Merge remote-tracking branch 'public/bug12169_relay_check'

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.
+

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;