#!/usr/bin/perl -w

use strict;
use IP;

#snmpwalk flags reference (full version man snmpwalkcmd
#
#-Oq    Removes the equal sign and type information:
#-Os    Deletes all but the last symbolic part of the OID:
#-Ov    Output only the variable value, not the OID:
#-O0    Print leading zero before HEX data

#id is het ip
#0 = mac
#1 = subnet
#2 = member of node
my %ipDB = ();

#enable debugging
my $debug_enable = 1;
my $start_host= '172.16.1.161';
#dictionary variable
my $unknown_node = "unknown_node";
my $remote_node = "remote_node";

#regular expressions
my $ipv4_regexp = '(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})';
my $mac_regexp = '[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}';

#tmp variablen
my $raw_string = "";
my @raw_array = ();
my %raw_hash = ();


#debugging sub
sub debug {
  if( $debug_enable ) {
    print "$_[0] \n";
  }
};

#run snmp_command;
sub snmp_command {
  my $flags = $_[0];
  my $host = $_[1];
  my $identifier = $_[2];
  debug("host = $host");
  my $command = "snmpwalk -v 1 -O$flags -c public $host $identifier";
  debug("command =$command");
  my $raw_output = `$command`;
  debug("Raw output = $raw_output");
  $raw_output =~ s/\n.*$//;
  debug("Reniced output = $raw_output");
  return($raw_output);
};


#some hashes
  my %local_ips = ();
  my %remote_ips = ();
  my %ip2mac = ();
  my %ip2subnet = ();

# ip's who are used for special purposes like, loopback or general
# aliasss
sub allowed_ip {
  my %deny_list = ();
  $deny_list{'127.0.0.1'} = 1;
  $deny_list{'172.31.255.1'} =1;
  if( exists $deny_list{$_[0]} ) {
    return(0);
  }
  else {
    return(1);
  };
};


#during this part there will be checked whether we could use a ip
#address as neighboor ip or as local ip
#This is written to enimilate the acess point's ip of the clients
sub ip_remote_check {
  my $ip = $_[0];
  foreach my $local_ip (keys %local_ips) {
    debug("checking if $ip is at $local_ip / $ip2subnet{$local_ip}");
    if( IP::calcOnNetwork($local_ip, $ip, $ip2subnet{$local_ip}) ) {
      if( IP::getNetmask($ip2subnet{$local_ip}) > 28 ) {
        debug("$ip seems to be really remote of $local_ip");
        return(1);
      };
    };
  };
  return(0);
};

#ipAdEntNetMask.172.16.1.166 255.255.255.252 -> 
#$ip2subnetPart{172.16.1.166} = 255.255.255.252
$raw_string = snmp_command("qs",$start_host,"ipAdEntNetMask");
@raw_array = split(/\n/, $raw_string);
foreach my $line (@raw_array) {
  if( $line =~ /\S*\.($ipv4_regexp) ($ipv4_regexp)$/ ) {
    debug("ip $1 at $6");
    $ip2subnet{$1} = $6;
  };
};

#ipNetToMediaPhysAddress.4.172.27.129.1 00:02:6f:34:3a:ed -> 
#$ipDB{172.27.129.1}[0] = 00:02:6f:34:3a:ed
$raw_string = snmp_command("0qs", $start_host, "ipNetToMediaPhysAddress");
@raw_array = split(/\n/, $raw_string);
foreach my $line (@raw_array) {
  if( $line =~ /\S*\.($ipv4_regexp) ($mac_regexp)/ ) {
    $ipDB{$1}[0] = $6;
    $ipDB{$1}[1] = $ip2subnet{$1};
    $ipDB{$1}[2] = $unknown_node;
    debug("ip $1 has $6");
  };
};

my $nodename = snmp_command("sqv", $start_host, "sysName");
#my $ifaces = snmp_command("qs", $start_host, "ifNumber");


#ipAdEntIfIndex.127.0.0.1 3
#$ipDB{'127.0.0.1'}[2] = 'nodename'
#$local_ips{'127.0.0.1'} = subnet node
$raw_string = `snmpwalk -v 1 -Osq -c public $start_host ipAdEntIfIndex`;
@raw_array = split(/\n/, $raw_string);
foreach my $line (@raw_array) {
  if( $line =~ /\S*\.($ipv4_regexp) (\d+)/ ) {
    if( allowed_ip($1) ) {
      debug("local $1 is member of $nodename");
      $ipDB{$1}[2] = $nodename;
      $local_ips{$1} = $ipDB{$1}[1];
    };
  };
};


#atIfIndex.1.1.172.27.129.66 1
#als ip niet in local_ips voorkomt dan:
$raw_string = snmp_command("qs", $start_host, "atIfIndex");
@raw_array = split(/\n/, $raw_string);

foreach my $line (@raw_array) {
  if( $line =~ /\S*\.($ipv4_regexp) \S*/ ) {
    if( allowed_ip($1) ) {
      if( $ipDB{$1}[2] eq $unknown_node ) {
        debug("remote ip $1");
        if( ip_remote_check($1) ) {
          debug("remote ip $1 has probely node attached");
          $ipDB{$1}[2] = $remote_node;
          $remote_ips{$1} = $ipDB{$1}[0];
        }
        else {
          debug("remote ip $1 seems to be a exception");
        };
      };
    };
  };
};


exit;