Unify protection handling

filter.lua

@@ -26,8 +26,7 @@ local function filter_init(pos)
 end
 
 local function filter_receive_fields(pos, formname, fields, sender)
-	if minetest.is_protected(pos, sender) and not minetest.check_player_privs(sender, "protection_bypass") then
-		minetest.record_protection_violation(pos, sender)
+	if digiline_routing.is_protected(pos, sender) then
 		return
 	end
 	if not fields.channel then

multiblock.lua

@@ -12,16 +12,14 @@ digiline_routing.multiblock.build2 = function(node1, node2, itemstack, placer, p
 		pos = pointed_thing.above
 	end
 
-	if minetest.is_protected(pos, placer:get_player_name()) and not minetest.check_player_privs(placer, "protection_bypass") then
-		minetest.record_protection_violation(pos, placer:get_player_name())
+	if digiline_routing.is_protected(pos, placer) then
 		return itemstack, false
 	end
 
 	local dir = minetest.dir_to_facedir(placer:get_look_dir())
 	local botpos = vector.add(pos, minetest.facedir_to_dir(dir))
 
-	if minetest.is_protected(botpos, placer:get_player_name()) and not minetest.check_player_privs(placer, "protection_bypass") then
-		minetest.record_protection_violation(botpos, placer:get_player_name())
+	if digiline_routing.is_protected(botpos, placer) then
 		return itemstack, false
 	end
 
@@ -45,11 +43,11 @@ digiline_routing.multiblock.rotate2 = function(pos, node, user, mode, new_param2
 	local dir = minetest.facedir_to_dir(node.param2)
 	local p = vector.add(pos, dir)
 	local node2 = minetest.get_node_or_nil(p)
-	if not node2 or not node.param2 == node2.param2 then
+	if not node2 or node.param2 ~= node2.param2 then
 		return false
 	end
-	if minetest.is_protected(p, user:get_player_name()) then
-		minetest.record_protection_violation(p, user:get_player_name())
+	-- protection at `pos` is checked by the screwdriver
+	if digiline_routing.is_protected(p, user) then
 		return false
 	end
 	if mode ~= screwdriver.ROTATE_FACE then
@@ -61,8 +59,7 @@ digiline_routing.multiblock.rotate2 = function(pos, node, user, mode, new_param2
 	if not node_def or not node_def.buildable_to then
 		return false
 	end
-	if minetest.is_protected(newp, user:get_player_name()) then
-		minetest.record_protection_violation(newp, user:get_player_name())
+	if digiline_routing.is_protected(newp, user) then
 		return false
 	end
 	node.param2 = new_param2

util.lua

@@ -14,3 +14,16 @@ digiline_routing.get_base_rule = function(rule, param2)
 	end
 	return BASE_RULES[(rule + param2) % 4]
 end
+
+digiline_routing.is_protected = function(pos, player)
+	local name = player:get_player_name()
+	if not minetest.is_protected(pos, name) then
+		return false
+	end
+	-- FIXME: is this necessary?
+	if minetest.check_player_privs(name, "protection_bypass") then
+		return false
+	end
+	minetest.record_protection_violation(pos, name)
+	return true
+end