From 6be3d2e0d4f261028dc7b67a77f20877fe5cccf7 Mon Sep 17 00:00:00 2001
From: kay27 <kay27@bk.ru>
Date: Mon, 21 Mar 2022 05:36:02 +0400
Subject: [PATCH] Add mcl_antispam

---
 mods/PLAYER/mcl_antispam/init.lua | 113 ++++++++++++++++++++++++++++++
 mods/PLAYER/mcl_antispam/mod.conf |   2 +
 settingtypes.txt                  |  14 ++++
 3 files changed, 129 insertions(+)
 create mode 100644 mods/PLAYER/mcl_antispam/init.lua
 create mode 100644 mods/PLAYER/mcl_antispam/mod.conf

diff --git a/mods/PLAYER/mcl_antispam/init.lua b/mods/PLAYER/mcl_antispam/init.lua
new file mode 100644
index 000000000..21f550694
--- /dev/null
+++ b/mods/PLAYER/mcl_antispam/init.lua
@@ -0,0 +1,113 @@
+local ban_spammers = true
+local kick_spammers = true
+local revoke_shout_for_spammers = true
+local limit_messages = 10
+local limit_message_length = 200
+local block_special_chars = true
+local enable_antispam = ban_spammers or kick_spammers or revoke_shout_for_spammers
+
+local function update_settings()
+	ban_spammers = minetest.settings:get_bool("ban_spammers", true)
+	kick_spammers = minetest.settings:get_bool("kick_spammers", true)
+	revoke_shout_for_spammers = minetest.settings:get_bool("revoke_shout_for_spammers", true)
+	limit_messages = tonumber(minetest.settings:get("limit_messages") or 10)
+	limit_message_length = tonumber(minetest.settings:get("limit_message_length") or 200)
+	block_special_chars = minetest.settings:get_bool("block_special_chars", true)
+	enable_antispam = ban_spammers or kick_spammers or revoke_shout_for_spammers
+	minetest.after(7, update_settings)
+end
+update_settings()
+
+local last_messages = {}
+local exceeders = {}
+local special_users = {}
+
+local function ban(name)
+	if revoke_shout_for_spammers then
+		local privs = minetest.get_player_privs(name)
+		if privs then
+			privs.shoud = nil
+			privs.noclip = true
+			minetest.set_player_privs(name, privs)
+		end
+	end
+	if ban_spammers then
+		minetest.ban_player(name)
+	elseif kick_spammers then
+		minetest.kick_player(name)
+	end
+end
+
+local last_char = string.char(127)
+
+local function on_chat_message(name, message)
+	if not enable_antispam then return end
+	local length = message:len()
+	if last_messages.job then
+		last_messages.job:cancel()
+		last_messages.job = nil
+	end
+	if last_messages.name and last_messages.name == name then
+		last_messages.count = last_messages.count + 1
+		last_messages.summary_length = last_messages.summary_length + length
+		if last_messages.count >= limit_messages then
+			ban(name)
+		end
+	else
+		last_messages.name = name
+		last_messages.count = 1
+		last_messages.summary_length = length
+	end
+	last_messages.job = minetest.after(300, function()
+		last_messages.name = nil
+		last_messages.job = nil
+	end)
+	if limit_message_length > 0 and message:len() > limit_message_length then
+		if exceeders[name] then
+			exceeders[name] = exceeders[name] + 1
+			if exceeders[name] > limit_messages then
+				ban(name)
+			end
+		else
+			exceeders[name] = 1
+		end
+		message = message:sub(1, limit_message_length) .. ">8 >8 >8"
+		minetest.chat_send_all("<" .. name .. "> " .. message)
+		return true
+	else
+		if exceeders[name] then
+			exceeders[name] = nil
+		end
+	end
+	if block_special_chars then
+		local sc = false
+		local msg = ""
+		for i = 1, #message do
+			local c = message:sub(i,i)
+			if c >= " " and c <= last_char then
+				msg = msg .. c
+			else
+				sc = true
+			end
+		end
+		if sc then
+			if special_users[name] then
+				special_users[name] = special_users[name] + 1
+				if special_users[name] > limit_messages then
+					ban(name)
+				end
+			else
+				special_users[name] = 1
+			end
+			message = msg
+			minetest.chat_send_all("<" .. name .. "> " .. message)
+			return true
+		else
+			if special_users[name] then
+				special_users[name] = nil
+			end
+		end
+	end
+end
+
+minetest.register_on_chat_message(on_chat_message)
diff --git a/mods/PLAYER/mcl_antispam/mod.conf b/mods/PLAYER/mcl_antispam/mod.conf
new file mode 100644
index 000000000..ef259eab0
--- /dev/null
+++ b/mods/PLAYER/mcl_antispam/mod.conf
@@ -0,0 +1,2 @@
+name = mcl_antispam
+author = kay27
diff --git a/settingtypes.txt b/settingtypes.txt
index dca03b7e1..fc1d26c67 100644
--- a/settingtypes.txt
+++ b/settingtypes.txt
@@ -165,6 +165,20 @@ kick_cheaters (Kick Cheaters) bool false
 # Cheat kicking threshold
 kick_threshold (Cheat Kicking Threshold) int 10
 
+[Antispam]
+# Maximum player messages in a sequence
+limit_messages (Maximum player messages in a sequence) int 10
+# Maximum message length
+limit_message_length (Maximum message length) int 200
+# Block special characters
+block_special_chars (Block special characters) bool true
+# Ban spammers
+ban_spammers (Ban spammers) bool true
+# Kick spammers
+kick_spammers (Kick spammers) bool true
+# Revoke shout priv for spammers
+revoke_shout_for_spammers (Revoke shout priv for spammers) bool true
+
 [Debugging]
 # If enabled, this will show the itemstring of an item in the description.
 mcl_item_id_debug (Item ID Debug) bool false