Previously, each protocol (TCPDNS, TLSDNS) has specified own function to
disable pipelining on the connection. An oversight would lead to
assertion failure when opcode is not query over non-TCPDNS protocol
because the isc_nm_tcpdns_sequential() function would be called over
non-TCPDNS socket. This commit removes the per-protocol functions and
refactors the code to have and use common isc_nm_sequential() function
that would either disable the pipelining on the socket or would handle
the request in per specific manner. Currently it ignores the call for
HTTP sockets and causes assertion failure for protocols where it doesn't
make sense to call the function at all.
The built-in "_bind" view does not allow recursion and therefore does
not need a large cache database. However, as "max-cache-size" is not
explicitly set for that view in the default configuration, it inherits
that setting from global options. Set "max-cache-size" for the built-in
"_bind" view to a fixed value (2 MB, i.e. the smallest allowed value) to
prevent needlessly preallocating memory for its cache RBT hash table.
Currently the implicit default for the "max-cache-size" option is "90%".
As this option is inherited by all configured views, using multiple
views can lead to memory exhaustion over time due to overcommitment.
The "max-cache-size 90%;" default also causes cache RBT hash tables to
be preallocated for every configured view, which does not really make
sense for views which do not allow recursion.
To limit this problem's potential for causing operational issues, use a
minimal-sized cache for views which do not allow recursion and do not
have "max-cache-size" explicitly set (either in global configuration or
in view configuration).
For configurations which include multiple views allowing recursion,
adjusting "max-cache-size" appropriately is still left to the operator.
When locking key files for a zone, we iterate over all the views and
lock a mutex inside the zone structure. However, if we envounter an
in-view zone, we will try to lock the key files twice, one time for
the home view and one time for the in-view view. This will lead to
a deadlock because one thread is trying to get the same lock twice.
When "max-cache-size" is changed to "unlimited" (or "0") for a running
named instance (using "rndc reconfig"), the hash table size limit for
each affected cache DB is not reset to the maximum possible value,
preventing those hash tables from being allowed to grow as a result of
new nodes being added.
Extend dns_rbt_adjusthashsize() to interpret "size" set to 0 as a signal
to remove any previously imposed limits on the hash table size. Adjust
API documentation for dns_db_adjusthashsize() accordingly. Move the
call to dns_db_adjusthashsize() from dns_cache_setcachesize() so that it
also happens when "size" is set to 0.
Upon creation, each dns_rbt_t structure has its "maxhashbits" field
initialized to the value of the RBT_HASH_MAX_BITS preprocessor macro,
i.e. 32. When the dns_rbt_adjusthashsize() function is called for the
first time for a given RBT (for cache RBTs, this happens when they are
first created, i.e. upon named startup), it lowers the value of the
"maxhashbits" field to the number of bits required to index the
requested number of hash table slots. When a larger hash table size is
subsequently requested, the value of the "maxhashbits" field should be
increased accordingly, up to RBT_HASH_MAX_BITS. However, the loop in
the rehash_bits() function currently ensures that the number of bits
necessary to index the resized hash table will not be larger than
rbt->maxhashbits instead of RBT_HASH_MAX_BITS, preventing the hash table
from being grown once the "maxhashbits" field of a given dns_rbt_t
structure is set to any value lower than RBT_HASH_MAX_BITS.
Fix by tweaking the loop guard condition in the rehash_bits() function
so that it compares the new number of bits used for indexing the hash
table against RBT_HASH_MAX_BITS rather than rbt->maxhashbits.
The timeout originally picked for "rndc status" invocations (2 seconds)
in the test attempting to reproduce a deadlock caused by running
multiple "rndc addzone", "rndc modzone", and "rndc delzone" commands
concurrently causes intermittent failures of the "addzone" system test
in GitLab CI. Increase the timeout to 10 seconds to make such failures
less probable. Adjust code comments accordingly.
The requirements for BIND 9.17+ now requires C11 support from the
compiler, so we can safely drop most of the stdatomic.h shims from
lib/isc/unix/include/stdatomic.h.
This commit removes support for clang atomic builtins (clang >= 3.6.0
includes stdatomic.h header) and for Gcc __sync builtins.
The only compatibility shim that remains is support for __atomic
builtins for Gcc >= 4.7.0 since CentOS 7 still includes only Gcc 4.8.1
and the proper stdatomic.h header was only introduced in Gcc >= 4.9.
The warning was produced by an ASAN build:
runtime error: null pointer passed as argument 2, which is declared to
never be null
This commit fixes it by checking if nghttp2_session_mem_send() has
actually returned anything.
Resolve "ThreadSanitizer: data race lib/isc/task.c:435 in task_send (unprotected access to `task->threadid`)"
Closes#2739
See merge request isc-projects/bind9!5149
