proto-shell: add proto property for skipping device config

This is useful for PPPoE, where settings like MTU should not be applied to
the lower device

Signed-off-by: Felix Fietkau <nbd@nbd.name>

interface.c

@@ -652,7 +652,8 @@ interface_claim_device(struct interface *iface)
 	} else if (iface->device &&
 		!(iface->proto_handler->flags & PROTO_FLAG_NODEV)) {
 		dev = device_get(iface->device, true);
-		interface_set_device_config(iface, dev);
+		if (!(iface->proto_handler->flags & PROTO_FLAG_NODEV_CONFIG))
+			interface_set_device_config(iface, dev);
 	} else {
 		dev = iface->ext_dev.dev;
 	}

proto-shell.c

@@ -912,6 +912,10 @@ proto_shell_add_handler(const char *script, const char *name, json_object *obj)
 	if (tmp && json_object_get_boolean(tmp))
 		handler->proto.flags |= PROTO_FLAG_NODEV;
 
+	tmp = json_get_field(obj, "no-device-config", json_type_boolean);
+	if (tmp && json_object_get_boolean(tmp))
+		handler->proto.flags |= PROTO_FLAG_NODEV_CONFIG;
+
 	tmp = json_get_field(obj, "no-proto-task", json_type_boolean);
 	if (tmp && json_object_get_boolean(tmp))
 		handler->proto.flags |= PROTO_FLAG_NO_TASK;

proto.h

@@ -40,6 +40,7 @@ enum {
 	PROTO_FLAG_LASTERROR = (1 << 5),
 	PROTO_FLAG_TEARDOWN_ON_L3_LINK_DOWN = (1 << 6),
 	PROTO_FLAG_NO_TASK = (1 << 7),
+	PROTO_FLAG_NODEV_CONFIG = (1 << 8),
 };
 
 struct interface_proto_state {

scripts/netifd-proto.sh

@@ -437,6 +437,7 @@ init_proto() {
 		dump)
 			add_protocol() {
 				no_device=0
+				no_device_config=0
 				no_proto_task=0
 				available=0
 				renew_handler=0
@@ -450,6 +451,7 @@ init_proto() {
 				eval "proto_$1_init_config"
 				json_close_array
 				json_add_boolean no-device "$no_device"
+				json_add_boolean no-device-config "$no_device_config"
 				json_add_boolean no-proto-task "$no_proto_task"
 				json_add_boolean available "$available"
 				json_add_boolean renew-handler "$renew_handler"