lib/util/genrand.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Functions to create reasonable random numbers for crypto use.
   5
   6    Copyright (C) Jeremy Allison 2001
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "replace.h"
  23 #include "system/filesys.h"
  24 #include "lib/util/genrand.h"
  25 #include "sys_rw_data.h"
  26 #include "lib/util/blocking.h"
  27
  28 static int urand_fd = -1;
  29
  30 static void open_urandom(void)
  31 {
  32         if (urand_fd != -1) {
  33                 return;
  34         }
  35         urand_fd = open( "/dev/urandom", O_RDONLY,0);
  36         if (urand_fd == -1) {
  37                 abort();
  38         }
  39         smb_set_close_on_exec(urand_fd);
  40 }
  41
  42 _PUBLIC_ void generate_random_buffer(uint8_t *out, int len)
  43 {
  44         ssize_t rw_ret;
  45
  46         open_urandom();
  47
  48         rw_ret = read_data(urand_fd, out, len);
  49         if (rw_ret != len) {
  50                 abort();
  51         }
  52 }
  53
  54 /*
  55  * Keep generate_secret_buffer in case we ever want to do something
  56  * different
  57  */
  58 _PUBLIC_ void generate_secret_buffer(uint8_t *out, int len)
  59 {
  60         generate_random_buffer(out, len);
  61 }