Instead of mixing the dns_resolver and dns_validator units directly with
the EDE code, split-out the dns_ede functionality into own separate
compilation unit and hide the implementation details behind abstraction.
Additionally, the EDE codes are directly copied into the ns_client
buffers by passing the EDE context to dns_resolver_createfetch().
This makes the dns_ede implementation simpler to use, although sligtly
more complicated on the inside.
Co-authored-by: Colin Vidal <colin@isc.org>
Co-authored-by: Ondřej Surý <ondrej@isc.org>
(cherry picked from commit 2f8e0edf3b)
Add support for EDE codes 1 (Unsupported DNSKEY Algorithm) and 2
(Unsupported DS Digest Type) which might occurs during DNSSEC
validation in case of unsupported DNSKEY algorithm or DS digest type.
Because DNSSEC internally kicks off various fetches, we need to copy
all encountered extended errors from fetch responses to the fetch
context. Upon an event, the errors from the fetch context are copied
to the client response.
(cherry picked from commit 46a58acdf5)
Extended DNS error mechanism (EDE) enables to have several EDE raised
during a DNS resolution (typically, a DNSSEC query will do multiple
fetches which each of them can have an error). Add support to up to 3
EDE errors in an DNS response. If duplicates occur (two EDEs with the
same code, the extra text is not compared), only the first one will be
part of the DNS answer.
Because the maximum number of EDE is statically fixed, `ns_client_t`
object own a static vector of `DNS_DE_MAX_ERRORS` (instead of a linked
list, for instance). The array can be fully filled (all slots point to
an allocated `dns_ednsopt_t` object) or partially filled (or
empty). In such case, the first NULL slot means there is no more EDE
objects.
(cherry picked from commit 4096f27130)
When answering queries, don't add data to the additional section if
the answer has more than 13 names in the RDATA. This limits the
number of lookups into the database(s) during a single client query,
reducing query processing load.
Also, don't append any additional data to type=ANY queries. The
answer to ANY is already big enough.
(cherry picked from commit a1982cf1bb)
In dns_zone_getdnssecsignstats, dns_zone_getrcvquerystats and
dns_zone_getrequeststats attach to the statistics structure.
(cherry picked from commit fb50a71159)
Add support for Extended DNS Errors (EDE) error 22: No reachable
authority. This occurs when after a timeout delay when the resolver is
trying to query an authority server.
(cherry picked from commit d13e94b930)
Commit amended in order to fix usage of isc_log_write (adding dns_lctx
parameter)
Previously, the update policy rules check was moved earlier in the
sequence, and the keep rule match pointers were kept to maintain the
ability to verify maximum records by type.
However, these pointers can become invalid if server reloading
or reconfiguration occurs before update completion. To prevent
this issue, extract the maximum records by type value immediately
during processing and only keep the copy of the values instead of the
full ssurule.
(cherry picked from commit 44a54a29d8)
Instead of cleaning the dns_badcache opportunistically, add per-loop
LRU, so each thread-loop can clean the expired entries. This also
allows removal of the atomic operations as the badcache entries are now
immutable, instead of updating the badcache entry in place, the old
entry is now deleted from the hashtable and the LRU list, and the new
entry is inserted in the LRU.
(cherry picked from commit 2cb5a6210f)
Re-split format strings that had been poorly split by multiple
clang-format runs using different versions of clang-format.
(cherry picked from commit a24d6e1654)
maxlabels is the suffix length that corresponds to the latest
NXDOMAIN response. minlabels is the suffix length that corresponds
to longest found existing name.
(cherry picked from commit 67f31c5046)
Rename check_recursionquota() to acquire_recursionquota(), and
implement a new function called release_recursionquota() to
reverse the action. It helps with decreasing code duplication.
(cherry picked from commit 7bd44a4182)
In two places, after linking the client to the manager's
"recursing-clients" list using the check_recursionquota()
function, the query.c module fails to unlink it on error
paths. Fix the bugs by unlinking the client from the list.
Also make sure that unlinking happens before detaching the
client's handle, as it is the logically correct order, e.g.
in case if it's the last handle and ns__client_reset_cb()
can be called because of the detachment.
(cherry picked from commit 36c4808903)
The 'nodetach' member is a leftover from the times when non-zero
'stale-answer-client-timeout' values were supported, and currently
is always 'false'. Clean up the member and its usage.
(cherry picked from commit b8c068835e)
Query and response log shares the same flags. Move flags logging out of
log_query to share it with log_response. Use buffer instead of snprintf
to fill flags a bit faster.
Signed-off-by: Petr Menšík <pemensik@redhat.com>
(cherry picked from commit e6b19af2dd)
Remove answer flag from log, log instead count of records for each
message section. Include EDNS version and few flags of response. Add
also status of result.
Still does not include body of responses rrset.
(cherry picked from commit 6f879aba65)
Log to the querylog the rcode of a previous query using
the identifier 'response:' to diffenciate queries from
responses.
(cherry picked from commit 5fad79c92f)
Return partial match from dns_db_find/dns_db_find when requested
to short circuit the closest encloser discover process. Most of the
time this will be the actual closest encloser but may not be when
there yet to be committed / cleaned up versions of the zone with
names below the actual closest encloser.
(cherry picked from commit d42ea08f16)
Log canceled queries (e.g. when shutting down a hung fetch)
in DEBUG3 level instead of DEBUG1 which is used for the
"unrecognized" result codes.
(cherry picked from commit 8bb9568467)
MAX_RESTARTS is no longer hard-coded; ns_server_setmaxrestarts()
and dns_client_setmaxrestarts() can now be used to modify the
max-restarts value at runtime. in both cases, the default is 11.
(cherry picked from commit c5588babaf)
the number of steps that can be followed in a CNAME chain
before terminating the lookup has been reduced from 16 to 11.
(this is a hard-coded value, but will be made configurable later.)
(cherry picked from commit 05d78671bb)
When automatic-interface-scan is disabled, the route socket was still
being opened. Add new API to connect / disconnect from the route socket
only as needed.
Additionally, move the block that disables periodic interface rescans to
a place where it actually have access to the configuration values.
Previously, the values were being checked before the configuration was
loaded.
(cherry picked from commit b26079fdaf)
Due to the maximum query restart limitation a long CNAME chain
it is cut after 16 queries but named still returns NOERROR.
Return SERVFAIL instead and the partial answer.
(cherry picked from commit b621f1d88e)
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.
As ns_query_init() cannot fail now, remove the error paths, especially
in ns__client_setup() where we now don't have to care what to do with
the connection if setting up the client could fail. It couldn't fail
even before, but now it's formal.
Clear qctx->zversion when clearing qctx->zrdataset et al in
lib/ns/query.c:qctx_freedata. The uncleared pointer could lead to
an assertion failure if zone data needed to be re-saved which could
happen with stale data support enabled.
View matching on an incoming query checks the query's signature,
which can be a CPU-heavy task for a SIG(0)-signed message. Implement
an asynchronous mode of the view matching function which uses the
offloaded signature checking facilities, and use it for the incoming
queries.
In order to protect from a malicious DNS client that sends many
queries with a SIG(0)-signed message, add a quota of simultaneously
running SIG(0) checks.
This protection can only help when named is using more than one worker
threads. For example, if named is running with the '-n 4' option, and
'sig0checks-quota 2;' is used, then named will make sure to not use
more than 2 workers for the SIG(0) signature checks in parallel, thus
leaving the other workers to serve the remaining clients which do not
use SIG(0)-signed messages.
That limitation is going to change when SIG(0) signature checks are
offloaded to "slow" threads in a future commit.
The 'sig0checks-quota-exempt' ACL option can be used to exempt certain
clients from the quota requirements using their IP or network addresses.
The 'sig0checks-quota-maxwait-ms' option is used to define a maximum
amount of time for named to wait for a quota to appear. If during that
time no new quota becomes available, named will answer to the client
with DNS_R_REFUSED.
The changes in this MR prevent the memory used for sending the outgoing
TCP requests to spike so much. That strictly remove the extra need for
own memory context, and thus since we generally prefer simplicity,
remove the extra memory context with own jemalloc arenas just for the
outgoing send buffers.
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.
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.
The high-water allows administrators to better tune the recursive
clients limit without having to to poll the statistics channel in high
rates to get this number.
Returning the value allows for better high-water tracking without
running into edge cases like the following:
0. The counter is at value X
1. Increment the value (X+1)
2. The value is decreased multiple times in another threads (X+1-Y)
3. Get the value (X+1-Y)
4. Update-if-greater misses the X+1 value which should have been the
high-water
An RPZ response's SOA record TTL is set to 1 instead of the SOA TTL,
a boolean value is passed on to query_addsoa, which is supposed to be
a TTL value. I don't see what value is appropriate to be used for
overriding, so we will pass UINT32_MAX.
Because some tests don't have a legtimate handle, provide a temporary
return early that should be fixed and removed before squashing. This
short circuiting is still correct until DoQ/DoH3 support is introduced.
GCC might fail to compile because it expects a return after UNREACHABLE.
It should ideally just work anyway since UNREACHABLE is either a
noreturn or UB (__builtin_unreachable / C23 unreachable).
Either way, it should be optimized almost always so the fallback is
free or basically free anyway when it isn't optimized out.
Colin Vidal
Ondřej SurýandColin Vidal
Andoni Duarte Pintado
Matthijs Mekking
Evan Hunt
Aram Sargsyan
Petr MenšíkandMark Andrews
Aydın Mercan