Move code for launching tests out of router_add_to_routerlist()

router_add_to_routerlist() is supposed to be a nice minimal function
that only touches the routerlist structures, but it included a call to
dirserv_single_reachability_test().

We have a function that gets called _after_ adding descriptors
successfully: routerlist_descriptors_added.  This patch moves the
responsibility for testing there.

Because the decision of whether to test or not depends on whether
there was an old routerinfo for this router or not, we have to first
detect whether we _will_ want to run the tests if the router is added.
We make this the job of
routers_update_status_from_consensus_networkstatus().

Finally, this patch makes the code notice if a router is going from
hibernating to non-hibernating, and if so causes a reachability test
to get launched.

src/or/dirserv.c

@@ -730,6 +730,10 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
   desc = tor_strndup(ri->cache_info.signed_descriptor_body, desclen);
   nickname = tor_strdup(ri->nickname);
 
+  /* Tell if we're about to need to launch a test if we add this. */
+  ri->needs_retest_if_added =
+    dirserv_should_launch_reachability_test(ri, ri_old);
+
   r = router_add_to_routerlist(ri, msg, 0, 0);
   if (!WRA_WAS_ADDED(r)) {
     /* unless the routerinfo was fine, just out-of-date */
@@ -744,7 +748,7 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
 
     changed = smartlist_create();
     smartlist_add(changed, ri);
-    control_event_descriptors_changed(changed);
+    routerlist_descriptors_added(changed, 0);
     smartlist_free(changed);
     if (!*msg) {
       *msg =  ri->is_valid ? "Descriptor for valid server accepted" :
@@ -3115,6 +3119,26 @@ dirserv_orconn_tls_done(const char *address,
    * skip testing. */
 }
 
+/** Called when we, as an authority, receive a new router descriptor either as
+ * an upload or a download.  Used to decide whether to relaunch reachability
+ * testing for the server. */
+int
+dirserv_should_launch_reachability_test(routerinfo_t *ri, routerinfo_t *ri_old)
+{
+  if (!authdir_mode_handles_descs(get_options(), ri->purpose))
+      return 0;
+  if (!ri_old) {
+    /* New router: Launch an immediate reachability test, so we will have an
+     * opinion soon in case we're generating a consensus soon */
+    return 1;
+  }
+  if (ri_old->is_hibernating && !ri->is_hibernating) {
+    /* It just came out of hibernation; launch a reachability test */
+    return 1;
+  }
+  return 0;
+}
+
 /** Helper function for dirserv_test_reachability(). Start a TLS
  * connection to <b>router</b>, and annotate it with when we started
  * the test. */

src/or/dirserv.h

@@ -100,6 +100,8 @@ void dirserv_orconn_tls_done(const char *address,
                              uint16_t or_port,
                              const char *digest_rcvd,
                              int as_advertised);
+int dirserv_should_launch_reachability_test(routerinfo_t *ri,
+                                            routerinfo_t *ri_old);
 void dirserv_single_reachability_test(time_t now, routerinfo_t *router);
 void dirserv_test_reachability(time_t now);
 int authdir_wants_to_reject_router(routerinfo_t *ri, const char **msg,

src/or/networkstatus.c

@@ -1924,6 +1924,15 @@ routers_update_status_from_consensus_networkstatus(smartlist_t *routers,
       router->is_bad_directory = rs->is_bad_directory;
       router->is_bad_exit = rs->is_bad_exit;
       router->is_hs_dir = rs->is_hs_dir;
+    } else {
+      /* If we _are_ an authority, we should check wither this router
+       * is one that will cause us to need a reachability test. */
+      routerinfo_t *old_router =
+        router_get_by_digest(router->cache_info.identity_digest);
+      if (old_router != router) {
+        router->needs_retest_if_added =
+          dirserv_should_launch_reachability_test(router, old_router);
+      }
     }
     if (router->is_running && ds) {
       download_status_reset(&ds->v2_ns_dl_status);

src/or/or.h

@@ -1453,6 +1453,9 @@ typedef struct {
                              * directory according to the authorities. */
   unsigned int policy_is_reject_star:1; /**< True iff the exit policy for this
                                          * router rejects everything. */
+  /** True if, after we have added this router, we should re-launch
+   * tests for it. */
+  unsigned int needs_retest_if_added:1;
 
 /** Tor can use this router for general positions in circuits. */
 #define ROUTER_PURPOSE_GENERAL 0

src/or/routerlist.c

@@ -3276,11 +3276,6 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg,
    * the list. */
   routerlist_insert(routerlist, router);
   if (!from_cache) {
-    if (authdir) {
-      /* launch an immediate reachability test, so we will have an opinion
-       * soon in case we're generating a consensus soon */
-      dirserv_single_reachability_test(time(NULL), router);
-    }
     signed_desc_append_to_journal(&router->cache_info,
                                   &routerlist->desc_store);
   }
@@ -3600,15 +3595,19 @@ routerlist_remove_old_routers(void)
 
 /** We just added a new set of descriptors. Take whatever extra steps
  * we need. */
-static void
+void
 routerlist_descriptors_added(smartlist_t *sl, int from_cache)
 {
   tor_assert(sl);
   control_event_descriptors_changed(sl);
-  SMARTLIST_FOREACH(sl, routerinfo_t *, ri,
+  SMARTLIST_FOREACH_BEGIN(sl, routerinfo_t *, ri) {
     if (ri->purpose == ROUTER_PURPOSE_BRIDGE)
       learned_bridge_descriptor(ri, from_cache);
-  );
+    if (ri->needs_retest_if_added) {
+      ri->needs_retest_if_added = 0;
+      dirserv_single_reachability_test(approx_time(), ri);
+    }
+  } SMARTLIST_FOREACH_END(ri);
 }
 
 /**

src/or/routerlist.h

@@ -115,6 +115,7 @@ was_router_added_t router_add_to_routerlist(routerinfo_t *router,
 was_router_added_t router_add_extrainfo_to_routerlist(
                                         extrainfo_t *ei, const char **msg,
                                         int from_cache, int from_fetch);
+void routerlist_descriptors_added(smartlist_t *sl, int from_cache);
 void routerlist_remove_old_routers(void);
 int router_load_single_router(const char *s, uint8_t purpose, int cache,
                               const char **msg);