	use Carp ;
8e07c86e	18
a79c1648	19	$tcp_proto = (getprotobyname('tcp'))[2];
a79c1648	20	$echo_port = (getservbyname('echo', 'tcp'))[2];
a0d0e21e	21
a0d0e21e	22	sub ping {
a79c1648	23	croak "ping not implemented yet. Use pingecho()";
a0d0e21e	24	}
	25
	26
	27	sub pingecho {
	28
a79c1648	29	croak "usage: pingecho host [timeout]"
a79c1648	30	unless @_ == 1 or @_ == 2 ;
a0d0e21e	31
8e07c86e	32	my ($host, $timeout) = @_;
	33	my ($saddr, $ip);
	34	my ($ret) ;
a0d0e21e	35	local (*PINGSOCK);
a0d0e21e	36
	37	# check if $host is alive by connecting to its echo port, within $timeout
	38	# (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found
	39
	40	$timeout = 5 unless $timeout;
	41
	42	if ($host =~ /^\s((\d+\.){3}\d+)\s$/)
	43	{ $ip = pack ('C4', split (/\./, $1)) }
	44	else
	45	{ $ip = (gethostbyname($host))[4] }
	46
	47	return 0 unless $ip; # "no such host"
	48
a79c1648	49	$saddr = pack('S n a4 x8', AF_INET, $echo_port, $ip);
a0d0e21e	50	$SIG{'ALRM'} = sub { die } ;
a0d0e21e	51	alarm($timeout);
8e07c86e	52
	53	$ret = 0;
	54	eval <<'EOM' ;
a79c1648	55	return unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $tcp_proto) ;
8e07c86e	56	return unless connect(PINGSOCK, $saddr) ;
8e07c86e	57	$ret=1 ;
a0d0e21e	58	EOM
a0d0e21e	59	alarm(0);
a0d0e21e	60	close(PINGSOCK);
8e07c86e	61	$ret;
a0d0e21e	62	}
	63
	64	1;
8e07c86e	65	__END__
	66
	67	=cut
	68
	69	=head1 NAME
	70
	71	Net::Ping, pingecho - check a host for upness
	72
	73	=head1 SYNOPSIS
	74
	75	use Net::Ping;
	76	print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ;
	77
	78	=head1 DESCRIPTION
	79
	80	This module contains routines to test for the reachability of remote hosts.
	81	Currently the only routine implemented is pingecho().
	82
	83	pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the
	84	remote host is reachable. This is usually adequate to tell that a remote
	85	host is available to rsh(1), ftp(1), or telnet(1) onto.
	86
	87	=head2 Parameters
	88
	89	=over 5
	90
	91	=item hostname
	92
	93	The remote host to check, specified either as a hostname or as an IP address.
	94
	95	=item timeout
	96
	97	The timeout in seconds. If not specified it will default to 5 seconds.
	98
	99	=back
	100
	101	=head1 WARNING
	102
	103	pingecho() uses alarm to implement the timeout, so don't set another alarm
	104	while you are using it.
	105
	106