#! /bin/bash

KEYSIZE=4096
SELECTOR=mail
DOMAINS=

function __usage
{
  printf "\e[35mOPEN-DKIM\e[31m(\e[93m8\e[31m)

\e[38;5;214mNAME\e[39m
    open-dkim - configure DomainKeys Identified Mail (DKIM)

\e[38;5;214mSYNOPSIS\e[39m
    ./setup.sh config dkim [ OPTIONS\e[31m...\e[39m ]

\e[38;5;214mDESCRIPTION\e[39m
    Configures DKIM keys. OPTIONS can be used to configure a more complex setup.
    LDAP setups require these options.

\e[38;5;214mOPTIONS\e[39m
    \e[94mGeneric Program Information\e[39m
        help       Print the usage information.

    \e[94mConfiguration adjustments\e[39m
        keysize    Set the size of the keys to be generated. Possible are 1024, 2024 and 4096 (default).
        selector   Set a manual selector (default is 'mail') for the key. (\e[96mATTENTION\e[39m: NOT IMPLEMENTED YET!)
        domain     Provide the domain(s) for which keys are to be generated.

\e[38;5;214mEXAMPLES\e[39m
    \e[37m./setup.sh config dkim keysize 2048\e[39m
        Creates keys of length 2048 bit in a default setup where domains are obtained from
        your accounts.

    \e[37m./setup.sh config dkim keysize 2048 selector 2021-dkim\e[39m
        Creates keys of length 2048 bit in a default setup where domains are obtained from
        your accounts. The DKIM selector used is '2021-dkim'.

    \e[37m./setup.sh config dkim keysize 2048 selector 2021-dkim domain 'whoami.com,whoareyou.org'\e[39m
        Appropriate for an LDAP setup. Creates keys of length 2048 bit in a default setup
        where domains are obtained from your accounts. The DKIM selector used is '2021-dkim'.
        The domains for which DKIM keys are generated are 'whoami.com' and 'whoareyou.org'.

\e[38;5;214mEXIT STATUS\e[39m
    Exit status is 0 if command was successful. If wrong arguments are provided or arguments contain
    errors, the script will exit early with exit status 2.

"
}

[[ ${1:-} == 'help' ]] && { __usage ; exit 0 ; }

while [[ ${#} -gt 0 ]]
do
  case ${1} in
    keysize )
      if [[ -n ${2+'set'} ]]
      then
        KEYSIZE="${2}"
        shift
        shift
      else
        echo "No keysize provided after 'keysize' argument. Aborting." >&2
        exit 2
      fi
      ;;

    selector )
      if [[ -n ${2+'set'} ]]
      then
        # shellcheck disable=SC2034
        SELECTOR="${2}"
        shift
        shift
      else
        echo "No selector provided after 'selector' argument. Aborting." >&2
        exit 2
      fi
      ;;

    domain )
      if [[ -n ${2+'set'} ]]
      then
        DOMAINS="${2}"
        shift
        shift
      else
        echo "No domain(s) provided after 'domain' argument. Aborting." >&2
        exit 2
      fi
      ;;

    * )
      __usage
      echo -e "\nUnknown options ${1} ${2:-}. Aborting." >&2
      exit 2
      ;;

  esac
done

touch /tmp/vhost.dkim.tmp

if [[ -z ${DOMAINS} ]]
then
  # getting domains FROM mail accounts
  if [[ -f /tmp/docker-mailserver/postfix-accounts.cf ]]
  then
    # shellcheck disable=SC2034
    while IFS=$'|' read -r LOGIN PASS
    do
      DOMAIN=$(echo "${LOGIN}" | cut -d @ -f2)
      echo "${DOMAIN}" >>/tmp/vhost.dkim.tmp
    done < <(grep -v "^\s*$\|^\s*\#" /tmp/docker-mailserver/postfix-accounts.cf || true)
  fi

  # getting domains FROM mail aliases
  if [[ -f /tmp/docker-mailserver/postfix-virtual.cf ]]
  then
    # shellcheck disable=SC2034
    while read -r FROM TO
    do
      UNAME=$(echo "${FROM}" | cut -d @ -f1)
      DOMAIN=$(echo "${FROM}" | cut -d @ -f2)

      [[ ${UNAME} != "${DOMAIN}" ]] && echo "${DOMAIN}" >>/tmp/vhost.dkim.tmp
    done < <(grep -v "^\s*$\|^\s*\#" /tmp/docker-mailserver/postfix-virtual.cf || true)
  fi
else
  tr ',' '\n' <<< "${DOMAINS}" > /tmp/vhost.dkim.tmp
fi

sort < /tmp/vhost.dkim.tmp | uniq >/tmp/vhost
rm /tmp/vhost.dkim.tmp

if [[ ! -s /tmp/vhost ]]
then
  echo "No entries found, no keys to make."
  exit 0
fi

while read -r DKIM_DOMAIN
do
  mkdir -p "/tmp/docker-mailserver/opendkim/keys/${DKIM_DOMAIN}"

  if [[ ! -f "/tmp/docker-mailserver/opendkim/keys/${DKIM_DOMAIN}/${SELECTOR}.private" ]]
  then
    echo "Creating DKIM private key /tmp/docker-mailserver/opendkim/keys/${DKIM_DOMAIN}/${SELECTOR}.private"

    opendkim-genkey \
      --bits="${KEYSIZE}" \
      --subdomains \
      --domain="${DKIM_DOMAIN}" \
      --selector="${SELECTOR}" \
      --directory="/tmp/docker-mailserver/opendkim/keys/${DKIM_DOMAIN}"
  fi

  # write to KeyTable if necessary
  KEYTABLEENTRY="${SELECTOR}._domainkey.${DKIM_DOMAIN} ${DKIM_DOMAIN}:${SELECTOR}:/etc/opendkim/keys/${DKIM_DOMAIN}/${SELECTOR}.private"
  if [[ ! -f "/tmp/docker-mailserver/opendkim/KeyTable" ]]
  then
    echo "Creating DKIM KeyTable"
    echo "${KEYTABLEENTRY}" >/tmp/docker-mailserver/opendkim/KeyTable
  else
    if ! grep -q "${KEYTABLEENTRY}" "/tmp/docker-mailserver/opendkim/KeyTable"
    then
      echo "${KEYTABLEENTRY}" >>/tmp/docker-mailserver/opendkim/KeyTable
    fi
  fi

  # write to SigningTable if necessary
  SIGNINGTABLEENTRY="*@${DKIM_DOMAIN} ${SELECTOR}._domainkey.${DKIM_DOMAIN}"
  if [[ ! -f /tmp/docker-mailserver/opendkim/SigningTable ]]
  then
    echo "Creating DKIM SigningTable"
    echo "*@${DKIM_DOMAIN} ${SELECTOR}._domainkey.${DKIM_DOMAIN}" >/tmp/docker-mailserver/opendkim/SigningTable
  else
    if ! grep -q "${SIGNINGTABLEENTRY}" /tmp/docker-mailserver/opendkim/SigningTable
    then
      echo "${SIGNINGTABLEENTRY}" >>/tmp/docker-mailserver/opendkim/SigningTable
    fi
  fi
done < <(grep -vE '^(\s*$|#)' /tmp/vhost)

# create TrustedHosts if missing
if [[ -d /tmp/docker-mailserver/opendkim ]] && [[ ! -f /tmp/docker-mailserver/opendkim/TrustedHosts ]]
then
  echo "Creating DKIM TrustedHosts"
  echo "127.0.0.1" >/tmp/docker-mailserver/opendkim/TrustedHosts
  echo "localhost" >>/tmp/docker-mailserver/opendkim/TrustedHosts
fi