add minimum minetest version key for contentdb

also make sure all names match from line-start
reduce digits match to 3-or-more (from 4-)

init.lua

@@ -0,0 +1,103 @@
+local disallowed = {
+	["^guest"]			=	"Temporary 'GuestXXXX' usernames are disallowed on this server.  "..
+						"Please choose a proper username and try again.",
+	["^player"]			=	"Temporary 'PlayerXXXX' usernames are disallowed on this server.  "..
+						"Please choose a proper username and try again.",
+	["^squeakecraft"]		=	"Temporary 'Squeakecraft' usernames are disallowed on this server.  "..
+						"Please choose a proper username and try again.",
+	["[4a]dm[1il]n"]		=	"That is a clearly false, misleading, or otherwise disallowed username. "..
+						"Please choose a unique username and try again.",
+	["^[0-9]+$"]			=	"All-numeric usernames are disallowed on this server. "..
+						"Please choose a proper username and try again.",
+	["[0-9].-[0-9].-[0-9]"] 	=	"Too many numbers in your username. "..
+						"Please try again with less than three digits in your username."
+}
+
+-- Original implementation (in Python) by sfan5
+local function judge(msg)
+	local numspeakable = 0
+	local numnotspeakable = 0
+	local cn = 0
+	local lastc = '____'
+	for c in msg:gmatch(".") do
+		c = c:lower()
+		if c:find("[aeiou0-9_-]") then
+			if cn > 2 and not c:find("[0-9]") then
+				numnotspeakable = numnotspeakable + 1
+			elseif not c:find("[0-9]") then
+				numspeakable = numspeakable + 1
+			end
+			cn = 0
+		else
+			if (cn == 1) and (lastc == c) and (lastc ~= 's') then
+				numnotspeakable = numnotspeakable + 1
+				cn = 0
+			end
+			if cn > 2 then
+				numnotspeakable = numnotspeakable + 1
+				cn = 0
+			end
+			if lastc:find("[aeiou]") then
+				numspeakable = numspeakable + 1
+				cn = 0
+			end
+			if not ((lastc:find("[aipfom]") and c == "r") or (lastc == "c" and c == "h")) then
+				cn = cn + 1
+			end
+		end
+		lastc = c
+	end
+	if cn > 0 then
+		numnotspeakable = numnotspeakable + 1
+	end
+	return (numspeakable >= numnotspeakable)
+end
+
+minetest.register_on_prejoinplayer(function(name, ip)
+	local lname = name:lower()
+	for re, reason in pairs(disallowed) do
+		if lname:find(re) and not minetest.auth_table[name] then
+			return reason
+		end
+	end
+
+	if #name < 2 then
+		return "Too short of a username. "..
+				"Please pick a name with at least two letters and try again."
+	end
+
+	if not judge(name) and #name > 5 then
+		return "Your username just plain looks like gibberish. "..
+				"Please pick something readable and try again."
+	end
+
+end)
+
+minetest.register_on_prejoinplayer(function(name, ip)
+	local lname = name:lower()
+	for iname, data in pairs(minetest.auth_table) do
+		if iname:lower() == lname and iname ~= name then
+			return "Sorry, someone else is already using this "
+				.."name, or maybe you mistyped it?  Please "
+				.."check your typing or pick another name."
+		end
+	end
+end)
+
+minetest.register_chatcommand("choosecase", {
+	description = "Choose the casing that a player name should have",
+	params = "<name>",
+	privs = {server=true},
+	func = function(name, params)
+		local lname = params:lower()
+		local worldpath = minetest.get_worldpath()
+		for iname, data in pairs(minetest.auth_table) do
+			if iname:lower() == lname and iname ~= params then
+				minetest.auth_table[iname] = nil
+				assert(not iname:find("/"))
+				os.remove(worldpath.."/players/"..iname)
+			end
+		end
+		minetest.chat_send_player(name, "Done.")
+	end,
+})

mod.conf

@@ -0,0 +1 @@
+min_minetest_version = 5.2.0