[tor-commits] [tor/master] Adjust n_intro_points_wanted when a service's intro points are closed
nickm at torproject.org
nickm at torproject.org
Tue Dec 20 16:17:05 UTC 2011
commit dae000735e75b178cdf27000d316f6504bf61373
Author: Robert Ransom <rransom.8774 at gmail.com>
Date: Tue Dec 13 05:00:09 2011 -0800
Adjust n_intro_points_wanted when a service's intro points are closed
---
changes/bug3825b | 7 +++
src/or/or.h | 5 ++
src/or/rendservice.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 124 insertions(+), 0 deletions(-)
diff --git a/changes/bug3825b b/changes/bug3825b
new file mode 100644
index 0000000..08c0c2d
--- /dev/null
+++ b/changes/bug3825b
@@ -0,0 +1,7 @@
+ o Major features:
+
+ - Adjust the number of introduction points that a hidden service
+ will try to maintain based on how long its introduction points
+ remain in use and how many introductions they handle. Fixes
+ part of bug 3825.
+
diff --git a/src/or/or.h b/src/or/or.h
index 6ff02ee..63ff5c4 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -4114,6 +4114,11 @@ typedef struct rend_intro_point_t {
* included in the last HS descriptor we generated. */
unsigned int listed_in_last_desc : 1;
+ /** (Service side only) Flag indicating that
+ * rend_service_note_removing_intro_point has been called for this
+ * intro point. */
+ unsigned int rend_service_note_removing_intro_point_called : 1;
+
/** (Service side only) A digestmap recording the INTRODUCE2 cells
* this intro point's circuit has received. Each key is the digest
* of the RSA-encrypted part of a received INTRODUCE2 cell; each
diff --git a/src/or/rendservice.c b/src/or/rendservice.c
index 0f22cdf..646d423 100644
--- a/src/or/rendservice.c
+++ b/src/or/rendservice.c
@@ -116,6 +116,17 @@ num_rend_services(void)
return smartlist_len(rend_service_list);
}
+/** Return a string identifying <b>service</b>, suitable for use in a
+ * log message. The result does not need to be freed, but may be
+ * overwritten by the next call to this function. */
+static const char *
+rend_service_describe_for_log(rend_service_t *service)
+{
+ /* XXX024 Use this function throughout rendservice.c. */
+ /* XXX024 Return a more useful description? */
+ return safe_str_client(service->service_id);
+}
+
/** Helper: free storage held by a single service authorized client entry. */
static void
rend_authorized_client_free(rend_authorized_client_t *client)
@@ -915,6 +926,104 @@ clean_accepted_intro_dh_parts(rend_service_t *service, time_t now)
} DIGESTMAP_FOREACH_END;
}
+/** Called when <b>intro</b> will soon be removed from
+ * <b>service</b>'s list of intro points. */
+static void
+rend_service_note_removing_intro_point(rend_service_t *service,
+ rend_intro_point_t *intro)
+{
+ time_t now = time(NULL);
+
+ /* Don't process an intro point twice here. */
+ if (intro->rend_service_note_removing_intro_point_called) {
+ return;
+ } else {
+ intro->rend_service_note_removing_intro_point_called = 1;
+ }
+
+ /* Update service->n_intro_points_wanted based on how long intro
+ * lasted and how many introductions it handled. */
+ if (intro->time_published == -1) {
+ /* This intro point was never used. Don't change
+ * n_intro_points_wanted. */
+ } else {
+ /* We want to increase the number of introduction points service
+ * operates if intro was heavily used, or decrease the number of
+ * intro points if intro was lightly used.
+ *
+ * We consider an intro point's target 'usage' to be
+ * INTRO_POINT_LIFETIME_INTRODUCTIONS introductions in
+ * INTRO_POINT_LIFETIME_MIN_SECONDS seconds. To calculate intro's
+ * fraction of target usage, we divide the fraction of
+ * _LIFETIME_INTRODUCTIONS introductions that it has handled by
+ * the fraction of _LIFETIME_MIN_SECONDS for which it existed.
+ *
+ * Then we take the reciprocal of that fraction of desired usage,
+ * then multiply by a fudge factor of 1.5, to decide how many new
+ * introduction points should ideally replace intro (which is now
+ * closed or soon to be closed). In theory, assuming that
+ * introduction load is distributed equally across all intro
+ * points and ignoring the fact that different intro points are
+ * established and closed at different times, that number of intro
+ * points should bring all of our intro points exactly to our
+ * target usage.
+ *
+ * Then we clamp that number to a number of intro points we might
+ * be willing to replace this intro point with and turn it into an
+ * integer. then we clamp it again to the number of new intro
+ * points we could establish now, then we adjust
+ * service->n_intro_points_wanted and let rend_services_introduce
+ * create the new intro points we want (if any).
+ */
+ double fractional_n_intro_points_wanted_to_replace_this_one =
+ ((((double)now - intro->time_published) /
+ INTRO_POINT_LIFETIME_MIN_SECONDS) *
+ ((intro_point_accepted_intro_count(intro)) /
+ INTRO_POINT_LIFETIME_INTRODUCTIONS)) * 1.5;
+ unsigned int n_intro_points_wanted_to_replace_this_one;
+ unsigned int n_intro_points_wanted_now;
+ unsigned int n_intro_points_really_wanted_now;
+ int n_intro_points_really_replacing_this_one;
+
+ if (fractional_n_intro_points_wanted_to_replace_this_one >
+ NUM_INTRO_POINTS_MAX) {
+ n_intro_points_wanted_to_replace_this_one = NUM_INTRO_POINTS_MAX;
+ } else if (fractional_n_intro_points_wanted_to_replace_this_one < 0) {
+ n_intro_points_wanted_to_replace_this_one = 0;
+ } else {
+ n_intro_points_wanted_to_replace_this_one =
+ fractional_n_intro_points_wanted_to_replace_this_one;
+ }
+
+ n_intro_points_wanted_now =
+ service->n_intro_points_wanted +
+ n_intro_points_wanted_to_replace_this_one - 1;
+
+ if (n_intro_points_wanted_now < NUM_INTRO_POINTS_DEFAULT) {
+ /* XXXX This should be NUM_INTRO_POINTS_MIN instead. Perhaps
+ * another use of NUM_INTRO_POINTS_DEFAULT should be, too. */
+ n_intro_points_really_wanted_now = NUM_INTRO_POINTS_DEFAULT;
+ } else if (n_intro_points_wanted_now > NUM_INTRO_POINTS_MAX) {
+ n_intro_points_really_wanted_now = NUM_INTRO_POINTS_MAX;
+ } else {
+ n_intro_points_really_wanted_now = n_intro_points_wanted_now;
+ }
+
+ n_intro_points_really_replacing_this_one =
+ n_intro_points_really_wanted_now - service->n_intro_points_wanted + 1;
+
+ log_info(LD_REND, "Replacing closing intro point for service %s "
+ "with %d new intro points (wanted %g replacements); "
+ "service will now try to have %u intro points",
+ rend_service_describe_for_log(service),
+ n_intro_points_really_replacing_this_one,
+ fractional_n_intro_points_wanted_to_replace_this_one,
+ n_intro_points_really_wanted_now);
+
+ service->n_intro_points_wanted = n_intro_points_really_wanted_now;
+ }
+}
+
/******
* Handle cells
******/
@@ -2073,6 +2182,7 @@ rend_services_introduce(void)
" (circuit disappeared).",
safe_str_client(extend_info_describe(intro->extend_info)),
safe_str_client(service->service_id));
+ rend_service_note_removing_intro_point(service, intro);
if (intro->time_expiring != -1) {
log_info(LD_REND, "We were already expiring the intro point; "
"no need to mark the HS descriptor as dirty over this.");
@@ -2095,6 +2205,8 @@ rend_services_introduce(void)
safe_str_client(extend_info_describe(intro->extend_info)),
safe_str_client(service->service_id));
+ rend_service_note_removing_intro_point(service, intro);
+
/* The polite (and generally Right) way to expire an intro
* point is to establish a new one to replace it, publish a
* new descriptor that doesn't list any expiring intro points,
More information about the tor-commits
mailing list