Retrieve IPv4 address of gateway via respondd

ddhcpd/Makefile

@@ -2,6 +2,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=ddhcpd
 PKG_VERSION:=2018-06-28
+PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://github.com/sargon/ddhcpd

ddhcpd/files/usr/sbin/ddhcpd-gateway-update

@@ -1,15 +1,85 @@
 #!/bin/sh
 
-GW="$(batctl gwl | grep '=>' | cut -f 2 -d ' ')"
-GW_MAC="$(batctl tg | grep "$GW" | cut -d ' ' -f 3)"
+CACHE_TTL=600
+CACHE_FILE=/tmp/ddhcp_gw_cache
 
-COUNT=0
-for gw_mac in "$GW_MAC" ; do
-  GW_ADDR=$(batctl dc | grep "$gw_mac" | sed -e 's/^[^0-9]*\([0-9]\+\)/\1/' | cut -d ' ' -f 1)
-  COUNT=$(expr $COUNT + 1)
+GW_UPDATE_TRIES=5
+
+
+verbose() {
+	[ -n "$VERBOSE" ] && ( >&2 echo $@ )
+}
+
+mac_to_ipv6_ll() {
+	IFS=':'; set $1; unset IFS
+	echo "fe80::$(printf %02x $((0x$1 ^ 2)))$2:${3}ff:fe$4:$5$6"
+}
+
+get_gw_ipv4_address() {
+	local gwmac="$1"
+	local gwid="`echo "$gwmac" | tr -d ':'`"
+	gluon-neighbour-info -p 1001 -d "`mac_to_ipv6_ll "$gwmac"`" -i br-client -r gateway | \
+		while read resp; do
+			local node_id="`echo "$resp" | jsonfilter -e '$.node_id'`"
+			if [ "$node_id" = "$gwid" ]; then
+				echo "$resp" | jsonfilter -e '$.address.ipv4'
+			fi
+		done
+}
+
+gateway_lost() {
+	verbose Gateway lost, removing dhcp options
+	rm -f "$CACHE_FILE"
+	/usr/sbin/ddhcpdctl -r 3
+	/usr/sbin/ddhcpdctl -r 6
+}
+
+update_gateway() {
+	verbose Updating dhcp options
+	/usr/sbin/ddhcpdctl -o "3:4:$1"
+	/usr/sbin/ddhcpdctl -o "6:4:$1"
+}
+
+gwmac="`batctl gwl | grep '=>' | cut -d' ' -f2`"
+[ -z "$gwmac" ] && {
+	verbose Failed to determine mac address of current gateway
+	gateway_lost
+	exit 1
+}
+
+verbose Got gateway mac address: "$gwmac"
+
+[ -f "$CACHE_FILE" ] && {
+	verbose Retrieving cache
+	source "$CACHE_FILE"
+	now="`date +'%s'`"
+	if echo "$last_update_time" | egrep -q '^[0-9]+$' && \
+	    echo "$last_gwaddr" | egrep -q '^(([0-9]){1,3}\.){3}[0-9]{1,3}$'; then
+		verbose Gateway mac address cache found, age $(($now - $last_update_time))
+		if [ "$gwmac" = "$last_gwmac" ] && \
+		    [ $(($now - $last_update_time)) -lt "$CACHE_TTL" ]; then
+			verbose Cache is up to date
+			update_gateway "$last_gwaddr"
+			exit 0
+		fi
+	fi
+	verbose Updating cache
+}
+
+for _ in seq "$GW_UPDATE_TRIES"; do
+	gwaddr="`get_gw_ipv4_address "$gwmac"`"
+	[ -n "$gwaddr" ] && break
 done
+[ -z "$gwaddr" ] && {
+	verbose Failed to retrieve gateway IPv4 address
+	gateway_lost
+	exit 2
+}
+
+verbose Got gateway IPv4 address: "$gwaddr"
 
-[[ "$COUNT" -eq 1 ]] || exit 1
+echo "last_gwmac=\"$gwmac\"" > "$CACHE_FILE"
+echo "last_gwaddr=\"$gwaddr\"" >> "$CACHE_FILE"
+echo "last_update_time=`date +'%s'`" >> "$CACHE_FILE"
 
-/usr/sbin/ddhcpdctl -o "3:4:${GW_ADDR}"
-/usr/sbin/ddhcpdctl -o "6:4:${GW_ADDR}"
+update_gateway "$gwaddr"