Previously, there was no limit to the number of concurrently served
queries over one pipelined TCP connection; an unlimited number of
queries sent over a single TCP connection could have potentially
exhausted the server's resources.
This variable will report the maximum number of simultaneous tcp clients
that BIND has served while running.
It can be verified by running rndc status, then inspect "tcp high-water:
count", or by generating statistics file, rndc stats, then inspect the
line with "TCP connection high-water" text.
The tcp-highwater variable is atomically updated based on an existing
tcp-quota system handled in ns/client.c.
(cherry picked from commit 66fe8627de)
This commit changes the BIND cookie algorithms to match
draft-sury-toorop-dnsop-server-cookies-00. Namely, it changes the Client Cookie
algorithm to use SipHash 2-4, adds the new Server Cookie algorithm using SipHash
2-4. The change doesn't make the SipHash 2-4 to be the default algorithm, this
is up to the operator.
(cherry picked from commit 196b342bc9)
Backport named command line switches implemented in commit
c81c9660f5 as they are needed by the
"legacy" system checks which are currently present in master and v9_14
branches, but missing in the v9_11 branch.
in the "refactor tcpquota and pipeline refs" commit, the counting
of active interfaces was tightened in such a way that named could
fail to listen on an interface if there were more interfaces than
tcp-clients. when checking the quota to start accepting on an
interface, if the number of active clients was above zero, then
it was presumed that some other client was able to handle accepting
new connections. this, however, ignored the fact that the current client
could be included in that count, so if the quota was already exceeded
before all the interfaces were listening, some interfaces would never
listen.
we now check whether the current client has been marked active; if so,
then the number of active clients on the interface must be greater
than 1, not 0.
(cherry picked from commit 0b4e2cd4c3192ba88569dd344f542a8cc43742b5)
(cherry picked from commit d01023aaac)
- if the TCP quota has been exceeded but there are no clients listening
for new connections on the interface, we can now force attachment to the
quota using isc_quota_force(), instead of carrying on with the quota not
attached.
- the TCP client quota is now referenced via a reference-counted
'ns_tcpconn' object, one of which is created whenever a client begins
listening for new connections, and attached to by members of that
client's pipeline group. when the last reference to the tcpconn
object is detached, it is freed and the TCP quota slot is released.
- reduce code duplication by adding mark_tcp_active() function.
- convert counters to atomic.
(cherry picked from commit 7e8222378ca24f1302a0c1c638565050ab04681b)
(cherry picked from commit 4939451275722bfda490ea86ca13e84f6bc71e46)
(cherry picked from commit 13f7c918b8)
- ensure that tcpactive is cleaned up correctly when accept() fails.
- set 'client->tcpattached' when the client is attached to the tcpquota.
carry this value on to new clients sharing the same pipeline group.
don't call isc_quota_detach() on the tcpquota unless tcpattached is
set. this way clients that were allowed to accept TCP connections
despite being over quota (and therefore, were never attached to the
quota) will not inadvertently detach from it and mess up the
accounting.
- simplify the code for tcpquota disconnection by using a new function
tcpquota_disconnect().
- before deciding whether to reject a new connection due to quota
exhaustion, check to see whether there are at least two active
clients. previously, this was "at least one", but that could be
insufficient if there was one other client in READING state (waiting
for messages on an open connection) but none in READY (listening
for new connections).
- before deciding whether a TCP client object can to go inactive, we
must ensure there are enough other clients to maintain service
afterward -- both accepting new connections and reading/processing new
queries. A TCP client can't shut down unless at least one
client is accepting new connections and (in the case of pipelined
clients) at least one additional client is waiting to read.
(cherry picked from commit c7394738b2445c16f728a88394864dd61baad900)
(cherry picked from commit e965d5f11d3d0f6d59704e614fceca2093cb1856)
(cherry picked from commit 87d4311614)
Track pipeline groups using a shared reference counter
instead of a linked list.
(cherry picked from commit 513afd33eb17d5dc41a3f0d2d38204ef8c5f6f91)
(cherry picked from commit 9446629b73)
the TCP client quota could still be ineffective under some
circumstances. this change:
- improves quota accounting to ensure that TCP clients are
properly limited, while still guaranteeing that at least one client
is always available to serve TCP connections on each interface.
- uses more descriptive names and removes one (ntcptarget) that
was no longer needed
- adds comments
(cherry picked from commit 924651f1d5e605cd186d03f4f7340bcc54d77cc2)
(cherry picked from commit 55a7a458e3)
tcp-clients settings could be exceeded in some cases by
creating more and more active TCP clients that are over
the set quota limit, which in the end could lead to a
DoS attack by e.g. exhaustion of file descriptors.
If TCP client we're closing went over the quota (so it's
not attached to a quota) mark it as mortal - so that it
will be destroyed and not set up to listen for new
connections - unless it's the last client for a specific
interface.
(cherry picked from commit f97131d21b97381cef72b971b157345c1f9b4115)
(cherry picked from commit 9689ffc485)
While implementing the new unit testing framework cmocka, it was found that the
BIND 9 code doesn't compile when assertions are disabled or replaced with any
function (such as mock_assert() from cmocka unit testing framework) that's not
directly recognized as assertion by the compiler.
This made the compiler to complain about blocks of code that was recognized as
unreachable before, but now it isn't.
The changes in this commit include:
* assigns default values to couple of local variables,
* moves some return statements around INSIST assertions,
* adds __builtin_unreachable(); annotations after some INSIST assertions,
* fixes one broken assertion (= instead of ==)
(cherry picked from commit fbd2e47f51)
(cherry picked from commit b222783ae9)
record trust-anchor-telementry in incoming requests.
Both _ta-XXXX.<anchor>/NULL and EDNS KEY-TAG options
are logged. [RT #46124]
(cherry picked from commit b41c1aacbc)
4722. [cleanup] Clean up uses of strcpy() and strcat() in favor of
strlcpy() and strlcat() for safety. [RT #45981]
(cherry picked from commit 114f95089c)
4569. [func] Store both local and remote addresses in dnstap
logging, and modify dnstap-read output format to
print them. [RT #43595]
(cherry picked from commit 650b5e7592)
4471. [cleanup] Render client/query logging format consistent for
ease of log file parsing. (Note that this affects
"querylog" format: there is now an additional field
indicating the client object address.) [RT #43238]
(cherry picked from commit c4b7db4932)
4459. [bug] TCP client objects created to handle pipeline queries
were not cleaned up correctly, causing uncontrolled
memory growth. [RT #43106]
(cherry picked from commit a26a62cef2)
Witold KręcickiandMichał Kępień
Diego FronzaandOndřej Surý
Mark Andrews
Evan HuntandOndřej Surý
Mukund SivaramanandEvan Hunt
Tony FinchandEvan Hunt
Tinderbox User