#!/usr/bin/perl -w
#
# Copyright (C) 2006 Lars Strand
#
# Munin plugin to monitor network connection by use of SNMP.
# Based on snmp__df plugin.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2 dated June,
# 1991.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
# $Log$
#
#%# family=snmpauto
#%# capabilities=snmpconf

use strict;
use Net::SNMP;

my $DEBUG = 0;

my $host      = $ENV{host}      || undef;
my $port      = $ENV{port}      || 161;
my $community = $ENV{community} || "public";

my $response;

my %tcpStates = ( 1 =>  [0, "GAUGE", "closed", "Connections waiting for a termination request acknowledgment from the remote TCP."],
		  2 =>  [0, "GAUGE", "listen", "Connections waiting for a request from any remote TCP and port."],
		  3 =>  [0, "GAUGE", "synSent", "Connections waiting for a matching request after having sent a connection request."],
		  4 =>  [0, "GAUGE", "synReceived", "Connections waiting for a confirming request acknowledgment after having both received and sent a connection request."],
		  5 =>  [0, "GAUGE", "established", "Connections opened and data received can be delivered to the user. The normal state for the data transfer phase of the connection."],
		  6 =>  [0, "GAUGE", "finWait1", "Connections waiting for a termination request from the remote TCP, or an acknowledgment of the connection termination request previously sent."],
		  7 =>  [0, "GAUGE", "finWait2", "Connections waiting for a termination request from the remote TCP."],
		  8 =>  [0, "GAUGE", "closeWait", "Connections waiting for a termination request from the local user."],
		  9 =>  [0, "GAUGE", "lastAck", "Connections waiting for an acknowledgment of the termination request previously sent to the remote TCP (which includes an acknowledgment of its connection termination request)."],
		  10 => [0, "GAUGE", "closing", "Connections waiting for a termination request acknowledgment from the remote TCP."],
		  11 => [0, "GAUGE", "timeWait", "Connections waiting for enough time to pass to be sure the remote TCP received the acknowledgment of its termination request."],
		  12 => [0, "GAUGE", "deleteTCP", "Connections terminated by a SNMP Managment Station (put)"]
		  );

if (defined $ARGV[0] and $ARGV[0] eq "snmpconf")
{
    print "require 1.3.6.1.2.1.6.13.1.1. [0-9]\n";
    exit 0;
}

if ($0 =~ /^(?:|.*\/)snmp_([^_]+)_netstat$/)
{
    $host  = $1;
    if ($host =~ /^([^:]+):(\d+)$/)
    {
	$host = $1;
	$port = $2;
    }
}
elsif (!defined($host))
{
    print "# Debug: $0 -- $1\n" if $DEBUG;
    die "# Error: couldn't understand what I'm supposed to monitor.";
}

if (defined $ARGV[0] and $ARGV[0] eq "config")
{
    print "host_name $host\n";
    print "graph_title Netstat\n";
    print "graph_args -l 0 --base 1000\n";
    print "graph_period seconds\n";
    print "graph_category network\n";
    print "graph_order closed listen synSent synReceived established finWait1 finWait2 closeWait lastAck closing timeWait deleteTCP\n";
    print "graph_vlabel active connection\n";
    print "graph_info This graph shows the TCP activity of all the network interfaces combined.\n";
    
    foreach my $state (keys %tcpStates) {
	print "$tcpStates{$state}[2].label $tcpStates{$state}[2]\n";
	print "$tcpStates{$state}[2].type $tcpStates{$state}[1]\n";
	print "$tcpStates{$state}[2].max 50000\n";
	print "$tcpStates{$state}[2].min 0\n";
	print "$tcpStates{$state}[2].info $tcpStates{$state}[3]\n";
    }
   
    exit 0;
}

my $tcpConnState = "1.3.6.1.2.1.6.13.1.1.";

my ($session, $error) = Net::SNMP->session(
	   -hostname  => $host,
	   -community => $community,
	   -port      => $port
        );

if (!defined ($session))
{
    die "Croaking: $error";
}

my $connections = get_by_regex($session, $tcpConnState, "[1-9]");

# the values
while (my ($id, $state) = each(%$connections)) {
    $tcpStates{$state}[0] += 1;
}

foreach my $state (keys %tcpStates) {
    print "$tcpStates{$state}[2].value $tcpStates{$state}[0]\n";
}

sub get_by_regex
{
    my $handle = shift;
    my $oid    = shift;
    my $regex  = shift;
    my $result = {};
    my $num    = 0;
    my $ret    = $oid . "0";
    my $response;
    
    print "# Starting browse of $oid...\n" if $DEBUG;
    
    while (1)
    {
	if ($num == 0)
	{
	    print "# Checking for $ret...\n" if $DEBUG;
	    $response = $handle->get_request ($ret);
	}
	if ($num or !defined $response)
	{
	    print "# Checking for sibling of $ret...\n" if $DEBUG;
	    $response = $handle->get_next_request ($ret);
	}
	if (!$response)
	{
	    return undef;
	}
	my @keys = keys %$response;
	$ret = $keys[0];
	print "# Analyzing $ret (compared to $oid)...\n" if $DEBUG;
	last unless ($ret =~ /^$oid/);
	$num++;
	next unless ($response->{$ret} =~ /$regex/);
	@keys = split (/\./, $ret);
	$result->{$keys[-1]} = $response->{$ret};;
	print "# Index $num: ", $keys[-1], " (", $response->{$ret}, ")\n" if $DEBUG;
    };
    return $result;
}