docker-mailserver/target/bin/restrict-access

#!/bin/bash

# shellcheck source=../scripts/helpers/index.sh
source /usr/local/bin/helpers/index.sh

COMMAND=${1:-}
DIRECTION=${2:-}
DIRECTION=${DIRECTION,,} # make lowercase
USER=${3:-}

function __usage { _log 'info' "Usage: ${0} <add|del|list> <send|receive> [<email@domain.com>]" ; }

if [[ ${DIRECTION} =~ ^(send|receive)$ ]]
then
  DATABASE="/tmp/docker-mailserver/postfix-${DIRECTION}-access.cf"
else
  __usage
  _exit_with_error "Unknown or missing second parameter '${DIRECTION}' - specify 'send' or 'receive'"
fi

if [[ -z ${USER} ]] && [[ ${COMMAND} != list ]]
then
  read -r -p 'Provide a username: ' USER
  [[ -z ${USER} ]] && _exit_with_error 'User must not be empty'
fi

case "${COMMAND}" in

  ( 'add' )
    if [[ -f ${DATABASE} ]] && grep -q -F "${USER}" "${DATABASE}"
    then
      _exit_with_error "User '${USER}' already denied to ${DIRECTION} mails"
    fi

    echo -e "${USER} \t\t REJECT" >>"${DATABASE}"

    if [[ ${DIRECTION} == 'send' ]]
    then
      CHECK='check_sender_access'
      POSTFIX_OPTION='smtpd_sender_restrictions'
    else
      CHECK='check_recipient_access'
      POSTFIX_OPTION='smtpd_recipient_restrictions'
    fi

    # only adjust Postfix's `main.cf` if we haven't adjusted it before
    STRING_TO_BE_ADDED="${CHECK} texthash:/tmp/docker-mailserver/postfix-${DIRECTION}-access.cf"
    if ! grep -q "${STRING_TO_BE_ADDED}" /etc/postfix/main.cf
    then
      sed -i -E "s|^(${POSTFIX_OPTION} =)(.*)|\1 ${STRING_TO_BE_ADDED},\2|" /etc/postfix/main.cf
      _reload_postfix
    fi
    ;;

  ( 'del' )
    if ! sed -i "/^$(_escape "${USER}").*/d" "${DATABASE}" 2>/dev/null
    then
      _exit_with_error "User '${USER}' not found"
    fi
    ;;

  ( 'list' )
    grep "REJECT" "${DATABASE}" 2>/dev/null || _log 'info' "Everyone is allowed to ${DIRECTION} mails"
    ;;

  ( * )
    __usage
    _exit_with_error "Unknown or missing command '${COMMAND}' - specify 'add', 'del' or 'list'"
    ;;

esac