Fix assert on clients of and authorities for v0 HS descs

diff --git a/changes/bug4411 b/changes/bug4411
new file mode 100644 (file)
index 0000000..1273d02
--- /dev/null
+++ b/changes/bug4411
@@ -0,0 +1,10 @@
+  o Major bugfixes
+
+    - Fix a rare assertion failure when checking whether a v0 hidden
+      service descriptor has any usable introduction points left, and
+      we don't have enough information to build a circuit to the first
+      intro point named in the descriptor.  The HS client code in
+      0.2.3.x no longer uses v0 HS descriptors, but this assertion can
+      trigger on (and crash) v0 HS authorities.  Fixes bug 4411.
+      Bugfix on 0.2.3.1-alpha; diagnosed by frosty_un.
+

diff --git a/src/or/rendclient.c b/src/or/rendclient.c
index 1038378de197d33e399aa32db2e9ed55e77f176a..79714f958e229ad88f303819d59a210a205811d8 100644 (file)
--- a/src/or/rendclient.c
+++ b/src/or/rendclient.c
@@ -1048,6 +1048,7 @@ rend_client_get_random_intro_impl(const rend_cache_entry_t *entry,
   /* Do we need to look up the router or is the extend info complete? */
   if (!intro->extend_info->onion_key) {
     const node_t *node;
+    extend_info_t *new_extend_info;
     if (tor_digest_is_zero(intro->extend_info->identity_digest))
       node = node_get_by_hex_id(intro->extend_info->nickname);
     else
@@ -1058,8 +1059,18 @@ rend_client_get_random_intro_impl(const rend_cache_entry_t *entry,
       smartlist_del(usable_nodes, i);
       goto again;
     }
-    extend_info_free(intro->extend_info);
-    intro->extend_info = extend_info_from_node(node);
+    new_extend_info = extend_info_from_node(node);
+    if (!new_extend_info) {
+      log_info(LD_REND, "We don't have a descriptor for the intro-point relay "
+               "'%s'; trying another.",
+               extend_info_describe(intro->extend_info));
+      smartlist_del(usable_nodes, i);
+      goto again;
+    } else {
+      extend_info_free(intro->extend_info);
+      intro->extend_info = new_extend_info;
+    }
+    tor_assert(intro->extend_info != NULL);
   }
   /* Check if we should refuse to talk to this router. */
   if (strict &&