diff options
| author | Ben Pfaff <blp@nicira.com> | 2010-08-12 11:12:13 -0700 |
|---|---|---|
| committer | Ben Pfaff <blp@nicira.com> | 2010-08-12 15:49:18 -0700 |
| commit | 10df718e73122df2f3b04ed585e50e4b299a8cbd (patch) | |
| tree | 7ccb5f20556753e9e4b0c6eaf8429fea722dbff2 | |
| parent | e251c8d0050acf8d3f35c91b6d2708fab5314ce7 (diff) | |
random: Get random seed from /dev/urandom.
Even though this PRNG is not meant to be cryptographically secure, there is
no reason not to get a high-quality seed.
CC: Stephen Hemminger <shemminger@vyatta.com>
| -rw-r--r-- | AUTHORS | 1 | ||||
| -rw-r--r-- | lib/random.c | 17 |
2 files changed, 10 insertions, 8 deletions
@@ -45,6 +45,7 @@ Rob Hoes rob.hoes@citrix.com Sajjad Lateef slateef@nicira.com Sean Brady sbrady@gtfservices.com Srini Seetharaman seethara@stanford.edu +Stephen Hemminger shemminger@vyatta.com Takayuki HAMA t-hama@cb.jp.nec.com kk yap yapkke@stanford.edu diff --git a/lib/random.c b/lib/random.c index 78a5916a..88ddb4a5 100644 --- a/lib/random.c +++ b/lib/random.c @@ -21,6 +21,7 @@ #include <stdlib.h> #include <sys/time.h> +#include "entropy.h" #include "util.h" /* This is the 32-bit PRNG recommended in G. Marsaglia, "Xorshift RNGs", @@ -29,7 +30,10 @@ * * We use this PRNG instead of libc's rand() because rand() varies in quality * and because its maximum value also varies between 32767 and INT_MAX, whereas - * we often want random numbers in the full range of uint32_t. */ + * we often want random numbers in the full range of uint32_t. + * + * This random number generator is intended for purposes that do not require + * cryptographic-quality randomness. */ /* Current random state. */ static uint32_t seed; @@ -39,19 +43,16 @@ static uint32_t random_next(void); void random_init(void) { - if (!seed) { + while (!seed) { struct timeval tv; + uint32_t entropy; if (gettimeofday(&tv, NULL) < 0) { ovs_fatal(errno, "gettimeofday"); } + get_entropy_or_die(&entropy, 4); - seed = tv.tv_sec ^ tv.tv_usec; - if (!seed) { - /* A 'seed' of 0 is fatal to randomness--the random value will - * always be 0--so use the initial seed mentioned by Marsaglia. */ - seed = UINT32_C(2463534242); - } + seed = tv.tv_sec ^ tv.tv_usec ^ entropy; } } |