On TCPDNS/TLSDNS read callback, the socket buffer could be reallocated
if the received contents would be larger than the buffer. The existing
code would not preserve the contents of the existing buffer which lead
to the loss of the already received data.
This commit changes the isc_mem_put()+isc_mem_get() with isc_mem_reget()
to preserve the existing contents of the socket buffer.
The netmgr, has an internal cache for freed active handles. This cache
was allocated using isc_mem_allocate()/isc_mem_free() API because it was
simpler to reallocate the cache when we needed to grow it. The new
isc_mem_reget() function could be used here reducing the need to use
isc_mem_allocate() API which is tad bit slower than isc_mem_get() API.
Previously, we cannot use isc_mem_reallocate() for growing the buffer
dynamically, because the memory was allocated using the
isc_mem_get()/isc_mem_put() API. With the introduction of the
isc_mem_reget() function, we can use grow/shrink the memory directly
without always moving the memory around as the allocator might have
reserved some extra space after the initial allocation.
Previously, the zero-sized allocations would return NULL pointer and the
caller had to make sure to not dereference such pointer. The C standard
defines the zero-sized calls to malloc() as implementation specific and
jemalloc mallocx() with zero size would be undefined behaviour. This
complicated the code as it had to handle such cases in a special manner
in all allocator and deallocator functions.
Now, for realloc(), the situation is even more complicated. In C
standard up to C11, the behavior would be implementation defined, and
actually some implementation would free to orig ptr and some would not.
Since C17 (via DR400) would deprecate such usage and since C23, the
behaviour would be undefined.
This commits changes helper mem_get(), mem_put() and mem_realloc()
functions to grow the zero-allocation from 0 to sizeof(void *).
This way we get a predicable behaviour that all the allocations will
always return valid pointer.
The isc_mem_get() and isc_mem_put() functions are leaving the memory
allocation size tracking to the users of the API, while
isc_mem_allocate() and isc_mem_free() would track the sizes internally.
This allowed to have isc_mem_rellocate() to manipulate the memory
allocations by the later set, but not the former set of the functions.
This commit introduces isc_mem_reget(ctx, old_ptr, old_size, new_size)
function that operates on the memory allocations with external size
tracking completing the API.
The native PKCS#11 support has been removed in favour of better
maintained, more performance and easier to use OpenSSL PKCS#11 engine
from the OpenSC project.
This commit adds new function isc_nm_http_makeuri() which is supposed
to unify DoH URI construction throughout the codebase.
It handles IPv6 addresses, hostnames, and IPv6 addresses given as
hostnames properly, and replaces similar ad-hoc code in the codebase.
The previous versions of BIND 9 exported its internal libraries so that
they can be used by third-party applications more easily. Certain
library functions were altered from specific BIND-only behavior to more
generic behavior when used by other applications.
This commit removes the function isc_lib_register() that was used by
external applications to enable the functionality.
this commit removes isc__nm_tcpdns_keepalive() and
isc__nm_tlsdns_keepalive(); keepalive for these protocols and
for TCP will now be set directly from isc_nmhandle_keepalive().
protocols that have an underlying TCP socket (i.e., TLS stream
and HTTP), now have protocol-specific routines, called by
isc_nmhandle_keeaplive(), to set the keepalive value on the
underlying socket.
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.
- fix some duplicated and out-of-order prototypes declared in
netmgr-int.h
- rename isc_nm_tcpdns_keepalive to isc__nm_tcpdns_keepalive as
it's for internal use
This commit changes the DoH code in such a way that it makes no
assumptions regarding which headers are expected to be processed
first. In particular, the code expected the :method: pseudo-header to
be processed early, which might not be true.
Add a new function to resize the number of counters in a statistics
counter structure. This will be needed when we keep track of DNSSEC
sign statistics and new keys are introduced due to a rollover.
Add a simple stats unit test that tests the existing library functions
isc_stats_ncounters, isc_stats_increment, isc_stats_decrement,
isc_stats_set, and isc_stats_update_if_greater.
Instead of disabling the fragmentation on the UDP sockets, we now
disable the Path MTU Discovery by setting IP(V6)_MTU_DISCOVER socket
option to IP_PMTUDISC_OMIT on Linux and disabling IP(V6)_DONTFRAG socket
option on FreeBSD. This option sets DF=0 in the IP header and also
ignores the Path MTU Discovery.
As additional mitigation on Linux, we recommend setting
net.ipv4.ip_no_pmtu_disc to Mode 3:
Mode 3 is a hardend pmtu discover mode. The kernel will only accept
fragmentation-needed errors if the underlying protocol can verify
them besides a plain socket lookup. Current protocols for which pmtu
events will be honored are TCP, SCTP and DCCP as they verify
e.g. the sequence number or the association. This mode should not be
enabled globally but is only intended to secure e.g. name servers in
namespaces where TCP path mtu must still work but path MTU
information of other protocols should be discarded. If enabled
globally this mode could break other protocols.
The commit fixes the doh_recv_send() because occasionally it would
fail because it did not wait for all responses to be sent, making the
check for ssends value to nit pass.
This commit changes TLS stream behaviour in such a way, that it is now
optimised for small writes. In the case there is a need to write less
or equal to 512 bytes, we could avoid calling the memory allocator at
the expense of possibly slight increase in memory usage. In case of
larger writes, the behviour remains unchanged.
At least at this point doing memory copying is not required. Probably
it was a workaround for some problem in the earlier days of DoH, at
this point it appears to be a waste of CPU cycles.
This commit significantly simplifies the code in http_send_outgoing()
as it was unnecessary complicated, because it was dealing with
multiple statically and dynamically allocated buffers, making it
extremely hard to follow, as well as making it to do unnecessary
memory copying in some situations. This commit fixes these issues,
while retaining the high level buffering logic.
When an HTTP/2 client terminates a session it means that it is about
to close the underlying connection. However, we were not doing that.
As a result, with the latest changes to the test suite, which made it
to limit amount of requests per a transport connection, the tests
using quota would hang for quite a while. This commit fixes that.
This commit ensures that only a limited number of requests is going to
be sent over a single HTTP/2 connection. Before that change was
introduced, it was possible to complete all of the planned sends via
only one transport connection, which undermines the purpose of the
tests using the quota facility.
The function should not be called here because it is, in general,
supposed to be called at the end of the transport level callbacks to
perform I/O, and thus, calling it here is clearly a mistake because it
breaks other code expectations. As a result of the call to
http_do_bio() from within isc__nm_http_request() the unit tests were
running slower than expected in some situations.
In this particular situation http_do_bio() is going to be called at
the end of the transport_connect_cb() (initially), or http_readcb(),
sending all of the scheduled requests at once.
This change affects only the test suite because it is the only place
in the codebase where isc__nm_http_request() is used in order to
ensure that the server is able to handle multiple HTTP/2 streams at
once.
This commit fixes a crash in DoH caused by transport handle to be
detached too early when sending outgoing data.
We need to attach to the session->handle earlier because as an
indirect result of the nghttp2_session_mem_send() the session might
get closed and the handle detached. However, there is still might be
some outgoing data to handle. Besides, even when the underlying socket
was closed via the handle, we still should try to attempt to send
outgoing data via isc_nm_send() to let it call write callback, passed
to the http_send_outgoing().
This commit gets rid of custom code taking care of response buffering
by replacing the custom code with isc_buffer_t. Also, it gets rid of
an unnecessary memory copying when sending a response.
This commit replaces the ad-hoc 64K buffer for incoming POST data with
isc_buffer_t backed by dynamically allocated buffer sized accordingly
to the value in the "Content-Length" header.
The commit replaces an ad-hoc incoming DNS-message buffer in the
client-side DoH code with isc_buffer_t.
The commit also fixes a timing issue in the unit tests revealed by the
change.
This commit replaces a static ad-hoc HTTP/2 session's temporary buffer
with a realloc-able isc_buffer_t object, which is being allocated on
as needed basis, lowering the memory consumption somewhat. The buffer
is needed in very rare cases, so allocating it prematurely is not
wise.
Also, it fixes a bug in http_readcb() where the ad-hoc buffer appeared
to be improperly used, leading to a situation when the processed data
from the receiving regions can be processed twice, while unprocessed
data will never be processed.
This commit gets rid of RW locks in a hot path of the DoH code. In the
original design, it was implied that we add new endpoints after the
HTTP listener was created. Such a design implies some locking. We do
not need such flexibility, though. Instead, we could build a set of
endpoints before the HTTP listener gets created. Such a design does
not need RW locks at all.
On the isc_mem water change the old water_t structure could be used
after free. Instead of introducing reference counting on the hot-path
we are going to introduce additional constraints on the
isc_mem_setwater. Once it's set for the first time, the additional
calls have to be made with the same water and water_arg arguments.
This commit makes number of concurrent HTTP/2 streams per connection
configurable as a mean to fight DDoS attacks. As soon as the limit is
reached, BIND terminates the whole session.
The commit adds a global configuration
option (http-streams-per-connection) which can be overridden in an
http <name> {...} statement like follows:
http local-http-server {
...
streams-per-connection 100;
...
};
For now the default value is 100, which should be enough (e.g. NGINX
uses 128, but it is a full-featured WEB-server). When using lower
numbers (e.g. ~70), it is possible to hit the limit with
e.g. flamethrower.
This commit adds support for http-listener-clients global options as
well as ability to override the default in an HTTP server description,
like:
http local-http-server {
...
listener-clients 100;
...
};
This way we have ability to specify per-listener active connections
quota globally and then override it when required. This is exactly
what AT&T requested us: they wanted a functionality to specify quota
globally and then override it for specific IPs. This change
functionality makes such a configuration possible.
It makes sense: for example, one could have different quotas for
internal and external clients. Or, for example, one could use BIND's
internal ability to serve encrypted DoH with some sane quota value for
internal clients, while having un-encrypted DoH listener without quota
to put BIND behind a load balancer doing TLS offloading for external
clients.
Moreover, the code no more shares the quota with TCP, which makes
little sense anyway (see tcp-clients option), because of the nature of
interaction of DoH clients: they tend to keep idle opened connections
for longer periods of time, preventing the TCP and TLS client from
being served. Thus, the need to have a separate, generally larger,
quota for them.
Also, the change makes any option within "http <name> { ... };"
statement optional, making it easier to override only required default
options.
By default, the DoH connections are limited to 300 per listener. I
hope that it is a good initial guesstimate.
This commit adds the code (and some tests) which allows verifying
validity of HTTP paths both in incoming HTTP requests and in BIND's
configuration file.
An unhandled code path left GET query string data uninitialised (equal
to NULL) and led to a crash during the requests' base64 data
decoding. This commit fixes that.
It was discovered that setting the thread affinity on both the netmgr
and netthread threads lead to inconsistent recursive performance because
sometimes the netmgr and netthread threads would compete over single
resource and sometimes not.
Removing setting the affinity causes a slight dip in the authoritative
performance around 5% (the measured range was from 3.8% to 7.8%), but
the recursive performance is now consistently good.
