#!/usr/bin/perl -w
# nagios: -epn

use strict;
use Net::SNMP;
use Getopt::Long;
use Pod::Usage;

my $rmon_oid = '.1.3.6.1.2.1.2.2.1.2';
my $name_oid = '.1.3.6.1.2.1.31.1.1.1.1';
my $in_oct_oid = '.1.3.6.1.2.1.2.2.1.10';
my $out_oct_oid = '.1.3.6.1.2.1.2.2.1.16';
my $in_uni_pkt_oid = '.1.3.6.1.2.1.2.2.1.11';
my $out_uni_pkt_oid = '.1.3.6.1.2.1.2.2.1.17';
my $in_non_uni_pkt_oid = '.1.3.6.1.2.1.2.2.1.12';
my $out_non_uni_pkt_oid = '.1.3.6.1.2.1.2.2.1.18';

sub snmp_walk($$$) {
    my $session = shift;
    my $start = shift;
    my $callback = shift;

    my $oid = $start;

    while (1) {
        my $results = $session->get_next_request(
            -varbindlist => [ $oid ]
        );
        nagios_die($session->error()) unless $results;
    
        foreach my $result (keys %{ $results }) {
            return unless index($result, "${start}.") eq 0;
            $oid = $result;
    
            $callback->($start, $result, $results->{$result});
        }
    }
}

sub get_ifaces($) {
    my $session = shift;
    my $IFACES;
    
    snmp_walk($session, $rmon_oid, sub ($$) {
        my $root = shift;
        my $oid = shift;
        my $value = shift;

        if ($value =~ m/Ethernet|Port/) {
            my $id = substr($oid, length($root) + 1);
            $value =~ s/RMON://;
            $IFACES->{$id}{'name'} = $value;
            $IFACES->{$id}{'in'} = 0;
            $IFACES->{$id}{'out'} = 0;
        }
    });

    return $IFACES;
} 

sub generate_oids ($@) {
    my $root = shift;
    my @results = ();

    foreach my $val (@_) {
        push(@results, "${root}.${val}");
    }

    return @results;
}

sub get_info ($$$$) {
    my $session = shift;
    my $in_oid = shift;
    my $out_oid = shift;
    my $IFACES = shift;

    foreach my $root ($name_oid, $in_oid, $out_oid) {
        my $info = $session->get_request(
            -varbindlist => [ generate_oids($root, keys %{ $IFACES }) ]
        );
    
        if (defined $info) {
            foreach my $oid (keys %{ $info }) {
                if (index($oid, $name_oid) eq 0) {
                    if ($info->{$oid}) {
                        my $id = substr($oid, length($name_oid) + 1);
                        $IFACES->{$id}{'name'} = $info->{$oid};
                    }
                }
                elsif (index($oid, $in_oid) eq 0) {
                    my $id = substr($oid, length($in_oid) + 1);
                    $IFACES->{$id}{'in'} = $info->{$oid};
                }
                elsif (index($oid, $out_oid) eq 0) {
                    my $id = substr($oid, length($out_oid) + 1);
                    $IFACES->{$id}{'out'} = $info->{$oid};
                }
            }
        }
        else {
            nagios_die($session->error());
        }
    }

    return $IFACES;
}

sub nagios_die ($) {
    my $err = shift;
    $err = "Unknown error" unless defined $err;
    print "SNMP UNKNOWN - $err\n";
    exit 3;
}

my $host;
my $port = 161;
my $community = 'public';
my $timeout = 10;
my $packets = 0;
my $non_unicast_packets = 0;
my $help = 0;

Getopt::Long::Configure ("bundling");
GetOptions('host|H=s'            => \$host,
           'port|p=i'            => \$port,
           'community|C=s'       => \$community,
           'timeout|t=i'         => \$timeout,
           'packets'             => \$packets,
           'non-unicast-packets' => \$non_unicast_packets,
           'help|?'              => \$help)
or pod2usage(2);
pod2usage(0) if $help;
pod2usage(2) unless (defined $host);

$SIG{'ALRM'} = sub {
    nagios_die('Check timed out');
};
alarm($timeout);

my ($session, $err) = Net::SNMP->session(
    -hostname => $host,
    -port => $port,
    -community => $community
);
nagios_die($err) unless defined $session;

my $in_oid;
my $out_oid;
if ($non_unicast_packets) {
    $in_oid = $in_non_uni_pkt_oid;
    $out_oid = $out_non_uni_pkt_oid;
}
elsif ($packets) {
    $in_oid = $in_uni_pkt_oid;
    $out_oid = $out_uni_pkt_oid;
}
else {
    $in_oid = $in_oct_oid;
    $out_oid = $out_oct_oid;
}

my $IFACES = get_ifaces($session);
get_info($session, $in_oid, $out_oid, $IFACES);
$session->close();

my $channel = grep { $IFACES->{$_}{'name'} =~ /^ch/} keys %{ $IFACES };
my $if = grep { $IFACES->{$_}{'name'} !~ /^ch/} keys %{ $IFACES };
print "SNMP OK - $if interfaces, $channel port channel |";
foreach my $key (sort {$a <=> $b} keys %{ $IFACES }) {
    printf " %s(in)=%sc; %s(out)=%sc;", $IFACES->{$key}{'name'}, $IFACES->{$key}{'in'}, $IFACES->{$key}{'name'}, $IFACES->{$key}{'out'};
}
print "\n";
exit 0;

__END__

=head1 check_snmp_switch_traffic

check_snmp_switch_traffic - Monitor switch ports via SNMP

=head1 SYNOPSIS

check_snmp_swtich_traffic --host|-H HOSTNAME [options]

=item B<Options:>

  --port|-p PORT
  --community|-C COMMUNITY
  --timeout|-t TIMEOUT
  --packets
  --non-unicast-packets
  --help|-?

=head1 OPTIONS

=over 8

=item B<--host|-H>

Specify the host to connect to via SNMP. This option is required.

=item B<--port|-p>

Port to connect to. If not specified it defaults to 161.

=item B<--community|-C>

SNMPv1 Community string. If not specified it defaults to "public".

=item B<--timeout|-t>

Maximum runtime in seconds of this script before returning UNKNOWN.
If not specified it defaults to 10.

=item B<--packets>

Get the counter for the send and received unicast packets.

=item B<--non-unicast-packets>

Get the counter for the send and received non unicast packets.
If B<--packets> and B<--non-unicast-packets> are given, the
B<--packets> switch is ignored.

=item B<--help|-?>

Display a help message about the available options.

=back

=head1 DESCRIPTION

B<check_snmp_switch_traffic> fetches the available ports of a switch
and queries the in and out octet counters via SNMP. It is also possible
to get the counter for unicast and non-unicast packets.

=cut