When generating a new salt, compare it with the previous NSEC3
paremeters to ensure the new parameters are different from the
previous ones.
This moves the salt generation call from 'bin/named/*.s' to
'lib/dns/zone.c'. When setting new NSEC3 parameters, you can set a new
function parameter 'resalt' to enforce a new salt to be generated. A
new salt will also be generated if 'salt' is set to NULL.
Logging salt with zone context can now be done with 'dnssec_log',
removing the need for 'dns_nsec3_log_salt'.
Upon request from Mark, change the configuration of salt to salt
length.
Introduce a new function 'dns_zone_checknsec3aram' that can be used
upon reconfiguration to check if the existing NSEC3 parameters are
in sync with the configuration. If a salt is used that matches the
configured salt length, don't change the NSEC3 parameters.
The 'rndc signing' command allows you to manipulate the private
records that are used to store signing state. Don't use these with
'dnssec-policy' as such manipulations may violate the policy (if you
want to change the NSEC3 parameters, change the policy and reconfig).
When doing 'rndc reconfig', named may complain about a zone not being
reusable because it has a raw version of the zone, and the new
configuration has not set 'inline-signing'. However, 'inline-signing'
may be implicitly true if a 'dnssec-policy' is used for the zone, and
the zone is not dynamic.
Improve the check in 'named_zone_reusable'. Create a new function for
checking 'inline-signing' configuration that matches existing code in
'bin/named/server.c'.
Implement support for NSEC3 in dnssec-policy. Store the configuration
in kasp objects. When configuring a zone, call 'dns_zone_setnsec3param'
to queue an nsec3param event. This will ensure that any previous
chains will be removed and a chain according to the dnssec-policy is
created.
Add tests for dnssec-policy zones that uses the new 'nsec3param'
option, as well as changing to new values, changing to NSEC, and
changing from NSEC.
Before this update, BIND would attempt to do a full recursive resolution
process for each query received if the requested rrset had its ttl
expired. If the resolution fails for any reason, only then BIND would
check for stale rrset in cache (if 'stale-cache-enable' and
'stale-answer-enable' is on).
The problem with this approach is that if an authoritative server is
unreachable or is failing to respond, it is very unlikely that the
problem will be fixed in the next seconds.
A better approach to improve performance in those cases, is to mark the
moment in which a resolution failed, and if new queries arrive for that
same rrset, try to respond directly from the stale cache, and do that
for a window of time configured via 'stale-refresh-time'.
Only when this interval expires we then try to do a normal refresh of
the rrset.
The logic behind this commit is as following:
- In query.c / query_gotanswer(), if the test of 'result' variable falls
to the default case, an error is assumed to have happened, and a call
to 'query_usestale()' is made to check if serving of stale rrset is
enabled in configuration.
- If serving of stale answers is enabled, a flag will be turned on in
the query context to look for stale records:
query.c:6839
qctx->client->query.dboptions |= DNS_DBFIND_STALEOK;
- A call to query_lookup() will be made again, inside it a call to
'dns_db_findext()' is made, which in turn will invoke rbdb.c /
cache_find().
- In rbtdb.c / cache_find() the important bits of this change is the
call to 'check_stale_header()', which is a function that yields true
if we should skip the stale entry, or false if we should consider it.
- In check_stale_header() we now check if the DNS_DBFIND_STALEOK option
is set, if that is the case we know that this new search for stale
records was made due to a failure in a normal resolution, so we keep
track of the time in which the failured occured in rbtdb.c:4559:
header->last_refresh_fail_ts = search->now;
- In check_stale_header(), if DNS_DBFIND_STALEOK is not set, then we
know this is a normal lookup, if the record is stale and the query
time is between last failure time + stale-refresh-time window, then
we return false so cache_find() knows it can consider this stale
rrset entry to return as a response.
The last additions are two new methods to the database interface:
- setservestale_refresh
- getservestale_refresh
Those were added so rbtdb can be aware of the value set in configuration
option, since in that level we have no access to the view object.
This commit adds couple of additional safeguards against running
sends/reads on inactive sockets. The changes was modeled after the
changes we made to netmgr/tcpdns.c
Parse the configuration of tls objects into SSL_CTX* objects. Listen on
DoT if 'tls' option is setup in listen-on directive. Use DoT/DoH ports
for DoT/DoH.
This commit adds stub parser support and tests for:
- "tls" statement, specifying key and cert.
- an optional "tls" keyvalue in listen-on statements for DoT
configuration.
Documentation for these options has also been added to the ARM, but
needs further work.
there were two failures during observed in testing, both occurring
when 'rndc halt' was run rather than 'rndc stop' - the latter dumps
zone contents to disk and presumably introduced enough delay to
prevent the races:
- a failure when the zone was shut down and called dns_xfrin_detach()
before the xfrin had finished connecting; the connect timeout
terminated without detaching its handle
- a failure when the tcpdns socket timer fired after the outerhandle
had already been cleared.
this commit incidentally addresses a failure observed in mutexatomic
due to a variable having been initialized incorrectly.
This commit extends the perl Configure script to also check for libssl
in addition to libcrypto and change the vcxproj source files to link
with both libcrypto and libssl.
If the call to cd->dlz_create() in dlopen_dlz_create() fails, cd->dbdata
may be NULL when dlopen_dlz_destroy() gets called in the cleanup path
and passing NULL to the cd->dlz_destroy() callback may cause a NULL
dereference. Ensure that does not happen by checking whether cd->dbdata
is non-NULL before calling the cd->dlz_destroy() callback.
While libltdl is a feature-rich library, BIND 9 code only uses its basic
capabilities, which are also provided by libuv and which BIND 9 already
uses for other purposes. As libuv's cross-platform shared library
handling interface is modeled after the POSIX dlopen() interface,
converting code using the latter to the former is simple. Replace
libltdl function calls with their libuv counterparts, refactoring the
code as necessary. Remove all use of libltdl from the BIND 9 source
tree.
The cleanup code that would clean the object after plugin/dlz/dyndb
loading has failed was duplicating the destructor for the object, so
instead of the extra code, we just use the destructor instead.
Make sure an error gets logged when any lt_dlopen() call in the source
tree fails. Also make sure that NULL values returned by lt_dlerror()
are replaced with a generic error message to prevent passing NULL as an
argument for the %s format specifier.
The redundant lt_dlerror() calls were taken from the examples to clean
any previous errors from lt_dl...() calls. However upon code
inspection, it was discovered there are no such paths that could cause
the lt_dlerror() to return spurious error messages.
When `rndc stop` is received, the isc_app_shutdown() was being called
before response to the rndc client has been sent; as the
isc_app_shutdown() also tears down the netmgr, the message was never
sent and rndc would complain about connection being interrupted in the
middle of the transaction. We now postpone the shutdown after the rndc
response has been sent.
1. The isc__nm_tcp_send() and isc__nm_tcp_read() was not checking
whether the socket was still alive and scheduling reads/sends on
closed socket.
2. The isc_nm_read(), isc_nm_send() and isc_nm_resumeread() have been
changed to always return the error conditions via the callbacks, so
they always succeed. This applies to all protocols (UDP, TCP and
TCPDNS).
The controllistener could be freed before the event posted by
isc_nm_stoplistening() has been processed. This commit adds
a reference counter to the controllistener to determine when
to free the listener.
The DNS Flag Day 2020 aims to remove the IP fragmentation problem from
the UDP DNS communication. In this commit, we implement the required
changes and simplify the logic for picking the EDNS Buffer Size.
1. The defaults for `edns-udp-size`, `max-udp-size` and
`nocookie-udp-size` have been changed to `1232` (the value picked by
DNS Flag Day 2020).
2. The probing heuristics that would try 512->4096->1432->1232 buffer
sizes has been removed and the resolver will always use just the
`edns-udp-size` value.
3. Instead of just disabling the PMTUD mechanism on the UDP sockets, we
now set IP_DONTFRAG (IPV6_DONTFRAG) flag. That means that the UDP
packets won't get ever fragmented. If the ICMP packets are lost the
UDP will just timeout and eventually be retried over TCP.
This command is similar in arguments as -checkds so refactor the
'named_server_dnssec' function accordingly. The only difference
are that:
- It does not take a "publish" or "withdrawn" argument.
- It requires the key id to be set (add a check to make sure).
Add tests that will trigger rollover immediately and one that
schedules a test in the future.
The dotat() function has been changed to send the TAT
query asynchronously, so there's no lock order loop
because we initialize the data first and then we schedule
the TAT send to happen asynchronously.
This breaks following lock-order loops:
zone->lock (dns_zone_setviewcommit) while holding view->lock
(dns_view_setviewcommit)
keytable->lock (dns_keytable_find) while holding zone->lock
(zone_asyncload)
view->lock (dns_view_findzonecut) while holding keytable->lock
(dns_keytable_forall)
No issues with the glue cache feature have been reported since its
introduction in BIND 9.12. As the rationale for introducing the
"glue-cache" option was to have a safety switch readily available in
case the glue cache turns out to cause problems, it is time to deprecate
the option. Glue cache will be permanently enabled in a future release,
at which point the "glue-cache" option will be made obsolete.
Attaching and detaching handle pointers will make it easier to
determine where and why reference counting errors have occurred.
A handle needs to be referenced more than once when multiple
asynchronous operations are in flight, so callers must now maintain
multiple handle pointers for each pending operation. For example,
ns_client objects now contain:
- reqhandle: held while waiting for a request callback (query,
notify, update)
- sendhandle: held while waiting for a send callback
- fetchhandle: held while waiting for a recursive fetch to
complete
- updatehandle: held while waiting for an update-forwarding
task to complete
control channel connection objects now contain:
- readhandle: held while waiting for a read callback
- sendhandle: held while waiting for a send callback
- cmdhandle: held while an rndc command is running
httpd connections contain:
- readhandle: held while waiting for a read callback
- sendhandle: held while waiting for a send callback
An implicit default of "max-cache-size 90%;" may cause memory use issues
on hosts which run numerous named instances in parallel (e.g. GitLab CI
runners) due to the cache RBT hash table now being pre-allocated [1] at
startup. Add a new command line option, "-T maxcachesize=...", to allow
the default value of "max-cache-size" to be overridden at runtime. When
this new option is in effect, it overrides any other "max-cache-size"
setting in the configuration, either implicit or explicit. This
approach was chosen because it is arguably the simplest one to
implement.
The following alternative approaches to solving this problem were
considered and ultimately rejected (after it was decided they were not
worth the extra code complexity):
- adding the same command line option, but making explicit
configuration statements have priority over it,
- adding a build-time option that allows the implicit default of
"max-cache-size 90%;" to be overridden.
[1] see commit e24bc324b4
