#!/bin/bash
#
# Mojohost
# Script: dkim_keygen
#
# Description: Mojohost dkim generation script
#
#
# Requires:               opendkim / opendkim-genkey
#
# Author: Joseph Laws
#
# Adapted from the "install_dkim" script by Joseph Laws (Centos6/7).

HOSTNAME=$(hostname)
GREEN=$(tput setaf 2)
RED=$(tput setaf 1)
YELLOW=$(tput setaf 3)
COLOROFF=$(tput sgr0)

ODKGK=$(which opendkim-genkey 2>/dev/null)
ODKDIR=/etc/opendkim
ODKKEYT=${ODKDIR}/KeyTable
ODKSIGN=${ODKDIR}/SigningTable
ODKTRUST=${ODKDIR}/TrustedHosts


#Determine the outbout public IPv4 address
BASEIP=$(ip route get 8.8.8.8 2>/dev/null | grep -oP 'src \K\S+')

if [[ -z "${BASEIP}" ]]; then
    BASEIP=$(curl -4 -s --max-time 3 ifconfig.co 2>/dev/null)
    if [[ ! "${BASEIP}" =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
        BASEIP=$(ip -4 -o addr show scope global | awk '{print $4}' | cut -d/ -f1 | head -n1)
        if [[ -z "${BASEIP}" ]]; then
            echo "Can't determine the local outbound IP. Please check network settings"
            exit 1
        fi
    fi
fi

usage() {
    echo
    echo "Usage: $0 -d DOMAIN [-s SELECTOR]"
    echo
    echo "  -d DOMAIN     The domain to create a DKIM key for (required)"
    echo "  -s SELECTOR   Key selector name (default: 'default')"
    echo
    echo "Example: $0 -d example.com -s default"
    echo
    exit 0
}

check_inputs() {
    if [[ -z "${DOMAIN}" ]]; then
        echo "${RED}Error:${COLOROFF} You must provide a domain with -d DOMAIN"
        exit 1
    fi

    if [[ -z "${SELECTOR}" ]]; then
        echo "No selector provided — using 'default'."
        SELECTOR=default
    fi

    if [[ -z "${ODKGK}" ]]; then
        echo "${RED}Error:${COLOROFF} opendkim-genkey not found. Is OpenDKIM installed?"
        exit 1
    fi
}

create_key() {
    if [[ -d ${ODKDIR}/keys/${DOMAIN} ]]; then
        echo "OpenDKIM - ${GREEN}${DOMAIN} key folder already exists${COLOROFF}"
        if [[ -f ${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.priv ]] || \
           [[ -f ${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.pub ]]; then
            echo "OpenDKIM - ${RED}Key files already exist for ${DOMAIN}.${COLOROFF}"
            echo "Manually remove ${ODKDIR}/keys/${DOMAIN}/ if you want to regenerate."
            exit 1
        fi
    fi

    mkdir -p ${ODKDIR}/keys/${DOMAIN}
    ${ODKGK} -D ${ODKDIR}/keys/${DOMAIN}/ -d ${DOMAIN} -s ${SELECTOR}
    if [[ $? -ne 0 ]] || [[ ! -f ${ODKDIR}/keys/${DOMAIN}/${SELECTOR}.private ]]; then
        echo "${RED}Error:${COLOROFF} opendkim-genkey failed to produce key files."
        exit 1
    fi
    chown -R opendkim:opendkim ${ODKDIR}/keys/${DOMAIN}

    mv ${ODKDIR}/keys/${DOMAIN}/${SELECTOR}.private ${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.priv
    mv ${ODKDIR}/keys/${DOMAIN}/${SELECTOR}.txt     ${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.txt

    # Append to KeyTable if entry doesn't already exist
    if ! grep -q "^${SELECTOR}._domainkey.${DOMAIN} " ${ODKKEYT} 2>/dev/null; then
        echo "${SELECTOR}._domainkey.${DOMAIN} ${DOMAIN}:${SELECTOR}:${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.priv" >> ${ODKKEYT}
    fi

    # Append to SigningTable if entry doesn't already exist
    if ! grep -q "^\\*@${DOMAIN} " ${ODKSIGN} 2>/dev/null; then
        echo "*@${DOMAIN} ${SELECTOR}._domainkey.${DOMAIN}" >> ${ODKSIGN}
        echo "*@*.${DOMAIN} ${SELECTOR}._domainkey.${DOMAIN}" >> ${ODKSIGN}
    fi

    # Add server IP to TrustedHosts if not already there
    if ! grep -q "^${BASEIP}$" ${ODKTRUST} 2>/dev/null; then
        echo "${BASEIP}" >> ${ODKTRUST}
    fi

    systemctl restart opendkim
    if [[ $? -ne 0 ]]; then
        echo "${RED}Warning:${COLOROFF} opendkim failed to restart. Check: systemctl status opendkim"
    fi

    output_information
}

output_information() {
    echo
    echo "DKIM DNS records for ${DOMAIN}:"
    echo "=================================================="
    echo
    cat ${ODKDIR}/keys/${DOMAIN}/${DOMAIN}.txt
    echo
    echo "Ensure the outbound IP of ${HOSTNAME} [${BASEIP}] is in the SPF record for ${DOMAIN}."
    echo
}

##Argument gathering
if [[ -z "${1}" ]] || [[ "${1}" == "--help" ]] || [[ "${1}" == "-h" ]]; then
    usage
fi

while getopts ":d:s:" OPTION; do
    case "${OPTION}" in
        d) DOMAIN="${OPTARG}" ;;
        s) SELECTOR="${OPTARG}" ;;
        *) usage ;;
    esac
done

check_inputs
create_key