When -T cookiealwaysvalid is passed to named, DNS cookie checks for
the incoming queries always pass, given they are structurally correct.
(cherry picked from commit 807ef8545d)
When sending fails, the ns__client_request() would not reset the
connection and continue as nothing is happening. This comes from the
model that we don't care about failed UDP sends because datagrams are
unreliable anyway, but it greatly affects TCP connections with
keep-alive.
The worst case scenario is as follows:
1. the 3-way TCP handshake gets completed
2. the libuv calls the "uv_connection_cb" callback
3. the TCP connection gets queue because of the tcp-clients quota
4. the TCP client sends as many DNS messages as the buffers allow
5. the TCP connection gets dropped by the client due to the timeout
6. the TCP connection gets accepted by the server
7. the data already sent by the client gets read
8. all sending fails immediately because the TCP connection is dead
9. we consume all the data in the buffer in a very tight loop
As it doesn't make sense to trying to process more data on the TCP
connection when the sending is failing, drop the connection immediately
on the first sending error.
(cherry picked from commit bf9fd2a6ff)
As a single thread can process only one TCP send at the time, we don't
really need a memory pool for the TCP buffers, but it's enough to have
a single per-loop (client manager) static buffer that's being used to
assemble the DNS message and then it gets copied into own sending
buffer.
In the future, this should get optimized by exposing the uv_try API
from the network manager, and first try to send the message directly
and allocate the sending buffer only if we need to send the data
asynchronously.
(cherry picked from commit 297cc840fbaf34b9dfa1d02d88a023cd5bf5dc4a)
Constantly allocating, reallocating and deallocating 64K TCP send
buffers by 'ns_client' instances takes too much CPU time.
There is an existing mechanism to reuse the ns_clent_t structure
associated with the handle using 'isc_nmhandle_getdata/_setdata'
(see ns_client_request()), but it doesn't work with TCP, because
every time ns_client_request() is called it gets a new handle even
for the same TCP connection, see the comments in
streamdns_on_complete_dnsmessage().
To solve the problem, we introduce an array of available (unused)
TCP buffers stored in ns_clientmgr_t structure so that a 'client'
working via TCP can have a chance to reuse one (if there is one)
instead of allocating a new one every time.
All these pointers are guaranteed to be non-NULL.
Additionally, update a comment to remove obviously outdated
information about the function's requirements.
(cherry picked from commit b970556f21)
In the ns__client_put_cb() callback function the 'client->manager'
pointer is guaranteed to be non-NULL, because in ns__client_request(),
before setting up the callback, the ns__client_setup() function is
called for the 'client', which makes sure that 'client->manager' is set.
Removing the NULL-check resolves the following static analyzer warning:
/lib/ns/client.c: 1675 in ns__client_put_cb()
1669 dns_message_puttemprdataset(client->message, &client->opt);
1670 }
1671 client_extendederror_reset(client);
1672
1673 dns_message_detach(&client->message);
1674
>>> CID 465168: Null pointer dereferences (REVERSE_INULL)
>>> Null-checking "client->manager" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
1675 if (client->manager != NULL) {
1676 ns_clientmgr_detach(&client->manager);
1677 }
1678
1679 /*
1680 * Detaching the task must be done after unlinking from
This commit changes send buffers allocation strategy for stream based
transports. Before that change we would allocate a dynamic buffers
sized at 64Kb even when we do not need that much. That could lead to
high memory usage on server. Now we resize the send buffer to match
the size of the actual data, freeing the memory at the end of the
buffer for being reused later.
(cherry picked from commit d8a5feb556)
this function was just a front-end for gethostname(). it was
needed when we supported windows, which has a different function
for looking up the hostname; it's not needed any longer.
(cherry picked from commit 197334464e)
The ns_client_aclchecksilent is used to check multiple ACLs before
the decision is made that a query is denied. It is also used to
determine if recursion is available. In those cases we should not
set the extended DNS error "Prohibited".
(cherry picked from commit 798c8f57d4)
Send the ns_query_cancel() on the recursing clients when we initiate the
named shutdown for faster shutdown.
When we are shutting down the resolver, we cancel all the outstanding
fetches, and the ISC_R_CANCEL events doesn't propagate to the ns_client
callback.
In the future, the better solution how to fix this would be to look at
the shutdown paths and let them all propagate from bottom (loopmgr) to
top (f.e. ns_client).
(cherry picked from commit d861d403bb9a7912e29a06aba6caf6d502839f1b)
The incrementing and decrementing of 'ns_statscounter_recursclients'
were not properly balanced: for example, it would be incremented for
a prefetch query but not decremented if the query failed.
This commit ensures that the recursion quota and the recursive clients
counter are always in sync with each other.
It is possible to bypass Response Rate Limiting (RRL)
`responses-per-second` limitation using specially crafted wildcard
names, because the current implementation, when encountering a found
DNS name generated from a wildcard record, just strips the leftmost
label of the name before making a key for the bucket.
While that technique helps with limiting random requests like
<random>.example.com (because all those requests will be accounted
as belonging to a bucket constructed from "example.com" name), it does
not help with random names like subdomain.<random>.example.com.
The best solution would have been to strip not just the leftmost
label, but as many labels as necessary until reaching the suffix part
of the wildcard record from which the found name is generated, however,
we do not have that information readily available in the context of RRL
processing code.
Fix the issue by interpreting all valid wildcard domain names as
the zone's origin name concatenated to the "*" name, so they all will
be put into the same bucket.
(cherry picked from commit baa9698c9d)
The BUFSIZ value varies between platforms, it could be 8K on Linux and
512 bytes on mingw. Make sure the buffers are always big enough for the
output data to prevent truncation of the output by appropriately
enlarging or sizing the buffers.
(cherry picked from commit b19d932262e84608174cb89eeed32ae0212f8a87)
The current logic for determining the address of the socket to which a
client sent its query is:
1. Get the address:port tuple from the netmgr handle using
isc_nmhandle_localaddr().
2. Convert the address:port tuple from step 1 into an isc_netaddr_t
using isc_netaddr_fromsockaddr().
3. Convert the address from step 2 back into a socket address with the
port set to 0 using isc_sockaddr_fromnetaddr().
Note that the port number (readily available in the netmgr handle) is
needlessly lost in the process, preventing it from being recorded in
dnstap captures of client traffic produced by named.
Fix by first storing the address:port tuple returned by
isc_nmhandle_localaddr() in client->destsockaddr and then creating an
isc_netaddr_t from that structure. This allows the port number to be
retained in client->destsockaddr, which is what subsequently gets passed
to dns_dt_send().
(cherry picked from commit 2f945703f2)
The .lock, .exiting and .excl members were not using for anything else
than starting task exclusive mode, setting .exiting to true and ending
exclusive mode.
Remove all the stray members and dead code eliminating the task
exclusive mode use from ns_clientmgr.
(cherry picked from commit 4f74e1010e)
Historically, the inline keyword was a strong suggestion to the compiler
that it should inline the function marked inline. As compilers became
better at optimising, this functionality has receded, and using inline
as a suggestion to inline a function is obsolete. The compiler will
happily ignore it and inline something else entirely if it finds that's
a better optimisation.
Therefore, remove all the occurences of the inline keyword with static
functions inside single compilation unit and leave the decision whether
to inline a function or not entirely on the compiler
NOTE: We keep the usage the inline keyword when the purpose is to change
the linkage behaviour.
(cherry picked from commit 20f0936cf2)
Previously, the unreachable code paths would have to be tagged with:
INSIST(0);
ISC_UNREACHABLE();
There was also older parts of the code that used comment annotation:
/* NOTREACHED */
Unify the handling of unreachable code paths to just use:
UNREACHABLE();
The UNREACHABLE() macro now asserts when reached and also uses
__builtin_unreachable(); when such builtin is available in the compiler.
(cherry picked from commit 584f0d7a7e)
The C17 standard deprecated ATOMIC_VAR_INIT() macro (see [1]). Follow
the suite and remove the ATOMIC_VAR_INIT() usage in favor of simple
assignment of the value as this is what all supported stdatomic.h
implementations do anyway:
* MacOSX.plaform: #define ATOMIC_VAR_INIT(__v) {__v}
* Gcc stdatomic.h: #define ATOMIC_VAR_INIT(VALUE) (VALUE)
1. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1138r0.pdf
(cherry picked from commit f251d69eba)
When invalid DNS message is received, there was a handling mechanism for
DoH that would be called to return proper HTTP response.
Reuse this mechanism and reset the TCP connection when the client is
blackholed, DNS message is completely bogus or the ns_client receives
response instead of query.
(cherry picked from commit 4716c56ebb)
This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
The memory context created in the clientmgr context was missing a name,
so it was nameless in the memory context statistics.
Set the clientmgr memory context name to "clientmgr".
This commit completes the integration of the new, extended ACL syntax
featuring 'port' and 'transport' options.
The runtime presentation and ACL loading code are extended to allow
the syntax to be used beyond the 'allow-transfer' option (e.g. in
'acl' definitions and other 'allow-*' options) and can be used to
ultimately extend the ACL support with transport-only
ACLs (e.g. 'transport-acl tls-acl port 853 transport tls'). But, due
to fundamental nature of such a change, it has not been completed as a
part of 9.17.X release series due to it being close to 9.18 stable
release status. That means that we do not have enough time to fully
test it.
The complete integration is planned as a part of 9.19.X release
series.
The code was manually verified to work as expected by temporarily
enabling the extended syntax for 'acl' statements and 'allow-query'
options, including ACL merging, negated ACLs.
Add a new parameter to 'ns_client_t' to store potential extended DNS
error. Reset when the client request ends, or is put back.
Add defines for all well-known info-codes.
Update the number of DNS_EDNSOPTIONS that we are willing to set.
Create a new function to set the extended error for a client reply.
This commit makes BIND set the "max-age" value of the "Cache-Control"
HTTP header to the minimal TTL from the Answer section for positive
answers, as RFC 8484 advises in section 5.1.
We calculate the minimal TTL as a side effect of rendering the
response DNS message, so it does not change the code flow much, nor
should it have any measurable negative impact on the performance.
For negative answers, the "max-age" value is set using the TTL and
SOA-minimum values from an SOA record in the Authority section.
Remove the dynamic registration of result codes. Convert isc_result_t
from unsigned + #defines into 32-bit enum type in grand unified
<isc/result.h> header. Keep the existing values of the result codes
even at the expense of the description and identifier tables being
unnecessary large.
Additionally, add couple of:
switch (result) {
[...]
default:
break;
}
statements where compiler now complains about missing enum values in the
switch statement.
- Responses received by the dispatch are no longer sent to the caller
via a task event, but via a netmgr-style recv callback. the 'action'
parameter to dns_dispatch_addresponse() is now called 'response' and
is called directly from udp_recv() or tcp_recv() when a valid response
has been received.
- All references to isc_task and isc_taskmgr have been removed from
dispatch functions.
- All references to dns_dispatchevent_t have been removed and the type
has been deleted.
- Added a task to the resolver response context, to be used for fctx
events.
- When the caller cancels an operation, the response handler will be
called with ISC_R_CANCELED; it can abort immediately since the caller
will presumably have taken care of cleanup already.
- Cleaned up attach/detach in resquery and request.
previously, receiving a keepalive option had no effect on how
long named would keep the connection open; there was a place to
configure the keepalive timeout but it was never used. this commit
corrects that.
this also fixes an error in isc__nm_{tcp,tls}dns_keepalive()
in which the sense of a REQUIRE test was reversed; previously this
error had not been noticed because the functions were not being
used.
The client->rcode_override was originally created to force the server
to send SERVFAIL in some cases when it would normally have sent FORMERR.
More recently, it was used in a3ba95116e
commit (part of GL #2790) to force the sending of a TC=1 NOERROR
response, triggering a retry via TCP, when a UDP packet could not be
sent due to ISC_R_MAXSIZE.
This ran afoul of a pre-existing INSIST in ns_client_error() when
RRL was in use. the INSIST was based on the assumption that
ns_client_error() could never result in a non-error rcode. as
that assumption is no longer valid, the INSIST has been removed.
The additional processing method has been expanded to take the
owner name of the record, as HTTPS and SVBC need it to process "."
in service form.
The additional section callback can now return the RRset that was
added. We use this when adding CNAMEs. Previously, the recursion
would stop if it detected that a record you added already exists. With
CNAMEs this rule doesn't work, as you ultimately care about the RRset
at the target of the CNAME and not the presence of the CNAME itself.
Returning the record allows the caller to restart with the target
name. As CNAMEs can form loops, loop protection was added.
As HTTPS and SVBC can produce infinite chains, we prevent this by
tracking recursion depth and stopping if we go too deep.
This commit makes BIND return HTTP status codes for malformed or too
small requests.
DNS request processing code would ignore such requests. Such an
approach works well for other DNS transport but does not make much
sense for HTTP, not allowing it to complete the request/response
sequence.
Suppose execution has reached the point where DNS message handling
code has been called. In that case, it means that the HTTP request has
been successfully processed, and, thus, we are expected to respond to
it either with a message containing some DNS payload or at least to
return an error status code. This commit ensures that BIND behaves
this way.
The isc/platform.h header was left empty which things either already
moved to config.h or to appropriate headers. This is just the final
cleanup commit.
When the fragmentation is disabled on UDP sockets, the uv_udp_send()
call can fail with UV_EMSGSIZE for messages larger than path MTU.
Previously, this error would end with just discarding the response. In
this commit, a proper handling of such case is added and on such error,
a new DNS response with truncated bit set is generated and sent to the
client.
This change allows us to disable the fragmentation on the UDP
sockets again.
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 Windows support has been completely removed from the source tree
and BIND 9 now no longer supports native compilation on Windows.
We might consider reviewing mingw-w64 port if contributed by external
party, but no development efforts will be put into making BIND 9 compile
and run on Windows again.
configuring with --enable-mutex-atomics flagged these incorrectly
initialised variables on systems where pthread_mutex_init doesn't
just zero out the structure.
Previously, as a way of reducing the contention between threads a
clientmgr object would be created for each interface/IP address.
We tasks being more strictly bound to netmgr workers, this is no longer
needed and we can just create clientmgr object per worker queue (ncpus).
Each clientmgr object than would have a single task and single memory
context.
Since a client object is bound to a netmgr handle, each client
will always be processed by the same netmgr worker, so we can
simplify the code by binding client->task to the same thread as
the client. Since ns__client_request() now runs in the same event
loop as client->task events, is no longer necessary to pause the
task manager before launching them.
Also removed some functions in isc_task that were not used.
The number of memory contexts created in the clientmgr was enormous. It
could easily create thousands of memory contexts because the formula was:
nprotocols * ncpus * ninterfaces * CLIENT_NMCTXS_PERCPU (8)
The original goal was to reduce the contention when allocating the
memory, but after a while nobody noticed that the amount of memory
context allocated would not reduce contention at all.
This commit removes the whole mctxpool and just uses the mctx from
clientmgr as the contention will be reduced directly in the allocator.
dns_message_gettempname() now returns a pointer to an initialized
name associated with a dns_fixedname_t object. it is no longer
necessary to allocate a buffer for temporary names associated with
the message object.
