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 1.30 2001/03/15 09:44:08 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
             $retry_wait
            );

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;
$retry_wait = 600;

# write our PID to a file
$pidfile = "/var/tmp/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);


#-----------------------------------------------------------------------
# wait_then_retry
# Waits for the period of time specified in $retry_wait, then attempts
# to reconfigure with the server.
#-----------------------------------------------------------------------
sub wait_then_retry() {
    print "Will retry configuration with filter manager in $retry_wait seconds.\n";
    `sleep $retry_wait`;
}


#-----------------------------------------------------------------------
# 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() {
    
    while (1) {
        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";
            wait_then_retry();
            next;
        }

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

        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";
            close($sock);
            wait_then_retry();
            next;
        }

        print "Config ended.\n";
    
        print $sock "FILTER\n";
        $response = <$sock>;
        unless (defined($response)) {
            print "Failed: Could not get a filter address from the filter manager.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        chop $response;
        $response =~ /(.*);(.*);(.*)/;
        if ($response eq "ERROR") {
            print "There are no active configured filters for your host.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        ($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: $response\n";
            close($sock);
            wait_then_retry();
            next;
        }
    
        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.";
            close($sock);
            wait_then_retry();
            next;
        }
    
        close($sock);

        print "Configuration finished sucessfully!\n";
        last;
    }
    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";
        &tcp_configure();
        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";
        &tcp_configure();
        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";
        &tcp_configure();
        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";
        &tcp_configure();
        return;
    }
    
    print $sock "$last_modified\n";
    $response = <$sock>;
    return if (!defined $response);
    chop $response;
    if ($response eq "ERROR") {
        close($sock);
        print "Server configuration changed.  Reconfiguring with filter manager.\n";
        &tcp_configure();
        return;
    }
    if (!$response eq "OK") {
        close($sock);
        print "Server gave wrong response to HEARTBEAT: $response\n";
        &tcp_configure();
        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";
        &tcp_configure();
        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:	1.31
Committed:	Thu Mar 15 09:46:18 2001 UTC (23 years, 8 months ago) by pjm2
Content type:	text/plain
Branch:	MAIN
Changes since 1.30:	+2 -2 lines
Log Message:	Just changed the expression within the connection while loop.
#	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	1.28	# $Author: pjm2 $
13	pjm2	1.31	# $Id: ihost.pl,v 1.30 2001/03/15 09:44:08 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	1.28	$retry_wait
38	pjm2	1.1	);
39
40			if (@ARGV != 2) {
41			die "Usage: ihost.pl [i-scream filter manager] [TCP port]\n";
42			}
43
44			$filter_manager_addr = $ARGV[0];
45			$filter_manager_port = $ARGV[1];
46
47			$seq_no = 1;
48	pjm2	1.29	$retry_wait = 600;
49	pjm2	1.1
50	tdb	1.25	# write our PID to a file
51	tdb	1.26	$pidfile = "/var/tmp/ihost.pid";
52	tdb	1.25	&write_pid();
53
54	pjm2	1.1	&tcp_configure();
55			&send_udp_packet();
56
57			$last_udp_time = time;
58			$last_tcp_time = time;
59			while (1) {
60	pjm2	1.9	my($time) = time;
61			if ($time >= $last_udp_time + $udp_update_time) {
62	pjm2	1.1	&send_udp_packet();
63	pjm2	1.9	$last_udp_time = $time;
64	pjm2	1.1	}
65	pjm2	1.9	if ($time >= $last_tcp_time + $tcp_update_time) {
66	pjm2	1.1	&send_tcp_heartbeat();
67	pjm2	1.9	$last_tcp_time = $time;
68	pjm2	1.1	}
69	pjm2	1.9	my($next_udp) = $udp_update_time - $time + $last_udp_time;
70			my($next_tcp) = $tcp_update_time - $time + $last_tcp_time;
71			my($delay);
72			if ($next_udp < $next_tcp) {
73			$delay = $next_udp
74			}
75			else {
76			$delay = $next_tcp;
77			}
78			`sleep $delay`;
79	pjm2	1.1	}
80
81	tdb	1.25	# we'll probably never get here...
82			`rm -f $pidfile`;
83	pjm2	1.1	exit(0);
84
85	pjm2	1.12
86			#-----------------------------------------------------------------------
87	pjm2	1.28	# wait_then_retry
88			# Waits for the period of time specified in $retry_wait, then attempts
89			# to reconfigure with the server.
90			#-----------------------------------------------------------------------
91			sub wait_then_retry() {
92			print "Will retry configuration with filter manager in $retry_wait seconds.\n";
93			`sleep $retry_wait`;
94			}
95
96
97			#-----------------------------------------------------------------------
98	pjm2	1.12	# tcp_configure
99			# Establishes a TCP connection to the specified i-scream filter manager.
100			# The host then requests details from the server, such as the intervals
101			# at which to send UDP packets.
102			#-----------------------------------------------------------------------
103	pjm2	1.1	sub tcp_configure() {
104
105	pjm2	1.31	while (1) {
106	pjm2	1.28	my($sock) = new IO::Socket::INET(
107			PeerAddr => $filter_manager_addr,
108			PeerPort => $filter_manager_port,
109			Proto => 'tcp'
110			) or die "Cannot connect!";
111			if (!defined $sock) {
112			print "IHOST ERROR: Could not connect to $filter_manager_addr:$filter_manager_port.\n";
113			print "Please check that there is an i-scream server at this address.\n";
114			wait_then_retry();
115			next;
116			}
117
118			# Now run through the configuration process...
119			my($response);
120
121			print $sock "STARTCONFIG\n";
122			$response = <$sock>;
123			if (!chop $response eq "OK") {
124			print "The i-scream server rejected the STARTCONFIG command. Terminated.";
125			close($sock);
126			wait_then_retry();
127			next;
128			}
129
130			print "Config started okay.\n";
131
132			print $sock "LASTMODIFIED\n";
133			$response = <$sock>;
134			chop $response;
135			$last_modified = $response;
136
137			print "Config last modified: ". (scalar localtime $last_modified/1000) . "\n";
138
139			print $sock "FILELIST\n";
140			$response = <$sock>;
141			chop $response;
142			$file_list = $response;
143
144			print "File list obtained: $file_list\n";
145
146			print $sock "FQDN\n";
147			$response = <$sock>;
148			chop $response;
149			$fqdn = $response;
150
151			print "FQDN returned: $fqdn\n";
152
153			print $sock "UDPUpdateTime\n";
154			$response = <$sock>;
155			chop $response;
156			$udp_update_time = $response;
157
158			print $sock "TCPUpdateTime\n";
159			$response = <$sock>;
160			chop $response;
161			$tcp_update_time = $response;
162
163			print "UDP packet period: $udp_update_time seconds.\nTCP heartbeat period: $tcp_update_time seconds.\n";
164
165			print $sock "ENDCONFIG\n";
166			$response = <$sock>;
167			chomp $response;
168			if (!$response eq "OK") {
169			print "ENDCONFIG command to server failed. Terminated.\n";
170			close($sock);
171			wait_then_retry();
172			next;
173			}
174
175			print "Config ended.\n";
176
177			print $sock "FILTER\n";
178			$response = <$sock>;
179			unless (defined($response)) {
180			print "Failed: Could not get a filter address from the filter manager.\n";
181			close($sock);
182			wait_then_retry();
183			next;
184			}
185			chop $response;
186			$response =~ /(.);(.);(.*)/;
187			if ($response eq "ERROR") {
188			print "There are no active configured filters for your host.\n";
189			close($sock);
190			wait_then_retry();
191			next;
192			}
193			($filter_addr, $udp_port, $tcp_port) = ($1, $2, $3);
194			unless (defined($filter_addr) && defined($udp_port) && defined($tcp_port)) {
195			print "Failed: Filter address response from server did not make sense: $response\n";
196			close($sock);
197			wait_then_retry();
198			next;
199			}
200
201			print "Got filter data ($filter_addr, $udp_port, $tcp_port)\n";
202
203			print $sock "END\n";
204			$response = <$sock>;
205			chop $response;
206			if ($response eq "OK") {
207			print "Host successfully configured via TCP.\n"
208			}
209			else {
210			print "The server failed the host configuration on the END command.";
211			close($sock);
212			wait_then_retry();
213			next;
214			}
215	pjm2	1.1
216	pjm2	1.28	close($sock);
217	pjm2	1.1
218	pjm2	1.28	print "Configuration finished sucessfully!\n";
219			last;
220	pjm2	1.1	}
221	pjm2	1.12	return;
222	pjm2	1.1	}
223
224	pjm2	1.12
225
226
227			#-----------------------------------------------------------------------
228			# send_udp_packet
229			# Sends a UDP packet to an i-scream filter.
230			# The packet contains XML markup describing some of the machine's state.
231			# Receipt of UDP packets is not guaranteed.
232			#-----------------------------------------------------------------------
233	pjm2	1.1	sub send_udp_packet() {
234
235			my(@statgrab) = `./statgrab.pl`;
236			my(%packet);
237	pjm2	1.13	for (my($i) = 0; $i <= $#statgrab; $i++) {
238	pjm2	1.1	$statgrab[$i] =~ /^([^\s]) (.)$/;
239			$packet{$1} = $2;
240			}
241
242			my($date) = time;
243
244			my($disk_info) = "<disk>";
245			my($i) = 0;
246			while (defined $packet{"packet.disk.p$i.attributes.mount"}) {
247	pjm2	1.15	$disk_info .= "<p$i";
248			$disk_info .= " name=\"" . $packet{"packet.disk.p$i.attributes.name"} . "\"";
249			$disk_info .= " kbytes=\"" . $packet{"packet.disk.p$i.attributes.kbytes"} . "\"";
250			$disk_info .= " used=\"" . $packet{"packet.disk.p$i.attributes.used"} . "\"";
251			$disk_info .= " avail=\"" . $packet{"packet.disk.p$i.attributes.avail"} . "\"";
252			$disk_info .= " mount=\"" . $packet{"packet.disk.p$i.attributes.mount"} . "\"";
253			$disk_info .= "></p$i>";
254	pjm2	1.1	++$i;
255			}
256			$disk_info .= "</disk>";
257	pjm2	1.13
258	tdb	1.19	my($ip) = inet_ntoa(scalar(gethostbyname(hostname())) \|\| 'localhost');
259	pjm2	1.1
260			# Build the XML packet this way, as we can clearly
261			# see the structure and contents... I like this ;-)
262	pjm2	1.12	# [Note that the server rejects UDP packets that are
263			# larger than 8196 bytes]
264	pjm2	1.1	my($xml) = <<EOF;
265
266	tdb	1.19	<packet seq_no="$seq_no" machine_name="$fqdn" date="$date" type="data" ip="$ip">
267	pjm2	1.1	<load>
268			<load1>$packet{"packet.load.load1"}</load1>
269			<load5>$packet{"packet.load.load5"}</load5>
270			<load15>$packet{"packet.load.load15"}</load15>
271			</load>
272			<os>
273			<name>$packet{"packet.os.name"}</name>
274			<release>$packet{"packet.os.release"}</release>
275			<platform>$packet{"packet.os.platform"}</platform>
276			<sysname>$packet{"packet.os.sysname"}</sysname>
277			<version>$packet{"packet.os.version"}</version>
278	tdb	1.10	<uptime>$packet{"packet.os.uptime"}</uptime>
279	pjm2	1.1	</os>
280			<users>
281			<count>$packet{"packet.users.count"}</count>
282			<list>$packet{"packet.users.list"}</list>
283			</users>
284			<processes>
285			<total>$packet{"packet.processes.total"}</total>
286			<sleeping>$packet{"packet.processes.sleeping"}</sleeping>
287			<zombie>$packet{"packet.processes.zombie"}</zombie>
288			<stopped>$packet{"packet.processes.stopped"}</stopped>
289			<cpu>$packet{"packet.processes.cpu"}</cpu>
290			</processes>
291			<cpu>
292			<idle>$packet{"packet.cpu.idle"}</idle>
293			<user>$packet{"packet.cpu.user"}</user>
294			<kernel>$packet{"packet.cpu.kernel"}</kernel>
295			<iowait>$packet{"packet.cpu.iowait"}</iowait>
296			<swap>$packet{"packet.cpu.swap"}</swap>
297			</cpu>
298			<memory>
299	pjm2	1.13	<total>$packet{"packet.memory.total"}</total>
300	pjm2	1.1	<free>$packet{"packet.memory.free"}</free>
301			</memory>
302			<swap>
303	pjm2	1.13	<total>$packet{"packet.swap.total"}</total>
304			<free>$packet{"packet.swap.free"}</free>
305	pjm2	1.1	</swap>
306			$disk_info
307			</packet>
308
309			EOF
310
311	pjm2	1.12	# Make the packet smaller by stripping out newlines and leading spaces.
312	pjm2	1.1	$xml =~ s/\n\s*//g;
313	tdb	1.19
314	pjm2	1.1	my($sock) = new IO::Socket::INET (
315			PeerPort => $udp_port,
316			PeerAddr => $filter_addr,
317			Proto => 'udp'
318	pjm2	1.21	) or die "Could not send UDP: $!\n";
319	pjm2	1.1
320			print $sock $xml or die "Could not send UDP packet: $!\n";
321			close($sock);
322			$seq_no++;
323			print "-";
324	pjm2	1.12
325			return;
326	pjm2	1.1	}
327
328	pjm2	1.12
329
330
331			#-----------------------------------------------------------------------
332			# send_tcp_heartbeat
333			# Establishes a TCP connection to an i-scream filter.
334			# The heartbeat is used as a guaranteed "I'm alive" delivery mechanism.
335			#-----------------------------------------------------------------------
336	pjm2	1.1	sub send_tcp_heartbeat() {
337
338			my($sock) = new IO::Socket::INET(
339			PeerAddr => $filter_addr,
340			PeerPort => $tcp_port,
341			Proto => 'tcp'
342	pjm2	1.21	) or return;
343	pjm2	1.11	if (!defined $sock) {
344			print "IHOST WARNING: Failed to deliver a heartbeat to the i-scream filter.\n";
345	pjm2	1.27	&tcp_configure();
346	pjm2	1.11	return;
347			}
348	pjm2	1.1
349			# Now run through the configuration process.
350			my($response);
351
352			print $sock "HEARTBEAT\n";
353			$response = <$sock>;
354	pjm2	1.23	return if (!defined $response);
355			chop $response;
356	pjm2	1.1	if (!$response eq "OK") {
357			close($sock);
358			print "Server gave wrong response to HEARTBEAT: $response\n";
359	pjm2	1.27	&tcp_configure();
360	pjm2	1.1	return;
361			}
362
363			print $sock "CONFIG\n";
364			$response = <$sock>;
365	pjm2	1.23	return if (!defined $response);
366			chop $response;
367	pjm2	1.1	if (!$response eq "OK") {
368			close($sock);
369			print "Server gave wrong response to CONFIG: $response\n";
370	pjm2	1.27	&tcp_configure();
371	pjm2	1.1	return;
372			}
373
374			print $sock "$file_list\n";
375			$response = <$sock>;
376	pjm2	1.23	return if (!defined $response);
377			chop $response;
378	pjm2	1.1	if (!$response eq "OK") {
379			close($sock);
380			print "Server gave wrong response to file list: $response\n";
381	pjm2	1.27	&tcp_configure();
382	pjm2	1.1	return;
383			}
384
385			print $sock "$last_modified\n";
386			$response = <$sock>;
387	pjm2	1.23	return if (!defined $response);
388			chop $response;
389	pjm2	1.1	if ($response eq "ERROR") {
390			close($sock);
391	pjm2	1.27	print "Server configuration changed. Reconfiguring with filter manager.\n";
392	pjm2	1.1	&tcp_configure();
393			return;
394			}
395			if (!$response eq "OK") {
396			close($sock);
397			print "Server gave wrong response to HEARTBEAT: $response\n";
398	pjm2	1.27	&tcp_configure();
399	pjm2	1.1	return;
400			}
401
402			print $sock "ENDHEARTBEAT\n";
403	pjm2	1.23	$response = <$sock>;
404			return if (!defined $response);
405	pjm2	1.1	chop $response;
406			if (!$response eq "OK") {
407			close($sock);
408			print "Server gave wrong response to ENDHEARTBEAT: $response\n";
409	pjm2	1.27	&tcp_configure();
410	pjm2	1.1	return;
411			}
412
413			close($sock);
414			print "^";
415	tdb	1.25
416			return;
417			}
418
419			#-----------------------------------------------------------------------
420			# write_pid
421			# Writes the PID (process ID) of this instance to $pidfile.
422			# This is then used by a seperate script to check (and restart) ihost.
423			#-----------------------------------------------------------------------
424			sub write_pid() {
425			open PID, ">$pidfile";
426			print PID $$;
427			close PID;
428	pjm2	1.12
429			return;
430	pjm2	1.1	}