Use C23 attribute styles if available:
* Add new ISC_ATTR_UNUSED attribute macro that either expands to C23's
[[maybe_unused]] or __attribute__((__unused__));
* Add default expansion of the `noreturn` to [[noreturn]] if available;
* Move the FALLTHROUGH from <isc/util.h> to <isc/attributes.h>
With the changes to tls_try_handshake() made in
2846888c573fcc610cdf71bcdd5bb6f92ffaf499 there are some incorrect
INSISTS() related to handshake handling which better to be removed.
When accepting a TCP connection in the higher layers (tlsstream,
streamdns, and http) attach to the socket the connection was accepted
on, and use this socket instead of the parent listening socket.
This has an advantage - accessing the sock->listener now doesn't break
the thread boundaries, so we can properly check whether the socket is
being closed without requiring .closing member to be atomic_bool.
The last atomic_bool variable sock->active was converted to non-atomic
bool by properly handling the listening socket case where we were
checking parent socket instead of children sockets.
This is no longer necessary as we properly set the .active to false on
the children sockets.
Additionally, cleanup the .rchildren - the atomic variable was used for
mutex+condition to block until all children were listening, but that's
now being handled by a barrier.
Finally, just remove dead .self and .active_child_connections members of
the netmgr socket.
Now that everything runs on their own loop and we don't cross the thread
boundaries (with few exceptions), most of the atomic_bool variables used
to track the socket state have been unatomicized because they are always
accessed from the matching thread.
The remaining few have been relaxed: a) the sock->active is now using
acquire/release memory ordering; b) the various global limits are now
using relaxed memory ordering - we don't really care about the
synchronization for those.
Previously, isc_job_run() could have been used to run the job on the
current loop and the isc_job_run() would take care of allocating and
deallocating the job. After the change in this MR, the isc_job_run()
is more complicated to use, so we introduce the isc_async_current()
macro to suplement isc_async_run() when we need to run the job on the
current loop.
Change the isc_job_run() to not-make any allocations. The caller must
make sure that it allocates isc_job_t - usually as part of the argument
passed to the callback.
For simple jobs, using isc_async_run() is advised as it allocates its
own separate isc_job_t.
Change the isc__nm_uvreq_t to have the idle callback as a separate
member as we always need to use it to properly close the uvreq.
Slightly refactor uvreq_put and uvreq_get to remove the unneeded
arguments - in uvreq_get(), we always use sock->worker, and in
uvreq_put, we always use req->sock, so there's not reason to pass those
extra arguments.
Instead of using isc_job_run() that's quite heavy as it allocates memory
for every new job, add uv_idle_t to uvreq union, and use uv_idle API
directly to execute the connect/read/send callback without any
additional allocations.
Put the comment back, so it's more obvious that we are only restarting
timer when there's a last handle attached to the socket; there has to be
always at least one.
It's sometimes helpful to get a quick idea of the call stack when
debugging. This change factors out the backtrace logging from named's
fatal error handler so that it's easy to use in other places too.
The isc_nm_httpconnect() would succeed even if the netmgr would be
already shuttingdown. This has been fixed and the unit test has been
updated to cope with fact that the handle would be NULL when
isc_nm_httpconnect() returns with an error.
when isc_nm_listenstreamdns() is called with a local port of 0,
a random port is chosen. call uv_getsockname() to determine what
the port is as soon as the socket is bound, and add a function
isc_nmsocket_getaddr() to retrieve it, so that the caller can
connect to the listening socket. this will be used in cases
where the same process is acting as both client and server.
add a public function ns_interface_create() allowing the caller
to set up a listening interface directly without having to set
up listen-on and scan network interfaces.
Simplify the stopping of the generic socket children by using the
isc_async API from the loopmgr instead of using the asychronous
netievent mechanism in the netmgr.
Simplify the setting of the TLS contexts by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the canceling of the StreamDNS socket by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the reading from the StreamDNS socket by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the setting of the DoH endpoints by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the acception the new TCP connection by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the canceling of the UDP socket by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the stopping of the TCP children by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the starting of the TCP children by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the stopping of the UDP children by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
Simplify the starting of the UDP children by using the isc_async API
from the loopmgr instead of using the asychronous netievent mechanism in
the netmgr.
The active handles accounting was both using atomic counter and ISC_LIST
to keep track of active handles. Remove the atomic counter that was in
use before the ISC_LIST was added for better tracking of the handles
attached to the socket.
Instead of calling isc__nmhandle_detach calling
nmhandle_detach_cb() asynchronously when there's closehandle_cb
initialized, convert the closehandle_cb to use isc_job, and make the
isc__nmhandle_detach() to be fully synchronous.
The netmgr connect, read and send callbacks can now only be executed on
the same loop, convert it from asynchronous netievent queue event to
more direct isc_job.
BIND needs a collection of standard lock-free data structures,
which we can find in liburcu, along with its RCU safe memory
reclamation machinery. We will use liburcu's QSBR variant instead
of the home-grown isc_qsbr.
ISC_REFCOUNT_TRACE_IMPL uses isc_tid(), but the corresponding header
file is not included, which breaks, for example, compiling BIND with
DNS_CATZ_TRACE defined in lib/dns/include/dns/catz.h.
Add '#include <isc/tid.h>' in lib/isc/include/isc/refcount.h.
In base32_decode_char the GCC 12 static analyser fails to determine
that ctx->val[1], ctx->val[3], ctx->val[4] and ctx->val[6] are
assigned values by the previous call to base32_decode_char. Initialise
ctx->val to zeros when initalising the rest of ctx to silence the
false positive.
This "quiescent state based reclamation" module provides support for
the qp-trie module in dns/qp. It is a replacement for liburcu, written
without reference to the urcu source code, and in fact it works in a
significantly different way.
A few specifics of BIND make this variant of QSBR somewhat simpler:
* We can require that wait-free access to a qp-trie only happens in
an isc_loop callback. The loop provides a natural quiescent state,
after the callbacks are done, when no qp-trie access occurs.
* We can dispense with any API like rcu_synchronize(). In practice,
it takes far too long to wait for a grace period to elapse for each
write to a data structure.
* We use the idea of "phases" (aka epochs or eras) from EBR to
reduce the amount of bookkeeping needed to track memory that is no
longer needed, knowing that the qp-trie does most of that work
already.
I considered hazard pointers for safe memory reclamation. They have
more read-side overhead (updating the hazard pointers) and it wasn't
clear to me how to nicely schedule the cleanup work. Another
alternative, epoch-based reclamation, is designed for fine-grained
lock-free updates, so it needs some rethinking to work well with the
heavily read-biased design of the qp-trie. QSBR has the fastest read
side of the basic SMR algorithms (with no barriers), and fits well
into a libuv loop. More recent hybrid SMR algorithms do not appear to
have enough benefits to justify the extra complexity.
the isc_glob module was originally needed to support posix-style glob
processing on Windows, but is now just an unnecessary wrapper around
glob(3). this commit removes it.
Previously, the async job queue would use a locked-list (ISC_LIST).
With introduction of atomic stack (that has to be drained at once), we
could use it to remove some contention between the threads and simplify
the async queue.
Fortunately, the reverse order still works for us - instead of append
and tail/prev operation on the list, we are now using prepend and
head/next operation on the atomic stack.
Add a singly-linked stack that supports lock-free prepend and drain (to
empty the list and clean up its elements). Intended for use with QSBR
to collect objects that need safe memory reclamation, or any other user
that works with adding objects to the stack and then draining them in
one go like various work queues.
In <isc/atomic.h>, add an `atomic_ptr()` macro to make type
declarations a little less abominable, and clean up a duplicate
definition of `atomic_compare_exchange_strong_acq_rel()`
removed references in code comments, doc/dev documentation, etc, to
isc_task, isc_timer_reset(), and isc_timertype_inactive. also removed a
coccinelle patch related to isc_timer_reset() that was no longer needed.
as there is no further use of isc_task in BIND, this commit removes
it, along with isc_taskmgr, isc_event, and all other related types.
functions that accepted taskmgr as a parameter have been cleaned up.
as a result of this change, some functions can no longer fail, so
they've been changed to type void, and their callers have been
updated accordingly.
the tasks table has been removed from the statistics channel and
the stats version has been updated. dns_dyndbctx has been changed
to reference the loopmgr instead of taskmgr, and DNS_DYNDB_VERSION
has been udpated as well.
