When 'ISC_R_TIMEDOUT' is received in 'tcp_recv()', it times out the
oldest response in the active responses queue, and only after that it
checks whether other active responses have also timed out. So when
setting a timeout value for a read operation after a successful
connection, it makes sense to take the timeout value from the oldest
response in the active queue too, because, theoretically, the responses
can have different timeout values, e.g. when the TCP dispatch is shared.
Currently 'resp' is always NULL. Previously when connect and read
timeouts were not separated in dispatch this affected only logging, but
now since we are setting a new timeout after a successful connection,
we need to choose a suitable response from the active queue.
Previously, this function always acquires a node write lock if it
might need node cleanup in case the reference decrements to 0. In
fact, the lock is unnecessary if the reference is larger than 1 and it
can be optimized as an "easy" case. This optimization could even be
"necessary". In some extreme cases, many worker threads could repeat
acquring and releasing the reference on the same node, resulting in
severe lock contention for nothing (as the ref wouldn't decrement to 0
in most cases). This change would prevent noticeable performance
drop like query timeout for such cases.
Co-authored-by: JINMEI Tatuya <jtatuya@infoblox.com>
Co-authored-by: Ondřej Surý <ondrej@isc.org>
Currently, the fetch context will continue running even when the last
fetch (response) has been removed from the context, so named can process
and cache the answer. This can lead to a situation where the number of
outgoing recursing clients exceeds the the configured number for
recursive-clients.
Be more stringent about the recursive-clients limit and shutdown the
fetch context immediately after the last fetch has been canceled from
that particular fetch context.
Address Database (ADB) shares the memory for the short lived ADB
objects (finds, fetches, addrinfo) and the long lived ADB
objects (names, entries, namehooks). This could lead to a situation
where the resolver-heavy load would force evict ADB objects from the
database to point where ADB is completely empty, leading to even more
resolver-heavy load.
Make the short lived ADB objects use the other memory context that we
already created for the hashmaps. This makes the ADB overmem condition
to not be triggered by the ongoing resolver fetches.
In some places there was a limitation of the maximum timeout
value of INT16_MAX, which is only about 32 seconds. Refactor
the code to remove the limitation.
The network manager layer has two different timers with their
own timeout values for TCP connections: connect timeout and read
timeout. Separate the connect and the read TCP timeouts in the
dispatch module too.
struct fetchctx does have a list of pending validators as well as a
pointer to the HEAD validator. Remove the validator pointer to avoid
confusion, as there is no perticular reasons to have it directly
accessible outside of the list.
there was a database bug in which dns_db_find() could get a partial
match for the query name, but still set foundname to match the full
query name. this triggered an assertion when query_addwildcardproof()
assumed that foundname would be shorter.
the database bug has been fixed, but in case it happens again, we
can just copy the name instead of splitting it. we will also log a
warning that the closest-encloser name was invalid.
when adding a new NSEC3 record, dns_nsec3_addnsec3() uses a
dbiterator to seek to the newly created node and then find its
predecessor. dbiterators in the qpzone use snapshots, so changes
to the database are not reflected in an already-existing iterator.
consequently, when we add a new node, we have to create a new iterator
before we can seek to it.
when a requested name is found in the QP trie during a lookup, but its
records have been marked as nonexistent by a previous deletion, then
it's treated as a partial match, but the foundname could be left
pointing to the original qname rather than the parent. this could
lead to an assertion failure in query_findclosestnsec3().
The code in zone_startload() disables RPZ and CATZ for a zone if
dns_master_loadfile() returns anything other than ISC_R_SUCCESS,
which makes sense, but it's an error because zone_startload() can
also return DNS_R_SEENINCLUDE upon success when the zone had an
$INCLUDE statement.
Ensure the log prefixes passed to the dns_message_logpacketfrom()
function by its callers do not include the word "from" as the latter is
now emitted by the logfmtpacket() helper function.
Ensure the log prefixes passed to the dns_message_logpacketfromto()
function by its callers do not include the words "from" or "to" as those
are now emitted by the logfmtpacket() helper function.
Move dns_dispentry_getlocaladdress() calls around so that they are not
only invoked when dnstap support is compiled in. This function calls
isc_nmhandle_localaddr(), which may issue a system call, but only if the
ISC_SOCKET_DETAILS preprocessor macro is set at compile time.
Pass the value extracted by dns_dispentry_getlocaladdress() to
dns_message_logpacketfromto() so that it gets logged, adding useful
information to the relevant debug messages.
Since dns_message_logpacket() only takes a single socket address as a
parameter (and it is always the sending socket's address), rename it to
dns_message_logpacketfrom() so that its name better conveys its purpose
and so that the difference in purpose between this function and
dns_message_logpacketfromto() becomes more apparent.
Since dns_message_logfmtpacket() needs to be provided with both "from"
and "to" socket addresses, rename it to dns_message_logpacketfromto() so
that its name better conveys its purpose. Clean up the code comments
for that function.
Change the function prototype for dns_message_logfmtpacket() so that it
takes two isc_sockaddr_t parameters: one for the sending side and
another one for the receiving side. This enables debug messages to be
more precise.
Also adjust the function prototype for logfmtpacket() accordingly.
Unlike dns_message_logfmtpacket(), this function must not require both
'from' and 'to' parameters to be non-NULL as it is still going to be
used by dns_message_logpacket(), which only provides a single socket
address. Adjust its log format to handle both of these cases properly.
Adjust both dns_message_logfmtpacket() call sites accordingly, without
actually providing the second socket address yet. (This causes the
revised REQUIRE() assertion in dns_message_logfmtpacket() to fail; the
issue will be addressed in a separate commit.)
Both existing callers of the dns_message_logfmtpacket() function set the
argument passed as 'style' to &dns_master_style_comment. To simplify
these call sites, drop the 'style' parameter from the prototype for
dns_message_logfmtpacket() and use a fixed value of
&dns_master_style_comment in the function's body instead.
All callers of the logfmtpacket() helper function require the argument
passed as 'address' to be non-NULL. Meanwhile, the 'newline' and
'space' local variables in logfmtpacket() are only set to values
different than their initial values if the 'address' parameter is NULL.
Replace the 'newline' and 'space' local variables in logfmtpacket() with
fixed strings to improve code readability.
Extracting the exact address that each wildcard/TCP socket is bound to
locally requires issuing the getsockname() system call, which libuv
exposes via its uv_*_getsockname() functions. This is only required for
detailed logging and comes at a noticeable performance cost, so it
should not happen by default. However, it is useful for debugging
certain problems (e.g. cryptic system test failures), so a convenient
way of enabling that behavior should exist.
Update isc_nmhandle_localaddr() so that it calls uv_*_getsockname() when
the ISC_SOCKET_DETAILS preprocessor macro is set at compile time.
Ensure proper handling of sockets that wrap other sockets.
Set the new ISC_SOCKET_DETAILS macro by default when --enable-developer
is passed to ./configure. This enables detailed logging in the system
tests run in GitLab CI without affecting performance in non-development
BIND 9 builds.
Note that setting the ISC_SOCKET_DETAILS preprocessor macro at compile
time enables all callers of isc_nmhandle_localaddr() to extract the
exact address of a given local socket, which results e.g. in dnstap
captures containing more accurate information.
Mention the new preprocessor macro in the section of the ARM that
discusses why exact socket addresses may not be logged by default.
The dns_dispatch_gettcp() function is used for finding an existing TCP
connection that can be reused for sending a query from a specified local
address to a specified remote address. The logic for matching the
provided <local address, remote address> tuple to one of the existing
TCP connections is implemented in the dispatch_match() function:
- if the examined TCP connection already has a libuv handle assigned,
it means the connection has already been established; therefore,
compare the provided <local address, remote address> tuple against
the corresponding address tuple for the libuv handle associated with
the connection,
- if the examined TCP connection does not yet have a libuv handle
assigned, it means the connection has not yet been established;
therefore, compare the provided <local address, remote address>
tuple against the corresponding address tuple that the TCP
connection was originally created for.
This logic limits TCP connection reuse potential as the libuv handle
assigned to an existing dispatch object may have a more specific local
<address, port> tuple associated with it than the local <address, port>
tuple that the dispatch object was originally created for. That's
because the local address for outgoing connections can be set to a
wildcard <address, port> tuple (indicating that the caller does not care
what source <address, port> tuple will be used for establishing the
connection, thereby delegating the task of picking it to the operating
system) and then get "upgraded" to a specific <address, port> tuple when
the socket is bound (and a libuv handle gets associated with it). When
another dns_dispatch_gettcp() caller then tries to look for an existing
TCP connection to the same peer and passes a wildcard address in the
local part of the tuple, the function will not match that request to a
previously-established TCP connection (unless isc_nmhandle_localaddr()
returns a wildcard address as well).
Simplify dispatch_match() so that the libuv handle associated with an
existing dispatch object is not examined for the purpose of matching it
to the provided <local address, remote address> tuple; instead, always
examine the <local address, remote address> tuple that the dispatch
object was originally created for. This enables reuse of TCP
connections created without providing a specific local socket address
while still preventing other connections (created for a specific local
socket address) from being inadvertently shared.
This commit ensures that BIND enables TLS SNI support for outgoing DoT
connections (when possible) in order to improve compatibility with
other DNS server software.
This commit adds support for setting SNI hostnames in outgoing
connections over TLS.
Most of the changes are related to either adapting the code to accept
and extra argument in *connect() functions and a couple of changes to
the TLS Stream to actually make use of the new SNI hostname
information.
Previously, we had an ISC_CONSTEXPR macro that was expanded to either
`constexpr` or `static const`, depending on compiler support. To make
the code cleaner, move `constexpr` support detection to Autoconf; if
`constexpr` support is missing from the compiler, define `constexpr` as
`static const` in config.h.
Since BIND 9 headers are not longer public, there's no reason to keep
the ISC_LANG_BEGINDECL and ISC_LANG_ENDDECL macros to support including
them from C++ projects.
This is a second attempt to rewrite the GLUE cache to not use per
database version hash table. Instead of keeping a hash table indexed by
the node, use a directly linked list of GLUE records for each
slabheader. This was attempted before, but there was a data race caused
by the fact that the thread cleaning the GLUE records could be slower
than accessing the slab headers again and reinitializing the wait-free
stack.
The improved design builds on the previous design, but adds a new
dns_gluelist structure that has a pointer to the database version.
If a dns_gluelist belonging to a different (old) version is detected, it
is just detached from the slabheader and left for the closeversion() to
clean it up later.
The 'remote-servers' named.conf reference conflicts with the standard
term from the glossary. Rename the standard term to server-list to
make the docs build.
Add back the top blocks 'parental-agents', 'primaries', and 'masters'
to the configuration. Do not document them as so many names for the
same clause is confusing.
This has a slight negative side effect that a top block 'primaries'
can be referred to with a zone statement 'parental-agents' for example,
but that shouldn't be a big issue.
Having zone statements that are also top blocks is confusing, and if
we want to add more in the future (which I suspect will be for
generalized notifications, multi-signer), we need to duplicate a lot
of code.
Remove top blocks 'parental-agents' and 'primaries' and just have one
top block 'remote-servers' that you can refer to with zone statements.
this commit removes the deprecated "sortlist" option. the option
is now marked as ancient; it is a fatal error to use it in
named.conf.
the sortlist system test has been removed, and other tests that
referenced the option have been modified.
the enabling functions, dns_message_setsortorder() and
dns_rdataset_towiresorted(), have also been removed.
named-checkzone will now, as part of the zone's integrity checks,
look to see if there are A or AAAA records being served and if so
check that the nameservers have A or AAAA records respectively.
These are a sometimes overlooked checks that, if not met, can mean
that a service that is supposed to reachable over IPv6 will not be
resolvable when the recursive resolver is IPv6 only. Similarly for
IPv4 servers when there are IPv4 only resolvers.
- remove obsolete DNS_LOGMODULE_RBT and DNS_LOGMODULE_RBTDB
- correct the misuse of the wrong log modules in dns/rpz.c and
dns/catz.c, and add DNS_LOGMODULE_RPZ and DNS_LOGMODULE_CATZ
to support them.
`shutdown_trigger_close_cb` is not called in the main loop since
queued events in the `loop->async_trigger`, including loop teardown
(shutdown_server) are processed first, before the `uv_close` callback
is executed..
In order to pass the information to the queued events, it is necessary
to set the flag earlier in the process and not wait for the `uv_close`
callback to trigger.
Search directive from resolv.conf had a maximum of 8 domains. Any
more were ignored. Do not ignore them anymore; iterate over any
number of domains.
Test resolv.conf support by checking the first and last domain in
the search list. Ignore the domains between; just ensure that the
last domain in the configuration is the last domain parsed.
Only call eatline() to skip to the next line if we're not
already at the end of a line when parsing an unknown directive.
We were accidentally skipping the next line when there was only
a single unknown directive on the current line.
The DNS_R_MUSTBESECURE lost its meaning with removal of
dnssec-must-be-secure option, so replace the few remaining (and a bit
confusing) use of this result code with DNS_R_NOVALIDSIG.
The dnssec-must-be-secure feature was added in the early days of BIND 9
and DNSSEC and it makes sense only as a debugging feature. There are no
reasons to keep this feature in the production code anymore.
Remove the feature to simplify the code.
Commit af7db89513 as part of #4141 was
supposed to apply the 'max-recursion-queries' quota to validator
queries, but the counter was never actually passed on to
dns_resolver_createfetch(). This has been fixed, and the global query
counter ('max-query-count', per client request) is now also added.
Upstream code doesn't do regular releases, so we need to regularly
sync the code from the upstream repository. This is synchronization up
to the commit f8d0513 from Jan 29, 2024.
