gre: Support multicast configurable gre interfaces

UCI paramater multicast is added which allows to toggle multicast support on gre interfaces.
By default multicast support is enabled as gre tunnels are often used in combination with
routing protocols using multicast.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
Signed-off-by: Nick Podolak <nicholas.podolak@dtechlabs.com>

SVN-Revision: 48596

package/network/config/gre/files/gre.sh

@@ -13,10 +13,11 @@ gre_generic_setup() {
 	local local="$3"
 	local remote="$4"
 	local link="$5"
-	local mtu ttl tos zone ikey okey icsum ocsum iseqno oseqno
-	json_get_vars mtu ttl tos zone ikey okey icsum ocsum iseqno oseqno
+	local mtu ttl tos zone ikey okey icsum ocsum iseqno oseqno multicast
+	json_get_vars mtu ttl tos zone ikey okey icsum ocsum iseqno oseqno multicast
 
 	[ -z "$zone" ] && zone="wan"
+	[ -z "$multicast" ] && multicast=1
 
 	proto_init_update "$link" 1
 
@@ -26,6 +27,7 @@ gre_generic_setup() {
 	[ -n "$df" ] && json_add_boolean df "$df"
 	json_add_int ttl "${ttl:-64}"
 	[ -n "$tos" ] && json_add_string tos "$tos"
+	json_add_boolean multicast "$multicast"
 	json_add_string local "$local"
 	json_add_string remote "$remote"
 	[ -n "$tunlink" ] && json_add_string link "$tunlink"
@@ -203,6 +205,7 @@ gre_generic_init_config() {
 	proto_config_add_boolean "ocsum"
 	proto_config_add_boolean "iseqno"
 	proto_config_add_boolean "oseqno"
+	proto_config_add_boolean "multicast"
 }
 
 proto_gre_init_config() {