config-sync

#!/usr/bin/env lua
-- SPDX-FileCopyrightText: (c) 2024 Ring Zero Desenvolvimento de Software LTDA
-- SPDX-License-Identifier: GPL-2.0-only
--
-- This script synchronizes block and allow lists from a PostgreSQL database
-- and generates a config.lua file based on the user-defined settings from the
-- admin interface.
--
-- Install dependencies:
--   sudo apt install libssl-dev
--   for p in argparse pgmoon luaossl luasec luaposix serpent; do
--      sudo luarocks install $p
--   done
--
-- Configuration:
--   Copy domerc.example to $HOME/.domerc and edit it as needed.
--
-- Example usage:
--   LIB=/lib/modules/lua/dome ./config-sync -v --output $LIB/config.lua $LIB

local posix    = require("posix")
local argparse = require("argparse")
local pgmoon   = require("pgmoon")
local serpent  = require("serpent")

local argparser = argparse(arg[0], "Dome blocklist fetcher for PostgreSQL")
argparser:flag("-v --verbose", "Enable verbose messages.")
argparser:flag("-d --daemon", "Run in daemon mode, executing every 'domerc.interval' seconds.")
argparser:option("-o --output", "Update config.lua with the fetched information.")
argparser:argument("directory", "Directory where the custom lists wil be written.")
local args = argparser:parse()

local home = os.getenv("HOME")
local rc   = dofile(home .. "/.domerc")
local db   = pgmoon.new{
	host     = rc.host,
	port     = tostring(rc.port),
	database = rc.database,
	user     = rc.user,
	password = rc.password
}

local function log(fmt, ...)
	if args.verbose then
		print(string.format(fmt, ...))
	end
end

local function query(db, query, callback)
	assert(db:connect())
	local res = assert(db:query(query))
	for _, row in ipairs(res) do
		callback(row)
	end
	db:disconnect()
end

local function write_list(path, domains)
	local file = io.open(path, "w")
	file:write("return {\n")
	for domain in string.gmatch(domains, "[^\n]*") do
		domain = domain:gsub("^%s*(.-)%s*$", "%1") -- trim
		if #domain > 0 then
			file:write(string.format("\t[\"%s\"]=true,\n", domain))
		end
	end
	file:write("}\n")
	file:close()
end

local function download_custom(db, dir)
	query(db, 'SELECT * FROM "PolicyCategory" WHERE custom = true;', function (row)
		if row.domains and #row.domains > 0 then
			local path = dir .. "/" .. string.lower(row.name) .. ".lua"
			write_list(path, row.domains)
			log("wrote: %s", path)
		end
	end)
end

local function fetch_config(db, output)
	local config = dofile(output)
	log("loaded: %s", output)
	config.blocklists = {}
	config.allowlists = {}
	query(db, 'select * from "PolicyCategory";', function (row)
		local name = row.custom and string.lower(row.name) or row.basename
		name = string.gsub(name, "%s", "_")
		log("+ %s: %s", name, row.blocked and "block" or "allow")
		if row.blocked then
			table.insert(config.blocklists, name)
		else
			table.insert(config.allowlists, name)
		end
	end)
	return config
end

local function write_config(db, output)
	local config = fetch_config(db, output)
	local module = "return " .. serpent.block(config, {comment = false})
	local file = io.open(output, "w")
	file:write(module)
	file:close()
end

local function update_config(db, args)
	download_custom(db, args.directory)
	if args.output then
		write_config(db, args.output)
	end
end

posix.signal(posix.SIGINT, function (_)
	print("\nInterrupted.")
	os.exit(0)
end)
posix.mkdir(args.directory)
if args.daemon then
	while true do
		update_config(db, args)
		posix.unistd.sleep(tonumber(rc.interval) or 150)
	end
else
	update_config(db, args)
end