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prop224: Refactor descriptor rotation logic.

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The problem was that when we went from overlap mode to non-overlap mode,
we were not wiping the 'desc_next' descriptor and instead we left it on
the service. This meant that all functions that iterated service
descriptors were also inspecting the useless 'desc_next' descriptor that
should have been deleted.

This commit refactors rotate_all_descriptors() so that it rotates
descriptor both when entering overlap mode and also when leaving it.
This commit is contained in:
George Kadianakis 2017-08-24 16:16:44 +03:00
parent f9cd870f50
commit 8b8e39e04b
1 changed files with 72 additions and 26 deletions
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74
src/or/hs_service.c
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@ -1714,10 +1714,35 @@ rotate_service_descriptors(hs_service_t *service)
service->desc_next = NULL;
}
/* Rotate descriptors for each service if needed. If we are just entering
* the overlap period, rotate them that is point the previous descriptor to
* the current and cleanup the previous one. A non existing current
* descriptor will trigger a descriptor build for the next time period. */
/** Return true if <b>service</b> **just** entered overlap mode. */
static int
service_just_entered_overlap_mode(const hs_service_t *service,
int overlap_mode_is_active)
{
if (overlap_mode_is_active && !service->state.in_overlap_period) {
return 1;
}
return 0;
}
/** Return true if <b>service</b> **just** left overlap mode. */
static int
service_just_left_overlap_mode(const hs_service_t *service,
int overlap_mode_is_active)
{
if (!overlap_mode_is_active && service->state.in_overlap_period) {
return 1;
}
return 0;
}
/* Rotate descriptors for each service if needed. If we are just entering or
* leaving the overlap period, rotate them that is point the previous
* descriptor to the current and cleanup the previous one. A non existing
* current descriptor will trigger a descriptor build for the next time
* period. */
STATIC void
rotate_all_descriptors(time_t now)
{
@ -1725,35 +1750,56 @@ rotate_all_descriptors(time_t now)
* be wise, to rotate service descriptors independently to hide that all
* those descriptors are on the same tor instance */
int overlap_mode_is_active = hs_overlap_mode_is_active(NULL, now);
FOR_EACH_SERVICE_BEGIN(service) {
/* We are _not_ in the overlap period so skip rotation. */
if (!hs_overlap_mode_is_active(NULL, now)) {
service->state.in_overlap_period = 0;
continue;
int service_entered_overlap = service_just_entered_overlap_mode(service,
overlap_mode_is_active);
int service_left_overlap = service_just_left_overlap_mode(service,
overlap_mode_is_active);
/* This should not be possible */
if (BUG(service_entered_overlap && service_left_overlap)) {
return;
}
/* We've entered the overlap period already so skip rotation. */
if (service->state.in_overlap_period) {
continue;
/* No changes in overlap mode: nothing to do here */
if (!service_entered_overlap && !service_left_overlap) {
return;
}
/* To get down there means that some change happened to overlap mode */
tor_assert(service_entered_overlap || service_left_overlap);
/* Update the overlap marks on this service */
if (service_entered_overlap) {
/* It's the first time the service encounters the overlap period so flag
* it in order to make sure we don't rotate at next check. */
service->state.in_overlap_period = 1;
} else if (service_left_overlap) {
service->state.in_overlap_period = 0;
}
if (service_entered_overlap) {
/* We just entered overlap period: recompute all HSDir indices. We need to
* do this otherwise nodes can get stuck with old HSDir indices until we
* fetch a new consensus, and we might need to reupload our desc before
* that. */
/* XXX find a better place than rotate_all_descriptors() to do this */
nodelist_recompute_all_hsdir_indices();
}
/* If we just entered or left overlap mode, rotate our descriptors */
log_info(LD_REND, "We just %s overlap period. About to rotate %s "
"descriptors (%p / %p).",
service_entered_overlap ? "entered" : "left",
safe_str_client(service->onion_address),
service->desc_current, service->desc_next);
/* If we have a next descriptor lined up, rotate the descriptors so that it
* becomes current. */
if (service->desc_next) {
rotate_service_descriptors(service);
}
log_info(LD_REND, "We've just entered the overlap period. Service %s "
"descriptors have been rotated!",
safe_str_client(service->onion_address));
} FOR_EACH_SERVICE_END;
}