util/uuid.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 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 error = error;
  10 local round_up = math.ceil;
  11 local urandom, urandom_err = io.open("/dev/urandom", "r+");
  12
  13 module "uuid"
  14
  15 local function get_nibbles(n)
  16         local binary_random = urandom:read(round_up(n/2));
  17         local hex_random = binary_random:gsub(".",
  18                 function (x) return ("%02x"):format(x:byte()) end);
  19         return hex_random:sub(1, n);
  20 end
  21 local function get_twobits()
  22         return ("%x"):format(urandom:read(1):byte() % 4 + 8);
  23 end
  24
  25 function generate()
  26         if not urandom then
  27                 error("Unable to obtain a secure random number generator, please see https://prosody.im/doc/random ("..urandom_err..")");
  28         end
  29         -- generate RFC 4122 complaint UUIDs (version 4 - random)
  30         return get_nibbles(8).."-"..get_nibbles(4).."-4"..get_nibbles(3).."-"..(get_twobits())..get_nibbles(3).."-"..get_nibbles(12);
  31 end
  32
  33 function seed(x)
  34         urandom:write(x);
  35         urandom:flush();
  36 end
  37
  38 return _M;