#!/usr/bin/env bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin

datum=`/bin/date +"%d.%m.%Y"`

email_to=$1
email_to=${email_to:="root"}

email_from="$(whoami)@$(hostname --long)"

file=/tmp/mail_ip-up$$

INET_INTERFACE="$(netstat -rn | grep -e"^0.0.0" | awk '{print$8}')"
if [[  -n "$INET_INTERFACE" ]] ; then
   EXTERN_IPv4="$(ip addr show $INET_INTERFACE | grep -E "\s+inet\s+" | awk '{print$2}')"
   EXTERN_IPv6="$(ip addr show $INET_INTERFACE | grep global | grep -E "\s+inet6\s+" | awk '{print$2}')"
fi

if [[ -n "${EXTERN_IPv4}" ]] ; then
   if [[ "${EXTERN_IPv4}" =~ ^10\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.16\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.17\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.18\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.19\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.20\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.21\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.22\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.23\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.24\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.25\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.26\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.27\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.28\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.29\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.30\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^172\.31\. ]] \
      || [[ "${EXTERN_IPv4}" =~ ^192\.168\. ]] ; then
      
      PUBLIC_IPv4="$(wget -qO- https://meine-ip.oopen.de 2> /dev/null)"
   fi
fi


DNS_SERVER="$(cat /etc/resolv.conf | grep -v -e"^#" | grep nameserver | cut -d " " -f2)"
DEFAULT_GW="$(netstat -rn | grep -e"^0.0.0" | awk '{print$2}')"

echo "" > $file
echo " *******************************************************" >> $file
echo " ***          This is an autogenerated mail          ***" >> $file
echo "" >> $file
echo -e "\tHost.........................: `hostname --long`" >> $file
echo "" >> $file
echo -e "\tSender.......................: $email_from" >> $file
echo "" >> $file
if [[ -n "$INET_INTERFACE" ]] ; then
   echo -e "\tInterface extern.............: $INET_INTERFACE" >> $file
   echo "" >> $file
   declare -i i=1
   for ip in $EXTERN_IPv4 ; do
      if [ $i -eq 1 ]; then 
         echo -e "\t   Local IPv4 address...........: $ip" >> $file
      else
         echo -e "\t                                  $ip" >> $file
      fi
      let i++
   done
   i=1
   for ip in $EXTERN_IPv6 ; do
      if [ $i -eq 1 ]; then
         echo "" >> $file
         echo -e "\t   Local IPv6 address...........: $ip" >> $file
      else
         echo -e "\t                                  $ip" >> $file
      fi
      let i++
   done
fi
echo "" >> $file
if [ "$DEFAULT_GW" ] ; then
   echo -e "\t   Default Gateway..............: $DEFAULT_GW" >> $file
fi
if [[ -n "${PUBLIC_IPv4}" ]] && [[ "${PUBLIC_IPv4}" != "${EXTERN_IPv4}" ]]; then
   echo "" >> $file
   echo -e "\t   öffentliche IPv4 address.....: ${PUBLIC_IPv4}" >> $file
fi
   
echo "" >> $file
declare -i i=1
for dns in $DNS_SERVER ; do
   echo -e "\tNameserver $i.................: $dns" >> $file
   let i++
done
echo "" >> $file
echo -e "\tDate.........................: $(date +"%d.%m.%Y")" >> $file
echo -e "\tTime.........................: $(date +"%H:%M:%S")" >> $file
echo "" >> $file
echo " ***                                                 ***" >> $file
echo " *******************************************************" >> $file


echo -e "From:${email_from}\nTo:${email_to}\nSubject:Test on $(hostname --long) at  $datum\n\n$(/bin/cat $file)" | /usr/sbin/sendmail -F "$(whoami)" -f $email_from  $email_to


rm -f $file
exit 0