prosody
bd812a7713ad
util/random.lua

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util/random.lua @ 6376:bd812a7713ad

util.random: Generic util lib for generating strings of random bytes
author Matthew Wild <mwild1@gmail.com>
date Tue, 02 Sep 2014 17:57:18 +0100
child 6420:0c070e30a7db
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6375:76d8907d5301 6376:bd812a7713ad
1 -- Prosody IM
2 -- Copyright (C) 2008-2014 Matthew Wild
3 -- Copyright (C) 2008-2014 Waqas Hussain
4 --
5 -- This project is MIT/X11 licensed. Please see the
6 -- COPYING file in the source package for more information.
7 --
8
9 local tostring = tostring;
10 local os_time = os.time;
11 local os_clock = os.clock;
12 local ceil = math.ceil;
13 local sha1 = require "util.hashes".sha1;
14
15 local last_uniq_time = 0;
16 local function uniq_time()
17 local new_uniq_time = os_time();
18 if last_uniq_time >= new_uniq_time then new_uniq_time = last_uniq_time + 1; end
19 last_uniq_time = new_uniq_time;
20 return new_uniq_time;
21 end
22
23 local function new_random(x)
24 return sha1(x..os_clock()..tostring({}));
25 end
26
27 local buffer = new_random(uniq_time());
28
29 local function seed(x)
30 buffer = new_random(buffer..x);
31 end
32
33 local function bytes(n)
34 if #buffer < n then seed(uniq_time()); end
35 local r = buffer:sub(0, n);
36 buffer = buffer:sub(n+1);
37 return r;
38 end
39
40 return {
41 seed = seed;
42 bytes = bytes;
43 };