diff options
Diffstat (limited to 'src/common')
| -rw-r--r-- | src/common/crypto.c | 21 | ||||
| -rw-r--r-- | src/common/crypto.h | 1 | ||||
| -rw-r--r-- | src/common/tortls.c | 3 |
3 files changed, 23 insertions, 2 deletions
diff --git a/src/common/crypto.c b/src/common/crypto.c index 1b45639a7c..e723f3d5d2 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -2317,6 +2317,25 @@ crypto_rand_int(unsigned int max) } } +/** Return a pseudorandom integer, chosen uniformly from the values <i>i</i> + * such that <b>min</b> <= <i>i</i> < <b>max</b>. + * + * <b>min</b> MUST be in range [0, <b>max</b>). + * <b>max</b> MUST be in range (min, INT_MAX]. + */ +int +crypto_rand_int_range(unsigned int min, unsigned int max) +{ + tor_assert(min < max); + tor_assert(max <= INT_MAX); + + /* The overflow is avoided here because crypto_rand_int() returns a value + * between 0 and (max - min - 1) with max being <= INT_MAX and min <= max. + * This is why we add 1 to the maximum value so we can actually get max as + * a return value. */ + return min + crypto_rand_int(max - min); +} + /** Return a pseudorandom 64-bit integer, chosen uniformly from the values * between 0 and <b>max</b>-1. */ uint64_t @@ -2379,7 +2398,7 @@ crypto_random_hostname(int min_rand_len, int max_rand_len, const char *prefix, if (min_rand_len > max_rand_len) min_rand_len = max_rand_len; - randlen = min_rand_len + crypto_rand_int(max_rand_len - min_rand_len + 1); + randlen = crypto_rand_int_range(min_rand_len, max_rand_len+1); prefixlen = strlen(prefix); resultlen = prefixlen + strlen(suffix) + randlen + 16; diff --git a/src/common/crypto.h b/src/common/crypto.h index aedc51b844..aa587fd08b 100644 --- a/src/common/crypto.h +++ b/src/common/crypto.h @@ -254,6 +254,7 @@ int crypto_seed_rng(int startup); MOCK_DECL(int,crypto_rand,(char *to, size_t n)); int crypto_strongest_rand(uint8_t *out, size_t out_len); int crypto_rand_int(unsigned int max); +int crypto_rand_int_range(unsigned int min, unsigned int max); uint64_t crypto_rand_uint64(uint64_t max); double crypto_rand_double(void); struct tor_weak_rng_t; diff --git a/src/common/tortls.c b/src/common/tortls.c index 32106eb2df..7809c1adaa 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -659,7 +659,8 @@ tor_tls_create_certificate(crypto_pk_t *rsa, * than having it start right now. Don't choose quite uniformly, since * then we might pick a time where we're about to expire. Lastly, be * sure to start on a day boundary. */ - start_time = time(NULL) - crypto_rand_int(cert_lifetime) + 2*24*3600; + time_t now = time(NULL); + start_time = crypto_rand_int_range(now - cert_lifetime, now) + 2*24*3600; start_time -= start_time % (24*3600); tor_assert(rsa); |