Client should check if dir server has open dir port or handles tunnelled requests

Final piece of prop 237. Closes 12538.

changes/feature12538

@@ -0,0 +1,6 @@
+  o Minor features (directory system):
+    Previously only relays who explicitly opened a directory port (DirPort)
+    accepted directory requests from clients.  Now all relays, with and without
+    a DirPort, who do not disable the DirCache option accept and serve
+    directory requests sent (tunnelled) through their ORPort.
+    Closes ticket 12538.

src/or/nodelist.c

@@ -644,12 +644,19 @@ node_is_named(const node_t *node)
 int
 node_is_dir(const node_t *node)
 {
-  if (node->rs)
-    return node->rs->dir_port != 0;
-  else if (node->ri)
-    return node->ri->dir_port != 0;
-  else
+  if (node->rs) {
+    routerstatus_t * rs = node->rs;
+    /* This is true if supports_tunnelled_dir_requests is true which
+     * indicates that we support directory request tunnelled or through the
+     * DirPort. */
+    return rs->is_v2_dir;
+  } else if (node->ri) {
+    routerinfo_t * ri = node->ri;
+    /* Both tunnelled request is supported or DirPort is set. */
+    return ri->supports_tunnelled_dir_requests;
+  } else {
     return 0;
+  }
 }
 
 /** Return true iff <b>node</b> has either kind of usable descriptor -- that

src/or/routerlist.c

@@ -1512,7 +1512,7 @@ router_pick_directory_server_impl(dirinfo_type_t type, int flags,
     if (!status)
       continue;
 
-    if (!node->is_running || !status->dir_port || !node->is_valid)
+    if (!node->is_running || !node_is_dir(node) || !node->is_valid)
       continue;
     if (requireother && router_digest_is_me(node->identity))
       continue;

src/test/test_nodelist.c

@@ -60,12 +60,51 @@ test_nodelist_node_get_verbose_nickname_not_named(void *arg)
   return;
 }
 
+/** A node should be considered a directory server if it has an open dirport
+ * of it accepts tunnelled directory requests.
+ */
+static void
+test_nodelist_node_is_dir(void *arg)
+{
+  routerstatus_t rs;
+  routerinfo_t ri;
+  node_t node;
+  memset(&node, 0, sizeof(node_t));
+  memset(&rs, 0, sizeof(routerstatus_t));
+  memset(&ri, 0, sizeof(routerinfo_t));
+
+  tt_assert(!node_is_dir(&node));
+
+  node.rs = &rs;
+  tt_assert(!node_is_dir(&node));
+
+  rs.is_v2_dir = 1;
+  tt_assert(node_is_dir(&node));
+
+  rs.is_v2_dir = 0;
+  rs.dir_port = 1;
+  tt_assert(node_is_dir(&node));
+
+  node.rs = NULL;
+  tt_assert(!node_is_dir(&node));
+  node.ri = &ri;
+  ri.supports_tunnelled_dir_requests = 1;
+  tt_assert(node_is_dir(&node));
+  ri.supports_tunnelled_dir_requests = 0;
+  ri.dir_port = 1;
+  tt_assert(node_is_dir(&node));
+
+  done:
+    return;
+}
+
 #define NODE(name, flags) \
   { #name, test_nodelist_##name, (flags), NULL, NULL }
 
 struct testcase_t nodelist_tests[] = {
   NODE(node_get_verbose_nickname_by_id_null_node, TT_FORK),
   NODE(node_get_verbose_nickname_not_named, TT_FORK),
+  NODE(node_is_dir, TT_FORK),
   END_OF_TESTCASES
 };