#!/usr/bin/sh
# -*- mode: sh; sh-shell: sh -*-
#
# default letsencrypt script for OE utilities
#
# Copyright (C) 2019 Rishabh Rishabh <rishabh0402@gmail.com>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.  See <https://www.gnu.org/licenses/gpl2.txt>.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.

# record original umask
umask=$(umask)

# CA certificates URL
CERT1="https://letsencrypt.org/certs/isrgrootx1.pem.txt"
CERT2="https://letsencrypt.org/certs/trustid-x3-root.pem.txt"

# Intermediate certificates URL and CERT4 Name
CERT3="https://letsencrypt.org/certs/lets-encrypt-x3-cross-signed.pem.txt"
CERT4="https://letsencrypt.org/certs/letsencryptauthorityx3.pem.txt"
CERT4NAME="letsencryptauthorityx3.pem.txt"

# /etc/ipsec.d variable for getting location to save the configuration files
# Installing for -server or -client
ServerClient=$1
HostName=$2

# function for checking if the command is run as root
check_root() {
    # Checking if the command is run as root, This command needs to be run as root
    if [ "$(id -u)" -ne 0 ]; then
	echo "This command should be run as root."
	exit 1
    fi
}

# function for testing OE connection
test() {
    # Checking for any existing OE connections
    oeExisting=$(ipsec trafficstatus | grep private)
    if [ ! -z "${oeExisting}" ]; then
	echo "Existing OE Connections Found."
	echo "Please stop the connections using 'ipsec restart' and try again."
	echo "${oeExisting}"
	exit 1
    fi

    # Establishing an OE connection and sending pings to letsencrypt.libreswan.org server
    echo "Sending ping(IPv4) to letsencrypt.libreswan.org server."
    ping -4 -c 5 letsencrypt.libreswan.org >/dev/null 2>/dev/null

    # Checking the success of establishing OE connection
    oeSuccess=$(ipsec trafficstatus | grep private)
    if [ -z "${oeSuccess}" ]; then
	echo "Failed to establish an OE connection."
	echo "Try 'ipsec restart' and test again using 'ipsec letsencrypt --test'."
	exit 1
    else
	echo "OE Connection established successfully."
	# Displaying connection status
	ipsec trafficstatus | grep private
    fi
}

# Function for performaing Initial setup
setup() {
    # Installing for client or server?
    if [ "${ServerClient}" = "--client" ]; then
	echo "Installing for Client."
    else
	echo "Installing for Server."
    fi

    # Downloading the letsencrypt certificates
    echo "Downloading the letsencrypt certificates"

    # set secure umask
    umask 077

    CERTDIR1=$(mktemp -d)
    if [ $? -gt 0 ]; then
	echo "ERROR: could not create temp directory"
	exit 1
    fi
    CERTDIR2=$(mktemp -d)
    if [ $? -gt 0 ]; then
	echo "ERROR: could not create temp directory"
	exit 1
    fi

    # Downloading the CA certificates
    wget_output=$(wget -q -P "${CERTDIR1}" "${CERT1}" "${CERT2}")
    if [ $? -ne 0 ]; then
	echo "ERROR: CA Certificates NOT Found OR Saving the certificates in directory failed."
	exit 1
    fi

    # Downloading the Intermediate certificates
    wget_output=$(wget -q -P "${CERTDIR2}" "${CERT3}" "${CERT4}")
    if [ $? -ne 0 ]; then
	echo "ERROR: Intermediate Certificates NOT Found OR"
	echo "Saving the certificates in directory failed."
	exit 1
    fi

    # Checking if nss database exists
    dbFileCheck=$(ls "/etc/ipsec.d"/*.db 2>/dev/null)
    if [ -z "${dbFileCheck}" ]; then
	# NSS database does not exist. Initializing the nss database
	ipsec initnss
    fi

    # Importing the CA certificates in NSS database
    echo "Importing the downloaded certificates into the database"
    for file in "${CERTDIR1}"/*; do
	file=${file##*/}
	certutil -A -d "sql:/etc/ipsec.d" -n "${file%.pem.txt}" -i "${CERTDIR1}"/"${file}" -t "CT,,"
    done

    # Importing the Intermediate certificates in NSS database
    for file in "${CERTDIR2}"/*; do
	file=${file##*/}
	certutil -A -d "sql:/etc/ipsec.d" -n "${file%.pem.txt}" -i "${CERTDIR2}"/"${file}" -t "u,u,u"
    done

    # restore umask
    umask ${umask}

    # Copying the required configuration
    if [ "${ServerClient}" = "--server" ]; then
	configFile="/usr/share/doc/libreswan/examples/oe-letsencrypt-server.conf"
	configFileName="oe-letsencrypt-server.conf"
    else
	configFile="/usr/share/doc/libreswan/examples/oe-letsencrypt-client.conf"
	configFileName="oe-letsencrypt-client.conf"
    fi

    echo "Saving the required configuration"
    cp "${configFile}" "/etc/ipsec.d/"

    # restoring the security context of /etc/ipsec.d/$configFileName using restorecon.
    checkRestorecon=$(which restorecon 2>/dev/null)
    if [ -n "${checkRestorecon}" -a -x "${checkRestorecon}" ]; then
	restorecon "/etc/ipsec.d/$configFileName"
    fi

    # Removing the temporary directories
    rm -rf "${CERTDIR1}" "${CERTDIR2}"

    echo "To confirm the success try running 'ipsec letsencrypt --test' on the client"
}

# function for generating a certificates
generate_certificate() {
    # Generating the certificate using Certbot
    certBotInstalled=$(which certbot 2>/dev/null)
    if [ -n "${certBotInstalled}" -a -x "${certBotInstalled}" ]; then
	certbot certonly --webroot -d "${HostName}"
    else
	echo "ERROR: Certbot not installed. Please install Certbot and try again."
	exit 1
    fi

    # set secure umask
    umask 077

    CERTDIR=$(mktemp -d)
    if [ $? -gt 0 ]; then
	echo "ERROR: could not create temp directory"
	exit 1
    fi

    wget_output=$(wget -q -P "${CERTDIR}" "${CERT4}")
    if [ $? -ne 0 ]; then
	echo "ERROR: Certificates NOT Found OR Saving the certificate in directory failed"
	exit 1
    fi

    # Now generating the #pkcs12 (.p12) file
    LetsEncryptCertDir="/etc/letsencrypt/live/${HostName}"

    openssl pkcs12 -export -inkey "${LetsEncryptCertDir}/privkey.pem" -in "${LetsEncryptCertDir}/fullchain.pem" -CAfile "${CERTDIR}/${CERT4NAME}" -out "${LetsEncryptCertDir}/generatedCertificate.p12"

    # Importing the certificate in nss database
    echo "Importing the certificate in database. Password for PKCS12 file is the same as the Export Password you entered above."
    pk12util -d "sql:/etc/ipsec.d" -i "${LetsEncryptCertDir}/generatedCertificate.p12"

    # restore umask
    umask ${umask}

    # Displaying the certificates installed in nss database
    certutil -L -d "sql:/etc/ipsec.d"

    # Now generating the certbot configuration for reusing key
    LetsEncryptConfFile="/etc/letsencrypt/renewal/${HostName}.conf"
    echo "reuse_key = True" >>"${LetsEncryptConfFile}"

    # creating a crontab for automatic cert renewals
    if [ -d /etc/cron.d ]; then
	if [ ! -f /etc/cron.d/ipsec-cert-renewal ]; then
	    echo "0 1 * * * root certbot renew --deploy-hook 'ipsec letsencrypt --update-certificate ${HostName}'" \
		>>/etc/cron.d/ipsec-cert-renewal
	fi
    else
	echo "0 1 * * * certbot renew --deploy-hook 'ipsec letsencrypt --update-certificate ${HostName}'" >>cert-renewal
	crontab cert-renewal
	rm cert-renewal
    fi

    # Removing the temporary directory
    rm -fr "${CERTDIR}"

    echo "try running 'ipsec restart' to load the latest certificates"

    echo "To confirm the success try running 'ipsec letsencrypt --test' on the client"
}

# function for updating the issued certificates
update_certificate() {
    # Generating #pkcs12 file, Downloading the required Intermediate certificate
    # set secure umask
    umask 077

    CERTDIR=$(mktemp -d)

    wget_output=$(wget -q -P "${CERTDIR}" "${CERT4}")
    if [ $? -ne 0 ]; then
	echo "ERROR: Certificates NOT Found OR Saving the certificate in directory failed"
	exit 1
    fi

    # Now generating the #pkcs12 (.p12) file
    LetsEncryptCertDir="/etc/letsencrypt/live/${HostName}"

    openssl pkcs12 -export -inkey "${LetsEncryptCertDir}/privkey.pem" \
	-in "${LetsEncryptCertDir}/fullchain.pem" \
	-CAfile "${CERTDIR}/${CERT4NAME}" \
	-out "${LetsEncryptCertDir}/generatedCertificate.p12"

    # Importing the certificate in nss database
    echo "Importing the certificate in database."
    echo "Password for PKCS12 file is the same as the Export Password you entered above."
    pk12util -d "sql:/etc/ipsec.d" -i "${LetsEncryptCertDir}/generatedCertificate.p12"

    # restore umask
    umask ${umask}

    # Displaying the certificates installed in nss database
    echo "Displaying the certificates installed in the database."
    certutil -L -d "sql:/etc/ipsec.d"

    # restarting ipsec to load all certificates
    ipsec restart

    # Removing the temporary directory
    rm -fr "${CERTDIR}"

    # To confirm the success try running the test connection script on the client
    echo "To confirm the success try running 'ipsec letsencrypt --test' on the client"
}

# function for manual cert renewals
manual_cert_renew() {
    # Renewing the certificate using Certbot
    certBotInstalled=$(which certbot 2>/dev/null)
    if [ -n "${certBotInstalled}" -a -x "${certBotInstalled}" ]; then
	certbot renew --deploy-hook 'ipsec letsencrypt --update-certificate ${HostName}'
    else
	echo "ERROR: Certbot not installed. Please install Certbot and try again."
	exit 1
    fi
}

# function to disable ipsec by deleting the conf file in /etc/ipsec.d
disable_ipsec() {
    # Deleting the configuration files present in /etc/ipsec.d directory
    rm -f "/etc/ipsec.d"/oe-letsencrypt-*.conf
    echo "Please restart the IPsec service using 'ipsec restart' for changes to take effect."
}

# function for showing help
help() {
    echo "Usage: ipsec letsencrypt [arguments]"
    echo "Available [arguments]"
    echo "--server, --client, --test, --generate-certificate hostname, --renew hostname, --help, --disable"
    echo
    echo "--client :  For initial client setup."
    echo "usage: 'ipsec letsencrypt --client'"
    echo
    echo "--server :  For initial server setup."
    echo "usage: 'ipsec letsencrypt --server'"
    echo
    echo "--test  :  For testing the configuration/connections."
    echo "usage: 'ipsec letsencrypt --test'"
    echo
    echo "--generate-certificate hostname :  For generating the certificate."
    echo "usage: 'ipsec letsencrypt --generate-certificate hostname'"
    echo
    echo "--renew hostname :  For updating the generated certificate (keeping the private key same) use the following command."
    echo "usage: 'ipsec letsencrypt --renew hostname'"
    echo
    echo "--disable :  For disabling IPsec service."
    echo "usage: 'ipsec letsencrypt --disable'"
}

case "${1}" in
    --test)
	check_root
	test
	;;
    --server|--client)
	check_root
	setup
	;;
    --generate-certificate)
	check_root
	generate_certificate
	;;
    --update-certificate)
	check_root
	update_certificate
	;;
    --renew)
	check_root
	manual_cert_renew
	;;
    --disable)
	check_root
	disable_ipsec
	;;
    --help)
	help
	;;
    *)
	echo "[argument] \"${1}\" not found"
	echo "try: 'ipsec letsencrypt --help' for help"
	;;
esac