From 08c1af30738fac4e78a2ef4d94a63ef79550aa7d Mon Sep 17 00:00:00 2001
From: Not <not.git@protonmail.com>
Date: Mon, 14 Nov 2022 22:17:30 +0100
Subject: [PATCH] insert checksums

---
 lb_store.lua | 62 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 45 insertions(+), 17 deletions(-)

diff --git a/lb_store.lua b/lb_store.lua
index 5ca9f2f..4352d97 100644
--- a/lb_store.lua
+++ b/lb_store.lua
@@ -122,6 +122,26 @@ local function stat_str(stat)
 	return "0"
 end
 
+local function djb2(message)
+	local digest = 5381
+	for c in message:gmatch(".") do
+		digest = (($ << 5) + $) + string.byte(c)
+	end
+
+	return digest
+end
+
+-- Produce a checksum by using the maps title, subtitle and zone
+local function mapChecksum(mapnum)
+	local mh = mapheaderinfo[mapnum]
+	if not mh then
+		return nil
+	end
+
+	local digest = string.format("%04x", djb2(mh.lvlttl..mh.subttl..mh.zonttl))
+	return string.sub(digest, #digest - 3)
+end
+
 -- GLOBAL
 -- Save a record to the LiveStore and write to disk
 -- SaveRecord will replace the record holders previous record but it will not compare any record times
@@ -141,6 +161,11 @@ local function SaveRecord(score, map, modeSep)
 
 	for mapid, records in pairs(LiveStore) do
 		for _, record in ipairs(records) do
+			-- Insert checksum if missing
+			if (not record.checksum) or record.checksum == "" then
+				record.checksum = mapChecksum(mapid)
+			end
+
 			f:write(
 				mapid, "\t",
 				record.name, "\t",
@@ -149,7 +174,8 @@ local function SaveRecord(score, map, modeSep)
 				record.time, "\t",
 				table.concat(record.splits, " "), "\t",
 				record.flags, "\t",
-				stat_str(record.stat), "\n"
+				stat_str(record.stat), "\t",
+				record.checksum or "", "\n"
 			)
 		end
 	end
@@ -164,7 +190,7 @@ end
 
 addHook("NetVars", netvars)
 
-local function score_t(map, name, skin, color, time, splits, flags, stat)
+local function score_t(map, name, skin, color, time, splits, flags, stat, checksum)
 	return {
 		["map"]    = map,
 		["name"]   = name,
@@ -173,7 +199,8 @@ local function score_t(map, name, skin, color, time, splits, flags, stat)
 		["time"]   = time,
 		["splits"] = splits,
 		["flags"]  = flags,
-		["stat"] = stat
+		["stat"] = stat,
+		["checksum"] = checksum
 	}
 end
 
@@ -206,6 +233,8 @@ local function parseScore(str)
 		end
 	end
 
+	local checksum = t[9]
+
 	return score_t(
 		tonumber(t[1]), -- Map
 		t[2],		-- Name
@@ -214,25 +243,24 @@ local function parseScore(str)
 		tonumber(t[5]),	-- Time
 		splits,
 		flags,
-		stats
+		stats,
+		checksum
 	)
 end
 rawset(_G, "lb_parse_score", parseScore)
 
 -- Load the livestore
-do
-	if isserver then
-		local f = assert(
-			io.open(LEADERBOARD_FILE, "r"),
-			"Failed to open file: "..LEADERBOARD_FILE
-		)
+if isserver then
+	local f = assert(
+		io.open(LEADERBOARD_FILE, "r"),
+		"Failed to open file: "..LEADERBOARD_FILE
+	)
 
-		for l in f:lines() do
-			local score = parseScore(l)
-			LiveStore[score.map] = $ or {}
-			table.insert(LiveStore[score.map], score)
-		end
-
-		f:close()
+	for l in f:lines() do
+		local score = parseScore(l)
+		LiveStore[score.map] = $ or {}
+		table.insert(LiveStore[score.map], score)
 	end
+
+	f:close()
 end