#!/usr/bin/perl         
#
# This little program was written becuase I had a few freebsd
# machines that were not giving out the right information for
# snmpd's ifInOctets and ifOutOctets, thus remote monitoring
# for this information via snmpd was useless to me.
#
# After some heavy reading into some of the features ucd-snmpd
# provides I found a feature called "pass-through", which is a
# setting within the snmpd.conf that allows you to (unlike the
# exec option), pass entire mib tree's to an external program or
# script. Hence I can take data that is normally generated by
# snmpd (and in my case the failure to generate), and make it
# spit out the RIGHT information.
#
# This script uses the .1.3.6.1.2.1.2.2.1.10 and .16 oid tree's
# which are the default inoctets and outoctets. It reads the
# information it needs to get from netstat. This supports both
# "get" requests and "getnext" requests.
#
# From what I have seen, this is *bsd only (due to the way it
# gets its information from netstat), yet can easily be changed
# to work with other unix variants..
#               
# In order to utilize this script, in your specified snmpd.conf
# put these lines somewhere in the file:
#
# pass .1.3.6.1.2.1.2.2.1.16 /local/bin/snmp-pass.pl
# pass .1.3.6.1.2.1.2.2.1.10 /local/bin/snmp-pass.pl
# 
# For quicker responses and a little faster output, try      
# compiling this program using perlcc.
# 
# Mark Thomas <mrk@ackers.net>

use strict;
 
my $oidreplace = ".1.3.6.1.2.1.2.2.1";
my $in = 10;
my $out = 16;
my $bytes = 0;
my $gorn = $ARGV[0];
my $oid  = $ARGV[1];

if ($gorn eq "-g") {

        if ($oid =~ /$oidreplace/) {
                my $num = $oid;
                $num =~ s/.*\.(\d+)\.(\d+$)/$1 $2/g;
                my $inorout = $1;
                my $num = $2;
                my(@ints) = get_int_info();
                my $num_ints = @ints;
                if ($num > $num_ints) { 
                        print "$num to big\n";
                        exit 0;
                }
                my $num_get = $num - 1;
                if ($num_get < 0) {
                        print "$num to small\n";
                        exit;
                }
                if ($inorout eq $in) {
                        $bytes = get_in_bytes($ints[$num_get]);
                }
                elsif ($inorout eq $out) {
                        $bytes = get_out_bytes($ints[$num_get]);
                }
                else {
                        exit 0;
                }
                do_output($bytes,$oid);
        }
        else {
                exit;
        }

}
elsif ($gorn eq "-n") {
        if ($oid =~ /$oidreplace/) {
                my(@ints) = get_int_info();
                my $num_ints = @ints;
                if ($oid =~ /.1.3.6.1.2.1.2.2.1.10$/) {
                        my $yoid = "$oidreplace.10.1";
                        $bytes = get_in_bytes($ints[0]);
                        do_gn_output($bytes,$yoid);
                }
                elsif ($oid =~ /.1.3.6.1.2.1.2.2.1.16$/) {
                        my $yoid = "$oidreplace.16.1";
                        $bytes = get_out_bytes($ints[0]);
                        do_gn_output($bytes,$yoid);
                }
                elsif ($oid =~ /$oidreplace.\d+.\d+$/) {
                        my $num = $oid;
                        $num =~ s/.*\.(\d+)\.(\d+$)/$1 $2/g;
                        my $inorout = $1;
                        my $num = $2;
                        my $numforint = $num;
                        my $numforoid = $num + 1;
                        if ($num+1 > $num_ints) {
                                print "$num to big\n";
                                exit 0;
                        }
                        if ($inorout eq $in) {
                                $bytes = get_in_bytes($ints[$num]);
                        }
                        elsif ($inorout eq $out) {
                                $bytes = get_out_bytes($ints[$num]);
                        }
                        my $yoid = "$oidreplace.$inorout.$numforoid";
                        do_output($bytes,$yoid);
                } else { exit 0; }
        } else { exit 0; }
}
else { exit; }

sub do_output {

        my($data,$yoid) = @_;
        if ($data eq "") {
                $data = 0;
        }
        print "$yoid\n";
        print "counter\n";
        print "$data\n";
        exit 0;
}

sub get_int_info {

        my $ifconfig = `/sbin/ifconfig -l 2>/dev/null`;
        $ifconfig =~ s/ /,/g;
        $ifconfig =~ s/\n//g;
        my(@ints) = split(/,/, $ifconfig);
        return @ints;
                                
}

sub get_in_bytes {
                                
        my ($int_name) = $_[0];
        my @netstat = `/usr/bin/netstat -b -I $int_name`;
        my $good_inf = $netstat[1];
        $good_inf =~ s/\://g;
        $good_inf =~ s/\D+/ /g;
        $good_inf =~ s/^\s//g;
        my($nu,$nu,$nu,$nu,$nu,$nu,$nu,$inbytes,$nu,$nu,$outbytes,$nu) = split(/ /, $good_inf);
        return $inbytes;  
}

sub get_out_bytes {
        my ($int_name) = $_[0];
        my @netstat = `/usr/bin/netstat -b -I $int_name`;
        my $good_inf = $netstat[1];
        $good_inf =~ s/\://g;
        $good_inf =~ s/\D+/ /g;
        $good_inf =~ s/^\s//g;
        my($nu,$nu,$nu,$nu,$nu,$nu,$nu,$inbytes,$nu,$nu,$outbytes,$nu) = split(/ /, $good_inf);
        return $outbytes; 
}