first cut at a workaround for the reachability bug: explicitly find a

server running the right version, if we can, and ask for that one.


svn:r6616

1 files changed, 46 insertions, 2 deletions

diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index d38de14bb..f557c5258 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -1457,6 +1457,46 @@ onion_append_to_cpath(crypt_path_t **head_ptr, crypt_path_t *new_hop)
   }
 }
 
+/** Pick a random server digest that's running a Tor version that
+ * doesn't have the reachability bug. These are versions 0.1.1.22+
+ * and 0.1.2.1-alpha+.
+ *
+ * We only return one, so this doesn't become stupid when the
+ * whole network has upgraded. */
+static char *
+compute_preferred_testing_list(const char *answer)
+{
+  smartlist_t *choices;
+  routerlist_t *rl = router_get_routerlist();
+  routerinfo_t *router;
+  char *s;
+
+  if (answer) /* they have one in mind -- easy */
+    return tor_strdup(answer);
+
+  choices = smartlist_create();
+  /* now count up our choices */
+  SMARTLIST_FOREACH(rl->routers, routerinfo_t *, r,
+    if (r->is_running && r->is_valid &&
+        ((tor_version_as_new_as(r->platform,"0.1.1.21-cvs") &&
+          !tor_version_as_new_as(r->platform,"0.1.2.0-alpha-cvs")) ||
+         tor_version_as_new_as(r->platform,"0.1.2.1-alpha")))
+      smartlist_add(choices, r));
+  router = smartlist_choose(choices);
+  smartlist_free(choices);
+  if (!router) {
+    log_info(LD_CIRC, "Looking for middle server that doesn't have the "
+             "reachability bug, but didn't find one. Oh well.");
+    return NULL;
+  }
+  log_info(LD_CIRC, "Looking for middle server that doesn't have the "
+             "reachability bug, and chose '%s'. Great.", router->nickname);
+  s = tor_malloc(HEX_DIGEST_LEN+1);
+  base16_encode(s, HEX_DIGEST_LEN+1,
+                router->cache_info.identity_digest, DIGEST_LEN);
+  return s;
+}
+
 /** A helper function used by onion_extend_cpath(). Use <b>purpose</b>
  * and <b>state</b> and the cpath <b>head</b> (currently populated only
  * to length <b>cur_len</b> to decide a suitable middle hop for a
@@ -1474,6 +1514,7 @@ choose_good_middle_server(uint8_t purpose,
   crypt_path_t *cpath;
   smartlist_t *excluded;
   or_options_t *options = get_options();
+  char *preferred = NULL;
   tor_assert(_CIRCUIT_PURPOSE_MIN <= purpose &&
              purpose <= _CIRCUIT_PURPOSE_MAX);
 
@@ -1493,11 +1534,14 @@ choose_good_middle_server(uint8_t purpose,
       routerlist_add_family(excluded, r);
     }
   }
-  choice = router_choose_random_node(
-           purpose == CIRCUIT_PURPOSE_TESTING ? options->TestVia : NULL,
+  if (purpose == CIRCUIT_PURPOSE_TESTING)
+    preferred = compute_preferred_testing_list(options->TestVia);
+  choice = router_choose_random_node(preferred,
            options->ExcludeNodes, excluded,
            state->need_uptime, state->need_capacity, 0,
            options->_AllowInvalid & ALLOW_INVALID_MIDDLE, 0);
+  if (preferred)
+    tor_free(preferred);
   smartlist_free(excluded);
   return choice;
 }