commit b1ee1a719db0a47fa27a8efd9a6e7e443dca2550 Author: Nick Mathewson nickm@torproject.org Date: Mon Jan 9 19:14:51 2012 -0500

Tweaks for bug4413 fix

The thing that's limited to 63 bytes is a "label", not a hostname.

Docment input constraints and behavior on bogus inputs.

Generally it's better to check for overflow-like conditions before than after. In this case, it's not a true overflow, so we're okay, but let's be consistent.

pedantic less->fewer in the documentation --- src/common/crypto.c | 19 +++++++++++-------- 1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/common/crypto.c b/src/common/crypto.c index 9ee3d98..7edc7f2 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -82,8 +82,8 @@ #include "sha256.c" #define SHA256_Final(a,b) sha256_done(b,a)

-/* Bug 4413*/ -#define MAX_HOSTNAME_SIZE 63 +/** Longest recognized */ +#define MAX_DNS_LABEL_SIZE 63

static unsigned char * SHA256(const unsigned char *m, size_t len, unsigned char *d) @@ -2545,9 +2545,12 @@ crypto_rand_double(void) }

/** Generate and return a new random hostname starting with <b>prefix</b>, - * ending with <b>suffix</b>, and containing no less than + * ending with <b>suffix</b>, and containing no fewer than * <b>min_rand_len</b> and no more than <b>max_rand_len</b> random base32 - * characters between. */ + * characters between. + * + * Clip <b>max_rand_len</b> to MAX_DNS_LABEL_SIZE. + **/ char * crypto_random_hostname(int min_rand_len, int max_rand_len, const char *prefix, const char *suffix) @@ -2556,12 +2559,12 @@ crypto_random_hostname(int min_rand_len, int max_rand_len, const char *prefix, int randlen, rand_bytes_len; size_t resultlen, prefixlen;

- tor_assert(max_rand_len >= min_rand_len); + if (max_rand_len > MAX_DNS_LABEL_SIZE) + max_rand_len = MAX_DNS_LABEL_SIZE; + 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); - if (randlen > MAX_HOSTNAME_SIZE) { - randlen = MAX_HOSTNAME_SIZE; - }

prefixlen = strlen(prefix); resultlen = prefixlen + strlen(suffix) + randlen + 16;