#!/bin/bash

# startup checks
if [ -z "$BASH" ]; then
  echo "Please use BASH."
  exit 3
fi
if [ ! -e "/usr/bin/which" ]; then
  echo "/usr/bin/which is missing."
  exit 3
fi
snmp=$(which snmpwalk)
if [ $? -ne 0 ]; then
  echo "Please install snmpwalk"
  exit 3
fi

# Default Values
community="pal-ro"
version="2"
more=""

# State Variables
STATE_OK=0
STATE_WARN=1
STATE_CRIT=2
STATE_UNK=3

# Default Outputs
STATE=$STATE_OK
STATE_STRING=""
PERFDATA=""

# Usage Info
usage() {
  echo '''
  Usage: check_snmp [OPTIONS]
  [OPTIONS]

  -p PORT            Port to send the snmp request to (default: 161)
  -N COMMUNITY       SNMP community name (default: public)
  -H HOST            Hostname to send SNMP queries to
  -o OID             SNMP OID to query
  -V VERSION         SNMP Version (default: 2)
  -M MORE            When using -V 3, pass all required snmpwalk parameters
                     with -M, i.E. "-u user -a MD5 -A 72d0815....D38 -x AES"

  -w WARNING         Defines limit for WARNING
  -c CRITICAL        Defines limit for CRITICAL
  '''
}

#main
#get options
while getopts "p:N:H:o:V:M:W:C:w:c:" opt; do
  case $opt in
      port=$OPTARG
      ;;
    N)
      community=$OPTARG
      ;;
    H)
      host=$OPTARG
      ;;
    o)
      oid=$OPTARG
      ;;
    V)
      version=$OPTARG
      ;;
    M)
      more=$OPTARG
      ;;
    w)
      warning=$OPTARG
      ;;
    c)
      critical=$OPTARG
      ;;
    *)
      usage
      exit 3
      ;;
  esac
done

#required paramters
if [ -z "$host" ]; then
  echo "Error: host is required"
  usage
  exit 3
fi
if [ -z "$oid" ]; then
  echo "Error: oid is required"
  usage
  exit 3
fi

if ! [[ "$version" =~ ^[0-9]+$ ]]; then
  echo "Error: -V must be 1 , 2 or 3"
  usage
  exit 3
fi
if [ $version -lt 1 ] || [ $version -gt 3 ]; then
  echo "Error: -V must be 1 , 2 or 3"
  usage
  exit 3
fi
oversion=$version
if [ $version -eq 2 ];then
  version="-v2c"
elif [ $version -eq 1 ]; then
  version="-v1"
fi

if [ $oversion -eq 3 ] ; then
  rtr=$(snmpwalk $version -c $community $host $oid)
fi
status=$?

rtr=$(echo $rtr | cut -d " " -f 4)

echo "Value is: $rtr"

exit 0