#!/usr/bin/perl
#
# monitor.pl - makes a series of checks to see that a machine, TCP network
# layer, Apache, and a particular web page are available.  It's designed 
# to be run on a separate host from the one being monitored.
# 
# This script must run as root so that ICMP can be used as the protocol
# for ping.  Most machines don't respond to TCP and UDP echo services
# (for a variety of reasons).
#
# remove hardcoded directory
# pass host as arg to child
# genericize naming 
# check for specific web page (in webdb's case this means that the database
#     is up and functional.
# actually send email
# pass interactive through cron entry
#
use Net::Ping;
use IO::Socket;
use strict;

my $p;
my $result; 
my $s;
my $got_it = 0;
my $output = ""; 
my $mode = "";
my $pid; 

my $program = "/clients/users/charliep/monitor-webdb-child.pl"; 
my @options = ""; 
my @args = "";

my $host = "dba.earlham.edu"; 
my $url = "webdb.earlham.edu"; 
my $check_text_webdb = "username:"; 
my $check_text_child = "success"; 

$mode = $ARGV[0]; 
$mode = "interactive";

#
# Ping the host to see if it at least has a pulse.
#
if (!($p = Net::Ping->new("icmp"))) {
    $output .= "monitor-webdb: unable to create new ping object - $!\n"; 
    goto done; 
}

$result = $p->ping($host); 
$p->close(); 

if ($result) {
    $output .= "monitor-webdb: $host is alive\n";
} else {
    $output .= "monitor-webdb: $host is down\n";
    goto done;
}

#
# See if the network is responding at all.  In its current failure
# mode dba.earlham.edu will respond to pings but hang (forever) on the 
# new IO::Socket call.  To avoid getting caught by this do the fork/exec
# shuffle.
#
if (!(defined($pid = open(CHILD, "-|")))) {
    $output .= "monitor-webdb: unable to create pipe - $!\n";
    goto done;
}

if ($pid) { # parent 
    # check to see if the pipe has anything to read, if so read it,
	$result = "";
	$got_it = 0; 
    sleep(5);

    while (<CHILD>) {
	$result = $_;
	if ($result =~ /success/g) {
	    $got_it = 1; 
	}
    }

    #
    # or timer or failure return
    #
    if ($got_it) {
        $output .= "monitor-webdb: $host is accepting TCP connections\n";
    } else {
	$output .= "monitor-webdb: $host is _NOT_ accepting TCP connections\n"; 
        goto done;
    }

    # set a timer and a counter, come back in n cycles
    # when the counter exceeds umm, kill the child (optional) and bail
    # update $output either way

} else { # child 
    exec($program, @options, @args) || 
        die "monitor-webdb (child): unable to exec $program - $!\n"; 
}

close(CHILD); 

# 
# Check if the Apache server is up and responding.  
#
if (!($s = new IO::Socket::INET (PeerAddr => $host,
                           PeerPort => '80',
			   Proto => 'tcp',
			   Type => SOCK_STREAM,
			   Timeout => 5))) {
    $output .= "monitor-webdb: unable to create new socket object - $@\n"; 
    goto done;
}

$result = "";
$got_it = 0; 
print $s "GET HTTP/1.0\r\n";

while (<$s>) {
    $result = $_; 
    if ($result =~ /!DOCTYPE HTML PUBLIC/g) {
	$got_it = 1;
    }
}

close($s); 

if ($got_it) {
    $output .= "monitor-webdb: $host is responding to http GET requests\n";
} else {
    $output .= "monitor-webdb: $host is _NOT_ responding to http GET requests\n"; 
    goto done;
}

#
# See if the URL returns the WebDB login page.
# 

# search for check_text_webdb (better variable name)

#
# Jump to here if any test fails, fall through to here if they all succeed.
#
done:

if ($mode eq "interactive") {
    print "$output"; 
} else {
    print "sending email\n"; 
}

exit;