util.random: Generic util lib for generating strings of random bytes

diff --git a/util/random.lua b/util/random.lua
new file mode 100644 (file)
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+++ b/util/random.lua
@@ -0,0 +1,43 @@
+-- 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 tostring = tostring;
+local os_time = os.time;
+local os_clock = os.clock;
+local ceil = math.ceil;
+local sha1 = require "util.hashes".sha1;
+
+local last_uniq_time = 0;
+local function uniq_time()
+       local new_uniq_time = os_time();
+       if last_uniq_time >= new_uniq_time then new_uniq_time = last_uniq_time + 1; end
+       last_uniq_time = new_uniq_time;
+       return new_uniq_time;
+end
+
+local function new_random(x)
+       return sha1(x..os_clock()..tostring({}));
+end
+
+local buffer = new_random(uniq_time());
+
+local function seed(x)
+       buffer = new_random(buffer..x);
+end
+
+local function bytes(n)
+       if #buffer < n then seed(uniq_time()); end
+       local r = buffer:sub(0, n);
+       buffer = buffer:sub(n+1);
+       return r;
+end
+
+return {
+       seed = seed;
+       bytes = bytes;
+};