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 1.31 2001/03/15 09:46:18 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 = 6;

# 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 ($response && !($response eq "OK\n")) {
            print "The i-scream server rejected the STARTCONFIG command.\n";
            close($sock);
            wait_then_retry();
            next;
        }

        print "Config started okay.\n";
    
        print $sock "LASTMODIFIED\n";
        $response = <$sock>;
        if (!$response) {
            print "The i-scream server did not return anything for the LASTMODIFIED command.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        chop $response;
        $last_modified = $response;
    
        print "Config last modified: ". (scalar localtime $last_modified/1000) . "\n";

        print $sock "FILELIST\n";
        $response = <$sock>;
        if (!$response) {
            print "The i-scream server did not provide a configuration file list.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        chop $response;
        $file_list = $response;

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

        print $sock "FQDN\n";
        $response = <$sock>;
        if (!$response) {
            print "The i-scream server did not tell us our FQDN.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        chop $response;
        $fqdn = $response;

        print "FQDN returned: $fqdn\n";

        print $sock "UDPUpdateTime\n";
        $response = <$sock>;
        if (!$response) {
            print "The i-scream server did not give us a UDPUpdateTime.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        chop $response;
        $udp_update_time = $response;

        print $sock "TCPUpdateTime\n";
        $response = <$sock>;
        if (!$response) {
            print "The i-scream server did not give us a TCPUpdateTime.\n";
            close($sock);
            wait_then_retry();
            next;
        }
        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>;
        if ($response && !($response eq "OK\n")) {
            print "ENDCONFIG command to server failed.  Terminated.\n";
            close($sock);
            wait_then_retry();
            next;
        }

        print "Config ended.\n";
    
        print $sock "FILTER\n";
        $response = <$sock>;
        if (!$response) {
            print "Failed: Could not get a filter address from the filter manager.\n";
            close($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>;
        if ($response && ($response eq "OK\n")) {
            print "Host successfully configured via TCP.\n"
        }
        else {
            print "The server failed the host configuration on the END command.\n";
            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>;
    if (!$response eq "OK\n") {
        close($sock);
        print "Server gave wrong response to HEARTBEAT: $response\n";
        &tcp_configure();
        return;
    }
    
    print $sock "CONFIG\n";
    $response = <$sock>;
    if (!$response eq "OK\n") {
        close($sock);
        print "Server gave wrong response to CONFIG: $response\n";
        &tcp_configure();
        return;
    }

    print $sock "$file_list\n";
    $response = <$sock>;
    if (!$response eq "OK\n") {
        close($sock);
        print "Server gave wrong response to file list: $response\n";
        &tcp_configure();
        return;
    }
    
    print $sock "$last_modified\n";
    $response = <$sock>;
    if ($response eq "ERROR\n") {
        close($sock);
        print "Server configuration changed.  Reconfiguring with filter manager.\n";
        &tcp_configure();
        return;
    }
    if (!$response eq "OK\n") {
        close($sock);
        print "Server gave wrong response to HEARTBEAT: $response\n";
        &tcp_configure();
        return;
    }
    
    print $sock "ENDHEARTBEAT\n";
    $response = <$sock>;
    if (!$response eq "OK\n") {
        close($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:	1.32
Committed:	Fri Mar 16 18:25:59 2001 UTC (23 years, 8 months ago) by pjm2
Content type:	text/plain
Branch:	MAIN
Changes since 1.31:	+45 -27 lines
Log Message:	Lots of changes in the TCP configuration and TCP heartbeats. The aim of this is to make the ihost much more resilient when dealing with broken servers.
#	Content
1	#!/usr/bin/perl -w
2
3	# -----------------------------------------------------------
4	# Perl i-scream Host.
5	# http://www.i-scream.org.uk
6	#
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	# $Author: pjm2 $
13	# $Id: ihost.pl,v 1.31 2001/03/15 09:46:18 pjm2 Exp $
14	#------------------------------------------------------------
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	$fqdn
36	$pidfile
37	$retry_wait
38	);
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	$retry_wait = 6;
49
50	# write our PID to a file
51	$pidfile = "/var/tmp/ihost.pid";
52	&write_pid();
53
54	&tcp_configure();
55	&send_udp_packet();
56
57	$last_udp_time = time;
58	$last_tcp_time = time;
59	while (1) {
60	my($time) = time;
61	if ($time >= $last_udp_time + $udp_update_time) {
62	&send_udp_packet();
63	$last_udp_time = $time;
64	}
65	if ($time >= $last_tcp_time + $tcp_update_time) {
66	&send_tcp_heartbeat();
67	$last_tcp_time = $time;
68	}
69	my($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	}
80
81	# we'll probably never get here...
82	`rm -f $pidfile`;
83	exit(0);
84
85
86	#-----------------------------------------------------------------------
87	# 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 $retry_wait`;
94	}
95
96
97	#-----------------------------------------------------------------------
98	# tcp_configure
99	# Establishes a TCP connection to the specified i-scream filter manager.
100	# The host then requests details from the server, such as the intervals
101	# at which to send UDP packets.
102	#-----------------------------------------------------------------------
103	sub tcp_configure() {
104
105	while (1) {
106	my($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 ($response && !($response eq "OK\n")) {
124	print "The i-scream server rejected the STARTCONFIG command.\n";
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	if (!$response) {
135	print "The i-scream server did not return anything for the LASTMODIFIED command.\n";
136	close($sock);
137	wait_then_retry();
138	next;
139	}
140	chop $response;
141	$last_modified = $response;
142
143	print "Config last modified: ". (scalar localtime $last_modified/1000) . "\n";
144
145	print $sock "FILELIST\n";
146	$response = <$sock>;
147	if (!$response) {
148	print "The i-scream server did not provide a configuration file list.\n";
149	close($sock);
150	wait_then_retry();
151	next;
152	}
153	chop $response;
154	$file_list = $response;
155
156	print "File list obtained: $file_list\n";
157
158	print $sock "FQDN\n";
159	$response = <$sock>;
160	if (!$response) {
161	print "The i-scream server did not tell us our FQDN.\n";
162	close($sock);
163	wait_then_retry();
164	next;
165	}
166	chop $response;
167	$fqdn = $response;
168
169	print "FQDN returned: $fqdn\n";
170
171	print $sock "UDPUpdateTime\n";
172	$response = <$sock>;
173	if (!$response) {
174	print "The i-scream server did not give us a UDPUpdateTime.\n";
175	close($sock);
176	wait_then_retry();
177	next;
178	}
179	chop $response;
180	$udp_update_time = $response;
181
182	print $sock "TCPUpdateTime\n";
183	$response = <$sock>;
184	if (!$response) {
185	print "The i-scream server did not give us a TCPUpdateTime.\n";
186	close($sock);
187	wait_then_retry();
188	next;
189	}
190	chop $response;
191	$tcp_update_time = $response;
192
193	print "UDP packet period: $udp_update_time seconds.\nTCP heartbeat period: $tcp_update_time seconds.\n";
194
195	print $sock "ENDCONFIG\n";
196	$response = <$sock>;
197	if ($response && !($response eq "OK\n")) {
198	print "ENDCONFIG command to server failed. Terminated.\n";
199	close($sock);
200	wait_then_retry();
201	next;
202	}
203
204	print "Config ended.\n";
205
206	print $sock "FILTER\n";
207	$response = <$sock>;
208	if (!$response) {
209	print "Failed: Could not get a filter address from the filter manager.\n";
210	close($sock);
211	wait_then_retry();
212	next;
213	}
214	chop $response;
215	$response =~ /^(.);(.);(.*)/;
216	if ($response eq "ERROR") {
217	print "There are no active configured filters for your host.\n";
218	close($sock);
219	wait_then_retry();
220	next;
221	}
222	($filter_addr, $udp_port, $tcp_port) = ($1, $2, $3);
223	unless (defined($filter_addr) && defined($udp_port) && defined($tcp_port)) {
224	print "Failed: Filter address response from server did not make sense: $response\n";
225	close($sock);
226	wait_then_retry();
227	next;
228	}
229
230	print "Got filter data ($filter_addr, $udp_port, $tcp_port)\n";
231
232	print $sock "END\n";
233	$response = <$sock>;
234	if ($response && ($response eq "OK\n")) {
235	print "Host successfully configured via TCP.\n"
236	}
237	else {
238	print "The server failed the host configuration on the END command.\n";
239	close($sock);
240	wait_then_retry();
241	next;
242	}
243
244	close($sock);
245
246	print "Configuration finished sucessfully!\n";
247	last;
248	}
249	return;
250	}
251
252
253
254
255	#-----------------------------------------------------------------------
256	# send_udp_packet
257	# Sends a UDP packet to an i-scream filter.
258	# The packet contains XML markup describing some of the machine's state.
259	# Receipt of UDP packets is not guaranteed.
260	#-----------------------------------------------------------------------
261	sub send_udp_packet() {
262
263	my(@statgrab) = `./statgrab.pl`;
264	my(%packet);
265	for (my($i) = 0; $i <= $#statgrab; $i++) {
266	$statgrab[$i] =~ /^([^\s]) (.)$/;
267	$packet{$1} = $2;
268	}
269
270	my($date) = time;
271
272	my($disk_info) = "<disk>";
273	my($i) = 0;
274	while (defined $packet{"packet.disk.p$i.attributes.mount"}) {
275	$disk_info .= "<p$i";
276	$disk_info .= " name=\"" . $packet{"packet.disk.p$i.attributes.name"} . "\"";
277	$disk_info .= " kbytes=\"" . $packet{"packet.disk.p$i.attributes.kbytes"} . "\"";
278	$disk_info .= " used=\"" . $packet{"packet.disk.p$i.attributes.used"} . "\"";
279	$disk_info .= " avail=\"" . $packet{"packet.disk.p$i.attributes.avail"} . "\"";
280	$disk_info .= " mount=\"" . $packet{"packet.disk.p$i.attributes.mount"} . "\"";
281	$disk_info .= "></p$i>";
282	++$i;
283	}
284	$disk_info .= "</disk>";
285
286	my($ip) = inet_ntoa(scalar(gethostbyname(hostname())) \|\| 'localhost');
287
288	# Build the XML packet this way, as we can clearly
289	# see the structure and contents... I like this ;-)
290	# [Note that the server rejects UDP packets that are
291	# larger than 8196 bytes]
292	my($xml) = <<EOF;
293
294	<packet seq_no="$seq_no" machine_name="$fqdn" date="$date" type="data" ip="$ip">
295	<load>
296	<load1>$packet{"packet.load.load1"}</load1>
297	<load5>$packet{"packet.load.load5"}</load5>
298	<load15>$packet{"packet.load.load15"}</load15>
299	</load>
300	<os>
301	<name>$packet{"packet.os.name"}</name>
302	<release>$packet{"packet.os.release"}</release>
303	<platform>$packet{"packet.os.platform"}</platform>
304	<sysname>$packet{"packet.os.sysname"}</sysname>
305	<version>$packet{"packet.os.version"}</version>
306	<uptime>$packet{"packet.os.uptime"}</uptime>
307	</os>
308	<users>
309	<count>$packet{"packet.users.count"}</count>
310	<list>$packet{"packet.users.list"}</list>
311	</users>
312	<processes>
313	<total>$packet{"packet.processes.total"}</total>
314	<sleeping>$packet{"packet.processes.sleeping"}</sleeping>
315	<zombie>$packet{"packet.processes.zombie"}</zombie>
316	<stopped>$packet{"packet.processes.stopped"}</stopped>
317	<cpu>$packet{"packet.processes.cpu"}</cpu>
318	</processes>
319	<cpu>
320	<idle>$packet{"packet.cpu.idle"}</idle>
321	<user>$packet{"packet.cpu.user"}</user>
322	<kernel>$packet{"packet.cpu.kernel"}</kernel>
323	<iowait>$packet{"packet.cpu.iowait"}</iowait>
324	<swap>$packet{"packet.cpu.swap"}</swap>
325	</cpu>
326	<memory>
327	<total>$packet{"packet.memory.total"}</total>
328	<free>$packet{"packet.memory.free"}</free>
329	</memory>
330	<swap>
331	<total>$packet{"packet.swap.total"}</total>
332	<free>$packet{"packet.swap.free"}</free>
333	</swap>
334	$disk_info
335	</packet>
336
337	EOF
338
339	# Make the packet smaller by stripping out newlines and leading spaces.
340	$xml =~ s/\n\s*//g;
341
342	my($sock) = new IO::Socket::INET (
343	PeerPort => $udp_port,
344	PeerAddr => $filter_addr,
345	Proto => 'udp'
346	) or die "Could not send UDP: $!\n";
347
348	print $sock $xml or die "Could not send UDP packet: $!\n";
349	close($sock);
350	$seq_no++;
351	print "-";
352
353	return;
354	}
355
356
357
358
359	#-----------------------------------------------------------------------
360	# send_tcp_heartbeat
361	# Establishes a TCP connection to an i-scream filter.
362	# The heartbeat is used as a guaranteed "I'm alive" delivery mechanism.
363	#-----------------------------------------------------------------------
364	sub send_tcp_heartbeat() {
365
366	my($sock) = new IO::Socket::INET(
367	PeerAddr => $filter_addr,
368	PeerPort => $tcp_port,
369	Proto => 'tcp'
370	) or return;
371	if (!defined $sock) {
372	print "IHOST WARNING: Failed to deliver a heartbeat to the i-scream filter.\n";
373	&tcp_configure();
374	return;
375	}
376
377	# Now run through the configuration process.
378	my($response);
379
380	print $sock "HEARTBEAT\n";
381	$response = <$sock>;
382	if (!$response eq "OK\n") {
383	close($sock);
384	print "Server gave wrong response to HEARTBEAT: $response\n";
385	&tcp_configure();
386	return;
387	}
388
389	print $sock "CONFIG\n";
390	$response = <$sock>;
391	if (!$response eq "OK\n") {
392	close($sock);
393	print "Server gave wrong response to CONFIG: $response\n";
394	&tcp_configure();
395	return;
396	}
397
398	print $sock "$file_list\n";
399	$response = <$sock>;
400	if (!$response eq "OK\n") {
401	close($sock);
402	print "Server gave wrong response to file list: $response\n";
403	&tcp_configure();
404	return;
405	}
406
407	print $sock "$last_modified\n";
408	$response = <$sock>;
409	if ($response eq "ERROR\n") {
410	close($sock);
411	print "Server configuration changed. Reconfiguring with filter manager.\n";
412	&tcp_configure();
413	return;
414	}
415	if (!$response eq "OK\n") {
416	close($sock);
417	print "Server gave wrong response to HEARTBEAT: $response\n";
418	&tcp_configure();
419	return;
420	}
421
422	print $sock "ENDHEARTBEAT\n";
423	$response = <$sock>;
424	if (!$response eq "OK\n") {
425	close($sock);
426	print "Server gave wrong response to ENDHEARTBEAT: $response\n";
427	&tcp_configure();
428	return;
429	}
430
431	close($sock);
432	print "^";
433
434	return;
435	}
436
437	#-----------------------------------------------------------------------
438	# write_pid
439	# Writes the PID (process ID) of this instance to $pidfile.
440	# This is then used by a seperate script to check (and restart) ihost.
441	#-----------------------------------------------------------------------
442	sub write_pid() {
443	open PID, ">$pidfile";
444	print PID $$;
445	close PID;
446
447	return;
448	}