prosody
e385f3a06673
util/random.lua

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util/random.lua @ 12995:e385f3a06673

moduleapi: Add 'peek' to :may() and new :could() helper to suppress logging The current method logs scary "access denied" messages on failure - this is generally very useful when debugging access control stuff, but in some cases the call is simply a check to see if someone *could* perform an action, even if they haven't requested it yet. One example is determining whether to show the user as an admin in disco. The 'peek' parameter, if true, will suppress such logging. The :could() method is just a simple helper that can make the calling code a bit more readable (suggested by Zash).
author Matthew Wild <mwild1@gmail.com>
date Sun, 26 Mar 2023 14:06:04 +0100
parent 12975:d10957394a3c
line wrap: on
line source

-- Prosody IM
-- Copyright (C) 2008-2014 Matthew Wild
-- Copyright (C) 2008-2014 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local ok, crand = pcall(require, "prosody.util.crand");
if ok and pcall(crand.bytes, 1) then return crand; end

local urandom, urandom_err = io.open("/dev/urandom", "r");

local function bytes(n)
	local data, err = urandom:read(n);
	if not data then
		if err then
			error("Unable to retrieve data from secure random number generator (/dev/urandom): "..tostring(err));
		else
			error("Secure random number generator (/dev/urandom) returned an end-of-file condition");
		end
	end
	return data;
end

if not urandom then
	function bytes()
		error("Unable to obtain a secure random number generator, please see https://prosody.im/doc/random ("..urandom_err..")");
	end
end

return {
	bytes = bytes;
	_source = "/dev/urandom";
};