diff options
Diffstat (limited to 'src/common/util.c')
| -rw-r--r-- | src/common/util.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/src/common/util.c b/src/common/util.c index cb2cfed64d..879a0e4bd3 100644 --- a/src/common/util.c +++ b/src/common/util.c @@ -459,7 +459,7 @@ strcmp_len(const char *s1, const char *s2, size_t s1_len) return -1; if (s1_len > s2_len) return 1; - return tor_memcmp(s1, s2, s2_len); + return fast_memcmp(s1, s2, s2_len); } /** Compares the first strlen(s2) characters of s1 with s2. Returns as for @@ -501,17 +501,17 @@ strcasecmpend(const char *s1, const char *s2) /** Compare the value of the string <b>prefix</b> with the start of the * <b>memlen</b>-byte memory chunk at <b>mem</b>. Return as for strcmp. * - * [As tor_memcmp(mem, prefix, strlen(prefix)) but returns -1 if memlen is less - * than strlen(prefix).] + * [As fast_memcmp(mem, prefix, strlen(prefix)) but returns -1 if memlen is + * less than strlen(prefix).] */ int -memcmpstart(const void *mem, size_t memlen, +fast_memcmpstart(const void *mem, size_t memlen, const char *prefix) { size_t plen = strlen(prefix); if (memlen < plen) return -1; - return tor_memcmp(mem, prefix, plen); + return fast_memcmp(mem, prefix, plen); } /** Return a pointer to the first char of s that is not whitespace and @@ -644,14 +644,16 @@ tor_mem_is_zero(const char *mem, size_t len) 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, }; while (len >= sizeof(ZERO)) { - if (tor_memcmp(mem, ZERO, sizeof(ZERO))) + /* It's safe to use fast_memcmp here, since the very worst thing an + * attacker could learn is how many initial bytes of a secret were zero */ + if (fast_memcmp(mem, ZERO, sizeof(ZERO))) return 0; len -= sizeof(ZERO); mem += sizeof(ZERO); } /* Deal with leftover bytes. */ if (len) - return tor_memeq(mem, ZERO, len); + return fast_memeq(mem, ZERO, len); return 1; } @@ -660,7 +662,10 @@ tor_mem_is_zero(const char *mem, size_t len) int tor_digest_is_zero(const char *digest) { - return tor_mem_is_zero(digest, DIGEST_LEN); + static const uint8_t ZERO_DIGEST[] = { + 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0 + }; + return tor_memeq(digest, ZERO_DIGEST, DIGEST_LEN); } /* Helper: common code to check whether the result of a strtol or strtoul or |