host/ihost-perl/ihost.pl

#!/usr/bin/perl -w

# -----------------------------------------------------------
# Perl i-scream Host.
# http://www.i-scream.org.uk
#
# An all-in-one script to act as an i-scream host on
# a typical Unix/Linux box.  You may adapt the data-gathering
# methods as you see fit.
#  - pjm2@ukc.ac.uk
#
# $Author: pjm2 $
# $Id: ihost.pl,v 1.24 2001/03/06 08:38:42 pjm2 Exp $
#------------------------------------------------------------

$| = 1;

use strict;
use IO::Socket;
use Sys::Hostname;

use vars qw (
             $filter_manager_addr
             $filter_manager_port
             $seq_no
             $udp_update_time
             $tcp_update_time
             $last_udp_time
             $last_tcp_time
             $last_modified
             $udp_port
             $tcp_port
             $filter_addr
             $file_list
             $fqdn
             $pidfile
            );

if (@ARGV != 2) {
    die "Usage: ihost.pl [i-scream filter manager] [TCP port]\n";
}

$filter_manager_addr = $ARGV[0];
$filter_manager_port = $ARGV[1];

$seq_no = 1;

# write our PID to a file
$pidfile = "ihost.pid";
&write_pid();

&tcp_configure();
&send_udp_packet();

$last_udp_time = time;
$last_tcp_time = time;
while (1) {
    my($time) = time;
    if ($time >= $last_udp_time + $udp_update_time) {
        &send_udp_packet();
        $last_udp_time = $time;
    }
    if ($time >= $last_tcp_time + $tcp_update_time) {
        &send_tcp_heartbeat();
        $last_tcp_time = $time;
    }
    my($next_udp) = $udp_update_time - $time + $last_udp_time;
    my($next_tcp) = $tcp_update_time - $time + $last_tcp_time;
    my($delay);
    if ($next_udp < $next_tcp) {
        $delay = $next_udp
    }
    else {
        $delay = $next_tcp;
    }
    `sleep $delay`;
}

# we'll probably never get here...
`rm -f $pidfile`;
exit(0);


#-----------------------------------------------------------------------
# tcp_configure
# Establishes a TCP connection to the specified i-scream filter manager.
# The host then requests details from the server, such as the intervals
# at which to send UDP packets.
#-----------------------------------------------------------------------
sub tcp_configure() {
    
    my($sock) = new IO::Socket::INET(
                                     PeerAddr => $filter_manager_addr,
                                     PeerPort => $filter_manager_port,
                                     Proto => 'tcp'
                                    ) or die "Cannot connect!";
    if (!defined $sock) {
        print "IHOST ERROR: Could not connect to $filter_manager_addr:$filter_manager_port.\n";
        print "Please check that there is an i-scream server at this address.\n";
        print "Program ended.\n";
        exit(1);
    }

    # Now run through the configuration process...
    my($response);
    
    print $sock "STARTCONFIG\n";
    $response = <$sock>;
    if (!chop $response eq "OK") {
        print "The i-scream server rejected the STARTCONFIG command.  Terminated.";
        exit(1);
    }

    print "Config started okay.\n";
    
    print $sock "LASTMODIFIED\n";
    $response = <$sock>;
    chop $response;
    $last_modified = $response;
    
    print "Config last modified: ". (scalar localtime $last_modified/1000) . "\n";

    print $sock "FILELIST\n";
    $response = <$sock>;
    chop $response;
    $file_list = $response;

    print "File list obtained: $file_list\n";

    print $sock "FQDN\n";
    $response = <$sock>;
    chop $response;
    $fqdn = $response;

    print "FQDN returned: $fqdn\n";

    print $sock "UDPUpdateTime\n";
    $response = <$sock>;
    chop $response;
    $udp_update_time = $response;

    print $sock "TCPUpdateTime\n";
    $response = <$sock>;
    chop $response;
    $tcp_update_time = $response;
    
    print "UDP packet period: $udp_update_time seconds.\nTCP heartbeat period: $tcp_update_time seconds.\n";

    print $sock "ENDCONFIG\n";
    $response = <$sock>;
    chomp $response;
    if (!$response eq "OK") {
        print "ENDCONFIG command to server failed.  Terminated.\n";
        exit(1);
    }

    print "Config ended.\n";
    
    print $sock "FILTER\n";
    $response = <$sock>;
    unless (defined($response)) {
        print "Failed: Could not get a filter address from the filter manager.\n";
        exit(1);
    }
    chop $response;
    $response =~ /(.*);(.*);(.*)/;
    ($filter_addr, $udp_port, $tcp_port) = ($1, $2, $3);
    unless (defined($filter_addr) && defined($udp_port) && defined($tcp_port)) {
        print "Failed: Filter address response from server did not make sense: $response\n";
        exit(1);
    }
    
    print "Got filter data ($filter_addr, $udp_port, $tcp_port)\n";

    print $sock "END\n";
    $response = <$sock>;
    chop $response;
    if ($response eq "OK") {
        print "Host successfully configured via TCP.\n"
    }
    else {
        print "The server failed the host configuration on the END command.";
        exit(1);
    }
    
    close($sock);

    print "Configuration finished sucessfully!\n";
    
    return;
}


#-----------------------------------------------------------------------
# send_udp_packet
# Sends a UDP packet to an i-scream filter.
# The packet contains XML markup describing some of the machine's state.
# Receipt of UDP packets is not guaranteed.
#-----------------------------------------------------------------------
sub send_udp_packet() {

    my(@statgrab) = `./statgrab.pl`;
    my(%packet);
    for (my($i) = 0; $i <= $#statgrab; $i++) {
        $statgrab[$i] =~ /^([^\s]*) (.*)$/;
        $packet{$1} = $2;
    }
    
    my($date) = time;
    
    my($disk_info) = "<disk>";
    my($i) = 0;
    while (defined $packet{"packet.disk.p$i.attributes.mount"}) {
        $disk_info .= "<p$i";
        $disk_info .= " name=\"" . $packet{"packet.disk.p$i.attributes.name"} . "\"";
        $disk_info .= " kbytes=\"" . $packet{"packet.disk.p$i.attributes.kbytes"} . "\"";
        $disk_info .= " used=\"" . $packet{"packet.disk.p$i.attributes.used"} . "\"";
        $disk_info .= " avail=\"" . $packet{"packet.disk.p$i.attributes.avail"} . "\"";
        $disk_info .= " mount=\"" . $packet{"packet.disk.p$i.attributes.mount"} . "\"";
        $disk_info .= "></p$i>";
        ++$i;
    }
    $disk_info .= "</disk>";

    my($ip) = inet_ntoa(scalar(gethostbyname(hostname())) || 'localhost');

    # Build the XML packet this way, as we can clearly
    # see the structure and contents... I like this ;-)
    # [Note that the server rejects UDP packets that are
    # larger than 8196 bytes]
    my($xml) = <<EOF;
    
<packet seq_no="$seq_no" machine_name="$fqdn" date="$date" type="data" ip="$ip">
    <load>
        <load1>$packet{"packet.load.load1"}</load1>
        <load5>$packet{"packet.load.load5"}</load5>
        <load15>$packet{"packet.load.load15"}</load15>
    </load>
    <os>
        <name>$packet{"packet.os.name"}</name>
        <release>$packet{"packet.os.release"}</release>
        <platform>$packet{"packet.os.platform"}</platform>
        <sysname>$packet{"packet.os.sysname"}</sysname>
        <version>$packet{"packet.os.version"}</version>
        <uptime>$packet{"packet.os.uptime"}</uptime>
    </os>
    <users>
        <count>$packet{"packet.users.count"}</count>
        <list>$packet{"packet.users.list"}</list>
    </users>
    <processes>
        <total>$packet{"packet.processes.total"}</total>
        <sleeping>$packet{"packet.processes.sleeping"}</sleeping>
        <zombie>$packet{"packet.processes.zombie"}</zombie>
        <stopped>$packet{"packet.processes.stopped"}</stopped>
        <cpu>$packet{"packet.processes.cpu"}</cpu>
    </processes>
    <cpu>
        <idle>$packet{"packet.cpu.idle"}</idle>
        <user>$packet{"packet.cpu.user"}</user>
        <kernel>$packet{"packet.cpu.kernel"}</kernel>
        <iowait>$packet{"packet.cpu.iowait"}</iowait>
        <swap>$packet{"packet.cpu.swap"}</swap>
    </cpu>
    <memory>
        <total>$packet{"packet.memory.total"}</total>
        <free>$packet{"packet.memory.free"}</free>
    </memory>
    <swap>
        <total>$packet{"packet.swap.total"}</total>
        <free>$packet{"packet.swap.free"}</free>
    </swap>
    $disk_info
</packet>

EOF

    # Make the packet smaller by stripping out newlines and leading spaces.
    $xml =~ s/\n\s*//g;

    my($sock) = new IO::Socket::INET (
                                      PeerPort => $udp_port,
                                      PeerAddr => $filter_addr,
                                      Proto => 'udp'
                                     ) or die "Could not send UDP: $!\n";

    print $sock $xml or die "Could not send UDP packet: $!\n";
    close($sock);
    $seq_no++;
    print "-";
    
    return;
}


#-----------------------------------------------------------------------
# send_tcp_heartbeat
# Establishes a TCP connection to an i-scream filter.
# The heartbeat is used as a guaranteed "I'm alive" delivery mechanism.
#-----------------------------------------------------------------------
sub send_tcp_heartbeat() {

    my($sock) = new IO::Socket::INET(
                                     PeerAddr => $filter_addr,
                                     PeerPort => $tcp_port,
                                     Proto => 'tcp'
                                    ) or return;
    if (!defined $sock) {
        print "IHOST WARNING: Failed to deliver a heartbeat to the i-scream filter.\n";
        return;
    }

    # Now run through the configuration process.
    my($response);

    print $sock "HEARTBEAT\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to HEARTBEAT: $response\n";
        return;
    }
    
    print $sock "CONFIG\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to CONFIG: $response\n";
        return;
    }

    print $sock "$file_list\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to file list: $response\n";
        return;
    }
    
    print $sock "$last_modified\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if ($response eq "ERROR") {
        close($sock);
        &tcp_configure();
        return;
    }
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to HEARTBEAT: $response\n";
        return;
    }
    
    print $sock "ENDHEARTBEAT\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to ENDHEARTBEAT: $response\n";
        return;
    }
    
    close($sock);
    print "^";
    
    return;
}

#-----------------------------------------------------------------------
# write_pid
# Writes the PID (process ID) of this instance to $pidfile.
# This is then used by a seperate script to check (and restart) ihost.
#-----------------------------------------------------------------------
sub write_pid() {
    open PID, ">$pidfile";
    print PID $$;
    close PID;
    
    return;
}
Revision:	1.25
Committed:	Mon Mar 12 23:20:43 2001 UTC (23 years, 8 months ago) by tdb
Content type:	text/plain
Branch:	MAIN
Changes since 1.24:	+21 -1 lines
Log Message:	ihost now writes it's PID to a file, ihost.pid. This is so the ihostchk.sh script can verify if it's still running.
#	User	Rev	Content
1	pjm2	1.6	#!/usr/bin/perl -w
2	pjm2	1.1
3			# -----------------------------------------------------------
4			# Perl i-scream Host.
5	pjm2	1.12	# http://www.i-scream.org.uk
6	pjm2	1.1	#
7			# An all-in-one script to act as an i-scream host on
8			# a typical Unix/Linux box. You may adapt the data-gathering
9			# methods as you see fit.
10			# - pjm2@ukc.ac.uk
11			#
12	pjm2	1.22	# $Author: pjm2 $
13	tdb	1.25	# $Id: ihost.pl,v 1.24 2001/03/06 08:38:42 pjm2 Exp $
14	pjm2	1.1	#------------------------------------------------------------
15
16			$\| = 1;
17
18			use strict;
19			use IO::Socket;
20			use Sys::Hostname;
21
22			use vars qw (
23			$filter_manager_addr
24			$filter_manager_port
25			$seq_no
26			$udp_update_time
27			$tcp_update_time
28			$last_udp_time
29			$last_tcp_time
30			$last_modified
31			$udp_port
32			$tcp_port
33			$filter_addr
34			$file_list
35	pjm2	1.17	$fqdn
36	tdb	1.25	$pidfile
37	pjm2	1.1	);
38
39			if (@ARGV != 2) {
40			die "Usage: ihost.pl [i-scream filter manager] [TCP port]\n";
41			}
42
43			$filter_manager_addr = $ARGV[0];
44			$filter_manager_port = $ARGV[1];
45
46			$seq_no = 1;
47
48	tdb	1.25	# write our PID to a file
49			$pidfile = "ihost.pid";
50			&write_pid();
51
52	pjm2	1.1	&tcp_configure();
53			&send_udp_packet();
54
55			$last_udp_time = time;
56			$last_tcp_time = time;
57			while (1) {
58	pjm2	1.9	my($time) = time;
59			if ($time >= $last_udp_time + $udp_update_time) {
60	pjm2	1.1	&send_udp_packet();
61	pjm2	1.9	$last_udp_time = $time;
62	pjm2	1.1	}
63	pjm2	1.9	if ($time >= $last_tcp_time + $tcp_update_time) {
64	pjm2	1.1	&send_tcp_heartbeat();
65	pjm2	1.9	$last_tcp_time = $time;
66	pjm2	1.1	}
67	pjm2	1.9	my($next_udp) = $udp_update_time - $time + $last_udp_time;
68			my($next_tcp) = $tcp_update_time - $time + $last_tcp_time;
69			my($delay);
70			if ($next_udp < $next_tcp) {
71			$delay = $next_udp
72			}
73			else {
74			$delay = $next_tcp;
75			}
76			`sleep $delay`;
77	pjm2	1.1	}
78
79	tdb	1.25	# we'll probably never get here...
80			`rm -f $pidfile`;
81	pjm2	1.1	exit(0);
82
83	pjm2	1.12
84			#-----------------------------------------------------------------------
85			# tcp_configure
86			# Establishes a TCP connection to the specified i-scream filter manager.
87			# The host then requests details from the server, such as the intervals
88			# at which to send UDP packets.
89			#-----------------------------------------------------------------------
90	pjm2	1.1	sub tcp_configure() {
91
92			my($sock) = new IO::Socket::INET(
93			PeerAddr => $filter_manager_addr,
94			PeerPort => $filter_manager_port,
95			Proto => 'tcp'
96	pjm2	1.21	) or die "Cannot connect!";
97	pjm2	1.11	if (!defined $sock) {
98			print "IHOST ERROR: Could not connect to $filter_manager_addr:$filter_manager_port.\n";
99			print "Please check that there is an i-scream server at this address.\n";
100			print "Program ended.\n";
101			exit(1);
102			}
103	pjm2	1.1
104	pjm2	1.12	# Now run through the configuration process...
105	pjm2	1.1	my($response);
106
107			print $sock "STARTCONFIG\n";
108			$response = <$sock>;
109			if (!chop $response eq "OK") {
110			print "The i-scream server rejected the STARTCONFIG command. Terminated.";
111			exit(1);
112			}
113
114			print "Config started okay.\n";
115
116			print $sock "LASTMODIFIED\n";
117			$response = <$sock>;
118			chop $response;
119			$last_modified = $response;
120
121	pjm2	1.7	print "Config last modified: ". (scalar localtime $last_modified/1000) . "\n";
122	pjm2	1.1
123			print $sock "FILELIST\n";
124			$response = <$sock>;
125			chop $response;
126			$file_list = $response;
127
128			print "File list obtained: $file_list\n";
129	pjm2	1.17
130			print $sock "FQDN\n";
131			$response = <$sock>;
132			chop $response;
133			$fqdn = $response;
134
135			print "FQDN returned: $fqdn\n";
136	pjm2	1.1
137			print $sock "UDPUpdateTime\n";
138			$response = <$sock>;
139			chop $response;
140			$udp_update_time = $response;
141
142			print $sock "TCPUpdateTime\n";
143			$response = <$sock>;
144			chop $response;
145			$tcp_update_time = $response;
146
147	pjm2	1.7	print "UDP packet period: $udp_update_time seconds.\nTCP heartbeat period: $tcp_update_time seconds.\n";
148	pjm2	1.1
149			print $sock "ENDCONFIG\n";
150			$response = <$sock>;
151			chomp $response;
152			if (!$response eq "OK") {
153			print "ENDCONFIG command to server failed. Terminated.\n";
154			exit(1);
155			}
156
157			print "Config ended.\n";
158
159			print $sock "FILTER\n";
160			$response = <$sock>;
161	pjm2	1.24	unless (defined($response)) {
162			print "Failed: Could not get a filter address from the filter manager.\n";
163			exit(1);
164			}
165	pjm2	1.1	chop $response;
166			$response =~ /(.);(.);(.*)/;
167			($filter_addr, $udp_port, $tcp_port) = ($1, $2, $3);
168	pjm2	1.24	unless (defined($filter_addr) && defined($udp_port) && defined($tcp_port)) {
169			print "Failed: Filter address response from server did not make sense: $response\n";
170			exit(1);
171			}
172	pjm2	1.1
173			print "Got filter data ($filter_addr, $udp_port, $tcp_port)\n";
174
175			print $sock "END\n";
176			$response = <$sock>;
177			chop $response;
178			if ($response eq "OK") {
179			print "Host successfully configured via TCP.\n"
180			}
181			else {
182			print "The server failed the host configuration on the END command.";
183			exit(1);
184			}
185
186			close($sock);
187
188			print "Configuration finished sucessfully!\n";
189	pjm2	1.12
190			return;
191	pjm2	1.1	}
192
193	pjm2	1.12
194
195
196			#-----------------------------------------------------------------------
197			# send_udp_packet
198			# Sends a UDP packet to an i-scream filter.
199			# The packet contains XML markup describing some of the machine's state.
200			# Receipt of UDP packets is not guaranteed.
201			#-----------------------------------------------------------------------
202	pjm2	1.1	sub send_udp_packet() {
203
204			my(@statgrab) = `./statgrab.pl`;
205			my(%packet);
206	pjm2	1.13	for (my($i) = 0; $i <= $#statgrab; $i++) {
207	pjm2	1.1	$statgrab[$i] =~ /^([^\s]) (.)$/;
208			$packet{$1} = $2;
209			}
210
211			my($date) = time;
212
213			my($disk_info) = "<disk>";
214			my($i) = 0;
215			while (defined $packet{"packet.disk.p$i.attributes.mount"}) {
216	pjm2	1.15	$disk_info .= "<p$i";
217			$disk_info .= " name=\"" . $packet{"packet.disk.p$i.attributes.name"} . "\"";
218			$disk_info .= " kbytes=\"" . $packet{"packet.disk.p$i.attributes.kbytes"} . "\"";
219			$disk_info .= " used=\"" . $packet{"packet.disk.p$i.attributes.used"} . "\"";
220			$disk_info .= " avail=\"" . $packet{"packet.disk.p$i.attributes.avail"} . "\"";
221			$disk_info .= " mount=\"" . $packet{"packet.disk.p$i.attributes.mount"} . "\"";
222			$disk_info .= "></p$i>";
223	pjm2	1.1	++$i;
224			}
225			$disk_info .= "</disk>";
226	pjm2	1.13
227	tdb	1.19	my($ip) = inet_ntoa(scalar(gethostbyname(hostname())) \|\| 'localhost');
228	pjm2	1.1
229			# Build the XML packet this way, as we can clearly
230			# see the structure and contents... I like this ;-)
231	pjm2	1.12	# [Note that the server rejects UDP packets that are
232			# larger than 8196 bytes]
233	pjm2	1.1	my($xml) = <<EOF;
234
235	tdb	1.19	<packet seq_no="$seq_no" machine_name="$fqdn" date="$date" type="data" ip="$ip">
236	pjm2	1.1	<load>
237			<load1>$packet{"packet.load.load1"}</load1>
238			<load5>$packet{"packet.load.load5"}</load5>
239			<load15>$packet{"packet.load.load15"}</load15>
240			</load>
241			<os>
242			<name>$packet{"packet.os.name"}</name>
243			<release>$packet{"packet.os.release"}</release>
244			<platform>$packet{"packet.os.platform"}</platform>
245			<sysname>$packet{"packet.os.sysname"}</sysname>
246			<version>$packet{"packet.os.version"}</version>
247	tdb	1.10	<uptime>$packet{"packet.os.uptime"}</uptime>
248	pjm2	1.1	</os>
249			<users>
250			<count>$packet{"packet.users.count"}</count>
251			<list>$packet{"packet.users.list"}</list>
252			</users>
253			<processes>
254			<total>$packet{"packet.processes.total"}</total>
255			<sleeping>$packet{"packet.processes.sleeping"}</sleeping>
256			<zombie>$packet{"packet.processes.zombie"}</zombie>
257			<stopped>$packet{"packet.processes.stopped"}</stopped>
258			<cpu>$packet{"packet.processes.cpu"}</cpu>
259			</processes>
260			<cpu>
261			<idle>$packet{"packet.cpu.idle"}</idle>
262			<user>$packet{"packet.cpu.user"}</user>
263			<kernel>$packet{"packet.cpu.kernel"}</kernel>
264			<iowait>$packet{"packet.cpu.iowait"}</iowait>
265			<swap>$packet{"packet.cpu.swap"}</swap>
266			</cpu>
267			<memory>
268	pjm2	1.13	<total>$packet{"packet.memory.total"}</total>
269	pjm2	1.1	<free>$packet{"packet.memory.free"}</free>
270			</memory>
271			<swap>
272	pjm2	1.13	<total>$packet{"packet.swap.total"}</total>
273			<free>$packet{"packet.swap.free"}</free>
274	pjm2	1.1	</swap>
275			$disk_info
276			</packet>
277
278			EOF
279
280	pjm2	1.12	# Make the packet smaller by stripping out newlines and leading spaces.
281	pjm2	1.1	$xml =~ s/\n\s*//g;
282	tdb	1.19
283	pjm2	1.1	my($sock) = new IO::Socket::INET (
284			PeerPort => $udp_port,
285			PeerAddr => $filter_addr,
286			Proto => 'udp'
287	pjm2	1.21	) or die "Could not send UDP: $!\n";
288	pjm2	1.1
289			print $sock $xml or die "Could not send UDP packet: $!\n";
290			close($sock);
291			$seq_no++;
292			print "-";
293	pjm2	1.12
294			return;
295	pjm2	1.1	}
296
297	pjm2	1.12
298
299
300			#-----------------------------------------------------------------------
301			# send_tcp_heartbeat
302			# Establishes a TCP connection to an i-scream filter.
303			# The heartbeat is used as a guaranteed "I'm alive" delivery mechanism.
304			#-----------------------------------------------------------------------
305	pjm2	1.1	sub send_tcp_heartbeat() {
306
307			my($sock) = new IO::Socket::INET(
308			PeerAddr => $filter_addr,
309			PeerPort => $tcp_port,
310			Proto => 'tcp'
311	pjm2	1.21	) or return;
312	pjm2	1.11	if (!defined $sock) {
313			print "IHOST WARNING: Failed to deliver a heartbeat to the i-scream filter.\n";
314			return;
315			}
316	pjm2	1.1
317			# Now run through the configuration process.
318			my($response);
319
320			print $sock "HEARTBEAT\n";
321			$response = <$sock>;
322	pjm2	1.23	return if (!defined $response);
323			chop $response;
324	pjm2	1.1	if (!$response eq "OK") {
325			close($sock);
326			print "Server gave wrong response to HEARTBEAT: $response\n";
327			return;
328			}
329
330			print $sock "CONFIG\n";
331			$response = <$sock>;
332	pjm2	1.23	return if (!defined $response);
333			chop $response;
334	pjm2	1.1	if (!$response eq "OK") {
335			close($sock);
336			print "Server gave wrong response to CONFIG: $response\n";
337			return;
338			}
339
340			print $sock "$file_list\n";
341			$response = <$sock>;
342	pjm2	1.23	return if (!defined $response);
343			chop $response;
344	pjm2	1.1	if (!$response eq "OK") {
345			close($sock);
346			print "Server gave wrong response to file list: $response\n";
347			return;
348			}
349
350			print $sock "$last_modified\n";
351			$response = <$sock>;
352	pjm2	1.23	return if (!defined $response);
353			chop $response;
354	pjm2	1.1	if ($response eq "ERROR") {
355			close($sock);
356			&tcp_configure();
357			return;
358			}
359			if (!$response eq "OK") {
360			close($sock);
361			print "Server gave wrong response to HEARTBEAT: $response\n";
362			return;
363			}
364
365			print $sock "ENDHEARTBEAT\n";
366	pjm2	1.23	$response = <$sock>;
367			return if (!defined $response);
368	pjm2	1.1	chop $response;
369			if (!$response eq "OK") {
370			close($sock);
371			print "Server gave wrong response to ENDHEARTBEAT: $response\n";
372			return;
373			}
374
375			close($sock);
376			print "^";
377	tdb	1.25
378			return;
379			}
380
381			#-----------------------------------------------------------------------
382			# write_pid
383			# Writes the PID (process ID) of this instance to $pidfile.
384			# This is then used by a seperate script to check (and restart) ihost.
385			#-----------------------------------------------------------------------
386			sub write_pid() {
387			open PID, ">$pidfile";
388			print PID $$;
389			close PID;
390	pjm2	1.12
391			return;
392	pjm2	1.1	}