Add CSM restriction flag to block third party CSMs (#162)

builtin/settingtypes.txt

@@ -1352,6 +1352,7 @@ server_side_occlusion_culling (Server side occlusion culling) bool true
 #    LOOKUP_NODES_LIMIT: 16 (limits get_node call client-side to
 #    csm_restriction_noderange)
 #    READ_PLAYERINFO: 32 (disable get_player_names call client-side)
+#    THIRD_PARTY_MODS: 256 (disable loading third-party CSMs)
 csm_restriction_flags (Client side modding restrictions) int 62
 
 #   If the CSM restriction for node range is enabled, get_node calls are limited

multicraft.conf.example

@@ -1611,6 +1611,7 @@
 #    LOOKUP_NODES_LIMIT: 16 (limits get_node call client-side to
 #    csm_restriction_noderange)
 #    READ_PLAYERINFO: 32 (disable get_player_names call client-side)
+#    THIRD_PARTY_MODS: 256 (disable loading third-party client-provided mods)
 #    type: int
 # csm_restriction_flags = 60
 

src/client/client.cpp

@@ -164,6 +164,7 @@ void Client::loadMods()
 	scanModIntoMemory(BUILTIN_MOD_NAME, getBuiltinLuaPath());
 	m_script->loadModFromMemory(BUILTIN_MOD_NAME);
 
+	if (!checkCSMRestrictionFlag(CSMRestrictionFlags::CSM_RF_THIRD_PARTY_MODS)) {
 		ClientModConfiguration modconf(getClientModsLuaPath());
 		m_mods = modconf.getMods();
 		// complain about mods with unsatisfied dependencies
@@ -191,6 +192,7 @@ void Client::loadMods()
 		// Run them
 		for (const ModSpec &mod : m_mods)
 			m_script->loadModFromMemory(mod.name);
+	}
 
 	// Mods are done loading. Unlock callbacks
 	m_mods_loaded = true;

src/network/networkprotocol.h

@@ -1051,6 +1051,7 @@ enum CSMRestrictionFlags : u64 {
 	CSM_RF_READ_NODEDEFS = 0x00000008,    // Disable nodedef lookups
 	CSM_RF_LOOKUP_NODES = 0x00000010,     // Limit node lookups
 	CSM_RF_READ_PLAYERINFO = 0x00000020,  // Disable player info lookups
+	CSM_RF_THIRD_PARTY_MODS = 0x00000100, // Don't load third-party CSMs
 	CSM_RF_ALL = 0xFFFFFFFF,
 };
 

src/script/lua_api/l_client.cpp

@@ -56,6 +56,7 @@ const static CSMFlagDesc flagdesc_csm_restriction[] = {
 	{"read_nodedefs",     CSM_RF_READ_NODEDEFS},
 	{"lookup_nodes",      CSM_RF_LOOKUP_NODES},
 	{"read_playerinfo",   CSM_RF_READ_PLAYERINFO},
+	{"third_party_mods",  CSM_RF_THIRD_PARTY_MODS},
 	{NULL,      0}
 };