Automatically use IPv6 when ClientUseIPv4 is 0

Consequential changes to log messages:
  * it's no longer possible to disable both IPv4 and IPv6,
  * refactor common string out of remaining log messages

2 files changed, 16 insertions, 11 deletions

diff --git a/src/test/test_entrynodes.c b/src/test/test_entrynodes.c
index a0208b9cfc..14baa8c9bf 100644
--- a/src/test/test_entrynodes.c
+++ b/src/test/test_entrynodes.c
@@ -215,20 +215,23 @@ test_choose_random_entry_one_possible_guard(void *arg)
    * time, so we can't be sure we get the guard */
   tt_assert(chosen_entry);
 
-  /* Check that we get the guard if it passes preferred address settings when
-   * they're auto */
+  /* Check that we get a node if it is allowed but not preferred when settings
+   * are auto */
   memset(&mocked_options, 0, sizeof(mocked_options));
   mocked_options.ClientUseIPv4 = 1;
   mocked_options.ClientPreferIPv6ORPort = -1;
 
   chosen_entry = choose_random_entry(NULL);
-  tt_ptr_op(chosen_entry, OP_EQ, the_guard);
+
+  /* We disable the guard check and the preferred address check at the same
+   * time, so we can't be sure we get the guard */
+  tt_assert(chosen_entry);
 
   /* and with IPv6 active */
   mocked_options.ClientUseIPv6 = 1;
 
   chosen_entry = choose_random_entry(NULL);
-  tt_ptr_op(chosen_entry, OP_EQ, the_guard);
+  tt_assert(chosen_entry);
 
  done:
   memset(&mocked_options, 0, sizeof(mocked_options));
diff --git a/src/test/test_policy.c b/src/test/test_policy.c
index 1daa38ecf2..2e87f13fc0 100644
--- a/src/test/test_policy.c
+++ b/src/test/test_policy.c
@@ -1310,7 +1310,8 @@ test_policies_fascist_firewall_allows_address(void *arg)
   tt_assert(fascist_firewall_allows_address(&r_ipv6_addr, port, policy, 0, 0)
             == 0);
 
-  /* Test the function's address matching with everything off */
+  /* Test the function's address matching with ClientUseIPv4 0.
+   * This means "use IPv6" regardless of the other settings. */
   memset(&mock_options, 0, sizeof(or_options_t));
   mock_options.ClientUseIPv4 = 0;
   mock_options.ClientUseIPv6 = 0;
@@ -1319,7 +1320,7 @@ test_policies_fascist_firewall_allows_address(void *arg)
   tt_assert(fascist_firewall_allows_address(&ipv4_addr, port, policy, 0, 0)
             == 0);
   tt_assert(fascist_firewall_allows_address(&ipv6_addr, port, policy, 0, 0)
-            == 0);
+            == 1);
   tt_assert(fascist_firewall_allows_address(&r_ipv4_addr, port, policy, 0, 0)
             == 0);
   tt_assert(fascist_firewall_allows_address(&r_ipv6_addr, port, policy, 0, 0)
@@ -1596,7 +1597,8 @@ test_policies_fascist_firewall_choose_address(void *arg)
                                                  FIREWALL_DIR_CONNECTION, 1)
             == &ipv6_dir_ap);
 
-  /* Choose an address with everything off */
+  /* Choose an address with ClientUseIPv4 0.
+   * This means "use IPv6" regardless of the other settings. */
   memset(&mock_options, 0, sizeof(or_options_t));
   mock_options.ClientUseIPv4 = 0;
   mock_options.ClientUseIPv6 = 0;
@@ -1604,16 +1606,16 @@ test_policies_fascist_firewall_choose_address(void *arg)
 
   tt_assert(fascist_firewall_choose_address(&ipv4_or_ap, &ipv6_or_ap, 0,
                                                  FIREWALL_OR_CONNECTION, 0)
-            == NULL);
+            == &ipv6_or_ap);
   tt_assert(fascist_firewall_choose_address(&ipv4_or_ap, &ipv6_or_ap, 0,
                                                  FIREWALL_OR_CONNECTION, 1)
-            == NULL);
+            == &ipv6_or_ap);
   tt_assert(fascist_firewall_choose_address(&ipv4_dir_ap, &ipv6_dir_ap, 0,
                                                  FIREWALL_DIR_CONNECTION, 0)
-            == NULL);
+            == &ipv6_dir_ap);
   tt_assert(fascist_firewall_choose_address(&ipv4_dir_ap, &ipv6_dir_ap, 0,
                                                  FIREWALL_DIR_CONNECTION, 1)
-            == NULL);
+            == &ipv6_dir_ap);
 
   /* Choose from unusual inputs */
   memset(&mock_options, 0, sizeof(or_options_t));