When serve-stale is enabled and recursive resolution fails, the fallback
to lookup stale data always happens in the cache database. Any
authoritative data is ignored, and only information learned through
recursive resolution is examined.
If there is data in the cache that could lead to an answer, and this can
be just the root delegation, the resolver will iterate further, getting
closer to the answer that can be found by recursing down the root, and
eventually puts the final response in the cache.
Change the fallback to serve-stale to use 'query_getdb()', that finds
out the best matching database for the given query.
The dns_aclenv_t contains two dns_acl_t - localhost and localnets that
can be swapped with a different ACLs as we configure BIND 9. Instead of
protecting those two pointers with heavyweight read-write lock, use RCU
mechanism to dereference and swap the pointers.
All these pointers are guaranteed to be non-NULL.
Additionally, update a comment to remove obviously outdated
information about the function's requirements.
Instead of creating new memory pools for each new dns_message, change
dns_message_create() method to optionally accept externally created
dns_fixedname_t and dns_rdataset_t memory pools. This allows us to
preallocate the memory pools in ns_client and dns_resolver units for the
lifetime of dns_resolver_t and ns_clientmgr_t.
Instead of high number of dispatches (4 * named_g_udpdisp)[1], make the
dispatches bound to threads and make dns_dispatchset_t create a dispatch
for each thread (event loop).
This required couple of other changes:
1. The dns_dispatch_createudp() must be called on loop, so the isc_tid()
is already initialized - changes to nsupdate and mdig were required.
2. The dns_requestmgr had only a single dispatch per v4 and v6. Instead
of using single dispatch, use dns_dispatchset_t for each protocol -
this is same as dns_resolver.
rr_exists errored if the name did not exist in the zone. This was
not an issue prior to the addition of krb5-subdomain-self-rhs and
ms-subdomain-self-rhs as the only name used was the zone name which
always existed.
when synthesizing a new CNAME, we now check whether the target
matches the query already being processed. if so, we do not
restart the query; this prevents a waste of resources.
Add a trace point that would report when a query gets dropped or slipped
by rate limits. It reports the client IP, the zone, and the RRL result
code.
Co-authored-by: Paul Frieden <pfrieden@yahooinc.com>
This adds support for User Statically Defined Tracing (USDT). On
Linux, this uses the header from SystemTap and dtrace utility, but the
support is universal as long as dtrace is available.
Also add the required infrastructure to add probes to libisc, libdns and
libns libraries, where most of the probes will be.
The dns_badcache unit had (yet another) own locked hashtable
implementation. Replace the hashtable used by dns_badcache with
lock-free cds_lfht implementation from liburcu.
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.
We removed DNSSEC management via dynamic update (see issue #3686),
this means we also should no longer add signing records (of private
type) for DNSKEY records added via dynamic update.
Under some circumstances when processing a query response - for example,
when it contains a CNAME or DNAME - a query will have to be restarted
from the beginning to look up a new target.
This was previously handled by recursively calling the ns__query_start()
function directly from ns_query_done(). However, performance test data
indicated that chains of CNAMEs could consume quite a bit of time inside
the worker thread, increasing latency for other waiting queries. This
has now been changed so that restarted queries are run asynchronously.
ultimately we want the slab implementation of dns_rdataset to
be usable by more database implementaions than just rbtdb. this
commit moves rdataset_methods to rdataslab.c, renamed
dns_rdataslab_rdatasetmethods.
new database methods have been added: locknode, unlocknode,
addglue, expiredata, and deletedata, allowing external functions to
perform functions that previously required internal access to the
database implementation.
database and heap pointers are now stored in the dns_slabheader object
so that header is the only thing that needs to be passed to some
functions; this will simplify moving functions that process slabheaders
out of rbtdb.c so they can be used by other database implementations.
BIND's rdataset structure is a view of some DNS records. It is
polymorphic, so the details of how the records are stored can vary.
For instance, the records can be held in an rdatalist, or in an
rdataslab in the rbtdb.
The dns_rdataset structure previously had a number of fields called
`private1` up to `private7`, which were used by the various rdataset
implementations. It was not at all clear what these fields were for,
without reading the code and working it out from context.
This change makes the rdataset inheritance hierarchy more clear. The
polymorphic part of a `struct dns_rdataset` is now a union of structs,
each of which is named for the class of implementation using it. The
fields of these structs replace the old `privateN` fields. (Note: the
term "inheritance hierarchy" refers to the fact that the builtin and
SDLZ implementations are based on and inherit from the rdatalist
implementation, which in turn inherits from the generic rdataset.
Most of this change is mechanical, but there are a few extras.
In keynode.c there were a number of REQUIRE()ments that were not
necessary: they had already been checked by the rdataset method
dispatch code. On the other hand, In ncache.c there was a public
function which needed to REQUIRE() that an rdataset was valid.
I have removed lots of "reset iterator state" comments, because it
should now be clear from `target->iter = NULL` where before
`target->private5 = NULL` could have been doing anything.
Initialization is a bit neater in a few places, using C structure
literals where appropriate.
The pointer arithmetic for translating between an rdataslab header and
its raw contents is now fractionally safer.
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.
view->adb may be referenced while the view is shutting down as the
zone uses a weak reference to the view and examines view->adb but
dns_view_detach call dns_adb_detach to clear view->adb.
- style fixes and general tidying-up in tkey.c
- remove the unused 'intoken' parameter from dns_tkey_buildgssquery()
- remove an unnecessary call to dns_tkeyctx_create() in ns_server_create()
(the TKEY context that was created there would soon be destroyed and
another one created when the configuration was loaded).
since it is not necessary to find partial matches when looking
up names in a TSIG keyring, we can use a hash table instead of
an RBT to store them.
the tsigkey object now stores the key name as a dns_fixedname
rather than allocating memory for it.
the `name` parameter to dns_tsigkeyring_add() has been removed;
it was unneeded since the tsigkey object already contains a copy
of the name.
the opportunistic cleanup_ring() function has been removed;
it was only slowing down lookups.
the prior practice of passing a dns_name containing the
expanded name of an algorithm to dns_tsigkey_create() and
dns_tsigkey_createfromkey() is unnecessarily cumbersome;
we can now pass the algorithm number instead.
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.
We recently fixed a bug where in some cases (when following an
expired CNAME for example), named could return SERVFAIL if the target
record is still valid (see isc-projects/bind9#3678, and
isc-projects/bind9!7096). We fixed this by considering non-stale
RRsets as well during the stale lookup.
However, this triggered a new bug because despite the answer from
cache not being stale, the lookup may be triggered by serve-stale.
If the answer from database is not stale, the fix in
isc-projects/bind9!7096 erroneously skips the serve-stale logic.
Add 'answer_found' checks to the serve-stale logic to fix this issue.
The following code block repeats quite often:
if (rdata.type == dns_rdatatype_dnskey ||
rdata.type == dns_rdatatype_cdnskey ||
rdata.type == dns_rdatatype_cds)
Introduce a new function to reduce the repetition.
The raw zone is not supposed to be signed. DNSKEY records in a raw zone
should not trigger zone signing. The update code needs to be able to
identify when it is working on a raw zone. Add dns_zone_israw() and
dns_zone_issecure() enable it to do this. Also, we need to check the
case for 'auto-dnssec maintain'.
When synchronizing the journal or database from the unsigned version of
the zone to the secure version of the zone, allow DNSKEY records to be
synced, because these may be added by the user with the sole intent to
publish the record (not used for signing). This may be the case for
example in the multisigner model 2 (RFC 8901).
Additional code needs to be added to ensure that we do not remove DNSKEY
records that are under our control. Keys under our control are keys that
are used for signing the zone and thus that we have key files for.
Same counts for CDNSKEY and CDS (records that are derived from keys).
Use current used pointer - 16 instead of a saved pointer as Coverity
thinks the memory may be freed between assignment and use of 'cp'.
isc_buffer_put{mem,uint{8,16,32}} can theoretically free the memory
if there is a dynamic buffer in use but that is not the case here.
'-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 e18541287231b721c9cdb7e492697a2a80fd83fc, 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 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.
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.
The isc_time_now() and isc_time_now_hires() were used inconsistently
through the code - either with status check, or without status check,
or via TIME_NOW() macro with RUNTIME_CHECK() on failure.
Refactor the isc_time_now() and isc_time_now_hires() to always fail when
getting current time has failed, and return the isc_time_t value as
return value instead of passing the pointer to result in the argument.
This is a simple replacement using the semantic patch from the previous
commit and as added bonus, one removal of previously undetected unused
variable in named/server.c.
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.
