bunkerized-nginx/confs/site/antibot-recaptcha.conf

location = {{ ANTIBOT_URI }} {

	default_type 'text/html';
	
	if ($request_method = GET) {
		content_by_lua_block {
			local cookie	= require "cookie"
			local recaptcha	= require "recaptcha"
			local logger	= require "logger"
			if not cookie.is_set("uri") then
				logger.log(ngx.WARN, "ANTIBOT", "recaptcha fail (1) for " .. ngx.var.remote_addr)
				return ngx.exit(ngx.HTTP_FORBIDDEN)
			end
			local code = recaptcha.get_code("{{ ANTIBOT_URI }}", "{{ ANTIBOT_RECAPTCHA_SITEKEY }}")
			ngx.say(code)
		}
	}
	
	if ($request_method = POST) {
		access_by_lua_block {
			local cookie	= require "cookie"
			local recaptcha	= require "recaptcha"
			local logger	= require "logger"
			if not cookie.is_set("uri") then
				logger.log(ngx.WARN, "ANTIBOT", "recaptcha fail (2) for " .. ngx.var.remote_addr)
				return ngx.exit(ngx.HTTP_FORBIDDEN)
			end
			ngx.req.read_body()
			local args, err = ngx.req.get_post_args(1)
			if err == "truncated" or not args or not args["token"] then
				logger.log(ngx.WARN, "ANTIBOT", "recaptcha fail (3) for " .. ngx.var.remote_addr)
				return ngx.exit(ngx.HTTP_FORBIDDEN)
			end
			local token	= args["token"]
			local check	= recaptcha.check(token, "{{ ANTIBOT_RECAPTCHA_SECRET }}")
			if check < {{ ANTIBOT_RECAPTCHA_SCORE }} then
				logger.log(ngx.WARN, "ANTIBOT", "recaptcha fail (4) for " .. ngx.var.remote_addr .. " (score = " .. tostring(check) .. ")")
				return ngx.exit(ngx.HTTP_FORBIDDEN)
			end
			cookie.set({recaptcha = "ok"})
			return ngx.redirect(cookie.get("uri"))
		}
	}
}