From 126a3f699a8ed6f9c4d2b6c5f4b09f8be159fdd8 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Thu, 19 Oct 2006 23:04:56 +0000
Subject: [PATCH] r9273@Kushana: nickm | 2006-10-19 15:43:39 -0400 Never
discard a descriptor for being too old until either it is recommended by no
authorities, or until we download a better (more recent and recommended) one
for the same router. This will eventually make it possible for servers to
publish less often.
svn:r8761
---
ChangeLog | 5 ++++
doc/TODO | 4 ++--
doc/dir-spec.txt | 8 ++++++-
src/or/or.h | 4 ++--
src/or/routerlist.c | 57 +++++++++++++++++++++++----------------------
5 files changed, 45 insertions(+), 33 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 9cd97f0710..c87c2aaab1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,11 @@ Changes in version 0.1.2.3-alpha - 2006-10-??
- If most authorities set a (newly defined) BadExit flag for a server,
do not consider it as a general-purpose exit. Only consider
authorities that advertise themselves as listing bad exits.
+ - Start making it possible for servers to publish less often: never
+ discard a descriptor simply for being too old until either it is
+ recommended by no authorities, or until we get a better one for the
+ same router. Make caches consider retaining old recommended
+ routers for even longer.
o Minor features, controller:
- Add a REASON field to CIRC events; for backward compatibility, this
diff --git a/doc/TODO b/doc/TODO
index 6d8b09ec33..0f15446a5c 100644
--- a/doc/TODO
+++ b/doc/TODO
@@ -142,8 +142,8 @@ x - Better estimates in the directory of whether servers have good uptime
x - spec
d - implement
- - A more efficient dir protocol.
-N - Later, servers will stop generating new descriptors simply
+ o Changes towards a more efficient dir protocol.
+ o Later, servers will stop generating new descriptors simply
because 18 hours have passed: we must start tolerating this now.
- Critical but minor bugs, backport candidates.
diff --git a/doc/dir-spec.txt b/doc/dir-spec.txt
index 92039ef251..949c2f91f4 100644
--- a/doc/dir-spec.txt
+++ b/doc/dir-spec.txt
@@ -628,7 +628,7 @@ $Id$
from an authority, they should not need to go to the authority directly
again.)
-5.2. Downloading router descriptors
+5.2. Downloading and storing router descriptors
Clients try to have the best descriptor for each router. A descriptor is
"best" if:
@@ -665,6 +665,12 @@ $Id$
No descriptors are downloaded until the client has downloaded more than
half of the network-status documents.
+ Clients retain the most recent descriptor they have downloaded for each
+ router so long as it is not too old (currently, 48 hours), OR so long as
+ it is recommended by at least one networkstatus AND no "better"
+ descriptor has been downloaded. [Versions of Tor before 0.1.2.3-alpha
+ would discard descriptors simply for being published too far in the past.]
+
5.3. Managing downloads
When a client has no live network-status documents, it downloads
diff --git a/src/or/or.h b/src/or/or.h
index d617a95086..1ca35c46fb 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -188,8 +188,8 @@
/** How old can a router get before we (as a server) will no longer
* consider it live? In seconds. */
#define ROUTER_MAX_AGE_TO_PUBLISH (60*60*20)
-/** How old do we let a saved descriptor get before removing it? */
-#define OLD_ROUTER_DESC_MAX_AGE (60*60*60)
+/** How old do we let a saved descriptor get before force-removing it? */
+#define OLD_ROUTER_DESC_MAX_AGE (60*60*24*5)
/** How old do we let a networkstatus get before ignoring it? */
#define NETWORKSTATUS_MAX_AGE (60*60*24)
diff --git a/src/or/routerlist.c b/src/or/routerlist.c
index 02e6f9650a..2f7e0e096e 100644
--- a/src/or/routerlist.c
+++ b/src/or/routerlist.c
@@ -1999,8 +1999,8 @@ routerlist_remove_old_cached_routers_with_id(time_t cutoff, int lo, int hi,
}
/** Deactivate any routers from the routerlist that are more than
- * ROUTER_MAX_AGE seconds old; remove old routers from the list of
- * cached routers if we have too many.
+ * ROUTER_MAX_AGE seconds old and not recommended by any networkstatuses;
+ * remove old routers from the list of cached routers if we have too many.
*/
void
routerlist_remove_old_routers(void)
@@ -2012,32 +2012,37 @@ routerlist_remove_old_routers(void)
routerinfo_t *router;
signed_descriptor_t *sd;
digestmap_t *retain;
- or_options_t *options = get_options();
if (!routerlist || !networkstatus_list)
return;
retain = digestmap_new();
cutoff = now - OLD_ROUTER_DESC_MAX_AGE;
- if (options->DirPort) {
- SMARTLIST_FOREACH(networkstatus_list, networkstatus_t *, ns,
- {
- SMARTLIST_FOREACH(ns->entries, routerstatus_t *, rs,
- if (rs->published_on >= cutoff)
- digestmap_set(retain, rs->descriptor_digest, (void*)1));
- });
- }
+ /* Build a list of all the descriptors that _anybody_ recommends. */
+ SMARTLIST_FOREACH(networkstatus_list, networkstatus_t *, ns,
+ {
+ SMARTLIST_FOREACH(ns->entries, routerstatus_t *, rs,
+ if (rs->published_on >= cutoff)
+ digestmap_set(retain, rs->descriptor_digest, (void*)1));
+ });
- cutoff = now - ROUTER_MAX_AGE;
- /* Remove too-old members of routerlist->routers. */
- for (i = 0; i < smartlist_len(routerlist->routers); ++i) {
- router = smartlist_get(routerlist->routers, i);
- if (router->cache_info.published_on <= cutoff &&
- !digestmap_get(retain, router->cache_info.signed_descriptor_digest)) {
- /* Too old. Remove it. */
- log_info(LD_DIR,
- "Forgetting obsolete (too old) routerinfo for router '%s'",
- router->nickname);
- routerlist_remove(routerlist, router, i--, 1);
+ /* If we have a bunch of networkstatuses, we should consider pruning current
+ * routers that are too old and that nobody recommends. (If we don't have
+ * enough networkstatuses, then we should get more before we decide to kill
+ * routers.) */
+ if (smartlist_len(networkstatus_list) > get_n_v2_authorities() / 2) {
+ cutoff = now - ROUTER_MAX_AGE;
+ /* Remove too-old unrecommended members of routerlist->routers. */
+ for (i = 0; i < smartlist_len(routerlist->routers); ++i) {
+ router = smartlist_get(routerlist->routers, i);
+ if (router->cache_info.published_on <= cutoff &&
+ !digestmap_get(retain,router->cache_info.signed_descriptor_digest)) {
+ /* Too old: remove it. (If we're a cache, just move it into
+ * old_routers.) */
+ log_info(LD_DIR,
+ "Forgetting obsolete (too old) routerinfo for router '%s'",
+ router->nickname);
+ routerlist_remove(routerlist, router, i--, 1);
+ }
}
}
@@ -2052,8 +2057,8 @@ routerlist_remove_old_routers(void)
}
}
- /* Now we're looking at routerlist->old_routers for extraneous
- * members. (We'd keep all the members if we could, but we'd like to save
+ /* Now we might have to look at routerlist->old_routers for extraneous
+ * members. (We'd keep all the members if we could, but we need to save
* space.) First, check whether we have too many router descriptors, total.
* We're okay with having too many for some given router, so long as the
* total number doesn't approach max_descriptors_per_router()*len(router).
@@ -3595,10 +3600,6 @@ client_would_use_router(routerstatus_t *rs, time_t now, or_options_t *options)
* But, if we want to have a complete list, fetch it anyway. */
return 0;
}
- if (rs->published_on + ROUTER_MAX_AGE < now) {
- /* This one is too old to consider. */
- return 0;
- }
if (rs->published_on + ESTIMATED_PROPAGATION_TIME > now) {
/* Most caches probably don't have this descriptor yet. */
return 0;
--
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