With 'stale-answer-enable yes;' and 'stale-answer-client-timeout off;',
consider the following situation:
A CNAME record and its target record are in the cache, then the CNAME
record expires, but the target record is still valid.
When a new query for the CNAME record arrives, and the query fails,
the stale record is used, and then the query "restarts" to follow
the CNAME target. The problem is that the query's multiple stale
options (like DNS_DBFIND_STALEOK) are not reset, so 'query_lookup()'
treats the restarted query as a lookup following a failed lookup,
and returns a SERVFAIL answer when there is no stale data found in the
cache, even if there is valid non-stale data there available.
With this change, query_lookup() now considers non-stale data in the
cache in the first place, and returns it if it is available.
Prime the cache with the following records:
shortttl.cname.example. 1 IN CNAME longttl.target.example.
longttl.target.example. 600 IN A 10.53.0.2
Wait for the CNAME record to expire, disable the authoritative server,
and query 'shortttl.cname.example' again, expecting a stale answer.
On some platforms, when a synchronizing barrier is cleared, one
thread can progress while other threads are still in the process
of releasing the barrier. If a barrier is reused by the progressing
thread during this window, it can cause a deadlock. This can occur if,
for example, we stop listening immediately after we start, because the
stop and listen functions both use socket->barrier. This has been
addressed by using separate barrier objects for stop and listen.
There were couple of redundant macros on both sides of
DNS_RBTDB_STRONG_RWLOCK_CHECK #ifdef block. Use a single set of
macros, but disable the extra REQUIRES if the #define is not set.
Extend the expire_header() to accept the node lock type as one of the
arguments and check whether the the node lock is always write locked +
fix that bug.
While doing that, it was found that expire_header() invocation in
rdataset_expire() passes `false` as a type of tree lock instead of
`isc_rwlocktype_none`.
(Un)fortunately, both values mapped to 0, so no harm was done, but it
has been fixed nevertheless.
There was a repetetive pattern:
if (NODE_TRYUPGRADE(&nodelock->lock, nlocktypep) != ISC_R_SUCCESS)
{
NODE_UNLOCK(&nodelock->lock, nlocktypep);
NODE_WRLOCK(&nodelock->lock, nlocktypep);
}
Instead of doing that over again, introduce new NODE_FORCEUPGRADE()
and TREE_FORCEUPGRADE() that does exactly this code, and simplify
the aforementioned code with just:
NODE_FORCEUPGRADE(&nodelock->lock, nlocktypep);
Previously, dns_dispatch_gettcp() could pick a TCP connection created by
different thread - this breaks our contractual promise to DNS dispatch
by using the TCP connection on a different thread than it was created.
Add .tid member to the dns_dispatch_t struct and skip the dispatches
from other threads when looking up a TCP dispatch that we can reuse in
dns_request.
NOTE: This is going to be properly refactored, but this change could be
also backported to 9.18 for better stability and thread-affinity.
Since dns_master_dump() can no longer return DNS_R_CONTINUE,
the error recovery code in synchronous calls to zone_dump() had
branches that could no longer be reached. This has been cleaned
up by using a boolean variable to determine whether the write
is asynchronous rather than depending on the result code.
This bug was masked in the tests because the `catz` test script did an
`rndc addzone` before an `rndc delzone`. The `addzone` autovivified
the NZF config, so `delzone` worked OK.
This commit swaps the order of two sections of the `catz` test script
so that it uses `delzone` before `addzone`, which provokes a crash
when `delzone` requires a non-NULL NZF config.
To fix the crash, we now try to remove the zone from the NZF config
only if it was dynamically added but not by a catalog zone.
The following report suggests that the 'size' parameter in the two
calls to 'isc_mem_get()' should be set to the
'count * sizeof(*tlsnames)' and 'count * sizeof(*keynames)'
respectively.
/lib/dns/remote.c: 117 in dns_remote_init()
111 }
112 } else {
113 remote->keynames = NULL;
114 }
115
116 if (tlsnames != NULL) {
>>> CID 432259: (SIZEOF_MISMATCH)
>>> Passing argument "count * 8UL /* sizeof (tlsnames) */" to
>>> function "isc__mem_get" and then casting the return value to
>>> "dns_name_t **" is suspicious. In this particular case
>>> "sizeof (dns_name_t **)" happens to be equal to
>>> "sizeof (dns_name_t *)", but this is not a portable assumption.
117 remote->tlsnames = isc_mem_get(mctx, count * sizeof(tlsnames));
118 for (i = 0; i < count; i++) {
119 remote->tlsnames[i] = NULL;
120 }
121 for (i = 0; i < count; i++) {
122 if (tlsnames[i] != NULL) {
/lib/dns/remote.c: 99 in dns_remote_init()
93 memmove(remote->dscps, dscp, count * sizeof(isc_dscp_t));
94 } else {
95 remote->dscps = NULL;
96 }
97
98 if (keynames != NULL) {
>>> CID 432259: (SIZEOF_MISMATCH)
>>> Passing argument "count * 8UL /* sizeof (keynames) */" to
>>> function "isc__mem_get" and then casting the return value to
>>> "dns_name_t **" is suspicious. In this particular case
>>> "sizeof (dns_name_t **)" happens to be equal to "sizeof
>>> (dns_name_t *)", but this is not a portable assumption.
99 remote->keynames = isc_mem_get(mctx, count * sizeof(keynames));
100 for (i = 0; i < count; i++) {
101 remote->keynames[i] = NULL;
102 }
103 for (i = 0; i < count; i++) {
104 if (keynames[i] != NULL) {
When shutting down, the cleanup path should not try to destroy
'newnodes', because it is NULL at that point.
Introduce another label for the "shuttingdown" scenario.
The clean_namehooks() function does't hold the 'adb->entries_lock'
lock, so calling maybe_expire_entry() is not thread-safe.
Instead of adding a lock/unlock, leave the expiration to later,
e.g. by the get_attached_and_locked_entry() function.
Also fix a couple of comment typos.
This commit replaces ad-hoc code for send requests buffer management
within TLS with the one based on isc_buffer_t.
Previous version of the code was trying to use pre-allocated small
buffers to avoid extra allocations. The code would allocate a larger
dynamic buffer when needed. There is no need to have ad-hoc code for
this, as isc_buffer_t now provides this functionality internally.
Additionally to the above, the old version of the code lacked any
logic to reuse the dynamically allocated buffers. Now, as we do not
manage memory buffers, but isc_buffer_t objects, we can implement this
strategy. It can be in particular helpful for longer lasting
connections, as in this case the buffer will adjust itself to the size
of the messages being transferred. That is, it is in particular useful
for XoT, as Stream DNS happen to order send requests in such a way
that the send request will get reused.
Remove parsing the configuration options 'alt-transfer-source',
'alt-transfer-source-v6', and 'use-alt-transfer-source', and remove
the corresponding code that implements the feature.
Use the configured 'source' and 'source-v6' when initiating a zone
transfer, sending a notify, or when checking for the DS. Remove the
special code for using alternate transfer sources.
Update some system tests to use the new configuration and make sure
the tests still work.
Add a new way to configure the preferred source address when talking to
remote servers such as primaries and parental-agents. This will
eventually deprecate options such as 'parental-source',
'parental-source-v6', 'transfer-source', etc.
Example of the new configuration:
parental-agents "parents" port 5353 \
source 10.10.10.10 port 5354 dscp 54 \
source-v6 2001:db8::10 port 5355 dscp 55 {
10.10.10.11;
2001:db8::11;
};
