Remove special authority semantics for AssumeReachable.

AssumeReachable should only be about whether a relay thinks that it
is reachable itself.  But previously, we've had it also turn off
reachability checking of _other_ relays on authorities.
(Technically, reachability tests were still run, but we would ignore
the results.)

With this patch, there is a new AuthDirTestReachability option
(default 1) that controls whether authorities run reachability
tests.

Making this change allows us to have test networks where authorities
set AssumeReachable without disabling their reachability testing
entirely.

Closes ticket #34445.

3 files changed, 15 insertions, 3 deletions

diff --git a/src/feature/dirauth/dirauth_options.inc b/src/feature/dirauth/dirauth_options.inc
index 21f4996c39..40ef7c3bab 100644
--- a/src/feature/dirauth/dirauth_options.inc
+++ b/src/feature/dirauth/dirauth_options.inc
@@ -44,6 +44,13 @@ CONF_VAR(AuthDirSharedRandomness, BOOL, 0, "1")
 /* NOTE: remove this option someday. */
 CONF_VAR(AuthDirTestEd25519LinkKeys, BOOL, 0, "1")
 
+/**
+ * Bool (default 1): As an authority, should we launch tests for
+ * reachability, and use those results to vote on "Running"?  If 0,
+ * we assume that every relay is Runnning.
+ **/
+CONF_VAR(AuthDirTestReachability, BOOL, 0, "1")
+
 /** Authority only: key=value pairs that we add to our networkstatus
  * consensus vote on the 'params' line. */
 CONF_VAR(ConsensusParams, STRING, 0, NULL)
diff --git a/src/feature/dirauth/reachability.c b/src/feature/dirauth/reachability.c
index 65fa27ed80..30938f528d 100644
--- a/src/feature/dirauth/reachability.c
+++ b/src/feature/dirauth/reachability.c
@@ -105,6 +105,8 @@ dirserv_should_launch_reachability_test(const routerinfo_t *ri,
 {
   if (!authdir_mode_handles_descs(get_options(), ri->purpose))
     return 0;
+  if (! dirauth_get_options()->AuthDirTestReachability)
+    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 */
@@ -189,6 +191,9 @@ dirserv_test_reachability(time_t now)
    * the testing, and directory authorities are easy to upgrade. Let's
    * wait til 0.2.0. -RD */
 //  time_t cutoff = now - ROUTER_MAX_AGE_TO_PUBLISH;
+  if (! dirauth_get_options()->AuthDirTestReachability)
+    return;
+
   routerlist_t *rl = router_get_routerlist();
   static char ctr = 0;
   int bridge_auth = authdir_mode_bridge(get_options());
diff --git a/src/feature/dirauth/voteflags.c b/src/feature/dirauth/voteflags.c
index 477eb6f0b7..3938b61adb 100644
--- a/src/feature/dirauth/voteflags.c
+++ b/src/feature/dirauth/voteflags.c
@@ -487,7 +487,6 @@ dirserv_set_router_is_running(routerinfo_t *router, time_t now)
     unreachable.
    */
   int answer;
-  const or_options_t *options = get_options();
   const dirauth_options_t *dirauth_options = dirauth_get_options();
   node_t *node = node_get_mutable_by_id(router->cache_info.identity_digest);
   tor_assert(node);
@@ -501,8 +500,9 @@ dirserv_set_router_is_running(routerinfo_t *router, time_t now)
     /* A hibernating router is down unless we (somehow) had contact with it
      * since it declared itself to be hibernating. */
     answer = 0;
-  } else if (options->AssumeReachable) {
-    /* If AssumeReachable, everybody is up unless they say they are down! */
+  } else if (! dirauth_options->AuthDirTestReachability) {
+    /* If we aren't testing reachability, then everybody is up unless they say
+     * they are down. */
     answer = 1;
   } else {
     /* Otherwise, a router counts as up if we found all announced OR