#!/usr/bin/env bash

# - Adds DKIM subdomain delegation for a given domain
# -
# - Return (Exit) Codes:
# -    success:
# -       0:    DKIM subdomain delegation already exists
# -       1:    DKIM subdomain delegation added
# -    error:
# -      11:    No zonefile found
# -      15:    Hostname/Domain not supported
# -      16:    Determin Nameservers failed
# -      21:    Adding Record failed
# -      99:    Fatal error
# - 
# - Example:
# -   bind_create_dkim_delegation.sh oopen.de

script_name="$(basename $(realpath $0))"
working_dir="$(dirname $(realpath $0))"

conf_file="${working_dir}/conf/bind.conf"

log_file="$(mktemp)"

backup_date="$(date +%Y-%m-%d-%H%M)"

# ----------
# Setting Defaults
# ----------

DEFAULT_CONF_FILE_DIR="/etc/bind"
DEFAULT_BIND_USER="bind"
DEFAULT_BIND_GROUP="bind"


# **********
# Don't make changes after this 
# **********


# ----------
# Base Function(s)
# ----------

usage() {


   [[ -n  "$1" ]] && error "$1"


   [[ $verbose ]] && echo -e "
\033[1mUsage:\033[m

   $(basename $0) [Options] <dkim-domain> | check

\033[1mDescription\033[m

   Scripts add a nameserver delegation for zone _domainkey.<dkim-domain>. The nameserver
   for the new zone are the same as for the domain itself.

\033[1mReturn (Exit) Codes\033[m

   success:
       0:    DKIM subdomain delegation already exists
       1:    DKIM subdomain delegation added

   error:
      11:    No zonefile found
      15:    Hostname/Domain not supported
      16:    Determin Nameservers failed
      21:    Adding Record failed
      99:    Fatal error

\033[1mOptions\033[m

   -h
      Prints this help.

   -q 
      Runs in silent mode.

\033[1mFiles\033[m

   $conf_file: Configuration file

\033[1mExample:\033[m
   
   Create DKIM delegation for domain oopen.de.

      \033[1m$(basename $0) oopen.de\033[m

   This results in NS Records like:

      _domainkey.oopen.de. IN NS name-server-1
      _domainkey.oopen.de. IN NS name-server-2

"

   clean_up 1

}


clean_up() {

   # Perform program exit housekeeping
   rm $log_file
   blank_line
   exit $1
}

echononl(){
   if $verbose ; then
      echo X\\c > /tmp/shprompt$$
      if [ `wc -c /tmp/shprompt$$ | awk '{print $1}'` -eq 1 ]; then
         echo -e -n "   $*\\c" 1>&2
      else
         echo -e -n "   $*" 1>&2
      fi
      rm /tmp/shprompt$$
   fi
}

warn (){
   if $verbose ; then
      echo ""
      echo -e "   [ \033[33m\033[1mWarning\033[m ]: $*"
      echo ""
   fi
}

info (){
   if $verbose ; then
      echo ""
      echo -e "   [ \033[32m\033[1mInfo\033[m ]: $*"
      echo ""
   fi
}

error(){
   if $verbose ; then
      echo ""
      echo -e "   [ \033[31m\033[1mFehler\033[m ]: $*"
      echo ""
   fi
}

echo_ok() {
   if $verbose ; then
      echo -e "\033[75G[ \033[32mok\033[m ]"
   fi
}
echo_failed(){
   if $verbose ; then
      echo -e "\033[75G[ \033[1;31mfailed\033[m ]"
   fi
}
echo_skipped() {
   if $verbose ; then
      echo -e "\033[75G[ \033[33m\033[1mskipped\033[m ]"
   fi
}

backup_dir () {
   dir_to_backup=$1
   echononl "Backup existing directory \"$dir_to_backup\" .."
   if [[ -d "$dir_to_backup" ]] ; then
      cp -a "$dir_to_backup" "${dir_to_backup}.$backup_date" > $log_file 2>&1
      if [[ $? -eq 0 ]]; then
         echo_ok
      else
         echo_failed
         error "Backup directory \"$dir_to_backup\" failed!"
         clean_up 99
      fi
   else
      echo_failed
      error "Directory \"$dir_to_backup\" not found. No Backup written!"
      clean_up 99
   fi

}

blank_line() {
   if $verbose ; then
      echo ""
   fi
}

trim() {
    local var="$*"
    var="${var#"${var%%[![:space:]]*}"}"   # remove leading whitespace characters
    var="${var%"${var##*[![:space:]]}"}"   # remove trailing whitespace characters
    echo -n "$var"
}


# ----------
# - Jobhandling 
# ----------

# - Run 'clean_up' for signals SIGHUP SIGINT SIGTERM
# -
trap clean_up SIGHUP SIGINT SIGTERM


# ----------
# - Some checks ..
# ----------

# - Running in a terminal?
# -
if [[ -t 1 ]] ; then
   verbose=true
else
   verbose=false
fi

# -Is systemd supported on this system?
# -
systemd_supported=false
systemd=$(which systemd)
systemctl=$(which systemctl)

if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
   systemd_supported=true
fi


# - Print help?
# -
if [[ "$(trim $*)" = " -h" ]] || [[ "$(trim $*)" = " --help" ]] ; then
    usage
fi

if [[ -z "$(which basename)" ]]; then
   fatal 'It seems "basename" is not installed, but needed!'
fi

if [[ -z "$(which realpath)" ]]; then
   fatal 'It seems "realpath" is not installed, but needed!'
fi


# ==========
# - Begin Main Script
# ==========

# ----------
# - Headline
# ----------

if $terminal ; then
   echo ""
   echo -e "\033[1m----------\033[m"
   echo -e "\033[32m\033[1mRunning script \033[m\033[1m$script_name\033[32m .. \033[m"
   echo -e "\033[1m----------\033[m"
fi


# ----------
# - Read commandline parameter
# ----------

while getopts bh opt ; do
   case $opt in
      q)    verbose=true
            ;;
      h)    usage
            ;;
      \?)   usage 
            ;;
      *)    ;;
   esac
done

#shift $(expr $OPTIND - 1)
#[[ $# -eq "1" ]] || usage "Wrong number of arguments!"


if [[ "$1" = "check" ]]; then
   info "Script \033[1m$(basename $0)\033[m was successfully invoked, but its only a test."
   clean_up 0
fi

dkim_domain="$1"


# ----------
#  Read Configurations from $conf_file
# ----------

blank_line
echononl "Loading default Configuration values from $(basename ${conf_file}).."
if [[ ! -f "$conf_file" ]]; then
   echo_skipped
else
   source "${conf_file}" > $log_file 2>&1
   if [[ $? -eq 0 ]]; then
      echo_ok
   else
      echo_failed
      fatal "$(cat $log_file)"
   fi
fi

[[ -n "$CONF_FILE_DIR" ]] || CONF_FILE_DIR="$DEFAULT_CONF_FILE_DIR"
[[ -n "$ZONES_DECLARATION_FILE" ]] || ZONES_DECLARATION_FILE="${CONF_FILE_DIR}/named.conf.local"
[[ -n "$BIND_USER" ]] || BIND_USER="$DEFAULT_BIND_USER"
[[ -n "$BIND_GROUP" ]] || BIND_GROUP="$DEFAULT_BIND_GROUP"


# - Determin zone (domain)
# -
blank_line
echononl "Determine zone for '$dkim_domain'"
_failed=false
_hostname=$dkim_domain
_tmp_hostname=$(echo ${_hostname//\./\\.})
while ! grep -e "$_tmp_hostname" $ZONES_DECLARATION_FILE > /dev/null 2>&1 ; do
   _hostname=${_hostname#*.}
   _tmp_hostname=$(echo ${_hostname//\./\\.})
   if [[ ! $_tmp_hostname =~ \. ]]; then
      _failed=true
      break
   fi
done

if $_failed ; then
   echo_failed
   error "Given hostname/domain \"$dkim_domain\" not supported by this nameserver!"
   exit 15
else
   echo_ok
   domain=$_hostname
fi


# - Determine zonefile (by reading bind configuration)
# -
echononl "Determine zonefile (by reading bind configuration)"
_found=false
declare -i _number=0
regex_zone="^[[:space:]]*zone[[:space:]]+\"$_tmp_hostname\""
regex_file="^[[:space:]]*file"
while IFS='' read -r line || [[ -n "$line" ]] ; do
   if [[ $line  =~ $regex_zone ]]; then
      _found=true
   fi
   if $_found ; then
      if [[ $line  =~ $regex_file ]]; then
         zone_file=`echo $line | awk '{print$2}'`
         shopt -s extglob
         if [[ $zone_file =~ \; ]]; then
            zone_file=${zone_file%%*(\;)}
         fi
         if [[ $zone_file =~ ^\" ]]; then
            zone_file=${zone_file##*(\")}
            zone_file=${zone_file%%*(\")}
         fi
         shopt -u extglob
         let number++
         break
      fi
   fi
done < $ZONES_DECLARATION_FILE

if [[ $number -eq 0 ]] ; then
   echo_failed
   error "No Zonefile (master) found for domain \"$dkim_domain\" ."
   clean_up 11
else
   echo_ok
   zone_file_dir="$(dirname $zone_file)"
fi


# - Check if subdomain delegation already exists
# -
record_name="_domainkey.$dkim_domain"
record_type="NS"
if grep -E "^(${record_name}\..+$record_type|_domainkey\s+.+$record_type)" $zone_file > /dev/null 2>&1 ; then
   info "Subdomain delegation for $record_name already exists!"
   clean_up 0
fi


# - We will place the new NS Record after the last existing one.
# -
# - first we will count the number ox existing NS records
# -
declare -i _count
search_string="^[^;].+\s+IN\s+NS"
_count=$(grep -Eo "$search_string" $zone_file | wc -l)
if [[ $_count -eq 0 ]]; then
   error "No existing NS record found. Check and add subdomain delegation manually!"
   clean_up 99
fi


# - Get DNS server
# -
echononl "Get Namservers for domain '$domain'" 
dns_servers="$(grep -E "^\s*(@|)\s+IN\s+NS" $zone_file 2>/dev/null | sed 's/@//' | sed 's/\.$//' | awk '{print$3}')"
if [[ -n "$dns_servers" ]]; then
   echo_ok
else
   echo_failed
   error "Determin DNS servers for domain '$domain' failed!"
   clean_up 16
fi

# - This is needed, because the dns servers are requested above, in
# - an IFS='' environment!
# -
declare -i i=0
for _dns_server in $dns_servers ; do
   dns_server_arr+=("$_dns_server")
done


# - Backup zone directory
# -
blank_line
backup_dir $zone_file_dir
blank_line


# - Add subdomain delegation
# -

CUR_IFS=$IFS
IFS=''
_tmpfile=`mktemp`
> $_tmpfile

echononl "Add Subdomain delegation for DKIM TXT Records .."
while read -r line || [[ -n "$line" ]]; do

   echo $line >> $_tmpfile

   if echo "$line" | grep -E "$search_string" > /dev/null 2>&1 ; then
      let _count--
   fi
   if [[ $_count -eq 0 ]]; then
      echo "" >> $_tmpfile
      echo "; Subdomain delegation for DKIM TXT Records" >> $_tmpfile
 
      declare -i _number=0

      while [[ $_number -lt ${#dns_server_arr[@]} ]] ; do 
         if [[ "$dkim_domain" = "$domain" ]] ; then
            echo -e "_domainkey.${dkim_domain}.     IN NS    ${dns_server_arr[${_number}]}." >> $_tmpfile
         fi
         ((_number++))
      done
      echo "" >> $_tmpfile

      _count=-1
   fi
done < "$zone_file"
if [[ $? -eq 0 ]] ; then
   echo_ok
else
   echo_failed
   rm $_tmpfile
   exit 21
fi

IFS=$CUR_IFS
mv $_tmpfile $zone_file


# - Set Correct Owner/Permission
# -
blank_line
echononl "Correct Owner for $zone_file .."
chown $BIND_USER:$BIND_GROUP $zone_file
if [[ $? -eq 0 ]] ; then
   echo_ok
else
   echo_failed
   error "Setting ownership for '$zone_file' failed!"
   clean_up 99
fi
echononl "Correct permissions on $zone_file .."
chmod 644 $zone_file
if [[ $? -eq 0 ]] ; then
   echo_ok
else
   echo_failed
   error "Correct permissions on '$zone_file' failed!"
   clean_up 99
fi

_return_value=1


# - Remove backup of zonefile directory if no changes are made
# -
if [[ -d "${zone_file_dir}.$backup_date" ]] ; then
   diff -Nur "$zone_file_dir" "${zone_file_dir}.$backup_date" > /dev/null 2>&1
   if [[ $? -eq 0 ]]; then
      info "No zone file has changed.\n             Removing previously created backup."
      echononl "Delete '${zone_file_dir}.$backup_date'.."
      rm -rf "${zone_file_dir}.$backup_date" > $log_file 2>&1
      if [[ $? -eq 0 ]]; then
         echo_ok
      else
         echo_failed
      fi
   fi
fi

warn "Serial was not incremented and zone not reloaded.\n                Use script \033[1mbind_set_new_serial.sh\033[m to do that."


blank_line
clean_up $_return_value