prop224: When HUPing, move HS state from old to new service.

We used to not copy the state which means that after HUP we would forget
if we are in overlap mode or not. That caused bugs where the service
would enter overlap mode twice, and rotate its descs twice, causing all
sorts of bugs.

src/or/hs_service.c

@@ -750,6 +750,26 @@ service_escaped_dir(const hs_service_t *s)
                                     escaped(s->config.directory_path);
 }
 
+/** Move the hidden service state from <b>src</b> to <b>dst</b>. We do this
+ *  when we receive a SIGHUP: <b>dst</b> is the post-HUP service */
+static void
+move_hs_state(hs_service_t *src_service, hs_service_t *dst_service)
+{
+  tor_assert(src_service);
+  tor_assert(dst_service);
+
+  hs_service_state_t *src = &src_service->state;
+  hs_service_state_t *dst = &dst_service->state;
+
+  /* Let's do a shallow copy */
+  dst->intro_circ_retry_started_time = src->intro_circ_retry_started_time;
+  dst->num_intro_circ_launched = src->num_intro_circ_launched;
+  dst->in_overlap_period = src->in_overlap_period;
+  dst->replay_cache_rend_cookie = src->replay_cache_rend_cookie;
+
+  src->replay_cache_rend_cookie = NULL; /* steal pointer reference */
+}
+
 /* Register services that are in the staging list. Once this function returns,
  * the global service map will be set with the right content and all non
  * surviving services will be cleaned up. */
@@ -785,6 +805,7 @@ register_all_services(void)
       /* Pass ownership of the descriptors from s (the current service) to
        * snew (the newly configured one). */
       move_descriptors(s, snew);
+      move_hs_state(s, snew);
       /* Remove the service from the global map because after this, we need to
        * go over the remaining service in that map that aren't surviving the
        * reload to close their circuits. */