if more than 10 seconds pass while we wait for netmgr
events to finish running on shutdown, something is almost
certainly wrong and we should assert and crash.
This commit updates and simplifies the checks for the readline support
in nslookup and nsupdate:
* Change the autoconf checks to pkg-config only, all supported
libraries have accompanying .pc files now.
* Add editline support in addition to libedit and GNU readline
* Add isc/readline.h shim header that defines dummy readline()
function when no readline library is available
Prevent intermittent false positives on slow platforms by subtracting
the number of seconds which passed between key creation and invoking
'rndc dnssec -checkds'.
This particularly fails for the step3.csk-roll2.autosign zone because
the closest next key event is when the zone signatures become
omnipresent. Running 'rndc dnssec -checkds' some time later means
that the next key event is in fact closer than the calculated time
and thus we need to adjust the expected time by the time already
passed.
Previously .txt files with full backtrace may be identified as a
crashed test:
I:Core dumps were found for the following system tests:
I: core.19948-backtrace.txt
I: shutdown
Now .txt files are removed from the list.
Change 'run.sh.in' to match the core matching pattern in
'testsummary.sh'.
Make sure the 'checkds' command correctly sets the right key timing
metadata and also make sure that it rejects setting the key timing
metadata if there are multiple keys with the KSK role and no key
identifier is provided.
With 'checkds' replacing 'parent-registration-delay', the kasp
test needs the expected times to be adjusted. Also the system test
needs to call 'rndc dnssec -checkds' to progress the rollovers.
Since we pretend that the KSK is active as soon as the DS is
submitted (and parent registration delay is no longer applicable)
we can simplify the 'csk_rollover_predecessor_keytimes' function
to take only one "addtime" parameter.
This commit also slightly changes the 'check_dnssecstatus' function,
passing the zone as a parameter.
Add a new 'rndc' command 'dnssec -checkds' that allows the user to
signal named that a new DS record has been seen published in the
parent, or that an existing DS record has been withdrawn from the
parent.
Upon the 'checkds' request, 'named' will write out the new state for
the key, updating the 'DSPublish' or 'DSRemoved' timing metadata.
This replaces the "parent-registration-delay" configuration option,
this was unreliable because it was purely time based (if the user
did not actually submit the new DS to the parent for example, this
could result in an invalid DNSSEC state).
Because we cannot rely on the parent registration delay for state
transition, we need to replace it with a different guard. Instead,
if a key wants its DS state to be moved to RUMOURED, the "DSPublish"
time must be set and must not be in the future. If a key wants its
DS state to be moved to UNRETENTIVE, the "DSRemoved" time must be set
and must not be in the future.
By default, with '-checkds' you set the time that the DS has been
published or withdrawn to now, but you can set a different time with
'-when'. If there is only one KSK for the zone, that key has its
DS state moved to RUMOURED. If there are multiple keys for the zone,
specify the right key with '-key'.
The named configuration files used in the "geoip2" system test cause a
rather large number of views (6-8) to be set up in each tested named
instance. Each view has its own cache.
Commit e24bc324b4 caused the RBT hash
table to be pre-allocated to a size derived from "max-cache-size", so
that it never needs to be rehashed. The size of that hash table is not
expected to be significant enough to cause memory use issues in typical
conditions even for large "max-cache-size" settings.
However, these two factors combined can cause memory exhaustion issues
in GitLab CI, where we run multiple "instances" of the test suite in
parallel on the same runner, each test suite executes multiple system
tests concurrently, and each system test may potentially start multiple
named instances at the same time. In practice, this problem currently
only seems to be affecting the "geoip2" system test, which is failing
intermittently due to named instances used by that test getting killed
by oom-killer.
Prevent the "geoip2" system test from failing intermittently by setting
"max-cache-size" in named configuration files used in that test to a low
value in order to keep memory usage at bay even with a large number of
views configured.
The current serve-stale implementation in BIND 9 stores all received
records in the cache for a max-stale-ttl interval (default 12 hours).
This allows DNS operators to turn the serve-stale answers in an event of
large authoritative DNS outage. The caching of the stale answers needs
to be enabled before the outage happens or the feature would be
otherwise useless.
The negative consequence of the default setting is the inevitable
cache-bloat that happens for every and each DNS operator running named.
In this MR, a new configuration option `stale-cache-enable` is
introduced that allows the operators to selectively enable or disable
the serve-stale feature of BIND 9 based on their decision.
The newly introduced option has been disabled by default,
e.g. serve-stale is disabled in the default configuration and has to be
enabled if required.
Created isc_refcount_decrement_expect macro to test conditionally
the return value to ensure it is in expected range. Converted
unchecked isc_refcount_decrement to use isc_refcount_decrement_expect.
Converted INSIST(isc_refcount_decrement()...) to isc_refcount_decrement_expect.
It seems that config.guess gets always created in source root, so for
that sake of out-of-tree system test, we should expect the file there
instead of where configure was run.
The $SYSTEMTESTTOP shell variable if often set to .. in various shell
scripts inside bin/tests/system/, but most of the time it is only
used one line later, while sourcing conf.sh. This hardly improves
code readability.
$SYSTEMTESTTOP is also used for the purpose of referencing
scripts/files living in bin/tests/system/, but given that the
variable is always set to a short, relative path, we can drop it and
replace all of its occurrences with the relative path without adversely
affecting code readability.
There were several problems with rbt hashtable implementation:
1. Our internal hashing function returns uint64_t value, but it was
silently truncated to unsigned int in dns_name_hash() and
dns_name_fullhash() functions. As the SipHash 2-4 higher bits are
more random, we need to use the upper half of the return value.
2. The hashtable implementation in rbt.c was using modulo to pick the
slot number for the hash table. This has several problems because
modulo is: a) slow, b) oblivious to patterns in the input data. This
could lead to very uneven distribution of the hashed data in the
hashtable. Combined with the single-linked lists we use, it could
really hog-down the lookup and removal of the nodes from the rbt
tree[a]. The Fibonacci Hashing is much better fit for the hashtable
function here. For longer description, read "Fibonacci Hashing: The
Optimization that the World Forgot"[b] or just look at the Linux
kernel. Also this will make Diego very happy :).
3. The hashtable would rehash every time the number of nodes in the rbt
tree would exceed 3 * (hashtable size). The overcommit will make the
uneven distribution in the hashtable even worse, but the main problem
lies in the rehashing - every time the database grows beyond the
limit, each subsequent rehashing will be much slower. The mitigation
here is letting the rbt know how big the cache can grown and
pre-allocate the hashtable to be big enough to actually never need to
rehash. This will consume more memory at the start, but since the
size of the hashtable is capped to `1 << 32` (e.g. 4 mio entries), it
will only consume maximum of 32GB of memory for hashtable in the
worst case (and max-cache-size would need to be set to more than
4TB). Calling the dns_db_adjusthashsize() will also cap the maximum
size of the hashtable to the pre-computed number of bits, so it won't
try to consume more gigabytes of memory than available for the
database.
FIXME: What is the average size of the rbt node that gets hashed? I
chose the pagesize (4k) as initial value to precompute the size of
the hashtable, but the value is based on feeling and not any real
data.
For future work, there are more places where we use result of the hash
value modulo some small number and that would benefit from Fibonacci
Hashing to get better distribution.
Notes:
a. A doubly linked list should be used here to speedup the removal of
the entries from the hashtable.
b. https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/
