On Windows, we were limiting the number of listening children to just 1,
but we were then iterating on mgr->nworkers. That lead to scheduling
more async_*listen() than actually allocated and out-of-bound read-write
operation on the heap.
As there's no TCP connection timeout socket option that we can use, we
need to configure the TCP connection timeout system-wide in the CI, so
the netmgr unit tests doesn't cause assertion failure when there stuck
outgoing TCP connection waiting for 150 second timeout.
When we were in nmthread, the isc__nm_async_<proto>connect() function
executes in the same thread as the isc__nm_<proto>connect() and on a
failure, it would block indefinitely because the failure branch was
setting sock->active to false before the condition around the wait had a
chance to skip the WAIT().
This also fixes the zero system test being stuck on FreeBSD 11, so we
re-enable the test in the commit.
The current issues with the way dig handles TCP "connection refused"
errors cause the "legacy" system test to consistently fail on Windows
due to the expected strings not being present in dig output.
Temporarily disable the "legacy" system test on Windows by moving it
from the PARALLEL_COMMON list to the PARALLEL_UNIX list until the
situation is rectified.
On FreeBSD, the option to configure connection timeout is called
TCP_KEEPINIT, use it to configure the connection timeout there.
This also fixes the dangling socket problems in the unit test, so
re-enable them.
On platforms without load-balancing socket all the queries would be
handle by a single thread. Currently, the support for load-balanced
sockets is present in Linux with SO_REUSEPORT and FreeBSD 12 with
SO_REUSEPORT_LB.
This commit adds workaround for such platforms that:
1. setups single shared listening socket for all listening nmthreads for
UDP, TCP and TCPDNS netmgr transports
2. Calls uv_udp_bind/uv_tcp_bind on the underlying socket just once and
for rest of the nmthreads only copy the internal libuv flags (should
be just UV_HANDLE_BOUND and optionally UV_HANDLE_IPV6).
3. start reading on UDP socket or listening on TCP socket
The load distribution among the nmthreads is uneven, but it's still
better than utilizing just one thread for processing all the incoming
queries
On FreeBSD, the stack is destroyed more aggressively than on Linux and
that revealed a bug where we were allocating the 16-bit len for the
TCPDNS message on the stack and the buffer got garbled before the
uv_write() sendback was executed. Now, the len is part of the uvreq, so
we can safely pass it to the uv_write() as the req gets destroyed after
the sendcb is executed.
On Windows, WSAStartup() needs to be called to initialize Winsock before
any sockets are created or else socket() calls will return error code
10093 (WSANOTINITIALISED). Since BIND's Network Manager is intended to
work as a reusable networking library, it should take care of calling
WSAStartup() - and its cleanup counterpart, WSACleanup() - itself rather
than relying on external code to do it. Add the necessary WSAStartup()
and WSACleanup() calls to isc_nm_start() and isc_nm_destroy(),
respectively.
uv_wrap.h is included in tcp_test.c and udp_test.c and therefore should
be listed in lib/isc/tests/Makefile.am, otherwise unit test run from
distribution tarball fails to compile:
tcp_test.c:37:10: fatal error: uv_wrap.h: No such file or directory
#include "uv_wrap.h"
^~~~~~~~~~~
udp_test.c:37:10: fatal error: uv_wrap.h: No such file or directory
#include "uv_wrap.h"
^~~~~~~~~~~
The DNS Flag Day 2020 reduced all the EDNS buffer sizes to 1232. In
this commit, we revert the default value for nocookie-udp-size back to
4096 because the option is too obscure and most people don't realize
that they also need to change this configuration option in addition to
max-udp-size.
After turning the users callbacks to be asynchronous, there was a
visible performance drop. This commit prevents the unnecessary
allocations while keeping the code paths same for both asynchronous and
synchronous calls.
The same change was done to the isc__nm_udp_{read,send} as those two
functions are in the hot path.
The new netmgr tests are not-yet fine-tuned for non-Linux platforms.
Disable them now, so we can move forward and fix the tests of *BSD
in the next iteration.
This commit will get reverted when we add support for netmgr
multi-threading.
Due to the platform differences, on non-Linux platforms, the xfer and
ixfr tests fails and zero test gets stuck.
This commit will get reverted when we add support for netmgr
multi-threading.
The isc/util.h header redefine the DbC checks (REQUIRE, INSIST, ...) to
be cmocka "fake" assertions. However that means that cmocka.h needs to
be included after UNIT_TESTING is defined but before isc/util.h is
included. Because isc/util.h is included in most of the project headers
this means that the sequence MUST be:
#define UNIT_TESTING
#include <cmocka.h>
#include <isc/_anything_.h>
See !2204 for other header requirements for including cmocka.h.
This is a part of the works that intends to make the netmgr stable,
testable, maintainable and tested. It contains a numerous changes to
the netmgr code and unfortunately, it was not possible to split this
into smaller chunks as the work here needs to be committed as a complete
works.
NOTE: There's a quite a lot of duplicated code between udp.c, tcp.c and
tcpdns.c and it should be a subject to refactoring in the future.
The changes that are included in this commit are listed here
(extensively, but not exclusively):
* The netmgr_test unit test was split into individual tests (udp_test,
tcp_test, tcpdns_test and newly added tcp_quota_test)
* The udp_test and tcp_test has been extended to allow programatic
failures from the libuv API. Unfortunately, we can't use cmocka
mock() and will_return(), so we emulate the behaviour with #define and
including the netmgr/{udp,tcp}.c source file directly.
* The netievents that we put on the nm queue have variable number of
members, out of these the isc_nmsocket_t and isc_nmhandle_t always
needs to be attached before enqueueing the netievent_<foo> and
detached after we have called the isc_nm_async_<foo> to ensure that
the socket (handle) doesn't disappear between scheduling the event and
actually executing the event.
* Cancelling the in-flight TCP connection using libuv requires to call
uv_close() on the original uv_tcp_t handle which just breaks too many
assumptions we have in the netmgr code. Instead of using uv_timer for
TCP connection timeouts, we use platform specific socket option.
* Fix the synchronization between {nm,async}_{listentcp,tcpconnect}
When isc_nm_listentcp() or isc_nm_tcpconnect() is called it was
waiting for socket to either end up with error (that path was fine) or
to be listening or connected using condition variable and mutex.
Several things could happen:
0. everything is ok
1. the waiting thread would miss the SIGNAL() - because the enqueued
event would be processed faster than we could start WAIT()ing.
In case the operation would end up with error, it would be ok, as
the error variable would be unchanged.
2. the waiting thread miss the sock->{connected,listening} = `true`
would be set to `false` in the tcp_{listen,connect}close_cb() as
the connection would be so short lived that the socket would be
closed before we could even start WAIT()ing
* The tcpdns has been converted to using libuv directly. Previously,
the tcpdns protocol used tcp protocol from netmgr, this proved to be
very complicated to understand, fix and make changes to. The new
tcpdns protocol is modeled in a similar way how tcp netmgr protocol.
Closes: #2194, #2283, #2318, #2266, #2034, #1920
* The tcp and tcpdns is now not using isc_uv_import/isc_uv_export to
pass accepted TCP sockets between netthreads, but instead (similar to
UDP) uses per netthread uv_loop listener. This greatly reduces the
complexity as the socket is always run in the associated nm and uv
loops, and we are also not touching the libuv internals.
There's an unfortunate side effect though, the new code requires
support for load-balanced sockets from the operating system for both
UDP and TCP (see #2137). If the operating system doesn't support the
load balanced sockets (either SO_REUSEPORT on Linux or SO_REUSEPORT_LB
on FreeBSD 12+), the number of netthreads is limited to 1.
* The netmgr has now two debugging #ifdefs:
1. Already existing NETMGR_TRACE prints any dangling nmsockets and
nmhandles before triggering assertion failure. This options would
reduce performance when enabled, but in theory, it could be enabled
on low-performance systems.
2. New NETMGR_TRACE_VERBOSE option has been added that enables
extensive netmgr logging that allows the software engineer to
precisely track any attach/detach operations on the nmsockets and
nmhandles. This is not suitable for any kind of production
machine, only for debugging.
* The tlsdns netmgr protocol has been split from the tcpdns and it still
uses the old method of stacking the netmgr boxes on top of each other.
We will have to refactor the tlsdns netmgr protocol to use the same
approach - build the stack using only libuv and openssl.
* Limit but not assert the tcp buffer size in tcp_alloc_cb
Closes: #2061
Since the queries sent towards root and TLD servers are now included in
the count (as a result of the fix for CVE-2020-8616),
"max-recursion-queries" has a higher chance of being exceeded by
non-attack queries. Increase its default value from 75 to 100.
