#!/bin/sh
# Begin $rc_base/init.d/unbound

# Description : Unbound DNS resolver boot script for IPfire
# Author      : Marcel Lorenz <marcel.lorenz@ipfire.org>

. /etc/sysconfig/rc
. ${rc_functions}

TEST_DOMAIN="ipfire.org"

# This domain will never validate
TEST_DOMAIN_FAIL="dnssec-failed.org"

INSECURE_ZONES=
USE_FORWARDERS=1

# Cache any local zones for 60 seconds
LOCAL_TTL=60

# EDNS buffer size
EDNS_DEFAULT_BUFFER_SIZE=4096

# Load optional configuration
[ -e "/etc/sysconfig/unbound" ] && . /etc/sysconfig/unbound

function cidr() {
    local cidr nbits IFS;
    IFS=. read -r i1 i2 i3 i4 <<< ${1}
    IFS=. read -r m1 m2 m3 m4 <<< ${2}
    cidr=$(printf "%d.%d.%d.%d\n" "$((i1 & m1))" "$((i2 & m2))" "$((i3 & m3))" "$((i4 & m4))")
    nbits=0
    IFS=.
    for dec in $2 ; do
        case $dec in
            255) let nbits+=8;;
            254) let nbits+=7;;
            252) let nbits+=6;;
            248) let nbits+=5;;
            240) let nbits+=4;;
            224) let nbits+=3;;
            192) let nbits+=2;;
            128) let nbits+=1;;
            0);;
            *) echo "Error: $dec is not recognised"; exit 1
        esac
    done
    echo "${cidr}/${nbits}"
}

ip_address_revptr() {
	local addr=${1}

	local a1 a2 a3 a4
	IFS=. read -r a1 a2 a3 a4 <<< ${addr}

	echo "${a4}.${a3}.${a2}.${a1}.in-addr.arpa"
}

read_name_servers() {
	local i
	for i in 1 2; do
		echo "$(</var/ipfire/red/dns${i})"
	done | xargs echo
}

config_header() {
	echo "# This file is automatically generated and any changes"
	echo "# will be overwritten. DO NOT EDIT!"
	echo
}

update_forwarders() {
	if [ "${USE_FORWARDERS}" = "1" -a -e "/var/ipfire/red/active" ]; then
		local forwarders
		local broken_forwarders

		local ns
		for ns in $(read_name_servers); do
			test_name_server ${ns} &>/dev/null
			case "$?" in
				# Only use DNSSEC-validating or DNSSEC-aware name servers
				0|2)
					forwarders="${forwarders} ${ns}"
					;;
				*)
					broken_forwarders="${broken_forwarders} ${ns}"
					;;
			esac
		done

		# Determine EDNS buffer size
		local new_edns_buffer_size=${EDNS_DEFAULT_BUFFER_SIZE}

		for ns in ${forwarders}; do
			local edns_buffer_size=$(ns_determine_edns_buffer_size ${ns})
			if [ -n "${edns_buffer_size}" ]; then
				if [ ${edns_buffer_size} -lt ${new_edns_buffer_size} ]; then
					new_edns_buffer_size=${edns_buffer_size}
				fi
			fi
		done

		if [ ${new_edns_buffer_size} -lt ${EDNS_DEFAULT_BUFFER_SIZE} ]; then
			boot_mesg "EDNS buffer size reduced to ${new_edns_buffer_size}" ${WARNING}
			echo_warning

			unbound-control -q set_option edns-buffer-size: ${new_edns_buffer_size}
		fi

		# Show warning for any broken upstream name servers
		if [ -n "${broken_forwarders}" ]; then
			boot_mesg "Ignoring broken upstream name server(s): ${broken_forwarders:1}" ${WARNING}
			echo_warning
		fi

		if [ -n "${forwarders}" ]; then
			boot_mesg "Configuring upstream name server(s): ${forwarders:1}" ${INFO}
			echo_ok

			# Make sure DNSSEC is activated
			enable_dnssec

			echo "${forwarders}" > /var/ipfire/red/dns
			unbound-control -q forward ${forwarders}
			return 0

		# In case we have found no working forwarders
		else
			# Test if the recursor mode is available
			if can_resolve_root +bufsize=${new_edns_buffer_size}; then
				# Make sure DNSSEC is activated
				enable_dnssec

				boot_mesg "Falling back to recursor mode" ${WARNING}
				echo_warning

			# If not, we set DNSSEC in permissive mode and allow using all recursors
			elif [ -n "${broken_forwarders}" ]; then
				disable_dnssec

				boot_mesg "DNSSEC has been set to permissive mode" ${FAILURE}
				echo_failure

				echo "${broken_forwarders}" > /var/ipfire/red/dns
				unbound-control -q forward ${broken_forwarders}
				return 0
			fi
		fi
	fi

	# If forwarders cannot be used we run in recursor mode
	echo "local recursor" > /var/ipfire/red/dns
	unbound-control -q forward off
}

own_hostname() {
	local hostname=$(hostname -f)
	# 1.1.1.1 is reserved for unused green, skip this
	if [ -n "${GREEN_ADDRESS}" -a "${GREEN_ADDRESS}" != "1.1.1.1" ]; then
		unbound-control -q local_data "${hostname} ${LOCAL_TTL} IN A ${GREEN_ADDRESS}"
	fi

	local address
	for address in ${GREEN_ADDRESS} ${BLUE_ADDRESS} ${ORANGE_ADDRESS}; do
		[ -n "${address}" ] || continue
		[ "${address}" = "1.1.1.1" ] && continue

		address=$(ip_address_revptr ${address})
		unbound-control -q local_data "${address} ${LOCAL_TTL} IN PTR ${hostname}"
	done
}

update_hosts() {
	local enabled address hostname domainname

	while IFS="," read -r enabled address hostname domainname; do
		[ "${enabled}" = "on" ] || continue

		# Build FQDN
		local fqdn="${hostname}.${domainname}"

		unbound-control -q local_data "${fqdn} ${LOCAL_TTL} IN A ${address}"

		# Skip reverse resolution if the address equals the GREEN address
		[ "${address}" = "${GREEN_ADDRESS}" ] && continue

		# Add RDNS
		address=$(ip_address_revptr ${address})
		unbound-control -q local_data "${address} ${LOCAL_TTL} IN PTR ${fqdn}"
	done < /var/ipfire/main/hosts
}

write_forward_conf() {
	(
		config_header

		local insecure_zones="${INSECURE_ZONES}"

		local enabled zone server remark
		while IFS="," read -r enabled zone server remark; do
			# Line must be enabled.
			[ "${enabled}" = "on" ] || continue

			# Zones that end with .local are commonly used for internal
			# zones and therefore not signed
			case "${zone}" in
				*.local)
					insecure_zones="${insecure_zones} ${zone}"
					;;
			esac

			echo "forward-zone:"
			echo "	name: ${zone}"
			echo "	forward-addr: ${server}"
			echo
		done < /var/ipfire/dnsforward/config

		if [ -n "${insecure_zones}" ]; then
			echo "server:"

			for zone in ${insecure_zones}; do
				echo "	domain-insecure: ${zone}"
			done
		fi
	) > /etc/unbound/forward.conf
}

write_tuning_conf() {
	# https://www.unbound.net/documentation/howto_optimise.html

	# Determine number of online processors
	local processors=$(getconf _NPROCESSORS_ONLN)

	# Determine number of slabs
	local slabs=1
	while [ ${slabs} -lt ${processors} ]; do
		slabs=$(( ${slabs} * 2 ))
	done

	# Determine amount of system memory
	local mem=$(get_memory_amount)

	# In the worst case scenario, unbound can use double the
	# amount of memory allocated to a cache due to malloc overhead

	# Even larger systems with more than 8GB of RAM
	if [ ${mem} -ge 8192 ]; then
		mem=1024

	# Extra large systems with more than 4GB of RAM
	elif [ ${mem} -ge 4096 ]; then
		mem=512

	# Large systems with more than 2GB of RAM
	elif [ ${mem} -ge 2048 ]; then
		mem=256

	# Medium systems with more than 1GB of RAM
	elif [ ${mem} -ge 1024 ]; then
		mem=128

	# Small systems with less than 256MB of RAM
	elif [ ${mem} -le 256 ]; then
		mem=16

	# Everything else
	else
		mem=64
	fi

	(
		config_header

		# We run one thread per processor
		echo "num-threads: ${processors}"
		echo "so-reuseport: yes"

		# Adjust number of slabs
		echo "infra-cache-slabs: ${slabs}"
		echo "key-cache-slabs: ${slabs}"
		echo "msg-cache-slabs: ${slabs}"
		echo "rrset-cache-slabs: ${slabs}"

		# Slice up the cache
		echo "rrset-cache-size: $(( ${mem} / 2 ))m"
		echo "msg-cache-size: $(( ${mem} / 4 ))m"
		echo "key-cache-size: $(( ${mem} / 4 ))m"

		# Increase parallel queries
		echo "outgoing-range: 8192"
		echo "num-queries-per-thread: 4096"

		# Use larger send/receive buffers
		echo "so-sndbuf: 4m"
		echo "so-rcvbuf: 4m"
	) > /etc/unbound/tuning.conf
}

get_memory_amount() {
	local key val unit

	while read -r key val unit; do
		case "${key}" in
			MemTotal:*)
				# Convert to MB
				echo "$(( ${val} / 1024 ))"
				break
				;;
		esac
	done < /proc/meminfo
}

test_name_server() {
	local ns=${1}
	local args

	# Return codes:
	# 0	DNSSEC validating
	# 1	Error: unreachable, etc.
	# 2	DNSSEC aware
	# 3	NOT DNSSEC-aware

	# Exit when the server is not reachable
	ns_is_online ${ns} || return 1

	# Determine the maximum edns buffer size that works
	local edns_buffer_size=$(ns_determine_edns_buffer_size ${ns})
	if [ -n "${edns_buffer_size}" ]; then
		args="${args} +bufsize=${edns_buffer_size}"
	fi

	local errors
	for rr in DNSKEY DS RRSIG; do
		if ! ns_forwards_${rr} ${ns} ${args}; then
			errors="${errors} ${rr}"
		fi
	done

	if [ -n "${errors}" ]; then
		echo >&2 "Unable to retrieve the following resource records from ${ns}: ${errors:1}"
		return 3
	fi

	if ns_is_validating ${ns} ${args}; then
		# Return 0 if validating
		return 0
	else
		# Is DNSSEC-aware
		return 2
	fi
}

# Sends an A query to the nameserver w/o DNSSEC
ns_is_online() {
	local ns=${1}
	shift

	dig @${ns} +nodnssec A ${TEST_DOMAIN} $@ >/dev/null
}

# Resolving ${TEST_DOMAIN_FAIL} will fail if the nameserver is validating
ns_is_validating() {
	local ns=${1}
	shift

	dig @${ns} A ${TEST_DOMAIN_FAIL} $@ | grep -q SERVFAIL
}

# Checks if we can retrieve the DNSKEY for this domain.
# dig will print the SOA if nothing was found
ns_forwards_DNSKEY() {
	local ns=${1}
	shift

	dig @${ns} DNSKEY ${TEST_DOMAIN} $@ | grep -qv SOA
}

ns_forwards_DS() {
	local ns=${1}
	shift

	dig @${ns} DS ${TEST_DOMAIN} $@ | grep -qv SOA
}

ns_forwards_RRSIG() {
	local ns=${1}
	shift

	dig @${ns} +dnssec A ${TEST_DOMAIN} $@ | grep -q RRSIG
}

ns_supports_tcp() {
	local ns=${1}
	shift

	dig @${ns} +tcp A ${TEST_DOMAIN} $@ >/dev/null || return 1
}

ns_determine_edns_buffer_size() {
	local ns=${1}
	shift

	local b
	for b in 4096 2048 1500 1480 1464 1400 1280 512; do
		if dig @${ns} +dnssec +bufsize=${b} A ${TEST_DOMAIN} $@ >/dev/null; then
			echo "${b}"
			return 0
		fi
	done

	return 1
}

get_root_nameservers() {
	while read -r hostname ttl record address; do
		# Searching for A records
		[ "${record}" = "A" ] || continue

		echo "${address}"
	done < /etc/unbound/root.hints
}

can_resolve_root() {
	local ns
	for ns in $(get_root_nameservers); do
		if dig @${ns} +dnssec SOA . $@ >/dev/null; then
			return 0
		fi
	done

	# none of the servers was reachable
	return 1
}

enable_dnssec() {
	local status=$(unbound-control get_option val-permissive-mode)

	# Don't do anything if DNSSEC is already activated
	[ "${status}" = "no" ] && return 0

	# Log DNSSEC status
	echo "on" > /var/ipfire/red/dnssec-status

	# Activate DNSSEC and flush cache with any stale and unvalidated data
	unbound-control -q set_option val-permissive-mode: no
	unbound-control -q flush_zone .
}

disable_dnssec() {
	# Log DNSSEC status
	echo "off" > /var/ipfire/red/dnssec-status

	unbound-control -q set_option val-permissive-mode: yes
}

case "$1" in
	start)
		# Print a nicer messagen when unbound is already running
		if pidofproc -s unbound; then
			statusproc /usr/sbin/unbound
			exit 0
		fi

		eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings)

		# Create control keys at first run
		if [ ! -r "/etc/unbound/unbound_control.key" ]; then
			unbound-control-setup -d /etc/unbound &>/dev/null
		fi

		# Update configuration files
		write_tuning_conf
		write_forward_conf

		boot_mesg "Starting Unbound DNS Proxy..."
		loadproc /usr/sbin/unbound || exit $?

		# Make own hostname resolveable
		own_hostname

		# Update any known forwarding name servers
		update_forwarders

		# Update hosts
		update_hosts
		;;

	stop)
		boot_mesg "Stopping Unbound DNS Proxy..."
		killproc /usr/sbin/unbound
		;;

	restart)
		$0 stop
		sleep 1
		$0 start
		;;

	status)
		statusproc /usr/sbin/unbound
		;;

	update-forwarders)
		# Do not try updating forwarders when unbound is not running
		if ! pgrep unbound &>/dev/null; then
			exit 0
		fi

		update_forwarders
		;;

	test-name-server)
		ns=${2}

		test_name_server ${ns}
		ret=${?}

		case "${ret}" in
			0)
				echo "${ns} is validating"
				;;
			2)
				echo "${ns} is DNSSEC-aware"
				;;
			3)
				echo "${ns} is NOT DNSSEC-aware"
				;;
			*)
				echo "Test failed for an unknown reason"
				exit ${ret}
				;;
		esac

		if ns_supports_tcp ${ns}; then
			echo "${ns} supports TCP fallback"
		else
			echo "${ns} does not support TCP fallback"
		fi

		edns_buffer_size=$(ns_determine_edns_buffer_size ${ns})
		if [ -n "${edns_buffer_size}" ]; then
			echo "EDNS buffer size for ${ns}: ${edns_buffer_size}"
		fi

		exit ${ret}
		;;

	*)
		echo "Usage: $0 {start|stop|restart|status|update-forwarders|test-name-server}"
		exit 1
		;;
esac

# End $rc_base/init.d/unbound