This is ticket 2479. Roger's original explanation was:
We have a series of bugs where relays publish a descriptor within
12 hours of their last descriptor, but the authorities drop it
because it's not different "enough" from the last one and it's
too close to the last one.
The original goal of this idea was to a) reduce the number of new
descriptors authorities accept (and thus have to store) and b)
reduce the total number of descriptors that clients and mirrors
fetch. It's a defense against bugs where relays publish a new
descriptor every minute.
Now that we're putting out one consensus per hour, we're doing
better at the total damage that can be caused by 'b'.
There are broader-scale design changes that would help here, and
we've had a trac entry open for years about how relays should
recognize that they're not in the consensus, or recognize when
their publish failed, and republish sooner.
In the mean time, I think we should change some of the parameters
to make the problem less painful.
When we started RefuseUnknownExits back in 0.2.2.11-alpha, we
started making exits act like they cache directory info (since they
need an up-to-date idea of who is really a router). But this
included fetching needless (unrecognized) authorities' certs, which
doesn't make any sense for them.
This is related to, but not necessarily the same as, the issue that
Ian reported for bug #2297.
(This patch is based on a patch from a user who I believe has asked
not to be named. If I'm wrong about that, please add the
appropriate name onto the changelog.)
==
Nick here. I tweaked this patch a little to make it apply cleanly to
master, to extract some common code into a function, and to replace
snprintf with tor_snprintf.
-- nickm
One of our unit tests checks that they behave correctly (giving an
error) when the base is negative. But there isn't a guarantee that
strtol and friends actually handle negative bases correctly.
Found by Coverity Scan; fix for CID 504.
Coverity doesn't like the fact that we were storing the value of
parse_config_line_from_str() but not checking it in a couple of
cases.
Fixes CID 505 and 506.
Calling crypto_cipher_free(NULL) is always safe, since (by
convention) all of our xyz_free() functions treat xyz_free(NULL) as
a no-op.
Flagged by coverity scan; fixes CID 508 and 509.
A previous commit in the 5527 branch had moved
router_get_mutable_by_digest(digest_rcvd) to happen before we did
tor_assert(digest_rcvd), which would have defeated the purpose of
the assert.
Specifically, I believe it dates back to when extend cells had address:port
but no digest in them. The special edge case is certainly not worth the
complexity these days.
Specifically, it was a fix on 33e2053ebc, where we introduced the
WRA_* and ROUTER_* codes for dirserv_add_descriptor. Previously, we
had checked for a _negative_ return from dirserv_add_descriptor, which
meant "rejected". An insufficiently new descriptor would give a
0-valued return. But when we switched from numbers to enums, we got
this check wrong and had init_keys() give an error whenever the
descriptor wasn't accepted.
