lua-captchastore: All-in-one captcha handling library

Just copy captchastore.lua into your source tree.

Tested on Linux with Lua 5.3, will probably work on other Unix systems, will probably NOT work on Windows.

Dependencies:

• lsqlite3
• ImageMagick's convert in $PATH

Usage

local newcaptchastore = require "captchastore"

-- Initialize a capchastore with 200 cached captchas.
-- It is assumed that the captchas directory exists.
local store = newcaptchastore("captchas.db", "./captchas/", 200)

-- Get a cached captcha.
local token, imagepath, correct_answer = store:get()

-- Give the user the image with `imagepath`,
-- then let the user send back `token` and their answer.

local user_answer = ...

-- Verify the user's answer
local is_correct, err = store:verify(token, answer)
if is_correct then -- Captcha completed
elseif err == store.EWRONG then -- The wrong answer is provided
elseif err == store.ETOKEN then -- The token does not exists anymore, request a new captcha
end


-- After some time, all captchas will have been solved,
-- you should periodically remake all captchas.
-- This method will create new captchas and remove the old.
-- A captcha given will work before and after the next refresh.
store:refresh()

This project neither been licensed nor thoroughly tested yet, use at your own discretion.