#!/bin/sh

set -e

# for iconv below
export LC_ALL=en_US.utf8

# 1st argument must be an ASN registered to peeringdb
# 2nd argument must be the IPv4 peering address
# 3rd argument must be the IPv6 peering address

if [ ! -f /usr/local/etc/bird-peers-update.conf ]; then
	printf "Write /usr/local/etc/bird-peers-update.conf with at least "
	printf "PDB_API_KEY, IXP_ASN and BIRD_CONF_PATH vars\n"
	exit 1
else
	. /usr/local/etc/bird-peers-update.conf
fi

PEER_AS=$1
IPv4=$2
IPv6=$3

if [ -z "${PEER_AS}" -o -z "${IPv4}" -o -z "${IPv6}" ]; then
	echo "1st argument must be an ASN registered to peeringdb"
	echo "2nd argument must be the IPv4 peering address"
	echo "3rd argument must be the IPv6 peering address"
	exit 1
fi

CACHE_DIR=/var/local/cache/peeringdb

if [ ! -d "${CACHE_DIR}" ]; then
	mkdir -p "${CACHE_DIR}"
fi

# re-fetch data if it's too old
if [ -z "$(find ${CACHE_DIR} -mmin -720 -name ${PEER_AS}.json)" ]; then
	curl -s -H 'Authorization: Api-Key '"${PDB_API_KEY}" \
		-X GET "https://www.peeringdb.com/api/net?asn=${PEER_AS}" \
		> "${CACHE_DIR}/${PEER_AS}.json"
fi

# test if the data is valid, -e will exit the script
jq -r '.data[] | .irr_as_set' "${CACHE_DIR}/${PEER_AS}.json" 1>/dev/null

IRRASSET=$(jq -r '.data[] | .irr_as_set' "${CACHE_DIR}/${PEER_AS}.json")
MAXPREF4=$(jq -r '.data[] | .info_prefixes4' "${CACHE_DIR}/${PEER_AS}.json")
MAXPREF6=$(jq -r '.data[] | .info_prefixes6' "${CACHE_DIR}/${PEER_AS}.json")
AS_NAME=$(jq -r '.data[] | .name' "${CACHE_DIR}/${PEER_AS}.json")

if [ -z "${IRRASSET}" ]; then
	IRRASSET="AS${PEER_AS}"
fi

# Remove diacritic first as potential question marks will remove afterward
AS_NAME="$(echo ${AS_NAME} | iconv -f utf-8 -t ascii//TRANSLIT)"
AS_NAME="$(echo ${AS_NAME} | tr '[:punct:]' '_')"
AS_NAME="$(echo ${AS_NAME} | tr '[:space:]' '_')"
AS_NAME="$(echo ${AS_NAME} | tr '[:lower:]' '[:upper:]')"
AS_NAME="$(echo ${AS_NAME} | sed -E 's/^_+//;s/_+$//;s/_+/_/g')"

IPv4_PFL="$(bgpq4 -4 -b -A -l AS${PEER_AS}_v4 -R 24 ${IRRASSET})"
IPv6_PFL="$(bgpq4 -6 -b -A -l AS${PEER_AS}_v6 -R 48 ${IRRASSET})"

if [ -z "${MAXPREF4}" ] || [ ${MAXPREF4} -eq 0 ]; then
	MAXPREF4=$(echo "${IPv4_PFL}" | wc -l)
fi
if [ "${MAXPREF4}" -lt 10 ]; then
	MAXPREF4=10
fi
if [ -z "${MAXPREF6}" ] || [ ${MAXPREF6} -eq 0 ]; then
	MAXPREF6=$(echo "${IPv6_PFL}" | wc -l)
fi
if [ "${MAXPREF6}" -lt 10 ]; then
	MAXPREF6=10
fi

# do we really trust peeringdb? we may want to limit maxpref

mkdir -p "${BIRD_CONF_PATH}"/functions

# AS16 - AS32 from whois AS47214
if [ "${PEER_AS}" -gt 65535 ]; then
	# la t'es bien
	eval $(whois AS47214 | awk '/AS32 to AS16/ { print "AS"$5"="$7";" }' | sed -E 's/AS([0-9]+)/\1/g')
	eval COMMU_PEER_AS=\$AS${PEER_AS}
else
	COMMU_PEER_AS=${PEER_AS}
fi

echo "# generated by $0 $@
function check_import_${PEER_AS}_ipv4(int peeras; ip nexthop)
prefix set AS${PEER_AS}_v4;
{
	${IPv4_PFL}

	# check if the announced prefix is in the bgpq set
	if net !~ AS${PEER_AS}_v4 then return false;

	# reject the route if the first as is not the peer
	# or if the nexthop is not the peer as well
	# we also check the rpki status there
	return check_ipv4(peeras, nexthop);
}

filter bgp_filters_${PEER_AS}_out {
	if ! (source = RTS_BGP) then reject;
	if (${IXP_ASN},${COMMU_PEER_AS}) ~ bgp_community then accept;
	if (0,${COMMU_PEER_AS}) ~ bgp_community then reject;
	if (0,${IXP_ASN}) ~ bgp_community then reject;
	if (${IXP_ASN},${IXP_ASN}) ~ bgp_community then accept;

	else accept;
}
" > "${BIRD_CONF_PATH}/functions/${PEER_AS}_v4.conf"

mkdir -p "${BIRD_CONF_PATH}"/peers

# bird does not support dots in the filters name, it must be dashes
DASH_IPv4="$(echo ${IPv4} | tr '.' '_')"

if [ -f "/usr/local/etc/bird-override/bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv4}.conf" ]; then
	BIRD_OVERRIDE_AFI_V4="include \"/usr/local/etc/bird-override/bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv4}.conf\";"
else
	BIRD_OVERRIDE_AFI_V4=""
fi

echo "# generated by $0 $@
filter bgp_filters_${DASH_IPv4}_in_ipv4 {
	if (check_import_${PEER_AS}_ipv4(${PEER_AS}, ${IPv4})) then {
		# Here we can set localpref or remove a prefix, for example
		accept;
	}
	else {
		reject \"Prefix \", net, \" filtered IN from ${IPv4}\";
	}
}

protocol bgp bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv4} from PEERS_IPv4 {
	description \"${AS_NAME} ${IRRASSET}\";
	neighbor ${IPv4} as ${PEER_AS};
	${BIRD_OVERRIDE_AFI_V4}

	ipv4 {
		receive limit ${MAXPREF4} action restart;
		import limit ${MAXPREF4} action disable;
		import filter bgp_filters_${DASH_IPv4}_in_ipv4;
		export filter bgp_filters_${PEER_AS}_out;
	};
}
" > "${BIRD_CONF_PATH}/peers/${PEER_AS}_${IPv4}.conf"

echo "# generated by $0 $@
function check_import_${PEER_AS}_ipv6(int peeras; ip nexthop)
prefix set AS${PEER_AS}_v6;
{
	${IPv6_PFL}

	# check if the announced prefix is in the bgpq set
	if net !~ AS${PEER_AS}_v6 then return false;

	# reject the route if the first as is not the peer
	# or if the nexthop is not the peer as well
	# we also check the rpki status there
	return check_ipv6(peeras, nexthop);
}
" > "${BIRD_CONF_PATH}/functions/${PEER_AS}_v6.conf"

# bird does not support semicollons in the filters name, it must be dashes
DASH_IPv6="$(echo ${IPv6} | tr ':' '_')"

if [ -f "/usr/local/etc/bird-override/bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv6}.conf" ]; then
	BIRD_OVERRIDE_AFI_V6="include \"/usr/local/etc/bird-override/bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv6}.conf\";"
else
	BIRD_OVERRIDE_AFI_V6=""
fi

echo "# generated by $0 $@
filter bgp_filters_${DASH_IPv6}_in_ipv6 {
	if (check_import_${PEER_AS}_ipv6(${PEER_AS}, ${IPv6})) then {
		# Here we can set localpref or remove a prefix, for example
		accept;
	}
	else {
		reject \"Prefix \", net, \" filtered IN from ${IPv6}\";
	}
}

protocol bgp bgp_${PEER_AS}_${AS_NAME}_${DASH_IPv6} from PEERS_IPv6 {
	description \"${AS_NAME} ${IRRASSET}\";
	neighbor ${IPv6} as ${PEER_AS};
	${BIRD_OVERRIDE_AFI_V6}

	ipv6 {
		receive limit ${MAXPREF6} action restart;
		import limit ${MAXPREF6} action disable;
		import filter bgp_filters_${DASH_IPv6}_in_ipv6;
		export filter bgp_filters_${PEER_AS}_out;
	};
}
" > "${BIRD_CONF_PATH}/peers/${PEER_AS}_${IPv6}.conf"

echo "# generated by $0 $@
function check_import_${PEER_AS}_ipv6(int peeras; ip nexthop)
prefix set AS${PEER_AS}_v6;
{
	${IPv6_PFL}

	if net !~ AS${PEER_AS}_v6 then return false;

	return check_ipv6(peeras, nexthop);
}
" > "${BIRD_CONF_PATH}/functions/${PEER_AS}_v6.conf"