Add an AssumeReachableIPv6 autobool option.

This option tells Tor that our IPv6 orport is reachable, and doesn't
need to be checked.

Closes the rest of 33224.

2 files changed, 10 insertions, 6 deletions

diff --git a/src/feature/relay/router.c b/src/feature/relay/router.c
index 97b630add7..d32d03fc1c 100644
--- a/src/feature/relay/router.c
+++ b/src/feature/relay/router.c
@@ -1374,13 +1374,13 @@ decide_if_publishable_server(void)
     return 1;
   if (!router_get_advertised_or_port(options))
     return 0;
-  if (!router_orport_seems_reachable(AF_INET)) {
+  if (!router_orport_seems_reachable(options, AF_INET)) {
     // We have an ipv4 orport, and it doesn't seem reachable.
     if (!publish_even_when_ipv4_orport_unreachable) {
       return 0;
     }
   }
-  if (!router_orport_seems_reachable(AF_INET6)) {
+  if (!router_orport_seems_reachable(options, AF_INET6)) {
     // We have an ipv6 orport, and it doesn't seem reachable.
     if (!publish_even_when_ipv6_orport_unreachable) {
       return 0;
diff --git a/src/feature/relay/selftest.c b/src/feature/relay/selftest.c
index 64b8578bac..ae24a04401 100644
--- a/src/feature/relay/selftest.c
+++ b/src/feature/relay/selftest.c
@@ -86,9 +86,8 @@ router_reachability_checks_disabled(const or_options_t *options)
  * orport checks.
  */
 int
-router_orport_seems_reachable(
-                                                const or_options_t *options,
-                                                int family)
+router_orport_seems_reachable(const or_options_t *options,
+                              int family)
 {
   tor_assert_nonfatal(family == AF_INET || family == AF_INET6 || family == 0);
   int reach_checks_disabled = router_reachability_checks_disabled(options);
@@ -96,6 +95,11 @@ router_orport_seems_reachable(
     return true;
   }
 
+  // Note that we do a == 1 here, not just a boolean check.  This value
+  // is also an autobool, so CFG_AUTO does not mean that we should
+  // assume IPv6 ports are reachable.
+  const bool ipv6_assume_reachable = (options->AssumeReachableIPv6 == 1);
+
   // Which reachability flags should we look at?
   const bool checking_ipv4 = (family == AF_INET || family == 0);
   const bool checking_ipv6 = (family == AF_INET6 || family == 0);
@@ -105,7 +109,7 @@ router_orport_seems_reachable(
       return false;
     }
   }
-  if (checking_ipv6) {
+  if (checking_ipv6 && !ipv6_assume_reachable) {
     if (have_orport_for_family(AF_INET6) && !can_reach_or_port_ipv6) {
       return false;
     }