[tor-commits] [tor/master] Backend for upgrading 'waiting' circuits to 'complete'
nickm at torproject.org
nickm at torproject.org
Fri Dec 16 16:26:17 UTC 2016
commit 36e9fbd7522fcee54b9f048bf506bfddc4bffc95
Author: Nick Mathewson <nickm at torproject.org>
Date: Mon Nov 21 09:40:45 2016 -0500
Backend for upgrading 'waiting' circuits to 'complete'
When a nonprimary guard's circuit is complete, we don't call it
actually usable until we are pretty sure that every better guard
is indeed not going to give us a working circuit.
---
src/or/entrynodes.c | 143 +++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 130 insertions(+), 13 deletions(-)
diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c
index 260b3d6..0e56147 100644
--- a/src/or/entrynodes.c
+++ b/src/or/entrynodes.c
@@ -1377,6 +1377,33 @@ entry_guards_all_primary_guards_are_down(guard_selection_t *gs)
return 1;
}
+/** Wrapper for entry_guard_has_higher_priority that compares the
+ * guard-priorities of a pair of circuits. */
+static int
+circ_state_has_higher_priority(origin_circuit_t *a,
+ origin_circuit_t *b)
+{
+ circuit_guard_state_t *state_a = origin_circuit_get_guard_state(a);
+ circuit_guard_state_t *state_b = origin_circuit_get_guard_state(b);
+
+ tor_assert(state_a);
+ tor_assert(state_b);
+
+ entry_guard_t *guard_a = entry_guard_handle_get(state_a->guard);
+ entry_guard_t *guard_b = entry_guard_handle_get(state_b->guard);
+
+ if (! guard_a) {
+ /* Unknown guard -- never higher priority. */
+ return 0;
+ } else if (! guard_b) {
+ /* Known guard -- higher priority than any unknown guard. */
+ return 1;
+ } else {
+ /* Both known -- compare.*/
+ return entry_guard_has_higher_priority(guard_a, guard_b);
+ }
+}
+
/**
* Look at all of the origin_circuit_t * objects in <b>all_circuits</b>,
* and see if any of them that were previously not ready to use for
@@ -1397,25 +1424,116 @@ entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
if (! entry_guards_all_primary_guards_are_down(gs)) {
/* We only upgrade a waiting circuit if the primary guards are all
* down. */
+ log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
+ "but not all primary guards were definitely down.");
+ return 0;
+ }
+
+ int n_waiting = 0;
+ int n_complete = 0;
+ origin_circuit_t *best_waiting_circuit = NULL;
+ origin_circuit_t *best_complete_circuit = NULL;
+ SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
+ circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
+ if (state == NULL)
+ continue;
+
+ if (state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD) {
+ ++n_waiting;
+ if (! best_waiting_circuit ||
+ circ_state_has_higher_priority(circ, best_waiting_circuit)) {
+ best_waiting_circuit = circ;
+ }
+ } else if (state->state == GUARD_CIRC_STATE_COMPLETE) {
+ ++n_complete;
+ if (! best_complete_circuit ||
+ circ_state_has_higher_priority(circ, best_complete_circuit)) {
+ best_complete_circuit = circ;
+ }
+ }
+ } SMARTLIST_FOREACH_END(circ);
+
+ if (! best_waiting_circuit) {
+ log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
+ "but didn't find any.");
return 0;
}
- /* XXXX finish implementing. prop271 */
+ if (best_complete_circuit) {
+ if (circ_state_has_higher_priority(best_complete_circuit,
+ best_waiting_circuit)) {
+ /* "If any circuit is <complete>, then do not use any
+ <waiting_for_better_guard> or <usable_if_no_better_guard> circuits
+ circuits whose guards have lower priority." */
+ log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
+ "%d complete and %d guard-stalled. At least one complete "
+ "circuit had higher priority, so not upgrading.",
+ n_complete, n_waiting);
+
+ /* XXXX prop271 implement: "(Time them out after a
+ {NONPRIMARY_GUARD_IDLE_TIMEOUT} seconds.)"
+ */
+ return 0;
+ }
+ }
/* "If any circuit is <waiting_for_better_guard>, and every currently
- {is_pending} circuit whose guard has higher priority has been
- in state <usable_if_no_better_guard> for at least
- {NONPRIMARY_GUARD_CONNECT_TIMEOUT} seconds, and all primary
- guards have reachable status of <no>, then call that circuit
- <complete>."
- */
+ {is_pending} circuit whose guard has higher priority has been in
+ state <usable_if_no_better_guard> for at least
+ {NONPRIMARY_GUARD_CONNECT_TIMEOUT} seconds, and all primary guards
+ have reachable status of <no>, then call that circuit <complete>."
- /* "If any circuit is <complete>, then do not use any
- <waiting_for_better_guard> or <usable_if_no_better_guard> circuits
- circuits whose guards have lower priority. (Time them out
- after a {NONPRIMARY_GUARD_IDLE_TIMEOUT} seconds.)"
+ XXXX --- prop271 deviation. there's no such thing in the spec as
+ an {is_pending circuit}; fix the spec.
*/
- return 0;
+ int n_blockers_found = 0;
+ const time_t state_set_at_cutoff =
+ approx_time() - NONPRIMARY_GUARD_CONNECT_TIMEOUT;
+ SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
+ circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
+ if (state == NULL)
+ continue;
+ if (state->state != GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD)
+ continue;
+ if (state->state_set_at > state_set_at_cutoff &&
+ circ_state_has_higher_priority(circ, best_waiting_circuit))
+ ++n_blockers_found;
+ } SMARTLIST_FOREACH_END(circ);
+
+ if (n_blockers_found) {
+ log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
+ "%d guard-stalled, but %d pending circuit(s) had higher "
+ "guard priority, so not upgrading.",
+ n_waiting, n_blockers_found);
+ return 0;
+ }
+
+ /* Okay. We have a best waiting circuit, and we aren't waiting for
+ anything better. Add all circuits with that priority to the
+ list, and call them COMPLETE. */
+ int n_succeeded = 0;
+ SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
+ circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
+ if (state == NULL)
+ continue;
+ if (state->state != GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD)
+ continue;
+ if (circ_state_has_higher_priority(best_waiting_circuit, circ))
+ continue;
+
+ state->state = GUARD_CIRC_STATE_COMPLETE;
+ state->state_set_at = approx_time();
+ smartlist_add(newly_complete_out, circ);
+ ++n_succeeded;
+ } SMARTLIST_FOREACH_END(circ);
+
+ log_info(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
+ "%d guard-stalled, %d complete. %d of the guard-stalled "
+ "circuit(s) had high enough priority to upgrade.",
+ n_waiting, n_complete, n_succeeded);
+
+ tor_assert_nonfatal(n_succeeded >= 1);
+ return 1;
}
/**
@@ -1669,7 +1787,6 @@ __attribute__((noreturn)) void
entry_guards_DUMMY_ENTRY_POINT(void)
{
// prop271 XXXXX kludge; remove this
- entry_guard_has_higher_priority(NULL, NULL);
entry_guard_encode_for_state(NULL);
entry_guard_parse_from_state(NULL);
tor_assert(0);
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