The dns_adb unit has been refactored to be much simpler. Following
changes have been made:
1. Simplify the ADB to always allow GLUE and hints
There were only two places where dns_adb_createfind() was used - in
the dns_resolver unit where hints and GLUE addresses were ok, and in
the dns_zone where dns_adb_createfind() would be called without
DNS_ADBFIND_HINTOK and DNS_ADBFIND_GLUEOK set.
Simplify the logic by allowing hint and GLUE addresses when looking
up the nameserver addresses to notify. The difference is negligible
and would cause a difference in the notified addresses only when
there's mismatch between the parent and child addresses and we
haven't cached the child addresses yet.
2. Drop the namebuckets and entrybuckets
Formerly, the namebuckets and entrybuckets were used to reduced the
lock contention when accessing the double-linked lists stored in each
bucket. In the previous refactoring, the custom hashtable for the
buckets has been replaced with isc_ht/isc_hashmap, so only a single
item (mostly, see below) would end up in each bucket.
Removing the entrybuckets has been straightforward, the only matching
was done on the isc_sockaddr_t member of the dns_adbentry.
Removing the zonebuckets required GLUEOK and HINTOK bits to be
removed because the find could match entries with-or-without the bits
set, and creating a custom key that stores the
DNS_ADBFIND_STARTATZONE in the first byte of the key, so we can do a
straightforward lookup into the hashtable without traversing a list
that contains items with different flags.
3. Remove unassociated entries from ADB database
Previously, the adbentries could live in the ADB database even after
unlinking them from dns_adbnames. Such entries would show up as
"Unassociated entries" in the ADB dump. The benefit of keeping such
entries is little - the chance that we link such entry to a adbname
is small, and it's simpler to evict unlinked entries from the ADB
cache (and the hashtable) than create second LRU cleaning mechanism.
Unlinked ADB entries are now directly deleted from the hash
table (hashmap) upon destruction.
4. Cleanup expired entries from the hash table
When buckets were still in place, the code would keep the buckets
always allocated and never shrink the hash table (hashmap). With
proper reference counting in place, we can delete the adbnames from
the hash table and the LRU list.
5. Stop purging the names early when we hit the time limit
Because the LRU list is now time ordered, we can stop purging the
names when we find a first entry that doesn't fullfil our time-based
eviction criteria because no further entry on the LRU list will meet
the criteria.
Future work:
1. Lock contention
In this commit, the focus was on correctness of the data structure,
but in the future, the lock contention in the ADB database needs to
be addressed. Currently, we use simple mutex to lock the hash
tables, because we almost always need to use a write lock for
properly purging the hashtables. The ADB database needs to be
sharded (similar to the effect that buckets had in the past). Each
shard would contain own hashmap and own LRU list.
2. Time-based purging
The ADB names and entries stay intact when there are no lookups.
When we add separate shards, a timer needs to be added for time-based
cleaning in case there's no traffic hashing to the inactive shard.
3. Revisit the 30 minutes limit
The ADB cache is capped at 30 minutes. This needs to be revisited,
and at least the limit should be configurable (in both directions).
This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
The ISC_MEM_DEBUGSIZE and ISC_MEM_DEBUGCTX did sanity checks on matching
size and memory context on the memory returned to the allocator. Those
will no longer needed when most of the allocator will be replaced with
jemalloc.
The system test framework starts all named instances with the "-d 99"
command line option (unless it is overridden by a named.args file in a
given instance's working directory). This causes a lot of log messages
to be written to named.run files - currently over 5 million lines for a
single test suite run. While debugging information preserved in the log
files is essential for troubleshooting intermittent test failures, some
system tests involve sending hundreds or even thousands of queries,
which causes the relevant log files to explode in size. When multiple
tests (or even multiple test suites) are run in parallel, excessive
logging contributes considerably to the I/O load on the test host,
increasing the odds of intermittent test failures getting triggered.
Decrease the debug level for the seven most verbose named instances:
- use "-d 3" for ns2 in the "cacheclean" system test (it is the lowest
logging level at which the test still passes without the need to
apply any changes to tests.sh),
- use "-d 1" for the other six named instances.
This roughly halves the number of lines logged by each test suite run
while still leaving enough information in the logs to allow at least
basic troubleshooting in case of test failures.
This approach was chosen as it results in a greater decrease in the
number of lines logged than running all named instances with "-d 3",
without causing any test failures.
In order to lower the amount of memory allocated at startup by named
instances used in the BIND system test suite, set the default value of
"max-cache-size" for these to 2 megabytes. The purpose of this change
is to prevent named instances (or even entire virtual machines) from
getting killed by the operating system on the test host due to excessive
memory use.
Remove all "max-cache-size" statements from named configuration files
used in system tests ("checkconf" notwithstanding) to prevent confusion
as the "-T maxcachesize=..." command line option takes precedence over
configuration files.
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.
this changes most visble uses of master/slave terminology in tests.sh
and most uses of 'type master' or 'type slave' in named.conf files.
files in the checkconf test were not updated in order to confirm that
the old syntax still works. rpzrecurse was also left mostly unchanged
to avoid interference with DNSRPS.
as "type primary" is preferred over "type master" now, it makes
sense to make "primaries" available as a synonym too.
added a correctness check to ensure "primaries" and "masters"
cannot both be used in the same zone.
The rewrite of BIND 9 build system is a large work and cannot be reasonable
split into separate merge requests. Addition of the automake has a positive
effect on the readability and maintainability of the build system as it is more
declarative, it allows conditional and we are able to drop all of the custom
make code that BIND 9 developed over the years to overcome the deficiencies of
autoconf + custom Makefile.in files.
This squashed commit contains following changes:
- conversion (or rather fresh rewrite) of all Makefile.in files to Makefile.am
by using automake
- the libtool is now properly integrated with automake (the way we used it
was rather hackish as the only official way how to use libtool is via
automake
- the dynamic module loading was rewritten from a custom patchwork to libtool's
libltdl (which includes the patchwork to support module loading on different
systems internally)
- conversion of the unit test executor from kyua to automake parallel driver
- conversion of the system test executor from custom make/shell to automake
parallel driver
- The GSSAPI has been refactored, the custom SPNEGO on the basis that
all major KRB5/GSSAPI (mit-krb5, heimdal and Windows) implementations
support SPNEGO mechanism.
- The various defunct tests from bin/tests have been removed:
bin/tests/optional and bin/tests/pkcs11
- The text files generated from the MD files have been removed, the
MarkDown has been designed to be readable by both humans and computers
- The xsl header is now generated by a simple sed command instead of
perl helper
- The <irs/platform.h> header has been removed
- cleanups of configure.ac script to make it more simpler, addition of multiple
macros (there's still work to be done though)
- the tarball can now be prepared with `make dist`
- the system tests are partially able to run in oot build
Here's a list of unfinished work that needs to be completed in subsequent merge
requests:
- `make distcheck` doesn't yet work (because of system tests oot run is not yet
finished)
- documentation is not yet built, there's a different merge request with docbook
to sphinx-build rst conversion that needs to be rebased and adapted on top of
the automake
- msvc build is non functional yet and we need to decide whether we will just
cross-compile bind9 using mingw-w64 or fix the msvc build
- contributed dlz modules are not included neither in the autoconf nor automake
The first step in all existing setup.sh scripts is to call clean.sh. To
reduce code duplication and ensure all system tests added in the future
behave consistently with existing ones, invoke clean.sh from run.sh
before calling setup.sh.
- all tests with "recursion yes" now also specify "dnssec-validation yes",
and all tests with "recursion no" also specify "dnssec-validation no".
this must be maintained in all new tests, or else validation will fail
when we use local root zones for testing.
- clean.sh has been modified where necessary to remove managed-keys.bind
and viewname.mkeys files.
- removed a few remaing places where output wasn't being passed
through echo_i or cat_i
- added a "digcomp" function to conf.sh.in to send digcomp.pl output
through cat_i and return the correct exit value
- set SYSTESTDIR when calling echo_i from nsX directories, so that
the test name will always be printed correctly
- fixed a test name typo in conf.sh.in
- add CHANGES note
- update copyrights and license headers
- add -j to the make commands in .gitlab-ci.yml to take
advantage of parallelization in the gitlab CI process
During the "check flushtree clears adb correctly" check, expecting
"ns.flushtest.example" to always be the first name in the ADB dump is
fragile, because in a certain corner case "a.root-servers.nil" will be
the first name instead.
As the purpose of the relevant check is to ensure "ns.flushtest.example"
is removed from ADB by "rndc flushtree flushtest.example", search the
entire list of names present in ADB instead of just the first entry when
looking for "ns.flushtest.example".
Dumping the cache is an asynchronous operation, so sleeping for a fixed
amount of time after running "rndc dumpdb" is imperfect as dumping cache
contents may take longer than expected on slower machines. Instead of
always sleeping for 1 second, wait until the "; Dump complete" line
appears in the dump or 10 seconds pass, whichever comes first.
Unless configured otherwise in named.conf, "rndc dumpdb" causes a cache
dump to be written to a file called "named_dump.db" in the working
directory of the given named instance. Repeatedly using this command
throughout different checks in the cacheclean system test causes cache
dumps for older checks to be overwritten, which hinders failure
diagnosis. Prevent this by moving each cache dump to a check-specific
location after running "rndc dumpdb".
Furthermore, during the "check flushtree clears adb correctly" check,
dump_cache() is called twice without renaming the resulting files.
Prevent the first cache dump from being overwritten by moving it to a
different file before calling "rndc dumpdb" for the second time.
Conflicts:
bin/tests/system/conf.sh.in
lib/dns/win32/libdns.def.in
lib/isc/win32/file.c
The merge also needed to update files in legacy and tcp system tests
(newly introduced in master after branch was created) to introduce use
of lockfile.
in draft-andrews-dnsext-expire-00. Retrivial of
remaining time to expiry from slave zones is supported.
EXPIRE uses an experimental option code (65002) and
is subject to change. [RT #35416]
Updated CHANGES note:
3606. [func] "rndc flushtree" now flushes matching
records in the address database and bad cache
as well as the DNS cache. (Previously only the
DNS cache was flushed.) [RT #33970]
3606. [func] "rndc flushtree -all" flushes matching
records in the ADB and bad cache as well as
the DNS cache. (Without the "-all" option,
flushtree will still only flush records from
the DNS cache.) [RT #33970]
