#!/usr/bin/env bash

# Author: Antonino Catinello
# License: MIT-License
# Description: Nagios HTTP/HTTPS check via wget (with/without Proxy)

#startup checks
if [ -z "$BASH" ]; then
  echo "Please use BASH."
  exit 3
fi

#bash builtin
if [ ! -e "/usr/bin/which" ]; then
  echo "/usr/bin/which is missing."
  exit 3
fi

#wget
wget=$(which wget)
if [ $? -ne 0 ]; then
  echo "Please install wget."
  exit 3
fi

#variables
version=0.3
wget=$(which wget)
ssl=""
fake=""
host=""
port=""
proxy=""
url="/"
times=1
timeout=10
warning=500
critical=2000
certificate=""
bindaddress=""

#functions
#set system proxy from environment
function getProxy() {
  if [ -z "$1" ]; then
    echo $http_proxy | awk -F'http://' '{print $2}'
  else
    echo $https_proxy | awk -F'http://' '{print $2}'
  fi
}


function version() {
  echo "  Version: ${version} - License: MIT"
}

#usage info
function usage() {
  echo '''Usage: check_website [OPTIONS] {HOSTNAME}
  {HOSTNAME}
	host to check (dns/ip)
  [OPTIONS]:
	-p PORT		port to check (default: 80)
	-u URL		url path (default: /)
	-f		use fake agent (windows xp/firefox 25)
	-s		use SSL via HTTPS (default: 443)
	-P PROXY	proxy access (hostname:port)
	-w WARNING	warning threshold in milliseconds (default: 500)
	-c CRITICAL	critical threshold in milliseconds (default: 2000)
	-n TRIES	number of times to try (default: 1)
	-t TIMEOUT	amount of time to wait in seconds (default: 10)
	-C CERTIFICATE	client certificate stored in file location (PEM AND DER file types allowed)
	-b IP		bind ip address used by wget (default: primary system address)'''
	version
}

#check which threshold was reached
function checkTime() {
  if [ $1 -gt $critical ]; then
    echo -n "CRITICAL"
  elif [ $1 -gt $warning ]; then
    echo -n "WARNING"
  else
    echo -n "OK"
  fi
}

#return code value
function getStatus() {
  if [ $1 -gt $critical ]; then
    retcode=2
  elif [ $1 -gt $warning ]; then
    retcode=1
  else
    retcode=0
  fi
}

#main
#get options
while getopts "w:c:p:sfu:P:n:t:C:b:" opt; do
  case $opt in
    w)
      warning=$OPTARG
      ;;
    c)
      critical=$OPTARG
      ;;
    p)
      port=$OPTARG
      ;;
    s)
      ssl=1
      ;;
    f)
      fake=1
      ;;
    u)
      url=$OPTARG
      ;;
    P)
      proxy=$OPTARG
      ;;
    n)
      times=$OPTARG
      ;;
    t)
      timeout=$OPTARG
      ;;
    C)
      client_certificate=$OPTARG
      ;;
    b)
      bindaddress=$OPTARG
      ;;
    *)
      usage
      exit 3
      ;;
  esac
done

#define host with last parameter
host=${@: -1}

#hostname is required
if [ -z "$host" ] || [ $# -eq 0 ]; then
  echo "Error: host is required"
  usage
  exit 3
fi

#set proxy from environment if available and no proxy option is given
if [ -z "$proxy" ]; then
  proxy="$(getProxy ssl)"
fi

#use ssl or not
if [ -z "$ssl" ]; then
  header="HTTP"
  proxy_cmd="http_proxy=$proxy"
  url_prefix="http://"
else
  header="HTTPS"
  proxy_cmd="https_proxy=$proxy"
  url_prefix="https://"
fi

#different port
if [ -z "$port" ]; then
  url="${url_prefix}${host}${url}"
else
  url="${url_prefix}${host}:${port}${url}"
fi

#check fake user agent
if [ -z "$fake" ] && [ -z "$client_certificate" ]; then
  #execute and capture execution time and return status of wget
  start=$(echo $(($(date +%s%N)/1000000)))
  $wget -t $times --timeout $timeout -O /dev/null -q -e $proxy_cmd --bind-address=${bindaddress} $url
  status=$?
  end=$(echo $(($(date +%s%N)/1000000)))
elif [ -z "$fake" ] && [ -n "$client_certificate" ]; then
  #execute and capture execution time and return status of wget with client certificate
  start=$(echo $(($(date +%s%N)/1000000)))
  $wget -t $times --timeout $timeout -O /dev/null -q -e $proxy_cmd --bind-address=${bindaddress} --certificate=$client_certificate $url
  status=$?
  end=$(echo $(($(date +%s%N)/1000000)))
elif [ -n "$fake" ] && [ -n "$client_certificate" ]; then
  #execute with fake user agent and capture execution time and return status of wget with client certificate
  start=$(echo $(($(date +%s%N)/1000000)))
  $wget -t $times --timeout $timeout -O /dev/null -q -e $proxy_cmd --bind-address=${bindaddress} --certificate=$client_certificate $url \
  --header="User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:25.0) Gecko/20100101 Firefox/25.0" \
  --header="Accept: image/png,image/*;q=0.8,*/*;q=0.5" \
  --header="Accept-Language: en-us,en;q=0.5" \
  --header="Accept-Encoding: gzip, deflate"
  status=$?
  end=$(echo $(($(date +%s%N)/1000000)))
else
  #execute with fake user agent and capture execution time and return status of wget
  start=$(echo $(($(date +%s%N)/1000000)))
  $wget -t $times --timeout $timeout -O /dev/null -q -e $proxy_cmd --bind-address=${bindaddress} $url \
  --header="User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:25.0) Gecko/20100101 Firefox/25.0" \
  --header="Accept: image/png,image/*;q=0.8,*/*;q=0.5" \
  --header="Accept-Language: en-us,en;q=0.5" \
  --header="Accept-Encoding: gzip, deflate"
  status=$?
  end=$(echo $(($(date +%s%N)/1000000)))
fi

#decide output by return code
if [ $status -eq 0 ] ; then
  echo "${header} $(checkTime $((end - start))): $((end - start))ms - ${url}|time=$((end - start))ms;${warning};${critical};0;"
  getStatus $((end - start))
  exit $retcode
else
  case $status in
    1)
      echo "${header} CRITICAL: Generic error code ($status) - ${url}"
      ;;
    2)
      echo "${header} CRITICAL: Parse error ($status) - ${url}"
      ;;
    3)
      echo "${header} CRITICAL: File I/O error ($status) - ${url}"
      ;;
    4)
      echo "${header} CRITICAL: Network failure ($status) - ${url}"
      ;;
    5)
      echo "${header} CRITICAL: SSL verification failure ($status) - ${url}"
      ;;
    6)
      echo "${header} CRITICAL: Authentication failure ($status) - ${url}"
      ;;
    7)
      echo "${header} CRITICAL: Protocol errors ($status) - ${url}"
      ;;
    8)
      echo "${header} CRITICAL: Server issued an error response ($status) - ${url}"
      ;;
    *)
      echo "${header} UNKNOWN: $status - ${url}"
      exit 3
      ;;
  esac
  exit 2
fi