commit deb8bcadced3c54d986c526662444a46e630621d Author: Nick Mathewson nickm@torproject.org Date: Thu Dec 8 12:47:29 2016 -0500

271: Algorithm tweak to allow multiple entry guards.

Previously, we had NumEntryGuards kind of hardwired to 1. Now we have the code (but not the configuarability) to choose randomly from among the first N primary guards that would work, where N defaults to 1.

Part of 20831 support for making NumEntryGuards work again. --- src/or/entrynodes.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index f89594b..5c64dfd 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -1795,6 +1795,9 @@ select_entry_guard_for_circuit(guard_selection_t *gs, if (!gs->primary_guards_up_to_date) entry_guards_update_primary(gs);

+ int num_entry_guards = 1; + smartlist_t *usable_primary_guards = smartlist_new(); + /* "If any entry in PRIMARY_GUARDS has {is_reachable} status of <maybe> or <yes>, return the first such guard." */ SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { @@ -1804,12 +1807,21 @@ select_entry_guard_for_circuit(guard_selection_t *gs, if (guard->is_reachable != GUARD_REACHABLE_NO) { *state_out = GUARD_CIRC_STATE_USABLE_ON_COMPLETION; guard->last_tried_to_connect = approx_time(); - log_info(LD_GUARD, "Selected primary guard %s for circuit.", - entry_guard_describe(guard)); - return guard; + smartlist_add(usable_primary_guards, guard); + if (smartlist_len(usable_primary_guards) >= num_entry_guards) + break; } } SMARTLIST_FOREACH_END(guard);

+ if (smartlist_len(usable_primary_guards)) { + entry_guard_t *guard = smartlist_choose(usable_primary_guards); + smartlist_free(usable_primary_guards); + log_info(LD_GUARD, "Selected primary guard %s for circuit.", + entry_guard_describe(guard)); + return guard; + } + smartlist_free(usable_primary_guards); + /* "Otherwise, if the ordered intersection of {CONFIRMED_GUARDS} and {USABLE_FILTERED_GUARDS} is nonempty, return the first entry in that intersection that has {is_pending} set to