configure: expose USE_GETIFADDRS configuration

The miniupnpd sources contain a working getifaddrs() based implementation
to fetch the IP address of an interface but that implementation is guarded
by a USE_GETIFADDRS define which can only be passed manually via CFLAGS.

Introduce a new `--getifaddrs` option to the configure script which can be
used to explicitly enable `getifaddrs()` usage.

Also extend the OpenWrt configuration case to enable `getifaddrs()` since
OpenWrt ships with a working implementation of it since several years
already.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

miniupnpd/configure

@@ -47,6 +47,7 @@ case "$argv" in
 	    FW=$(echo $argv | cut -d= -f2) ;;
 	--iptablespath=*)
 		IPTABLESPATH=$(echo $argv | cut -d= -f2) ;;
+	--getifaddrs) GETIFADDRS=1 ;;
 	--help|-h)
 		echo "Usage : $0 [options]"
 		echo " --ipv6      enable IPv6"
@@ -62,6 +63,7 @@ case "$argv" in
 		echo " --firewall=<name>  force the firewall type (nftables, iptables, pf, ipf, ipfw)"
 		echo " --iptablespath=/path/to/iptables use a specific version of iptables"
 		echo " --disable-fork     Do not go to background and do not write pid file"
+		echo " --getifaddrs       Force use getifaddrs() to obtain interface addresses"
 		exit 1
 		;;
 	*)
@@ -387,6 +389,7 @@ case $OS_NAME in
 	OpenWrt)
 		OS_URL=http://www.openwrt.org/
 		echo "#define USE_IFACEWATCHER 1" >> ${CONFIGFILE}
+		GETIFADDRS=1
 		;;
 	OpenEmbedded)
 		OS_URL=http://www.openembedded.org/
@@ -850,6 +853,13 @@ else
 	echo "/*#define NO_BACKGROUND_NO_PIDFILE*/" >> ${CONFIGFILE}
 fi
 
+echo "/* Whether to use getifaddrs() to determine interface addresses */" >> ${CONFIGFILE}
+if [ -n "$GETIFADDRS" ] && [ $GETIFADDRS -eq 1 ] ; then
+	echo "#define USE_GETIFADDRS" >> ${CONFIGFILE}
+else
+	echo "/*#define USE_GETIFADDRS*/" >> ${CONFIGFILE}
+fi
+
 echo "#endif /* ${CONFIGMACRO} */" >> ${CONFIGFILE}
 
 ${MV} ${CONFIGFILE} ${CONFIGFILE_FINAL}