#!/bin/sh
# dns based ad/abuse domain blocking
# written by Dirk Brenken (dev@brenken.org)

# This is free software, licensed under the GNU General Public License v3.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

# set initial defaults
#
LC_ALL=C
PATH="/usr/sbin:/usr/bin:/sbin:/bin"
adb_ver="3.5.5-2"
adb_sysver="unknown"
adb_enabled=0
adb_debug=0
adb_backup_mode=0
adb_forcesrt=0
adb_forcedns=0
adb_jail=0
adb_maxqueue=4
adb_notify=0
adb_notifycnt=0
adb_triggerdelay=0
adb_backup=0
adb_backupdir="/mnt"
adb_fetchutil="uclient-fetch"
adb_dns="dnsmasq"
adb_dnsprefix="adb_list"
adb_dnsfile="${adb_dnsprefix}.overall"
adb_dnsjail="${adb_dnsprefix}.jail"
adb_dnsflush=0
adb_whitelist="/etc/adblock/adblock.whitelist"
adb_rtfile="/tmp/adb_runtime.json"
adb_hashutil="$(command -v sha256sum)"
adb_hashold=""
adb_hashnew=""
adb_cnt=""
adb_rc=0
adb_action="${1:-"start"}"
adb_pidfile="/var/run/adblock.pid"

# load adblock environment
#
f_envload()
{
	local dns_up sys_call sys_desc sys_model sys_ver cnt=0

	# get system information
	#
	sys_call="$(ubus -S call system board 2>/dev/null)"
	if [ -n "${sys_call}" ]
	then
		sys_desc="$(printf '%s' "${sys_call}" | jsonfilter -e '@.release.description')"
		sys_model="$(printf '%s' "${sys_call}" | jsonfilter -e '@.model')"
		sys_ver="$(cat /etc/turris-version 2>/dev/null)"
		if [ -n "${sys_ver}" ]
		then
			sys_desc="${sys_desc}/${sys_ver}"
		fi
		adb_sysver="${sys_model}, ${sys_desc}"
	fi

	# check hash utility
	#
	if [ ! -x "${adb_hashutil}" ]
	then
		adb_hashutil="$(command -v md5sum)"
	fi

	# parse 'global' and 'extra' section by callback
	#
	config_cb()
	{
		local type="${1}"
		if [ "${type}" = "adblock" ]
		then
			option_cb()
			{
				local option="${1}"
				local value="${2}"
				eval "${option}=\"${value}\""
			}
		else
			reset_cb
		fi
	}

	# parse 'source' typed sections
	#
	parse_config()
	{
		local value opt section="${1}" options="enabled adb_src adb_src_rset adb_src_cat"
		eval "adb_sources=\"${adb_sources} ${section}\""
		for opt in ${options}
		do
			config_get value "${section}" "${opt}"
			if [ -n "${value}" ]
			then
				eval "${opt}_${section}=\"${value}\""
			fi
		done
	}

	# load adblock config
	#
	config_load adblock
	config_foreach parse_config source

	# check dns backend
	#
	case "${adb_dns}" in
		dnsmasq)
			adb_dnsinstance="${adb_dnsinstance:-"0"}"
			adb_dnsuser="${adb_dnsuser:-"dnsmasq"}"
			adb_dnsdir="${adb_dnsdir:-"/tmp"}"
			adb_dnsheader=""
			adb_dnsdeny="awk '{print \"server=/\"\$0\"/\"}'"
			adb_dnsallow="awk '{print \"server=/\"\$0\"/#\"}'"
			adb_dnshalt="server=/#/"
		;;
		unbound)
			adb_dnsinstance="${adb_dnsinstance:-"0"}"
			adb_dnsuser="${adb_dnsuser:-"unbound"}"
			adb_dnsdir="${adb_dnsdir:-"/var/lib/unbound"}"
			adb_dnsheader=""
			adb_dnsdeny="awk '{print \"local-zone: \042\"\$0\"\042 static\"}'"
			adb_dnsallow="awk '{print \"local-zone: \042\"\$0\"\042 transparent\"}'"
			adb_dnshalt="local-zone: \".\" static"
		;;
		named)
			adb_dnsinstance="${adb_dnsinstance:-"0"}"
			adb_dnsuser="${adb_dnsuser:-"bind"}"
			adb_dnsdir="${adb_dnsdir:-"/var/lib/bind"}"
			adb_dnsheader="\$TTL 2h"$'\n'"@ IN SOA localhost. root.localhost. (1 6h 1h 1w 2h)"$'\n'"  IN NS localhost."
			adb_dnsdeny="awk '{print \"\"\$0\" CNAME .\n*.\"\$0\" CNAME .\"}'"
			adb_dnsallow="awk '{print \"\"\$0\" CNAME rpz-passthru.\n*.\"\$0\" CNAME rpz-passthru.\"}'"
			adb_dnshalt="* CNAME ."
		;;
		kresd)
			adb_dnsinstance="${adb_dnsinstance:-"0"}"
			adb_dnsuser="${adb_dnsuser:-"root"}"
			adb_dnsdir="${adb_dnsdir:-"/etc/kresd"}"
			adb_dnsheader="\$TTL 2h"$'\n'"@ IN SOA localhost. root.localhost. (1 6h 1h 1w 2h)"$'\n'"  IN NS  localhost."
			adb_dnsdeny="awk '{print \"\"\$0\" CNAME .\n*.\"\$0\" CNAME .\"}'"
			adb_dnsallow="awk '{print \"\"\$0\" CNAME rpz-passthru.\n*.\"\$0\" CNAME rpz-passthru.\"}'"
			adb_dnshalt="* CNAME ."
		;;
		dnscrypt-proxy)
			adb_dnsinstance="${adb_dnsinstance:-"0"}"
			adb_dnsuser="${adb_dnsuser:-"nobody"}"
			adb_dnsdir="${adb_dnsdir:-"/tmp"}"
			adb_dnsheader=""
			adb_dnsdeny="awk '{print \$0}'"
			adb_dnsallow=""
			adb_dnshalt=""
		;;
	esac

	# check adblock status
	#
	if [ ${adb_enabled} -eq 0 ]
	then
		f_extconf
		f_temp
		f_rmdns
		f_jsnup "disabled"
		f_log "info" "adblock is currently disabled, please set adb_enabled to '1' to use this service"
		exit 0
	fi

	if [ -d "${adb_dnsdir}" ] && [ ! -f "${adb_dnsdir}/${adb_dnsfile}" ]
	then
		printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
	fi

	if [ "${adb_action}" = "start" ] && [ "${adb_trigger}" = "timed" ]
	then
		sleep ${adb_triggerdelay}
	fi

	while [ ${cnt} -le 30 ]
	do
		dns_up="$(ubus -S call service list "{\"name\":\"${adb_dns}\"}" 2>/dev/null | jsonfilter -l1 -e "@[\"${adb_dns}\"].instances.*.running" 2>/dev/null)"
		if [ "${dns_up}" = "true" ]
		then
			break
		fi
		sleep 1
		cnt=$((cnt+1))
	done

	if [ "${dns_up}" != "true" ] || [ -z "${adb_dns}" ] || [ ! -x "$(command -v ${adb_dns})" ]
	then
		f_log "err" "'${adb_dns}' not running or not executable"
	elif [ ! -d "${adb_dnsdir}" ]
	then
		f_log "err" "'${adb_dnsdir}' backend directory not found"
	fi
}

# check environment
#
f_envcheck()
{
	local ssl_lib

	# startup message
	#
	f_log "info" "adblock instance started ::: action: ${adb_action}, priority: ${adb_nice:-"0"}, pid: ${$}"
	f_jsnup "running"

	# check external uci config files
	#
	f_extconf

	# check fetch utility
	#
	case "${adb_fetchutil}" in
		uclient-fetch)
			if [ -f "/lib/libustream-ssl.so" ]
			then
				adb_fetchparm="${adb_fetchparm:-"--timeout=10 --no-check-certificate -O"}"
				ssl_lib="libustream-ssl"
			else
				adb_fetchparm="${adb_fetchparm:-"--timeout=10 -O"}"
			fi
		;;
		wget)
			adb_fetchparm="${adb_fetchparm:-"--no-cache --no-cookies --max-redirect=0 --timeout=10 --no-check-certificate -O"}"
			ssl_lib="built-in"
		;;
		wget-nossl)
			adb_fetchparm="${adb_fetchparm:-"--no-cache --no-cookies --max-redirect=0 --timeout=10 -O"}"
		;;
		busybox)
			adb_fetchparm="${adb_fetchparm:-"-O"}"
		;;
		curl)
			adb_fetchparm="${adb_fetchparm:-"--connect-timeout 10 --insecure -o"}"
			ssl_lib="built-in"
		;;
		aria2c)
			adb_fetchparm="${adb_fetchparm:-"--timeout=10 --allow-overwrite=true --auto-file-renaming=false --check-certificate=false -o"}"
			ssl_lib="built-in"
		;;
	esac
	adb_fetchutil="$(command -v "${adb_fetchutil}")"

	if [ ! -x "${adb_fetchutil}" ] || [ -z "${adb_fetchutil}" ] || [ -z "${adb_fetchparm}" ]
	then
		f_log "err" "download utility not found, please install 'uclient-fetch' with 'libustream-mbedtls' or the full 'wget' package"
	fi
	adb_fetchinfo="${adb_fetchutil} (${ssl_lib:-"-"})"
	f_temp
}

# create temporary files and directories
#
f_temp()
{
	if [ -z "${adb_tmpdir}" ]
	then
		adb_tmpdir="$(mktemp -p /tmp -d)"
		adb_tmpload="$(mktemp -p ${adb_tmpdir} -tu)"
		adb_tmpfile="$(mktemp -p ${adb_tmpdir} -tu)"
	fi
	if [ ! -s "${adb_pidfile}" ]
	then
		printf '%s' "${$}" > "${adb_pidfile}"
	fi
}

# remove temporary files and directories
#
f_rmtemp()
{
	if [ -d "${adb_tmpdir}" ]
	then
		rm -rf "${adb_tmpdir}"
	fi
	> "${adb_pidfile}"
}

# remove dns related files and directories
#
f_rmdns()
{
	if [ -n "${adb_dns}" ]
	then
		f_hash
		printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
		> "${adb_dnsdir}/.${adb_dnsfile}"
		> "${adb_rtfile}"
		rm -f "${adb_backupdir}/${adb_dnsprefix}"*.gz
		f_hash
		if [ ${?} -eq 1 ]
		then
			f_dnsup
		fi
		f_rmtemp
	fi
	f_log "debug" "f_rmdns::: dns: ${adb_dns}, dns_dir: ${adb_dnsdir}, dns_prefix: ${adb_dnsprefix}, dns_file: ${adb_dnsfile}, rt_file: ${adb_rtfile}, backup_dir: ${adb_backupdir}"
}

# commit uci changes
#
f_uci()
{
	local change config="${1}"

	if [ -n "${config}" ]
	then
		change="$(uci -q changes "${config}" | awk '{ORS=" "; print $0}')"
		if [ -n "${change}" ]
		then
			uci_commit "${config}"
			case "${config}" in
				firewall)
					/etc/init.d/firewall reload >/dev/null 2>&1
				;;
				*)
					/etc/init.d/"${adb_dns}" reload >/dev/null 2>&1
				;;
			esac
		fi
	fi
	f_log "debug" "f_uci  ::: config: ${config}, change: ${change}"
}

# list/overall count
#
f_count()
{
	local mode="${1}"

	adb_cnt=0
	if [ -s "${adb_dnsdir}/${adb_dnsfile}" ] && ([ -z "${mode}" ] || [ "${mode}" = "final" ])
	then
		adb_cnt="$(( $(wc -l 2>/dev/null < "${adb_dnsdir}/${adb_dnsfile}") - $(wc -l 2>/dev/null < "${adb_tmpdir}/tmp.add_whitelist") ))"
		if [ "${adb_dns}" = "named" ] || [ "${adb_dns}" = "kresd" ]
		then
			adb_cnt="$(( (${adb_cnt} - $(printf '%s' "${adb_dnsheader}" | grep -c "^")) / 2 ))"
		fi
	elif [ -s "${adb_tmpfile}" ]
	then
		adb_cnt="$(wc -l 2>/dev/null < "${adb_tmpfile}")"
	fi
}

# set external config options
#
f_extconf()
{
	local uci_config port port_list="53 853 5353"

	case "${adb_dns}" in
		dnsmasq)
			uci_config="dhcp"
			if [ ${adb_enabled} -eq 1 ] && [ -z "$(uci_get dhcp "@dnsmasq[${adb_dnsinstance}]" serversfile | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
			then
				uci_set dhcp "@dnsmasq[${adb_dnsinstance}]" serversfile "${adb_dnsdir}/${adb_dnsfile}"
			elif [ ${adb_enabled} -eq 0 ] && [ -n "$(uci_get dhcp "@dnsmasq[${adb_dnsinstance}]" serversfile | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
			then
				uci_remove dhcp "@dnsmasq[${adb_dnsinstance}]" serversfile
			fi
		;;
		kresd)
			uci_config="resolver"
			if [ ${adb_enabled} -eq 1 ] && [ -z "$(uci_get resolver kresd rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
			then
				uci -q add_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
			elif [ ${adb_enabled} -eq 0 ] && [ -n "$(uci_get resolver kresd rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
			then
				uci -q del_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
			fi
			if [ ${adb_enabled} -eq 1 ] && [ ${adb_dnsflush} -eq 0 ] && [ "$(uci_get resolver kresd keep_cache)" != "1" ]
			then
				uci_set resolver kresd keep_cache "1"
			elif [ ${adb_enabled} -eq 0 ] || ([ ${adb_dnsflush} -eq 1 ] && [ "$(uci_get resolver kresd keep_cache)" = "1" ])
			then
				uci_set resolver kresd keep_cache "0"
			fi
		;;
	esac
	f_uci "${uci_config}"

	uci_config="firewall"
	if [ ${adb_enabled} -eq 1 ] && [ ${adb_forcedns} -eq 1 ] && \
		[ -z "$(uci_get firewall adblock_dns_53)" ] && [ $(/etc/init.d/firewall enabled; printf '%u' ${?}) -eq 0 ]
	then
		for port in ${port_list}
		do
			uci_add firewall "redirect" "adblock_dns_${port}"
			uci_set firewall "adblock_dns_${port}" "name" "Adblock DNS, port ${port}"
			uci_set firewall "adblock_dns_${port}" "src" "lan"
			uci_set firewall "adblock_dns_${port}" "proto" "tcp udp"
			uci_set firewall "adblock_dns_${port}" "src_dport" "${port}"
			uci_set firewall "adblock_dns_${port}" "dest_port" "${port}"
			uci_set firewall "adblock_dns_${port}" "target" "DNAT"
		done
	elif [ -n "$(uci_get firewall adblock_dns_53)" ] && ([ ${adb_enabled} -eq 0 ] || [ ${adb_forcedns} -eq 0 ])
	then
		for port in ${port_list}
		do
			uci_remove firewall "adblock_dns_${port}"
		done
	fi
	f_uci "${uci_config}"
}

# restart of the dns backend
#
f_dnsup()
{
	local dns_up cache_util cache_rc cnt=0

	if [ ${adb_dnsflush} -eq 0 ] && [ ${adb_enabled} -eq 1 ] && [ "${adb_rc}" -eq 0 ]
	then
		case "${adb_dns}" in
			dnsmasq)
				killall -q -HUP "${adb_dns}"
				cache_rc=${?}
			;;
			unbound)
				cache_util="$(command -v unbound-control)"
				if [ -x "${cache_util}" ] && [ -d "${adb_tmpdir}" ] && [ -f "${adb_dnsdir}"/unbound.conf ]
				then
					"${cache_util}" -c "${adb_dnsdir}"/unbound.conf dump_cache > "${adb_tmpdir}"/adb_cache.dump 2>/dev/null
				fi
				"/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
			;;
			kresd)
				cache_util="keep_cache"
				"/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
				cache_rc=${?}
			;;
			named)
				cache_util="$(command -v rndc)"
				if [ -x "${cache_util}" ] && [ -f /etc/bind/rndc.conf ]
				then
					"${cache_util}" -c /etc/bind/rndc.conf reload >/dev/null 2>&1
					cache_rc=${?}
				else
					"/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
				fi
			;;
			*)
				"/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
			;;
		esac
	else
		"/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
	fi

	adb_rc=1
	while [ ${cnt} -le 10 ]
	do
		dns_up="$(ubus -S call service list "{\"name\":\"${adb_dns}\"}" | jsonfilter -l1 -e "@[\"${adb_dns}\"].instances.*.running")"
		if [ "${dns_up}" = "true" ]
		then
			case "${adb_dns}" in
				unbound)
					cache_util="$(command -v unbound-control)"
					if [ -x "${cache_util}" ] && [ -d "${adb_tmpdir}" ] && [ -s "${adb_tmpdir}"/adb_cache.dump ]
					then
						while [ ${cnt} -le 10 ]
						do
							"${cache_util}" -c "${adb_dnsdir}"/unbound.conf load_cache < "${adb_tmpdir}"/adb_cache.dump >/dev/null 2>&1
							cache_rc=${?}
							if [ ${cache_rc} -eq 0 ]
							then
								break
							fi
							cnt=$((cnt+1))
							sleep 1
						done
					fi
				;;
			esac
			adb_rc=0
			break
		fi
		cnt=$((cnt+1))
		sleep 1
	done
	f_log "debug" "f_dnsup::: cache_util: ${cache_util:-"-"}, cache_rc: ${cache_rc:-"-"}, cache_flush: ${adb_dnsflush}, cache_cnt: ${cnt}, rc: ${adb_rc}"
	return ${adb_rc}
}

# backup/restore/remove blocklists
#
f_list()
{
	local file mode="${1}" in_rc="${adb_rc}"

	case "${mode}" in
		backup)
			if [ -d "${adb_backupdir}" ]
			then
				gzip -cf "${adb_tmpfile}" 2>/dev/null > "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz"
				adb_rc=${?}
			fi
		;;
		restore)
			if [ -d "${adb_backupdir}" ] && [ -f "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" ]
			then
				gunzip -cf "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" 2>/dev/null > "${adb_tmpfile}"
				adb_rc=${?}
			fi
		;;
		remove)
			if [ -d "${adb_backupdir}" ]
			then
				rm -f "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz"
			fi
			adb_rc=${?}
		;;
		merge)
			for file in "${adb_tmpfile}".*
			do
				cat "${file}" 2>/dev/null >> "${adb_tmpdir}/${adb_dnsfile}"
				if [ ${?} -ne 0 ]
				then
					adb_rc=${?}
					break
				fi
				rm -f "${file}"
			done
			adb_tmpfile="${adb_tmpdir}/${adb_dnsfile}"
		;;
		final)
			> "${adb_dnsdir}/${adb_dnsfile}"

			if [ -s "${adb_tmpdir}/tmp.add_whitelist" ]
			then
				cat "${adb_tmpdir}/tmp.add_whitelist" >> "${adb_dnsdir}/${adb_dnsfile}"
			fi

			if [ -s "${adb_tmpdir}/tmp.rem_whitelist" ]
			then
				grep -vf "${adb_tmpdir}/tmp.rem_whitelist" "${adb_tmpdir}/${adb_dnsfile}" | eval "${adb_dnsdeny}" >> "${adb_dnsdir}/${adb_dnsfile}"
			else
				eval "${adb_dnsdeny}" "${adb_tmpdir}/${adb_dnsfile}" >> "${adb_dnsdir}/${adb_dnsfile}"
			fi

			if [ ${?} -eq 0 ] && [ -n "${adb_dnsheader}" ]
			then
				printf '%s\n' "${adb_dnsheader}" | cat - "${adb_dnsdir}/${adb_dnsfile}" > "${adb_tmpdir}/${adb_dnsfile}"
				mv -f "${adb_tmpdir}/${adb_dnsfile}" "${adb_dnsdir}/${adb_dnsfile}"
			fi
			adb_rc=${?}
		;;
	esac
	f_count "${mode}"
	f_log "debug" "f_list ::: name: ${src_name:-"-"}, mode: ${mode}, cnt: ${adb_cnt}, in_rc: ${in_rc}, out_rc: ${adb_rc}"
}

# top level domain compression
#
f_tld()
{
	local cnt cnt_srt cnt_tld source="${1}" temp="${1}.tld"

	cnt="$(wc -l 2>/dev/null < "${source}")"
	awk 'BEGIN{FS="."}{for(f=NF;f>1;f--)printf "%s.",$f;print $1}' "${source}" > "${temp}"
	if [ ${?} -eq 0 ]
	then
		sort -u "${temp}" > "${source}"
		if [ ${?} -eq 0 ]
		then
			cnt_srt="$(wc -l 2>/dev/null < "${source}")"
			awk '{if(NR==1){tld=$NF};while(getline){if($NF!~tld"\\."){print tld;tld=$NF}}print tld}' "${source}" > "${temp}"
			if [ ${?} -eq 0 ]
			then
				awk 'BEGIN{FS="."}{for(f=NF;f>1;f--)printf "%s.",$f;print $1}' "${temp}" > "${source}"
				if [ ${?} -eq 0 ]
				then
					cnt_tld="$(wc -l 2>/dev/null < "${source}")"
				else
					mv -f "${temp}" > "${source}"
				fi
			fi
		else
			mv -f "${temp}" "${source}"
		fi
	fi
	f_log "debug" "f_tld  ::: source: ${source}, cnt: ${cnt:-"-"}, cnt_srt: ${cnt_srt:-"-"}, cnt_tld: ${cnt_tld:-"-"}"
}

# blocklist hash compare
#
f_hash()
{
	local hash hash_rc=1

	if [ -x "${adb_hashutil}" ] && [ -f "${adb_dnsdir}/${adb_dnsfile}" ]
	then
		hash="$(${adb_hashutil} "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null | awk '{print $1}')"
		if [ -z "${adb_hashold}" ] && [ -n "${hash}" ]
		then
			adb_hashold="${hash}"
		elif [ -z "${adb_hashnew}" ] && [ -n "${hash}" ]
		then
			adb_hashnew="${hash}"
		fi
		if [ -n "${adb_hashold}" ] && [ -n "${adb_hashnew}" ]
		then
			if [ "${adb_hashold}" = "${adb_hashnew}" ]
			then
				hash_rc=0
			fi
			adb_hashold=""
			adb_hashnew=""
		fi
	fi
	f_log "debug" "f_hash ::: hash_util: ${adb_hashutil}, hash: ${hash}, out_rc: ${hash_rc}"
	return ${hash_rc}
}

# suspend/resume adblock processing
#
f_switch()
{
	local mode="${1}"

	if [ ! -s "${adb_dnsdir}/.${adb_dnsfile}" ] && [ "${mode}" = "suspend" ]
	then
		f_hash
		cat "${adb_dnsdir}/${adb_dnsfile}" > "${adb_dnsdir}/.${adb_dnsfile}"
		printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
		f_hash
	elif [ -s "${adb_dnsdir}/.${adb_dnsfile}" ] && [ "${mode}" = "resume" ]
	then
		f_hash
		cat "${adb_dnsdir}/.${adb_dnsfile}" > "${adb_dnsdir}/${adb_dnsfile}"
		> "${adb_dnsdir}/.${adb_dnsfile}"
		f_hash
	fi
	if [ ${?} -eq 1 ]
	then
		f_temp
		f_dnsup
		f_jsnup "${mode}"
		f_log "info" "${mode} adblock processing"
		f_rmtemp
		exit 0
	fi
}

# query blocklist for certain (sub-)domains
#
f_query()
{
	local search result prefix suffix field domain="${1}" tld="${1#*.}"

	if [ -z "${domain}" ] || [ "${domain}" = "${tld}" ]
	then
		printf '%s\n' "::: invalid domain input, please submit a single domain, e.g. 'doubleclick.net'"
	else
		case "${adb_dns}" in
			dnsmasq)
				prefix=".*[\/\.]"
				suffix="(\/)"
				field=2
			;;
			unbound)
				prefix=".*[\"\.]"
				suffix="(static)"
				field=3
			;;
			named)
				prefix="[^\*].*[\.]"
				suffix="( \.)"
				field=1
			;;
			kresd)
				prefix="[^\*].*[\.]"
				suffix="( \.)"
				field=1
			;;
			dnscrypt-proxy)
				prefix=".*[\.]"
				suffix=""
				field=1
			;;
		esac
		while [ "${domain}" != "${tld}" ]
		do
			search="${domain//./\.}"
			result="$(awk -F '/|\"| ' "/^($search|${prefix}+${search}.*${suffix}$)/{i++;{printf(\"  + %s\n\",\$${field})};if(i>9){printf(\"  + %s\n\",\"[...]\");exit}}" "${adb_dnsdir}/${adb_dnsfile}")"
			printf '%s\n' "::: results for domain '${domain}'"
			printf '%s\n' "${result:-"  - no match"}"
			domain="${tld}"
			tld="${domain#*.}"
		done
	fi
}

# update runtime information
#
f_jsnup()
{
	local run_time bg_pid status="${1:-"enabled"}" mode="normal mode" no_mail=0

	if [ ${adb_rc} -gt 0 ]
	then
		status="error"
		run_time="$(/bin/date "+%d.%m.%Y %H:%M:%S")"
	fi
	if [ "${status}" = "enabled" ]
	then
		run_time="$(/bin/date "+%d.%m.%Y %H:%M:%S")"
	fi
	if [ "${status}" = "suspend" ]
	then
		status="paused"
	fi
	if [ "${status}" = "resume" ]
	then
		no_mail=1
		status="enabled"
	fi
	if [ ${adb_backup_mode} -eq 1 ]
	then
		mode="backup mode"
	fi

	if [ -z "${adb_fetchinfo}" ]
	then
		json_get_var adb_fetchinfo "fetch_utility"
	fi
	if [ -z "${adb_cnt}" ]
	then
		json_get_var adb_cnt "overall_domains"
		adb_cnt="${adb_cnt%% *}"
	fi
	if [ -z "${run_time}" ]
	then
		json_get_var run_time "last_rundate"
	fi
	json_add_string "adblock_status" "${status}"
	json_add_string "adblock_version" "${adb_ver}"
	json_add_string "overall_domains" "${adb_cnt:-0} (${mode})"
	json_add_string "fetch_utility" "${adb_fetchinfo:-"-"}"
	json_add_string "dns_backend" "${adb_dns} (${adb_dnsdir})"
	json_add_string "last_rundate" "${run_time:-"-"}"
	json_add_string "system_release" "${adb_sysver}"
	json_dump > "${adb_rtfile}"

	if [ ${adb_notify} -eq 1 ] && [ ${no_mail} -eq 0 ] && [ -x /etc/adblock/adblock.notify ] && \
		([ "${status}" = "error" ] || ([ "${status}" = "enabled" ] && [ ${adb_cnt} -le ${adb_notifycnt} ]))
	then
		(/etc/adblock/adblock.notify >/dev/null 2>&1) &
		bg_pid=${!}
	fi
	f_log "debug" "f_jsnup::: status: ${status}, mode: ${mode}, cnt: ${adb_cnt}, notify: ${adb_notify}, notify_cnt: ${adb_notifycnt}, notify_pid: ${bg_pid:-"-"}"
}

# write to syslog
#
f_log()
{
	local class="${1}" log_msg="${2}"

	if [ -n "${log_msg}" ] && ([ "${class}" != "debug" ] || [ ${adb_debug} -eq 1 ])
	then
		logger -p "${class}" -t "adblock-${adb_ver}[${$}]" "${log_msg}"
		if [ "${class}" = "err" ]
		then
			f_rmdns
			f_jsnup
			logger -p "${class}" -t "adblock-${adb_ver}[${$}]" "Please also check 'https://github.com/openwrt/packages/blob/master/net/adblock/files/README.md'"
			exit 1
		fi
	fi
}

# main function for blocklist processing
#
f_main()
{
	local tmp_load tmp_file src_name src_rset src_url src_log src_arc src_cat cat list entry suffix mem_total mem_free enabled cnt=1

	mem_total="$(awk '/^MemTotal/ {print int($2/1000)}' "/proc/meminfo" 2>/dev/null)"
	mem_free="$(awk '/^MemFree/ {print int($2/1000)}' "/proc/meminfo" 2>/dev/null)"
	tmp_load="${adb_tmpload}"
	tmp_file="${adb_tmpfile}"
	> "${adb_dnsdir}/.${adb_dnsfile}"
	> "${adb_tmpdir}/tmp.raw_whitelist"
	> "${adb_tmpdir}/tmp.add_whitelist"
	> "${adb_tmpdir}/tmp.rem_whitelist"
	f_log "debug" "f_main ::: dns: ${adb_dns}, fetch_util: ${adb_fetchinfo}, backup: ${adb_backup}, backup_mode: ${adb_backup_mode}, dns_jail: ${adb_jail}, force_srt: ${adb_forcesrt}, force_dns: ${adb_forcedns}, mem_total: ${mem_total:-0}, mem_free: ${mem_free:-0}, max_queue: ${adb_maxqueue}"

	# prepare whitelist entries
	#
	if [ -s "${adb_whitelist}" ]
	then
		adb_whitelist_rset="/^([[:alnum:]_-]+\.)+[[:alpha:]]+([[:space:]]|$)/{print tolower(\$1)}"
		awk "${adb_whitelist_rset}" "${adb_whitelist}" > "${adb_tmpdir}/tmp.raw_whitelist"
		f_tld "${adb_tmpdir}/tmp.raw_whitelist"

		adb_whitelist_rset="/^([[:alnum:]_-]+\.)+[[:alpha:]]+([[:space:]]|$)/{gsub(\"\\\.\",\"\\\.\",\$1);print tolower(\"^\"\$1\"\\\|\\\.\"\$1)}"
		awk "${adb_whitelist_rset}" "${adb_tmpdir}/tmp.raw_whitelist" > "${adb_tmpdir}/tmp.rem_whitelist"

		if [ -n "${adb_dnsallow}" ]
		then
			eval "${adb_dnsallow}" "${adb_tmpdir}/tmp.raw_whitelist" > "${adb_tmpdir}/tmp.add_whitelist"
		fi
	fi

	# build 'dnsjail' list
	#
	if [ ${adb_jail} -eq 1 ]
	then
		cat "${adb_tmpdir}/tmp.add_whitelist" > "/tmp/${adb_dnsjail}"
		printf '%s\n' "${adb_dnshalt}" >> "/tmp/${adb_dnsjail}"
		if [ -n "${adb_dnsheader}" ]
		then
			printf '%s\n' "${adb_dnsheader}" | cat - "/tmp/${adb_dnsjail}" > "${adb_tmpdir}/tmp.dnsjail"
			cat "${adb_tmpdir}/tmp.dnsjail" > "/tmp/${adb_dnsjail}"
		fi
	fi

	# main loop
	#
	for src_name in ${adb_sources}
	do
		enabled="$(eval printf '%s' \"\${enabled_${src_name}\}\")"
		src_url="$(eval printf '%s' \"\${adb_src_${src_name}\}\")"
		src_rset="$(eval printf '%s' \"\${adb_src_rset_${src_name}\}\")"
		src_cat="$(eval printf '%s' \"\${adb_src_cat_${src_name}\}\")"
		adb_tmpload="${tmp_load}.${src_name}"
		adb_tmpfile="${tmp_file}.${src_name}"

		# basic pre-checks
		#
		f_log "debug" "f_main ::: name: ${src_name}, enabled: ${enabled}"
		if [ "${enabled}" != "1" ] || [ -z "${src_url}" ] || [ -z "${src_rset}" ]
		then
			f_list remove
			continue
		fi

		# backup mode
		#
		if [ ${adb_backup_mode} -eq 1 ] && [ "${adb_action}" = "start" ] && [ "${src_name}" != "blacklist" ]
		then
			f_list restore
			if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpfile}" ]
			then
				if ([ ${mem_total} -lt 64 ] || [ ${mem_free} -lt 40 ]) && [ ${adb_forcesrt} -eq 0 ]
				then
					f_tld "${adb_tmpfile}"
				fi
				continue
			fi
		fi

		# download queue processing
		#
		if [ "${src_name}" = "blacklist" ]
		then
			if [ -s "${src_url}" ]
			then
				(
					src_log="$(cat "${src_url}" > "${adb_tmpload}" 2>&1)"
					adb_rc=${?}
					if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpload}" ]
					then
						awk "${src_rset}" "${adb_tmpload}" 2>/dev/null > "${adb_tmpfile}"
						adb_rc=${?}
						if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpfile}" ]
						then
							rm -f "${adb_tmpload}"
							f_list download
							if ([ ${mem_total} -lt 64 ] || [ ${mem_free} -lt 40 ]) && [ ${adb_forcesrt} -eq 0 ]
							then
								f_tld "${adb_tmpfile}"
							fi
						fi
					else
						src_log="$(printf '%s' "${src_log}" | awk '{ORS=" ";print $0}')"
						f_log "debug" "f_main ::: name: ${src_name}, url: ${src_url}, rc: ${adb_rc}, log: ${src_log:-"-"}"
					fi
				) &
			else
				continue
			fi
		elif [ -n "${src_cat}" ]
		then
			(
				src_arc="${adb_tmpdir}/${src_url##*/}"
				src_log="$("${adb_fetchutil}" ${adb_fetchparm} "${src_arc}" "${src_url}" 2>&1)"
				adb_rc=${?}
				if [ ${adb_rc} -eq 0 ] && [ -s "${src_arc}" ]
				then
					list="$(tar -tzf "${src_arc}")"
					suffix="$(eval printf '%s' \"\${adb_src_suffix_${src_name}:-\"domains\"\}\")"
					for cat in ${src_cat}
					do
						entry="$(printf '%s' "${list}" | grep -E "[\^/]+${cat}/${suffix}")"
						if [ -n "${entry}" ]
						then
							tar -xOzf "${src_arc}" "${entry}" >> "${adb_tmpload}"
							adb_rc=${?}
							if [ ${adb_rc} -ne 0 ]
							then
								break
							fi
						fi
					done
				else
					src_log="$(printf '%s' "${src_log}" | awk '{ORS=" ";print $0}')"
					f_log "debug" "f_main ::: name: ${src_name}, url: ${src_url}, rc: ${adb_rc}, log: ${src_log:-"-"}"
				fi
				if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpload}" ]
				then
					rm -f "${src_arc}"
					awk "${src_rset}" "${adb_tmpload}" 2>/dev/null > "${adb_tmpfile}"
					adb_rc=${?}
					if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpfile}" ]
					then
						rm -f "${adb_tmpload}"
						f_list download
						if [ ${adb_backup} -eq 1 ]
						then
							f_list backup
						fi
						if ([ ${mem_total} -lt 64 ] || [ ${mem_free} -lt 40 ]) && [ ${adb_forcesrt} -eq 0 ]
						then
							f_tld "${adb_tmpfile}"
						fi
					elif [ ${adb_backup} -eq 1 ]
					then
						f_list restore
					fi
				elif [ ${adb_backup} -eq 1 ]
				then
					f_list restore
				fi
			) &
		else
			(
				src_log="$("${adb_fetchutil}" ${adb_fetchparm} "${adb_tmpload}" "${src_url}" 2>&1)"
				adb_rc=${?}
				if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpload}" ]
				then
					awk "${src_rset}" "${adb_tmpload}" 2>/dev/null > "${adb_tmpfile}"
					adb_rc=${?}
					if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpfile}" ]
					then
						rm -f "${adb_tmpload}"
						f_list download
						if [ ${adb_backup} -eq 1 ]
						then
							f_list backup
						fi
						if ([ ${mem_total} -lt 64 ] || [ ${mem_free} -lt 40 ]) && [ ${adb_forcesrt} -eq 0 ]
						then
							f_tld "${adb_tmpfile}"
						fi
					elif [ ${adb_backup} -eq 1 ]
					then
						f_list restore
					fi
				else
					src_log="$(printf '%s' "${src_log}" | awk '{ORS=" ";print $0}')"
					f_log "debug" "f_main ::: name: ${src_name}, url: ${src_url}, rc: ${adb_rc}, log: ${src_log:-"-"}"
					if [ ${adb_backup} -eq 1 ]
					then
						f_list restore
					fi
				fi
			) &
		fi
		hold=$(( cnt % adb_maxqueue ))
		if [ ${hold} -eq 0 ]
		then
			wait
		fi
		cnt=$(( cnt + 1 ))
	done

	# list merge
	#
	wait
	src_name="overall"
	adb_tmpfile="${tmp_file}"
	f_list merge

	# overall sort and conditional dns restart
	#
	f_hash
	if [ -s "${adb_tmpdir}/${adb_dnsfile}" ]
	then
		if ([ ${mem_total} -ge 64 ] && [ ${mem_free} -ge 40 ]) || [ ${adb_forcesrt} -eq 1 ]
		then
			f_tld "${adb_tmpdir}/${adb_dnsfile}"
		fi
		f_list final
	else
		> "${adb_dnsdir}/${adb_dnsfile}"
	fi
	chown "${adb_dnsuser}" "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null
	f_hash
	if [ ${?} -eq 1 ]
	then
		f_dnsup
	fi
	f_jsnup
	if [ ${?} -eq 0 ]
	then
		f_log "info" "blocklist with overall ${adb_cnt} domains loaded successfully (${adb_sysver})"
	else
		f_log "err" "dns backend restart with active blocklist failed"
	fi
	f_rmtemp
	exit ${adb_rc}
}

# source required system libraries
#
if [ -r "/lib/functions.sh" ] && [ -r "/usr/share/libubox/jshn.sh" ]
then
	. "/lib/functions.sh"
	. "/usr/share/libubox/jshn.sh"
else
	f_log "err" "system libraries not found"
fi

# initialize json runtime file
#
json_load_file "${adb_rtfile}" >/dev/null 2>&1
json_select data >/dev/null 2>&1
if [ ${?} -ne 0 ]
then
	> "${adb_rtfile}"
	json_init
	json_add_object "data"
fi

# handle different adblock actions
#
f_envload
case "${adb_action}" in
	stop)
		f_rmdns
	;;
	restart)
		f_rmdns
		f_envcheck
		f_main
	;;
	suspend)
		f_switch suspend
	;;
	resume)
		f_switch resume
	;;
	query)
		f_query "${2}"
	;;
	start|reload)
		f_envcheck
		f_main
	;;
esac