A `dns_qmpulti_t` no longer needs to know about its loopmgr. We no
longer keep a linked list of `dns_qpmulti_t` that have reclamation
work, and we no longer mark chunks with the phase in which they are to
be reclaimed. Instead, empty chunks are listed in an array in a
`qp_rcu_t`, which is passed to call_rcu().
Memory reclamation by `call_rcu()` is asynchronous, so during shutdown
it can lose a race with the destruction of its memory context. When we
defer memory reclamation, we need to attach to the memory context to
indicate that it is still in use, but that is not enough to delay its
destruction. So, call `rcu_barrier()` in `isc_mem_destroy()` to wait
for pending RCU work to finish before proceeding to destroy the memory
context.
It can be fairly long-winded to allocate space for a struct with a
flexible array member: in general we need the size of the struct, the
size of the member, and the number of elements. Wrap them all up in a
STRUCT_FLEX_SIZE() macro, and use the new macro for the flexible
arrays in isc_ht and dns_qp.
The zone_resigninc() function does not check the validity of
'zone->db', which can crash named if the zone was unloaded earlier,
for example with "rndc delete".
Check that 'zone->db' is not 'NULL' before attaching to it, like
it is done in zone_sign() and zone_nsec3chain() functions, which
can similarly be called by zone maintenance.
The Userspace-RCU headers are now needed for more parts of the libisc
and libdns, thus we need to add it globally to prevent compilation
failures on systems with non-standard Userspace-RCU installation path.
The isc_quota API was using locked list of isc_job_t objects to keep the
waiting TCP accepts. Change the isc_quota implementation to use
cds_wfcqueue internally - the enqueue is wait-free and only dequeue
needs to be locked.
The isc_async API was using lock-free stack (where enqueue operation was
not wait-free). Change the isc_async to use cds_wfcqueue internally -
enqueue and splice (move the queue members from one list to another) is
nonblocking and wait-free.
Instead of having a global hashtable with a global rwlock for the GLUE
cache, move the glue_list directly into rdatasetheader and use
Userspace-RCU to update the pointer when the glue_list is empty.
Additionally, the cached glue_lists needs to be stored in the RBTDB
version for early cleaning, otherwise the circular dependencies between
nodes and glue_lists will prevent nodes to be ever cleaned up.
Clang 16 LeakSanitizer reports a memory leak when dns_request_create()
returned a TLS error in the nsupdate system test. While technically a
memory leak on error handling, it's not a problem because the program is
immediately terminated; nsupdate is not expected to run for a prolonged
time.
If the resolver received a FORMERR response to a request with
an DNS COOKIE option present that echoes the option back, resend
the request without an DNS COOKIE option present.
Stop deliberately breaking const rules by copying file->name into
dirbuf and truncating it there. Handle files located in the root
directory properly. Use unlinkat() from POSIX 200809.
Removing old timestamp or increment versions of log backup files did
not work when the file is an absolute path: only the entry name was
provided to the file remove function.
The dirname was also bogus, since the file separater was put back too
soon.
Fix these issues to make log file rotation work when the file is
configured to be an absolute path.
All the per-loop `libuv` setup remains in `isc_loop`, but the per-thread
RCU setup is moved to `isc_thread` alongside the other per-thread setup.
This avoids repeating the per-thread setup for `call_rcu()` helpers,
and explains a little better why some parts of the per-thread setup
is missing for `call_rcu()` helpers.
This also removes the per-loop `call_rcu()` helpers as we refactored the
isc__random_initialize() in the previous commit.
Instead of writing complicated wrappers for every thread, move the
initialization back to isc_random unit and check whether the random seed
was initialized with a thread_local variable.
Ensure that isc_entropy_get() returns a non-zero seed.
This avoids problems with thread sanitizer tests getting stuck in an
infinite loop.
Remove the `isc_threadarg_t` and `isc_threadresult_t`
typedefs which were unhelpful disguises for `void *`,
and free the dummy jemalloc allocation sooner.
When liburcu is not installed from a system package, its headers are
not treated as system headers by the compiler, so BIND's -Werror and
other warning options take effect. The liburcu headers have a lot
of inline functions, some of which do not use all their arguments,
which BIND's build treats as an error.
This commit allows BIND 9 to be compiled with different flavours of
Userspace RCU, and improves the integration between Userspace RCU and
our event loop:
- In the RCU QSBR, the thread is put offline when polling and online
when rcu_dereference, rcu_assign_pointer (or friends) are called.
- In other RCU modes, we check that we are not reading when reaching the
quiescent callback in the event loop.
- We register the thread before uv_work_run() callback is called and
after it has finished. The rcu_(un)register_thread() has a large
overhead, but that's fine in this case.
There's a recurring pattern walking the ISC_LISTs that just repeats over
and over. Add two macros:
* ISC_LIST_FOREACH(list, elt, link) - walk the static list
* ISC_LIST_FOREACH_SAFE(list, elt, link, next) - walk the list in
a manner that's safe against list member deletions
When OPTOUT was in use we didn't ensure that NSEC3 records
for orphaned empty-non-terminals where removed. Check if
there are orphaned empty-non-terminal NSEC3 even if there
wasn't an NSEC3 RRset to be removed in dns_nsec3_delnsec3.
'-T transferinsecs' makes named interpret the max-transfer-time-out,
max-transfer-idle-out, max-transfer-time-in and max-transfer-idle-in
configuration options as seconds instead of minutes.
'-T transferslowly' makes named to sleep for one second for every
xfrout message.
'-T transferstuck' makes named to sleep for one minute for every
xfrout message.
After the dns_xfrin was changed to use network manager, the maximum
global (max-transfer-time-in) and idle (max-transfer-idle-in) times for
incoming transfers were turned inoperational because of missing
implementation.
Restore this functionality by implementing the timers for the incoming
transfers.
The spinlock is small (atomic_uint_fast32_t at most), lightweight
synchronization primitive and should only be used for short-lived and
most of the time a isc_mutex should be used.
Add a isc_spinlock unit which is either (most of the time) a think
wrapper around pthread_spin API or an efficient shim implementation of
the simple spinlock.
When shutting down TCP sockets, the read callback calling logic was
flawed, it would call either one less callback or one extra. Fix the
logic in the way:
1. When isc_nm_read() has been called but isc_nm_read_stop() hasn't on
the handle, the read callback will be called with ISC_R_CANCELED to
cancel active reading from the socket/handle.
2. When isc_nm_read() has been called and isc_nm_read_stop() has been
called on the on the handle, the read callback will be called with
ISC_R_SHUTTINGDOWN to signal that the dormant (not-reading) socket
is being shut down.
3. The .reading and .recv_read flags are little bit tricky. The
.reading flag indicates if the outer layer is reading the data (that
would be uv_tcp_t for TCP and isc_nmsocket_t (TCP) for TLSStream),
the .recv_read flag indicates whether somebody is interested in the
data read from the socket.
Usually, you would expect that the .reading should be false when
.recv_read is false, but it gets even more tricky with TLSStream as
the TLS protocol might need to read from the socket even when sending
data.
Fix the usage of the .recv_read and .reading flags in the TLSStream
to their true meaning - which mostly consist of using .recv_read
everywhere and then wrapping isc_nm_read() and isc_nm_read_stop()
with the .reading flag.
4. The TLS failed read helper has been modified to resemble the TCP code
as much as possible, clearing and re-setting the .recv_read flag in
the TCP timeout code has been fixed and .recv_read is now cleared
when isc_nm_read_stop() has been called on the streaming socket.
5. The use of Network Manager in the named_controlconf, isccc_ccmsg, and
isc_httpd units have been greatly simplified due to the improved design.
6. More unit tests for TCP and TLS testing the shutdown conditions have
been added.
Co-authored-by: Ondřej Surý <ondrej@isc.org>
Co-authored-by: Artem Boldariev <artem@isc.org>
When retrying in the DNS dispatch, the local port would be forgotten on
ISC_R_ADDRINUSE, keep the configured source-port even when retrying.
Additionally, treat ISC_R_NOPERM same as ISC_R_ADDRINUSE.
Closes: #3986
When dns_request_create() failed in notify_send_toaddr(), sending the
notify would silently fail. When notify_done() failed, the error would
be logged on the DEBUG(2) level.
This commit remedies the situation by:
* Promoting several messages related to notifies to INFO level and add
a "success" log message at the INFO level
* Adding a TCP fallback - when sending the notify over UDP fails, named
will retry sending notify over TCP and log the information on the
NOTICE level
* When sending the notify over TCP fails, it will be logged on the
WARNING level
Closes: #4001, #4002
If the zone forwards are canceled from dns_zonemgr_shutdown(), the
forward_cancel() would get called from the main loop, which is wrong.
It needs to be called from the matching zone->loop.
Run the dns_request_cancel() via isc_async_run() on the loop associated
with the zone instead of calling the dns_request_cancel() directly from
the main loop.
By inspecting the code, it was discovered that .sendbuf member of the
isc__nm_networker_t was unused and just consuming ~64k per worker.
Remove the member and the association allocation/deallocation.
In e185412872, the TCP accept quota code
became broken in a subtle way - the quota would get initialized on the
first accept for the server socket and then deleted from the server
socket, so it would never get applied again.
Properly fixing this required a bigger refactoring of the isc_quota API
code to make it much simpler. The new code decouples the ownership of
the quota and acquiring/releasing the quota limit.
After (during) the refactoring it became more clear that we need to use
the callback from the child side of the accepted connection, and not the
server side.
Instead of using isc_async_run() when closing StreamDNS handle, add
isc_job_t member to the isc_nmhandle_t structure and use isc_job_run()
to avoid allocation/deallocation on the StreamDNS hot-path.
If the quota callback is called on a thread matching the socket, call
the TCP accept function directly instead of using isc_async_run() which
allocates-deallocates memory.
The isc_tid() function is often called on the hot-path and it's the only
function is to return thread_local variable, make the isc_tid() function
a header-only to save several function calls during query-response
processing.
It should be floor(DNS_NAME_MAXWIRE / 2) + 1 == 128
The mistake was introduced in c6bf51492d because:
* I was refactoring an existing `DNS_MAX_LABELS` defined as 127
* There was a longstanding bug in `dns_name_isvalid()` which
checked the number of labels against 127U instead of 128
* I mistakenly thought `dns_name_isvalid()` was correct and
`dns_name_countlabels()` was incorrect, but the reverse was true.
After this commit, occurrances of `DNS_NAME_MAXLABELS` with value
128 are consistent with the use of 127 or 128 before commit
c6bf51492d except for the mistake in `dns_name_isvalid()`.
This commit adds a test case that checks the MAXLABELS case
in `dns_name_fromtext()` and `dns_name_isvalid()`.
This change makes the zone table lock-free for reads. Previously, the
zone table used a red-black tree, which is not thread safe, so the hot
read path acquired both the per-view mutex and the per-zonetable
rwlock. (The double locking was to fix to cleanup races on shutdown.)
One visible difference is that zones are not necessarily shut down
promptly: it depends on when the qp-trie garbage collector cleans up
the zone table. The `catz` system test checks several times that zones
have been deleted; the test now checks for zones to be removed from
the server configuration, instead of being fully shut down. The catz
test does not churn through enough zones to trigger a gc, so the zones
are not fully detached until the server exits.
After this change, it is still possible to improve the way we handle
changes to the zone table, for instance, batching changes, or better
compaction heuristics.
