[CSM] Add flavour limits controlled by server (#5930)

* [CSM] Add flavour limits controlled by server

Server send flavour limits to client permitting to disable or limit some Lua calls

* Add limits for reading nodedefs and itemdefs

* flavour: Add lookup node limits

* Merge get_node_or_nil into get_node.

Sending fake node doesn't make sense in CSM, just return nil if node is not available for any reason

* Add node range customization when noderange flavour is enabled (default 8 nodes)

* Limit nodes range & disable chat message sending by default

* Bump protocol version

1 files changed, 13 insertions, 0 deletions

diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index c710afdcf..60508d0dd 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -960,6 +960,19 @@ block_send_optimize_distance (block send optimize distance) int 4 2
 #    so that the utility of noclip mode is reduced.
 server_side_occlusion_culling (Server side occlusion culling) bool true
 
+#    Restricts the access of certain client-side functions on servers
+#    Combine these byteflags below to restrict more client-side features:
+#    LOOKUP_NODES_LIMIT: 1 (limits get_node call client-side to csm_flavour_noderange_limit)
+#    CHAT_MESSAGES: 2 (disable send_chat_message call client-side)
+#    READ_ITEMDEFS: 4 (disable get_item_def call client-side)
+#    READ_NODEDEFS: 8 (disable get_node_def call client-side)
+#    type: int
+csm_flavour_limits (Client side modding flavour limits) int 3
+
+#   If the CSM flavour for node range is enabled, get_node is limited to
+#   this many nodes from the player.
+csm_flavour_noderange_limit (Client side noderange flavour limit) int 8
+
 [*Mapgen]
 
 #    Name of map generator to be used when creating a new world.