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Make sure that the rng is not replaced if it is already replaced.

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This commit is contained in:
Nick Mathewson 2019-03-18 12:50:11 -04:00 committed by David Goulet
parent 604e849d36
commit 730dddc380
1 changed files with 15 additions and 0 deletions
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15
src/test/rng_test_helpers.c
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@ -24,6 +24,11 @@
#error "No. Never link this code into Tor proper."
#endif
/**
* True iff the RNG is currently replaced. Prevents double-replacement.
**/
static bool rng_is_replaced = false;
/**
* Mutex to protect deterministic prng.
*
@ -82,6 +87,9 @@ crypto_rand_deterministic(char *out, size_t n)
static void
enable_deterministic_rng_impl(const uint8_t *seed, size_t seed_len)
{
tor_assert(!rng_is_replaced);
tor_assert(crypto_rand == crypto_rand__real);
memset(rng_seed, 0, sizeof(rng_seed));
memcpy(rng_seed, seed, MIN(seed_len, sizeof(rng_seed)));
@ -100,6 +108,8 @@ enable_deterministic_rng_impl(const uint8_t *seed, size_t seed_len)
crypto_fast_rng_t *fast_rng = crypto_fast_rng_new_from_seed(fast_rng_seed);
crypto_fast_rng_disable_reseed(fast_rng);
stored_fast_rng = crypto_replace_thread_fast_rng(fast_rng);
rng_is_replaced = true;
}
/**
@ -196,6 +206,9 @@ testing_prefilled_rng_reset(void)
/**
* Undo the overrides for our PRNG. To be used at the end of testing.
*
* Note that this function should be safe to call even if the rng has not
* yet been replaced.
**/
void
testing_disable_rng_override(void)
@ -208,4 +221,6 @@ testing_disable_rng_override(void)
crypto_fast_rng_t *rng = crypto_replace_thread_fast_rng(stored_fast_rng);
crypto_fast_rng_free(rng);
rng_is_replaced = false;
}