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 zt_destroy() function was missing isc_refcount_destroy() on the two
reference counters. The isc_refcount_destroy() adds proper memory
ordering on destroy and also ensures that the reference counters have
been zeroed before destroying the object.
Commit 308bc46a59302c88ecff11d4831475ecfa8b8fb0 introduced a change to
the view_flushanddetach() function which makes the latter access
view->zonetable without holding view->lock. As confirmed by TSAN, this
enables races between threads for view->zonetable accesses.
Swap the view->zonetable pointer under view lock and then detach the
local swapped dns_zt_t later when the view lock is already unlocked.
This commit also changes the dns_zt interfaces, so the setting the
zonetable "flush" flag is separate operation to dns_zt_detach,
e.g. instead of doing:
if (view->flush) {
dns_zt_flushanddetach(&zt);
} else {
dns_zt_detach(&zt);
}
the code is now:
if (view->flush) {
dns_zt_flush(zt);
}
dns_zt_detach(&zt);
making the code more consistent with how we handle flushing and
detaching dns_zone_t pointers from the view.
Remove the dynamic registration of result codes. Convert isc_result_t
from unsigned + #defines into 32-bit enum type in grand unified
<isc/result.h> header. Keep the existing values of the result codes
even at the expense of the description and identifier tables being
unnecessary large.
Additionally, add couple of:
switch (result) {
[...]
default:
break;
}
statements where compiler now complains about missing enum values in the
switch statement.
The flow of operations in dispatch is changing and will now be similar
for both UDP and TCP queries:
1) Call dns_dispatch_addresponse() to assign a query ID and register
that we'll be listening for a response with that ID soon. the
parameters for this function include callback functions to inform the
caller when the socket is connected and when the message has been
sent, as well as a task action that will be sent when the response
arrives. (later this could become a netmgr callback, but at this
stage to minimize disruption to the calling code, we continue to use
isc_task for the response event.) on successful completion of this
function, a dispatch entry object will be instantiated.
2) Call dns_dispatch_connect() on the dispatch entry. this runs
isc_nm_udpconnect() or isc_nm_tcpdnsconnect(), as needed, and begins
listening for responses. the caller is informed via a callback
function when the connection is established.
3) Call dns_dispatch_send() on the dispatch entry. this runs
isc_nm_send() to send a request.
4) Call dns_dispatch_removeresponse() to terminate listening and close
the connection.
Implementation comments below:
- As we will be using netmgr buffers now. code to send the length in
TCP queries has also been removed as that is handled by the netmgr.
- TCP dispatches can be used by multiple simultaneous queries, so
dns_dispatch_connect() now checks whether the dispatch is already
connected before calling isc_nm_tcpdnsconnect() again.
- Running dns_dispatch_getnext() from a non-network thread caused a
crash due to assertions in the netmgr read functions that appear to be
unnecessary now. the assertions have been removed.
- fctx->nqueries was formerly incremented when the connection was
successful, but is now incremented when the query is started and
decremented if the connection fails.
- It's no longer necessary for each dispatch to have a pool of tasks, so
there's now a single task per dispatch.
- Dispatch code to avoid UDP ports already in use has been removed.
- dns_resolver and dns_request have been modified to use netmgr callback
functions instead of task events. some additional changes were needed
to handle shutdown processing correctly.
- Timeout processing is not yet fully converted to use netmgr timeouts.
- Fixed a lock order cycle reported by TSAN (view -> zone-> adb -> view)
by by calling dns_zt functions without holding the view lock.
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.
Use a zone's 'type' field instead of the value of its DNS_ZONEOPT_MIRROR
option for checking whether it is a mirror zone. This makes said zone
option and its associated helper function, dns_zone_mirror(), redundant,
so remove them. Remove a check specific to mirror zones from
named_zone_reusable() since another check in that function ensures that
changing a zone's type prevents it from being reused during
reconfiguration.
If transferring or loading a mirror zone fails, resolution should still
succeed by means of falling back to regular recursive queries.
Currently, though, if a slave zone is present in the zone table and not
loaded, a SERVFAIL response is generated. Thus, mirror zones need
special handling in this regard.
Add a new dns_zt_find() flag, DNS_ZTFIND_MIRROR, and set it every time a
domain name is looked up rather than a zone itself. Handle that flag in
dns_zt_find() in such a way that a mirror zone which is expired or not
yet loaded is ignored when looking up domain names, but still possible
to find when the caller wants to know whether the zone is configured.
This causes a fallback to recursion when mirror zone data is unavailable
without making unloaded mirror zones invisible to code checking a zone's
existence.
provisioning secondary servers in which a list of
zones to be served is stored in a DNS zone and can
be propagated to slaves via AXFR/IXFR. [RT #41581]
4375. [func] Add support for automatic reallocation of isc_buffer
to isc_buffer_put* functions. [RT #42394]
