#! /usr/bin/perl -w

use strict;
use Getopt::Std;
use Mail::Sendmail;

use constant FROM => 'mrtg@example.com';
use constant TO   => 'operator@example.com';

my %args;
getopt('t', \%args);
# t -- test: do not send mail

my( $date, $time, $no_response, $host, %error );
my %unmatched;
while( <> ) {
    chomp;
    if( /^((\d{4}-\d{2}-\d{2} \d{2}:\d{2}):\d{2}) -- SNMP Error:$/ ) {
        ($time, $date, $no_response, $host) = ($1, $2, undef, undef);
    }
    elsif( $date and $_ eq 'no response received' ) {
        $no_response = 1;
    }
    elsif( $date and $no_response and /^SNMPv1_Session \(remote host: "([^"]+)" \[([^\]]+)/ ) {
        push @{$error{$date}}, [$1,$2,$time];
        $_ = <> for (1..6); # throw away next six lines
    }
    elsif( /-- SNMPGET Problem for/
        or /-- WARNING: Expected a number/
        or m{at /usr/local/mrtg-2/bin/mrtg line \d+}
    ) {
        next;
    }
    else {
        $unmatched{$.} = $_;
    }
}

if( defined $args{t} ) {
    print( "$_ ", join( ", " => @{$error{$_}} ), "\n" ) for sort keys %error;
    exit;
}
exit 0 unless scalar keys %error or scalar keys %unmatched;

my $body = "The following gateways did not reply within 2 seconds\n\n";
foreach my $date( sort keys %error ) {
    $body .= "$date\n";
    foreach my $r( @{$error{$date}} ) {
        $body .= "    $r->[0] ($r->[1]) at $r->[2]\n";
    }
    $body .= "\n";
}

if( scalar keys %unmatched ) {
    $body .= "The following error messages were ignored\n";
    foreach( sort {$a<=>$b} keys %unmatched ) {
        $body .= "$_:$unmatched{$_}\n";
    }
    $body .= "\n";
}

$body .= "--end--";

my %mail;
@mail{ qw/From To Subject Body/ } = (
    FROM,
    TO,
    'Network Errors ' . join( ',' => sort keys %error ),
    $body,
);

sendmail(%mail) or die "$0: mail send failure:\n\t$Mail::Sendmail::error\n";

print "OK. Log says:\n", $Mail::Sendmail::log, "\n" if -t STDIN;

=head1 NAME

mrtg.errorcap - Capture and reformat MRTG errors, and send them via email

=head1 SYNOPSIS

B<mrtg.errorcap> [B<-t>]

=head1 DESCRIPTION

Capture and reformat the error messages that MRTG may emit when monitoring equiment

=head1 OPTIONS

=over 5

=item B<-t>

Test. Do not send email.

=head1 EXAMPLES

Usually run from cron. An example crontab entry may like the following

C<*/5 * * * * /usr/local/bin/mrtg /etc/mrtg.cfg 2E<gt>&1 | /usr/local/bin/mrtg.errorcap>

If a host does not reply to mrtg in the allotted time, a verbose error message is produced.
See the _END_ section at the end of this file for an example. This script cleans the messages
up and produces a report like

=over 4
The following gateways did not reply within 2 seconds

2002-01-25 11:10
    gw-ab (10.0.46.254) at 2002-01-25 11:10:14
    gw-jk (10.0.46.254) at 2002-01-25 11:10:26


--end--
=back

=head1 BUGS

None yet.

=head1 SEE ALSO

L<http://people.ee.ethz.ch/~oetiker/webtools/mrtg/mrtg.html|The MRTG web site>

=head1 COPYRIGHT

Copyright (c) 2002 David Landgren.

This script is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=head1 AUTHOR

     David "grinder" Landgren
     eval {join chr(64) => qw[landgren bpinet.com]}

=cut

__END__

2001-10-02 09:15:16 -- SNMP Error:
no response received
SNMPv1_Session (remote host: "gw-ab" [10.0.34.254].161)
                  community: "foo_bar"
                 request ID: 1857483728
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
2001-10-02 09:15:16 -- SNMPGET Problem for ifInOctets.8 ifOutOctets.8 sysUptime sysName on foo_bar@gw-ab:
 at /usr/local/mrtg-2/bin/mrtg line 1488
2001-10-02 09:15:16 -- WARNING: Expected a number but got ''
2001-10-02 09:15:16 -- WARNING: Expected a number but got ''
2001-10-02 09:15:26 -- SNMP Error:
no response received
SNMPv1_Session (remote host: "gw-cd" [10.0.37.254].161)
                  community: "foo_bar"
                 request ID: 1805349969
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
2001-10-02 09:15:26 -- SNMPGET Problem for ifInOctets.7 ifOutOctets.7 sysUptime sysName on foo_bar@gw-cd:
 at /usr/local/mrtg-2/bin/mrtg line 1488
2001-10-02 09:15:26 -- WARNING: Expected a number but got ''
2001-10-02 09:15:26 -- WARNING: Expected a number but got ''
2001-10-02 09:15:36 -- SNMP Error:
no response received
SNMPv1_Session (remote host: "gw-ef" [10.0.38.254].161)
                  community: "foo_bar"
                 request ID: 1479025078
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
2001-10-02 09:15:36 -- SNMPGET Problem for ifInOctets.7 ifOutOctets.7 sysUptime sysName on foo_bar@gw-ef:
 at /usr/local/mrtg-2/bin/mrtg line 1488
2001-10-02 09:15:36 -- WARNING: Expected a number but got ''
2001-10-02 09:15:36 -- WARNING: Expected a number but got ''