Clients connect to public relays over IPv6.

Add ClientUseIPv6 and ClientPreferIPv6ORPort configuration options.

Use "preferred OR port" for all entry nodes, not only for bridges.

Mark bridges with "prefer IPv6 OR port" if an IPv6 address is
configured in Bridge line and ClientPreferIPv6ORPort is set.

Mark relays with "prefer IPv6 OR port" if an IPv6 address is found in
descriptor and ClientPreferIPv6ORPort is set.

Filter "preferred OR port" through the ClientUseIPv6 config option. We
might want to move this test to where actual connection is being set
up once we have a fall back mechanism in place.

Have only non-servers pick an IPv6 address for the first hop: We
don't want relays to connect over IPv6 yet. (IPv6 has never been used
for second or third hops.)

Implements ticket 5535.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/or/nodelist.c b/src/or/nodelist.c
index 9d0247f4e..1d1bbfc02 100644
--- a/src/or/nodelist.c
+++ b/src/or/nodelist.c
@@ -242,6 +242,8 @@ nodelist_set_consensus(networkstatus_t *ns)
       node->is_bad_directory = rs->is_bad_directory;
       node->is_bad_exit = rs->is_bad_exit;
       node->is_hs_dir = rs->is_hs_dir;
+      if (options->ClientPreferIPv6ORPort == 1)
+        node->ipv6_preferred = !tor_addr_is_null(&rs->ipv6_addr);
     }
 
   } SMARTLIST_FOREACH_END(rs);
@@ -849,7 +851,13 @@ node_get_pref_orport(const node_t *node, tor_addr_port_t *ap_out)
 {
   tor_assert(ap_out);
 
-  if (node_ipv6_preferred(node))
+  /* Cheap implementation of config option ClientUseIPv6 -- simply
+     don't prefer IPv6 when ClientUseIPv6 is not set. (See #4455 for
+     more on this subject.) Note that this filter is too strict since
+     we're hindering not only clients! Erring on the safe side
+     shouldn't be a problem though. XXX move this check to where
+     outgoing connections are made? -LN */
+  if (get_options()->ClientUseIPv6 == 1 && node_ipv6_preferred(node))
     node_get_pref_ipv6_orport(node, ap_out);
   else
     node_get_prim_orport(node, ap_out);