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Another tweak for guard restrictions: don't let complete circs block

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If a complete circuit C2 doesn't obey the restrictions of C1, then
C2 cannot block C1.

The patch here is a little big-ish, since we can no longer look
through all the complete circuits and all the waiting circuits on a
single pass: we have to find the best waiting circuit first.
This commit is contained in:
Nick Mathewson 2016-11-30 09:04:34 -05:00
parent 87f9b42179
commit 2c8c58ab2f
1 changed files with 23 additions and 20 deletions
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43
src/or/entrynodes.c
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@ -2214,8 +2214,8 @@ entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
int n_waiting = 0;
int n_complete = 0;
int n_complete_blocking = 0;
origin_circuit_t *best_waiting_circuit = NULL;
origin_circuit_t *best_complete_circuit = NULL;
smartlist_t *all_circuits = smartlist_new();
SMARTLIST_FOREACH_BEGIN(all_circuits_in, origin_circuit_t *, circ) {
// We filter out circuits that aren't ours, or which we can't
@ -2241,12 +2241,6 @@ entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
circ_state_has_higher_priority(circ, NULL, 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, NULL, best_complete_circuit)) {
best_complete_circuit = circ;
}
}
} SMARTLIST_FOREACH_END(circ);
@ -2262,19 +2256,28 @@ entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
const entry_guard_restriction_t *rst_on_best_waiting =
origin_circuit_get_guard_state(best_waiting_circuit)->restrictions;
if (best_complete_circuit) {
if (circ_state_has_higher_priority(best_complete_circuit,
rst_on_best_waiting,
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);
goto no_change;
}
/* First look at the complete circuits: Do any block this circuit? */
SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if BUG((state == NULL))
continue;
if (state->state != GUARD_CIRC_STATE_COMPLETE)
continue;
++n_complete;
if (circ_state_has_higher_priority(circ, rst_on_best_waiting,
best_waiting_circuit))
++n_complete_blocking;
} SMARTLIST_FOREACH_END(circ);
if (n_complete_blocking) {
/* "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);
goto no_change;
}
/* "If any circuit is <waiting_for_better_guard>, and every currently