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Rewrite state transition logic in entry_guards_note_success()

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asn found while testing that this function can be reached with
GUARD_STATE_COMPLETE circuits; I believe this happens when
cannibalization occurs.

The added complexity of handling one more state made it reasonable
to turn the main logic here into a switch statement.
This commit is contained in:
Nick Mathewson 2016-12-08 10:22:23 -05:00
parent 2e2f3a4d99
commit fc7751a989
1 changed files with 23 additions and 17 deletions
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26
src/or/entrynodes.c
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@ -1927,25 +1927,31 @@ entry_guards_note_guard_success(guard_selection_t *gs,
} }
unsigned new_state; unsigned new_state;
if (old_state == GUARD_CIRC_STATE_USABLE_ON_COMPLETION) { switch (old_state) {
case GUARD_CIRC_STATE_COMPLETE:
case GUARD_CIRC_STATE_USABLE_ON_COMPLETION:
new_state = GUARD_CIRC_STATE_COMPLETE; new_state = GUARD_CIRC_STATE_COMPLETE;
} else { break;
tor_assert_nonfatal( default:
old_state == GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD); tor_assert_nonfatal_unreached();
/* Fall through. */
case GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD:
if (guard->is_primary) { if (guard->is_primary) {
/* XXXX prop271 -- I don't actually like this logic. It seems to make us /* XXXX prop271 -- I don't actually like this logic. It seems to make
* a little more susceptible to evil-ISP attacks. The mitigations I'm * us a little more susceptible to evil-ISP attacks. The mitigations
* thinking of, however, aren't local to this point, so I'll leave it * I'm thinking of, however, aren't local to this point, so I'll leave
* alone. */ * it alone. */
/* This guard may have become primary by virtue of being confirmed. /* This guard may have become primary by virtue of being confirmed.
If so, the circuit for it is now complete. * If so, the circuit for it is now complete.
*/ */
new_state = GUARD_CIRC_STATE_COMPLETE; new_state = GUARD_CIRC_STATE_COMPLETE;
} else { } else {
new_state = GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD; new_state = GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD;
} }
break;
}
if (! guard->is_primary) {
if (last_time_on_internet + get_internet_likely_down_interval() if (last_time_on_internet + get_internet_likely_down_interval()
< approx_time()) { < approx_time()) {
mark_primary_guards_maybe_reachable(gs); mark_primary_guards_maybe_reachable(gs);