Prevention: never die from extend_info_from_node() failure.

Bug 21242 occurred because we asserted that extend_info_from_node()
had succeeded...even though we already had the code to handle such a
failure.  We fixed that in 93b39c51629ed0ded2bf807cb6.

But there were four other cases in our code where we called
extend_info_from_node() and either tor_assert()ed that it returned
non-NULL, or [in one case] silently assumed that it returned
non-NULL. That's not such a great idea.  This patch makes those
cases check for a bug of this kind instead.

Fixes bug 21372; bugfix on 0.2.3.1-alpha when
extend_info_from_node() was introduced.

1 files changed, 2 insertions, 5 deletions

diff --git a/src/or/control.c b/src/or/control.c
index 2c71ea5bb9..b0a687679d 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -3377,7 +3377,8 @@ handle_control_extendcircuit(control_connection_t *conn, uint32_t len,
   SMARTLIST_FOREACH(nodes, const node_t *, node,
   {
     extend_info_t *info = extend_info_from_node(node, first_node);
-    if (first_node && !info) {
+    if (!info) {
+      tor_assert_nonfatal(first_node);
       log_warn(LD_CONTROL,
                "controller tried to connect to a node that doesn't have any "
                "addresses that are allowed by the firewall configuration; "
@@ -3385,10 +3386,6 @@ handle_control_extendcircuit(control_connection_t *conn, uint32_t len,
       circuit_mark_for_close(TO_CIRCUIT(circ), -END_CIRC_REASON_CONNECTFAILED);
       connection_write_str_to_buf("551 Couldn't start circuit\r\n", conn);
       goto done;
-    } else {
-      /* True, since node_has_descriptor(node) == true and we are extending
-       * to the node's primary address */
-      tor_assert(info);
     }
     circuit_append_new_exit(circ, info);
     extend_info_free(info);