The isc_stats_create() can no longer return anything else than
ISC_R_SUCCESS. Refactor isc_stats_create() and its variants in libdns,
libns and named to just return void.
The server was previously tolerant of out-of-date or otherwise bad
DNS SERVER COOKIES that where well formed unless require-cookie was
set. BADCOOKIE is now return for these conditions.
This commit changes send buffers allocation strategy for stream based
transports. Before that change we would allocate a dynamic buffers
sized at 64Kb even when we do not need that much. That could lead to
high memory usage on server. Now we resize the send buffer to match
the size of the actual data, freeing the memory at the end of the
buffer for being reused later.
'-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.
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.
This should have no functional effects.
The message size stats are specified by RSSAC002 so it's best not
to mess around with how they appear in the statschannel. But it's
worth changing the implementation to use general-purpose histograms,
to reduce code size and benefit from sharded counters.
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.
this function was just a front-end for gethostname(). it was
needed when we supported windows, which has a different function
for looking up the hostname; it's not needed any longer.
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.
callback events from dns_resolver_createfetch() are now posted
using isc_async_run.
other modules which called the resolver and maintained task/taskmgr
objects for this purpose have been cleaned up.
removed some functions that are no longer used and unlikely to
be resurrected, and also some that were only used to support Windows
and can now be replaced with generic versions.
limit the number of simultaneous DNS UPDATE events that can be
processed by adding a quota for update and update forwarding.
this quota currently, arbitrarily, defaults to 100.
also add a statistics counter to record when the update quota
has been exceeded.
DSCP has not been fully working since the network manager was
introduced in 9.16, and has been completely broken since 9.18.
This seems to have caused very few difficulties for anyone,
so we have now marked it as obsolete and removed the
implementation.
To ensure that old config files don't fail, the code to parse
dscp key-value pairs is still present, but a warning is logged
that the feature is obsolete and should not be used. Nothing is
done with configured values, and there is no longer any
range checking.
Send the ns_query_cancel() on the recursing clients when we initiate the
named shutdown for faster shutdown.
When we are shutting down the resolver, we cancel all the outstanding
fetches, and the ISC_R_CANCEL events doesn't propagate to the ns_client
callback.
In the future, the better solution how to fix this would be to look at
the shutdown paths and let them all propagate from bottom (loopmgr) to
top (f.e. ns_client).
the 'nupdates' field was originally used to track whether a client
was ready to shut down, along with other similar counters nreads,
nrecvs, naccepts and nsends. this is now tracked differently, but
nupdates was overlooked when the other counters were removed.
Don't attempt to resolve DNS responses for intermediate results. This
may create multiple refreshes and can cause a crash.
One scenario is where for the query there is a CNAME and canonical
answer in cache that are both stale. This will trigger a refresh of
the RRsets because we encountered stale data and we prioritized it over
the lookup. It will trigger a refresh of both RRsets. When we start
recursing, it will detect a recursion loop because the recursion
parameters will eventually be the same. In 'dns_resolver_destroyfetch'
the sanity check fails, one of the callers did not get its event back
before trying to destroy the fetch.
Move the call to 'query_refresh_rrset' to 'ns_query_done', so that it
is only called once per client request.
Another scenario is where for the query there is a stale CNAME in the
cache that points to a record that is also in cache but not stale. This
will trigger a refresh of the RRset (because we encountered stale data
and we prioritized it over the lookup).
We mark RRsets that we add to the message with
DNS_RDATASETATTR_STALE_ADDED to prevent adding a duplicate RRset when
a stale lookup and a normal lookup conflict with each other. However,
the other non-stale RRset when following a CNAME chain will be added to
the message without setting that attribute, because it is not stale.
This is a variant of the bug in #2594. The fix covered the same crash
but for stale-answer-client-timeout > 0.
Fix this by clearing all RRsets from the message before refreshing.
This requires the refresh to happen after the query is send back to
the client.
Previously:
* applications were using isc_app as the base unit for running the
application and signal handling.
* networking was handled in the netmgr layer, which would start a
number of threads, each with a uv_loop event loop.
* task/event handling was done in the isc_task unit, which used
netmgr event loops to run the isc_event calls.
In this refactoring:
* the network manager now uses isc_loop instead of maintaining its
own worker threads and event loops.
* the taskmgr that manages isc_task instances now also uses isc_loopmgr,
and every isc_task runs on a specific isc_loop bound to the specific
thread.
* applications have been updated as necessary to use the new API.
* new ISC_LOOP_TEST macros have been added to enable unit tests to
run isc_loop event loops. unit tests have been updated to use this
where needed.
* isc_timer was rewritten using the uv_timer, and isc_timermgr_t was
completely removed; isc_timer objects are now directly created on the
isc_loop event loops.
* the isc_timer API has been simplified. the "inactive" timer type has
been removed; timers are now stopped by calling isc_timer_stop()
instead of resetting to inactive.
* isc_manager now creates a loop manager rather than a timer manager.
* modules and applications using isc_timer have been updated to use the
new API.
This way only quota size is passed to the interface/listener
management code instead of a quota object. Thus, we can implement
updating the quota object size instead of recreating the object.
Similarly to how different code paths reused common client handle
pointers and fetch references despite being logically unrelated, they
also reuse client->recursionquota, the field in which a reference to the
recursion quota is stored. This unnecessarily forces all code using
that field to be aware of the fact that it is overloaded by different
features.
Overloading client->recursionquota also causes inconsistent behavior.
For example, if prefetch code triggers recursion and then delegation
handling code also triggers recursion, only one of these code paths will
be able to attach to the recursion quota, but both recursions will be
started anyway. In other words, each code path only checks whether the
recursion quota has not been exceeded if the quota has not yet been
attached to by another code path. This behavior theoretically allows
the configured recursion quota to be slightly exceeded; while it is not
expected to be a real-world operational issue, it is still confusing and
should therefore be fixed.
Extend the structures comprising the 'recursions' array with a new field
holding a pointer to the recursion quota that a given recursion process
attached to. Update all code paths using client->recursionquota so that
they use the appropriate slot in the 'recursions' array. Drop the
'recursionquota' field from ns_client_t.
Drop the 'fetchhandle' field from ns_client_t as all code using it has
been migrated to use the recursion-type-specific HANDLE_RECTYPE_*()
macros.
Drop the 'fetch' field from ns_query_t as all code using it has been
migrated to use the recursion-type-specific FETCH_RECTYPE_*() macros.
Async hooks are the last feature using the client->fetchhandle and
client->query.fetch pointers. Update ns_query_hookasync() and
query_hookresume() so that they use a dedicated slot in the 'recursions'
array. Note that async hooks are still not expected to initiate
recursion if one was already started by a prior ns_query_recurse() call,
so the REQUIRE assertion in ns_query_hookasync() needs to check the
RECTYPE_NORMAL slot rather than the RECTYPE_HOOK one.
With prefetch and RPZ code updated to use separate slots in the
'recursions' array, the code responsible for starting recursion in
ns_query_recurse() and resuming query handling in fetch_callback()
should follow suit, so that it does not need to explicitly cooperate
with other code paths that may initiate recursion.
Replace:
- client->fetchhandle with HANDLE_RECTYPE_NORMAL(client)
- client->query.fetch with FETCH_RECTYPE_NORMAL(client)
Also update other functions using client->fetchhandle and
client->query.fetch (ns_query_cancel(), query_usestale()) so that those
two fields can shortly be dropped altogether.
Replace:
- client->prefetchhandle with HANDLE_RECTYPE_PREFETCH(client)
- client->query.prefetch with FETCH_RECTYPE_PREFETCH(client)
This is preparatory work for separating prefetch code from RPZ code.
When a client waits for a prefetch- or RPZ-triggered recursion to
complete, its netmgr handle is attached to client->prefetchhandle and a
reference to the resolver fetch is stored in client->query.prefetch.
Both of these features use the same fields mentioned above. This makes
the code fragile and hard to follow as its logically distinct parts
become intertwined for no obvious reason.
Furthermore, storing pointers related to a specific recursion process in
two different structures makes their purpose harder to grasp than it has
to be.
To alleviate the problem, extend ns_query_t with an array of structures
containing recursion-related pointers. Each feature able to initiate
recursion is supposed to use its own slot in that array, allowing
logically unrelated code paths to be untangled. Prefetch and RPZ will
be the first users of that array.
Define helper macros for accessing specific recursion-related pointers
in order to improve code readability.
This commit disables periodic interface re-scans timer on Linux where
a kernel-based dynamic interface mechanisms make it a thing of the
past in most cases.
In order to modify the .localhost and .localnets members of the
dns_aclenv, all other processing on the netmgr loops needed to be
stopped using the task exclusive mode. Add the isc_rwlock to the
dns_aclenv, so any modifications to the .localhost and .localnets can be
done under the write lock.
The .lock, .exiting and .excl members were not using for anything else
than starting task exclusive mode, setting .exiting to true and ending
exclusive mode.
Remove all the stray members and dead code eliminating the task
exclusive mode use from ns_clientmgr.
This commit adds support for Strict/Mutual TLS into BIND. It does so
by implementing the backing code for 'hostname' and 'ca-file' options
of the 'tls' statement. The commit also updates the documentation
accordingly.
The way the ns_client_t .shuttingdown member was practically dead code.
The .shuttingdown would be set to true only in ns__client_put() function
meaning that we have detached from all ns_client_t .*handles and the
ns_client_t object being freed:
client->magic = 0;
client->shuttingdown = true;
[...]
isc_mem_put(manager->ctx, client, sizeof(*client))
Meanwhile the ns_client_t object is accessed like this:
isc_nmhandle_detach(&client->fetchhandle);
client->query.attributes &= ~NS_QUERYATTR_RECURSING;
client->state = NS_CLIENTSTATE_WORKING;
qctx_init(client, &devent, 0, &qctx);
client_shuttingdown = ns_client_shuttingdown(client);
if (fetch_canceled || fetch_answered || client_shuttingdown) {
[...]
}
Even if the isc_nmhandle_detach(...) was the last handle detach, it
would mean that immediatelly, after calling the isc_nmhandle_detach(),
we would be causing use-after-free, because the ns_client_t is
immediatelly destroyed after setting .shuttingdown to true.
The similar code in the query_hookresume() already noticed this:
/*
* This event is running under a client task, so it's safe to detach
* the fetch handle. And it should be done before resuming query
* processing below, since that may trigger another recursion or
* asynchronous hook event.
*/
The ns_client_t is always attached to ns_clientmgr_t which has
associated memory context, server context, task and threadid. Use those
directly from the ns_clientmgr_t instead of attaching it to an extra
copy in ns_client_t to make the ns_client_t more sleek and lean.
Additionally, remove some stray ns_client_t struct members that were not
used anywhere.
Instead of passing the "workers" variable back and forth along with
passing the single isc_nm_t instance, add isc_nm_getnworkers() function
that returns the number of netmgr threads are running.
Change the ns_interfacemgr and ns_taskmgr to utilize the newly acquired
knowledge.
Commit aab691d512 did not fix all possible
scenarios in which the ns_statscounter_recursclients counter underflows.
The solution implemented therein can be ineffective e.g. when CNAME
chaining happens with prefetching enabled.
Here is an example recursive resolution scenario in which the
ns_statscounter_recursclients counter can underflow with the current
logic in effect:
1. Query processing starts, the answer is not found in the cache, so
recursion is started. The NS_CLIENTATTR_RECURSING attribute is set.
ns_statscounter_recursclients is incremented (Δ = +1).
2. Recursion completes, returning a CNAME. client->recursionquota is
non-NULL, so the NS_CLIENTATTR_RECURSING attribute remains set.
ns_statscounter_recursclients is decremented (Δ = 0).
3. Query processing restarts.
4. The current QNAME (the target of the CNAME from step 2) is found in
the cache, with a TTL low enough to trigger a prefetch.
5. query_prefetch() attaches to client->recursionquota.
ns_statscounter_recursclients is not incremented because
query_prefetch() does not do that (Δ = 0).
6. Query processing restarts.
7. The current QNAME (the target of the CNAME from step 4) is not found
in the cache, so recursion is started. client->recursionquota is
already attached to (since step 5) and the NS_CLIENTATTR_RECURSING
attribute is set (since step 1), so ns_statscounter_recursclients is
not incremented (Δ = 0).
8. The prefetch from step 5 completes. client->recursionquota is
detached from in prefetch_done(). ns_statscounter_recursclients is
not decremented because prefetch_done() does not do that (Δ = 0).
9. Recursion for the current QNAME completes. client->recursionquota
is already detached from, i.e. set to NULL (since step 8), and the
NS_CLIENTATTR_RECURSING attribute is set (since step 1), so
ns_statscounter_recursclients is decremented (Δ = -1).
Another possible scenario is that after step 7, recursion for the target
of the CNAME from step 4 completes before the prefetch for the CNAME
itself. fetch_callback() then notices that client->recursionquota is
non-NULL and decrements ns_statscounter_recursclients, even though
client->recursionquota was attached to by query_prefetch() and therefore
not accompanied by an incrementation of ns_statscounter_recursclients.
The net result is also an underflow.
Instead of trying to properly handle all possible orderings of events
set into motion by normal recursion and prefetch-triggered recursion,
adjust ns_statscounter_recursclients whenever the recursive clients
quota is successfully attached to or detached from. Remove the
NS_CLIENTATTR_RECURSING attribute altogether as its only purpose is made
obsolete by this change.
The keep-response-order option has been obsoleted, and in this commit,
remove the keep-response-order ACL map rendering the option no-op, the
call the isc_nm_sequential() and the now unused isc_nm_sequential()
function itself.
While refactoring the lib/ns/xfrout.c, it was discovered that .shutdown
and .shutdown_arg members of ns_client_t structure are unused.
Remove the unused members and associated code that was using in it in
the ns_xfrout.
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.
Using the TLS context cache for server-side contexts could reduce the
number of contexts to initialise in the configurations when e.g. the
same 'tls' entry is used in multiple 'listen-on' statements for the
same DNS transport, binding to multiple IP addresses.
In such a case, only one TLS context will be created, instead of a
context per IP address, which could reduce the initialisation time, as
initialising even a non-ephemeral TLS context introduces some delay,
which can be *visually* noticeable by log activity.
Also, this change lays down a foundation for Mutual TLS (when the
server validates a client certificate, additionally to a client
validating the server), as the TLS context cache can be extended to
store additional data required for validation (like intermediates CA
chain).
Additionally to the above, the change ensures that the contexts are
not being changed after initialisation, as such a practice is frowned
upon. Previously we would set the supported ALPN tags within
isc_nm_listenhttp() and isc_nm_listentlsdns(). We do not do that for
client-side contexts, so that appears to be an overlook. Now we set
the supported ALPN tags right after server-side contexts creation,
similarly how we do for client-side ones.
reference counting of ns_interface objects has not been used
since the clientmgr cleanup in #2433, and it no longer really
makes sense now - when we want to destroy an interface on a
rescan, we want it to be destroyed, not kept active by some
other caller. so ns_interface_attach() has been removed,
ns_interface_detach() has been replaced with a static
interface_destroy(), and do_scan() has been simplified
accordingly.
previously, if "listen-on-v6" was set to "none", then every
time a scan saw an IPv6 address it would appear to be a new
one. this commit retains all known interfaces in a list
and sets a flag in the ones that are listening, so that
configured interfaces that have been seen before will be
recognized as such.
as an incidental fix, the ns__interfacemgr_getif() and _nextif()
functions have been removed since they were never used.
The 850e9e59bf commit intended to recreate
the HTTPS and TLS interfaces during reconfiguration, but they are being
recreated also during regular interface re-scans.
Make sure the HTTPS and TLS interfaces are being recreated only during
reconfiguration.
Add a new parameter to 'ns_client_t' to store potential extended DNS
error. Reset when the client request ends, or is put back.
Add defines for all well-known info-codes.
Update the number of DNS_EDNSOPTIONS that we are willing to set.
Create a new function to set the extended error for a client reply.
Some of the libns unit tests override the isc_nmhandle_attach() and
_detach() functions. This causes a failure in ns_interface_create()
if a route socket is being used, so we add a parameter to disable it.
