SSCSM: Compress long messages

builtin/game/sscsm/client.lua

@@ -307,17 +307,23 @@ core.register_on_receiving_chat_message(function(message)
 	if not callbacks then return true end
 
 	-- Handle split messages
-	local prefix = msg:sub(1, 1)
-	if prefix == '\001' then
+	local prefix = msg:byte(1)
+	if prefix == 1 then
 		msg = load_split_message(chan, msg)
 		if not msg then
 			return true
 		end
-		prefix = msg:sub(1, 1)
+		prefix = msg:byte(1)
+	end
+
+	-- Decompress messages
+	if prefix == 3 then
+		msg = minetest.decompress(minetest.decode_base64(msg:sub(2)))
+		prefix = msg:byte(1)
 	end
 
 	-- Load the message
-	if prefix == '\002' then
+	if prefix == 2 then
 		msg = msg:sub(2)
 	else
 		msg = core.parse_json(msg)

builtin/game/sscsm/init.lua

@@ -20,6 +20,7 @@
 --
 
 sscsm = {minify=true}
+local format = string.format
 local modpath = core.get_builtin_path() .. "game" .. DIR_DELIM ..
 	"sscsm" .. DIR_DELIM
 
@@ -218,8 +219,19 @@ function sscsm.com_send(pname, channel, msg)
 		msg = assert(core.write_json(msg))
 	end
 
+	-- Compress long messages
+	if #msg > 4096 then
+		-- Chat messages can't contain binary data so base64 is used
+		local compressed_msg = minetest.encode_base64(minetest.compress(msg))
+
+		-- Only use the compressed message if it's shorter
+		if #msg > #compressed_msg + 1 then
+			msg = "\003" .. compressed_msg
+		end
+	end
+
 	-- Short messages can be sent all at once
-	local prefix = "\001SSCSM_COM\001" .. channel .. "\001"
+	local prefix = format("\001SSCSM_COM\001%s\001", channel)
 	if #msg < 65300 then
 		core.chat_send_player(pname, prefix .. msg)
 		return