commit d9564d528514442e73221d8fbc3044856a2010a9 Author: Nick Mathewson nickm@torproject.org Date: Sun Jun 1 14:02:55 2014 -0400

Use uint32 !=, not tor_memneq, for relay cell integrity checking

tor_memeq has started to show up on profiles, and this is one of the most frequent callers of that function, appearing as it does on every cell handled for entry or exit.

59f9097d5c3dc010847c359888d31757d1c97904 introduced tor_memneq here; it went into Tor 0.2.1.31. Fixes part of 12169. --- changes/bug12169_simple | 5 +++++ src/or/relay.c | 10 +++++----- 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/changes/bug12169_simple b/changes/bug12169_simple new file mode 100644 index 0000000..f9a3007 --- /dev/null +++ b/changes/bug12169_simple @@ -0,0 +1,5 @@ + o Minor bugfixes (performance): + - Avoid using tor_memeq() for checking relay cell integrity. + This removes a possible performance bottleneck. Fixes part of bug + 12169; bugfix on 0.2.1.31. + diff --git a/src/or/relay.c b/src/or/relay.c index 5c430a6..509d7ce 100644 --- a/src/or/relay.c +++ b/src/or/relay.c @@ -111,14 +111,14 @@ relay_set_digest(crypto_digest_t *digest, cell_t *cell) static int relay_digest_matches(crypto_digest_t *digest, cell_t *cell) { - char received_integrity[4], calculated_integrity[4]; + uint32_t received_integrity, calculated_integrity; relay_header_t rh; crypto_digest_t *backup_digest=NULL;

backup_digest = crypto_digest_dup(digest);

relay_header_unpack(&rh, cell->payload); - memcpy(received_integrity, rh.integrity, 4); + memcpy(&received_integrity, rh.integrity, 4); memset(rh.integrity, 0, 4); relay_header_pack(cell->payload, &rh);

@@ -127,15 +127,15 @@ relay_digest_matches(crypto_digest_t *digest, cell_t *cell) // received_integrity[2], received_integrity[3]);

crypto_digest_add_bytes(digest, (char*) cell->payload, CELL_PAYLOAD_SIZE); - crypto_digest_get_digest(digest, calculated_integrity, 4); + crypto_digest_get_digest(digest, (char*) &calculated_integrity, 4);

- if (tor_memneq(received_integrity, calculated_integrity, 4)) { + if (calculated_integrity != received_integrity) { // log_fn(LOG_INFO,"Recognized=0 but bad digest. Not recognizing."); // (%d vs %d).", received_integrity, calculated_integrity); /* restore digest to its old form */ crypto_digest_assign(digest, backup_digest); /* restore the relay header */ - memcpy(rh.integrity, received_integrity, 4); + memcpy(rh.integrity, &received_integrity, 4); relay_header_pack(cell->payload, &rh); crypto_digest_free(backup_digest); return 0;