If we try to fetch a record from cache and need to look into
hints database we assume that the resolver is not primed and
start dns_resolver_prime(). Priming query is supposed to return
NSes for "." in ANSWER section and glue records for them in
ADDITIONAL section, so that we can fill that info in 'regular'
cache and not use hints db anymore.
However, if we're using a forwarder the priming query goes through
it, and if it's configured to return minimal answers we won't get
the addresses of root servers in ADDITIONAL section. Since the
only records for root servers we have are in hints database we'll
try to prime the resolver with every single query.
This patch adds a DNS_FETCHOPT_NOFORWARD flag which avoids using
forwarders if possible (that is if we have forward-first policy).
Using this flag on priming fetch fixes the problem as we get the
proper glue. With forward-only policy the problem is non-existent,
as we'll never ask for root server addresses because we'll never
have a need to query them.
Also added a test to confirm priming queries are not forwarded.
go back to regular resolution. When this happens the fetch timer is
already running, and we might end up in a situation where we we create
a fetch for qname-minimized query and after that the timer is triggered
and the query is retried (fctx_try) - which causes relaunching of
qname-minimization fetch - and since we already have a qmin fetch
for this fctx - assertion failure.
This fix stops the timer when doing qname minimization - qmin fetch
internal timer should take care of all the possible timeouts.
Log a message if a mirror zone becomes unusable for the resolver (most
usually due to the zone's expiration timer firing). Ensure that
verification failures do not cause a mirror zone to be unloaded
(instead, its last successfully verified version should be served if it
is available).
Log a message when a mirror zone is successfully loaded from disk and
subsequently verified.
This could have been implemented in a simpler manner, e.g. by modifying
an earlier code branch inside zone_postload() which checks whether the
zone already has a database attached and calls attachdb() if it does
not, but that would cause the resulting logs to indicate that a mirror
zone comes into effect before the "loaded serial ..." message is logged,
which would be confusing.
Tweak some existing sed commands used in the "mirror" system test to
ensure that separate test cases comprising it do not break each other.
Log a message when a mirror zone is successfully transferred and
verified, but only if no database for that zone was yet loaded at the
time the transfer was initiated.
This could have been implemented in a simpler manner, e.g. by modifying
zone_replacedb(), but (due to the calling order of the functions
involved in finalizing a zone transfer) that would cause the resulting
logs to suggest that a mirror zone comes into effect before its transfer
is finished, which would be confusing given the nature of mirror zones
and the fact that no message is logged upon successful mirror zone
verification.
Once the dns_zone_replacedb() call in axfr_finalize() is made, it
becomes impossible to determine whether the transferred zone had a
database attached before the transfer was started. Thus, that check is
instead performed when the transfer context is first created and the
result of this check is passed around in a field of the transfer context
structure. If it turns out to be desired, the relevant log message is
then emitted just before the transfer context is freed.
Taking this approach means that the log message added by this commit is
not timed precisely, i.e. mirror zone data may be used before this
message is logged. However, that can only be fixed by logging the
message inside zone_replacedb(), which causes arguably more dire issues
discussed above.
dns_zone_isloaded() is not used to double-check that transferred zone
data was correctly loaded since the 'shutdown_result' field of the zone
transfer context will not be set to ISC_R_SUCCESS unless axfr_finalize()
succeeds (and that in turn will not happen unless dns_zone_replacedb()
succeeds).
Since following a delegation resets most fetch context state, address
marks (FCTX_ADDRINFO_MARK) set inside lib/dns/resolver.c are not
preserved when a delegation is followed. This is fine for full
recursive resolution but when named is configured with "forward first;"
and one of the specified forwarders times out, triggering a fallback to
full recursive resolution, that forwarder should no longer be consulted
at each delegation point subsequently reached within a given fetch
context.
Add a new badnstype_t enum value, badns_forwarder, and use it to mark a
forwarder as bad when it times out in a "forward first;" configuration.
Since the bad server list is not cleaned when a fetch context follows a
delegation, this prevents a forwarder from being queried again after
falling back to full recursive resolution. Yet, as each fetch context
maintains its own list of bad servers, this change does not cause a
forwarder timeout to prevent that forwarder from being used by other
fetch contexts.
dnssec-signzone should sign a zonefile that contains a DNSKEY record
with an unsupported algorithm. Current behavior is that it will
fail, hitting a fatal error. The fix detects unsupported algorithms
and will not try to add it to the keylist.
Also when determining the maximum iterations for NSEC3, don't take
into account DNSKEY records in the zonefile with an unsupported
algorithm.
- "hook" is now used only for hook points and hook actions
- the "hook" statement in named.conf is now "plugin"
- ns_module and ns_modlist are now ns_plugin and ns_plugins
- ns_module_load is renamed ns_plugin_register
- the mandatory functions in plugin modules (hook_register,
hook_check, hook_version, hook_destroy) have been renamed
- use a per-view module list instead of global hook_modules
- create an 'instance' pointer when registering modules, store it in
the module structure, and use it as action_data when calling
hook functions - this enables multiple module instances to be set
up in parallel
- also some nomenclature changes and cleanup
- added a 'hookdata' array to qctx to store pointers to up to
16 blobs of data which are allocated by modules as needed.
each module is assigned an ID number as it's loaded, and this
is the index into the hook data array. this is to be used for
holding persistent state between calls to a hook module for a
specific query.
- instead of using qctx->filter_aaaa, we now use qctx->hookdata.
(this was the last piece of filter-aaaa specific code outside the
module.)
- added hook points for qctx initialization and destruction. we get
a filter-aaaa data pointer from the mempool when initializing and
store it in the qctx->hookdata table; return to to the mempool
when destroying the qctx.
- link the view to the qctx so that detaching the client doesn't cause
hooks to fail
- added a qctx_destroy() function which must be called after qctx_init;
this calls the QCTX_DESTROY hook and detaches the view
- general cleanup and comments
- make some cfg-parsing functions global so they can be run
from filter-aaaa.so
- add filter-aaaa options to the hook module's parser
- mark filter-aaaa options in named.conf as obsolete, remove
from named and checkconf, and update the filter-aaaa test not to
use checkconf anymore
- remove filter-aaaa-related struct members from dns_view
- allow multiple "hook" statements at global or view level
- add "optional bracketed text" type for optional parameter list
- load hook module from specified path rather than hardcoded path
- add a hooktable pointer (and a callback for freeing it) to the
view structure
- change the hooktable functions so they no longer update ns__hook_table
by default, and modify PROCESS_HOOK so it uses the view hooktable, if
set, rather than ns__hook_table. (ns__hook_table is retained for
use by unit tests.)
- update the filter-aaaa system test to load filter-aaaa.so
- add a prereq script to check for dlopen support before running
the filter-aaaa system test
not yet done:
- configuration parameters are not being passed to the filter-aaaa
module; the filter-aaaa ACL and filter-aaaa-on-{v4,v6} settings are
still stored in dns_view
- the goal of this change is for AAAA filtering to be fully contained
in the query logic, and implemented at discrete points that can be
replaced with hook callouts later on.
- the new code may be slightly less efficient than the old filter-aaaa
implementation, but maximum efficiency was never a priority for AAAA
filtering anyway.
- we now use the rdataset RENDERED attribute to indicate that an AAAA
rdataset should not be included when rendering the message. (this
flag was originally meant to indicate that an rdataset has already
been rendered and should not be repeated, but it can also be used to
prevent rendering in the first place.)
- the DNS_MESSAGERENDER_FILTER_AAAA, NS_CLIENTATTR_FILTER_AAAA,
and DNS_RDATASETGLUE_FILTERAAAA flags are all now unnecessary and
have been removed.
- move hooks.h to public include directory
- ns_hooktable_init() initializes a hook table. if NULL is passed in, it
initializes the global hook table
- ns_hooktable_save() saves a pointer to the current global hook table.
- ns_hooktable_reset() replaces the global hook table with different
one
- ns_hook_add() adds hooks at specified hook points in a hook table (or
the global hook table if the specified table is NULL)
- load and unload functions support dlopen() of hook modules (this is
adapted from dyndb and not yet functional)
- began adding new hook points to query.c
If we know that we'll have a task pool doing specific thing it's better
to use this knowledge and bind tasks to task queues, this behaves better
than randomly choosing the task queue.
- use bound resolver tasks - we have a pool of tasks doing resolutions,
we can spread the load evenly using isc_task_create_bound
- quantum set universally to 25
