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Merge remote-tracking branch 'rl1987/ticket21349_4'

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This commit is contained in:
Nick Mathewson 2018-07-30 08:49:49 -04:00
commit 13393b2d91
4 changed files with 257 additions and 105 deletions
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6
changes/ticket21349 Normal file
View File

@ -0,0 +1,6 @@
o Code simplification and refactoring:
- Split sampled_guards_update_from_consensus() and
select_entry_guard_for_circuit() into subfunctions.
In entry_guards_update_primary() unite
three smartlist enumerations into one and move smartlist
comparison code out of the function. Closes ticket 21349.

284
src/feature/client/entrynodes.c
View File

@ -406,6 +406,17 @@ get_remove_unlisted_guards_after_days(void)
DFLT_REMOVE_UNLISTED_GUARDS_AFTER_DAYS,
1, 365*10);
}
/**
* Return number of seconds that will make a guard no longer eligible
* for selection if unlisted for this long.
*/
static time_t
get_remove_unlisted_guards_after_seconds(void)
{
return get_remove_unlisted_guards_after_days() * 24 * 60 * 60;
}
/**
* We remove unconfirmed guards from the sample after this many days,
* regardless of whether they are listed or unlisted.
@ -1237,30 +1248,28 @@ entry_guard_is_listed,(guard_selection_t *gs, const entry_guard_t *guard))
}
/**
* Update the status of all sampled guards based on the arrival of a
* new consensus networkstatus document. This will include marking
* some guards as listed or unlisted, and removing expired guards. */
STATIC void
sampled_guards_update_from_consensus(guard_selection_t *gs)
* Enumerate <b>sampled_entry_guards</b> smartlist in <b>gs</b>.
* For each <b>entry_guard_t</b> object in smartlist, do the following:
* * Update <b>currently_listed</b> field to reflect if guard is listed
* in guard selection <b>gs</b>.
* * Set <b>unlisted_since_date</b> to approximate UNIX time of
* unlisting if guard is unlisted (randomize within 20% of
* get_remove_unlisted_guards_after_seconds()). Otherwise,
* set it to 0.
*
* Require <b>gs</b> to be non-null pointer.
* Return a number of entries updated.
*/
static size_t
sampled_guards_update_consensus_presence(guard_selection_t *gs)
{
size_t n_changes = 0;
tor_assert(gs);
const int REMOVE_UNLISTED_GUARDS_AFTER =
(get_remove_unlisted_guards_after_days() * 86400);
const int unlisted_since_slop = REMOVE_UNLISTED_GUARDS_AFTER / 5;
// It's important to use only a live consensus here; we don't want to
// make changes based on anything expired or old.
if (live_consensus_is_missing(gs)) {
log_info(LD_GUARD, "Not updating the sample guard set; we have "
"no live consensus.");
return;
}
log_info(LD_GUARD, "Updating sampled guard status based on received "
"consensus.");
const time_t unlisted_since_slop =
get_remove_unlisted_guards_after_seconds() / 5;
int n_changes = 0;
/* First: Update listed/unlisted. */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
/* XXXX #20827 check ed ID too */
const int is_listed = entry_guard_is_listed(gs, guard);
@ -1304,14 +1313,33 @@ sampled_guards_update_from_consensus(guard_selection_t *gs)
}
} SMARTLIST_FOREACH_END(guard);
const time_t remove_if_unlisted_since =
approx_time() - REMOVE_UNLISTED_GUARDS_AFTER;
const time_t maybe_remove_if_sampled_before =
approx_time() - get_guard_lifetime();
const time_t remove_if_confirmed_before =
approx_time() - get_guard_confirmed_min_lifetime();
return n_changes;
}
/**
* Enumerate <b>sampled_entry_guards</b> smartlist in <b>gs</b>.
* For each <b>entry_guard_t</b> object in smartlist, do the following:
* * If <b>currently_listed</b> is false and <b>unlisted_since_date</b>
* is earlier than <b>remove_if_unlisted_since</b> - remove it.
* * Otherwise, check if <b>sampled_on_date</b> is earlier than
* <b>maybe_remove_if_sampled_before</b>.
* * When above condition is correct, remove the guard if:
* * It was never confirmed.
* * It was confirmed before <b>remove_if_confirmed_before</b>.
*
* Require <b>gs</b> to be non-null pointer.
* Return number of entries deleted.
*/
static size_t
sampled_guards_prune_obsolete_entries(guard_selection_t *gs,
const time_t remove_if_unlisted_since,
const time_t maybe_remove_if_sampled_before,
const time_t remove_if_confirmed_before)
{
size_t n_changes = 0;
tor_assert(gs);
/* Then: remove the ones that have been junk for too long */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
int rmv = 0;
@ -1319,7 +1347,7 @@ sampled_guards_update_from_consensus(guard_selection_t *gs)
guard->unlisted_since_date < remove_if_unlisted_since) {
/*
"We have a live consensus, and {IS_LISTED} is false, and
{FIRST_UNLISTED_AT} is over {REMOVE_UNLISTED_GUARDS_AFTER}
{FIRST_UNLISTED_AT} is over get_remove_unlisted_guards_after_days()
days in the past."
*/
log_info(LD_GUARD, "Removing sampled guard %s: it has been unlisted "
@ -1355,6 +1383,45 @@ sampled_guards_update_from_consensus(guard_selection_t *gs)
}
} SMARTLIST_FOREACH_END(guard);
return n_changes;
}
/**
* Update the status of all sampled guards based on the arrival of a
* new consensus networkstatus document. This will include marking
* some guards as listed or unlisted, and removing expired guards. */
STATIC void
sampled_guards_update_from_consensus(guard_selection_t *gs)
{
tor_assert(gs);
// It's important to use only a live consensus here; we don't want to
// make changes based on anything expired or old.
if (live_consensus_is_missing(gs)) {
log_info(LD_GUARD, "Not updating the sample guard set; we have "
"no live consensus.");
return;
}
log_info(LD_GUARD, "Updating sampled guard status based on received "
"consensus.");
/* First: Update listed/unlisted. */
size_t n_changes = sampled_guards_update_consensus_presence(gs);
const time_t remove_if_unlisted_since =
approx_time() - get_remove_unlisted_guards_after_seconds();
const time_t maybe_remove_if_sampled_before =
approx_time() - get_guard_lifetime();
const time_t remove_if_confirmed_before =
approx_time() - get_guard_confirmed_min_lifetime();
/* Then: remove the ones that have been junk for too long */
n_changes +=
sampled_guards_prune_obsolete_entries(gs,
remove_if_unlisted_since,
maybe_remove_if_sampled_before,
remove_if_confirmed_before);
if (n_changes) {
gs->primary_guards_up_to_date = 0;
entry_guards_update_filtered_sets(gs);
@ -1816,28 +1883,24 @@ entry_guards_update_primary(guard_selection_t *gs)
smartlist_add(new_primary_guards, guard);
} SMARTLIST_FOREACH_END(guard);
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
/* Can we keep any older primary guards? First remove all the ones
* that we already kept. */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
if (smartlist_contains(new_primary_guards, guard)) {
SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
continue;
}
} SMARTLIST_FOREACH_END(guard);
/* Now add any that are still good. */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS)
break;
if (! guard->is_filtered_guard)
continue;
if (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS &&
guard->is_filtered_guard) {
guard->is_primary = 1;
smartlist_add(new_primary_guards, guard);
SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
} SMARTLIST_FOREACH_END(guard);
} else {
/* Mark the remaining previous primary guards as non-primary */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
guard->is_primary = 0;
}
} SMARTLIST_FOREACH_END(guard);
/* Finally, fill out the list with sampled guards. */
@ -1861,18 +1924,8 @@ entry_guards_update_primary(guard_selection_t *gs)
});
#endif /* 1 */
int any_change = 0;
if (smartlist_len(gs->primary_entry_guards) !=
smartlist_len(new_primary_guards)) {
any_change = 1;
} else {
SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, g) {
if (g != smartlist_get(new_primary_guards, g_sl_idx)) {
any_change = 1;
}
} SMARTLIST_FOREACH_END(g);
}
const int any_change = !smartlist_ptrs_eq(gs->primary_entry_guards,
new_primary_guards);
if (any_change) {
log_info(LD_GUARD, "Primary entry guards have changed. "
"New primary guard list is: ");
@ -1974,31 +2027,23 @@ entry_guards_note_internet_connectivity(guard_selection_t *gs)
}
/**
* Get a guard for use with a circuit. Prefer to pick a running primary
* guard; then a non-pending running filtered confirmed guard; then a
* non-pending runnable filtered guard. Update the
* Pick a primary guard for use with a circuit, if available. Update the
* <b>last_tried_to_connect</b> time and the <b>is_pending</b> fields of the
* guard as appropriate. Set <b>state_out</b> to the new guard-state
* of the circuit.
*/
STATIC entry_guard_t *
select_entry_guard_for_circuit(guard_selection_t *gs,
static entry_guard_t *
select_primary_guard_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
const entry_guard_restriction_t *rst,
unsigned *state_out)
{
const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
tor_assert(gs);
tor_assert(state_out);
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
entry_guard_t *chosen_guard = NULL;
int num_entry_guards = get_n_primary_guards_to_use(usage);
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) {
entry_guard_consider_retry(guard);
if (! entry_guard_obeys_restriction(guard, rst))
@ -2016,18 +2061,30 @@ select_entry_guard_for_circuit(guard_selection_t *gs,
} SMARTLIST_FOREACH_END(guard);
if (smartlist_len(usable_primary_guards)) {
entry_guard_t *guard = smartlist_choose(usable_primary_guards);
chosen_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;
entry_guard_describe(chosen_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
false." */
smartlist_free(usable_primary_guards);
return chosen_guard;
}
/**
* For use with a circuit, pick a non-pending running filtered confirmed guard,
* if one is available. Update the <b>last_tried_to_connect</b> time and the
* <b>is_pending</b> fields of the guard as appropriate. Set <b>state_out</b>
* to the new guard-state of the circuit.
*/
static entry_guard_t *
select_confirmed_guard_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
const entry_guard_restriction_t *rst,
unsigned *state_out)
{
const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
if (guard->is_primary)
continue; /* we already considered this one. */
@ -2048,34 +2105,93 @@ select_entry_guard_for_circuit(guard_selection_t *gs,
}
} SMARTLIST_FOREACH_END(guard);
/* "Otherwise, if there is no such entry, select a member at
random from {USABLE_FILTERED_GUARDS}." */
return NULL;
}
/**
* For use with a circuit, pick a confirmed usable filtered guard
* at random. Update the <b>last_tried_to_connect</b> time and the
* <b>is_pending</b> fields of the guard as appropriate. Set <b>state_out</b>
* to the new guard-state of the circuit.
*/
static entry_guard_t *
select_filtered_guard_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
const entry_guard_restriction_t *rst,
unsigned *state_out)
{
entry_guard_t *guard;
const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
entry_guard_t *chosen_guard = NULL;
unsigned flags = 0;
if (need_descriptor)
flags |= SAMPLE_EXCLUDE_NO_DESCRIPTOR;
guard = sample_reachable_filtered_entry_guards(gs,
chosen_guard = sample_reachable_filtered_entry_guards(gs,
rst,
SAMPLE_EXCLUDE_CONFIRMED |
SAMPLE_EXCLUDE_PRIMARY |
SAMPLE_EXCLUDE_PENDING |
flags);
if (guard == NULL) {
if (!chosen_guard) {
return NULL;
}
chosen_guard->is_pending = 1;
chosen_guard->last_tried_to_connect = approx_time();
*state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
log_info(LD_GUARD, "No primary or confirmed guards available. Selected "
"random guard %s for circuit. Will try other guards before "
"using this circuit.",
entry_guard_describe(chosen_guard));
return chosen_guard;
}
/**
* Get a guard for use with a circuit. Prefer to pick a running primary
* guard; then a non-pending running filtered confirmed guard; then a
* non-pending runnable filtered guard. Update the
* <b>last_tried_to_connect</b> time and the <b>is_pending</b> fields of the
* guard as appropriate. Set <b>state_out</b> to the new guard-state
* of the circuit.
*/
STATIC entry_guard_t *
select_entry_guard_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
const entry_guard_restriction_t *rst,
unsigned *state_out)
{
entry_guard_t *chosen_guard = NULL;
tor_assert(gs);
tor_assert(state_out);
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
/* "If any entry in PRIMARY_GUARDS has {is_reachable} status of
<maybe> or <yes>, return the first such guard." */
chosen_guard = select_primary_guard_for_circuit(gs, usage, rst, state_out);
if (chosen_guard)
return chosen_guard;
/* "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
false." */
chosen_guard = select_confirmed_guard_for_circuit(gs, usage, rst, state_out);
if (chosen_guard)
return chosen_guard;
/* "Otherwise, if there is no such entry, select a member at
random from {USABLE_FILTERED_GUARDS}." */
chosen_guard = select_filtered_guard_for_circuit(gs, usage, rst, state_out);
if (chosen_guard == NULL) {
log_info(LD_GUARD, "Absolutely no sampled guards were available. "
"Marking all guards for retry and starting from top again.");
mark_all_guards_maybe_reachable(gs);
return NULL;
}
guard->is_pending = 1;
guard->last_tried_to_connect = approx_time();
*state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
log_info(LD_GUARD, "No primary or confirmed guards available. Selected "
"random guard %s for circuit. Will try other guards before "
"using this circuit.",
entry_guard_describe(guard));
return guard;
}
return chosen_guard;
}
/**

27
src/lib/container/smartlist.c
View File

@ -189,6 +189,33 @@ smartlist_ints_eq(const smartlist_t *sl1, const smartlist_t *sl2)
return 1;
}
/**
* Return true if there is shallow equality between smartlists -
* i.e. all indices correspond to exactly same object (pointer
* values are matching). Otherwise, return false.
*/
int
smartlist_ptrs_eq(const smartlist_t *s1, const smartlist_t *s2)
{
if (s1 == s2)
return 1;
// Note: pointers cannot both be NULL at this point, because
// above check.
if (s1 == NULL || s2 == NULL)
return 0;
if (smartlist_len(s1) != smartlist_len(s2))
return 0;
for (int i = 0; i < smartlist_len(s1); i++) {
if (smartlist_get(s1, i) != smartlist_get(s2, i))
return 0;
}
return 1;
}
/** Return true iff <b>sl</b> has some element E such that
* tor_memeq(E,<b>element</b>,DIGEST_LEN)
*/

3
src/lib/container/smartlist.h
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@ -37,6 +37,9 @@ int smartlist_overlap(const smartlist_t *sl1, const smartlist_t *sl2);
void smartlist_intersect(smartlist_t *sl1, const smartlist_t *sl2);
void smartlist_subtract(smartlist_t *sl1, const smartlist_t *sl2);
int smartlist_ptrs_eq(const smartlist_t *s1,
const smartlist_t *s2);
void smartlist_sort(smartlist_t *sl,
int (*compare)(const void **a, const void **b));
void *smartlist_get_most_frequent_(const smartlist_t *sl,