plugins: add check_mailman_qrunner_answers

sends an email to the ${listname}-request@${listsrv} address, and checks
if a sensible reply is sent back. requires mail server to deliver mail
to the given checker email address, one file per message, into a
directory (which is inotify-watched)

plugins/check_mailman_qrunner_answers

+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+
+use Getopt::Std;
+use Linux::Inotify2;
+use Mail::Sendmail;
+use Monitoring::Plugin;
+use String::Random;
+
+use Data::Dumper;
+
+
+my $np = Monitoring::Plugin->new;
+
+my %opts = ();
+getopts('s:n:r:d:t:', \%opts);
+defined $opts{'s'} and
+defined $opts{'n'} and
+defined $opts{'r'} and
+defined $opts{'d'} and
+defined $opts{'t'} or
+	$np->plugin_exit(UNKNOWN, "must give all parameters");
+
+# random string to identify the reply by
+my $r = String::Random->new;
+my $ident = $r->randpattern("s" x 16);
+
+my %mail = (
+	From => $opts{'r'},
+	To => "$opts{'n'}-request" . "@" . "$opts{'s'}",
+	Subject => $ident,
+	Body => "info",
+);
+sendmail(%mail) or $np->plugin_exit(UNKNOWN, "cannot send mail: $!");
+
+# eval for sigalarm handling to implement timeout
+eval {
+	# note: http://perldoc.perl.org/functions/alarm.html says the '\n'
+	# is required!
+	local $SIG{ALRM} = sub { die "alarm\n" };
+	alarm $opts{'t'};
+
+	my $inotify = Linux::Inotify2->new or
+		$np->plugin_exit(UNKNOWN, "cannot create inotify watch");
+	$inotify->watch("$opts{'d'}", IN_CREATE | IN_CLOSE_WRITE | IN_MOVED_TO, sub {
+			my $e = shift;
+			my $p = MIME::Parser->new;
+			my $msg = $p->parse_open($e->fullname);
+			# make sure we haven't hit a bounce or something
+			unless (defined $msg->head->get('X-Mailman-Version') and
+				defined $msg->head->get('X-List-Administrivia')) {
+				$np->plugin_exit(WARNING, "answer not from mailman: " . $msg->head->get('Subject'));
+			}
+			# the original message is a MIME part of the response, so dig for it
+			for my $part ($msg->parts) {
+				my $b = $part->as_string;
+				if (index($b, "Subject: $ident") > -1) {
+					# found it, this is our reply
+					$np->plugin_exit(OK, "got reply");
+				}
+			}
+		}
+	);
+	while () {
+		$inotify->poll;
+	}
+};
+if ($@) {
+	die unless $@ eq "alarm\n"; # propagate different errors
+	# timeout
+	$np->plugin_exit(CRITICAL, "timeout receiving answer mail");
+} else {
+	# no timeout (or other error), everything fine
+	# do i need to do anything here?
+	# just default exit cannot hurt i guess
+	$np->plugin_exit($np->check_messages);
+}