This commit contains fixes to unit tests to make them work well on
various platforms (in particular ones shipping old versions of
OpenSSL) and for different configurations.
It also updates the generated manpage to include DoH configuration
options.
This commit completes the support for DNS-over-HTTP(S) built on top of
nghttp2 and plugs it into the BIND. Support for both GET and POST
requests is present, as required by RFC8484.
Both encrypted (via TLS) and unencrypted HTTP/2 connections are
supported. The latter are mostly there for debugging/troubleshooting
purposes and for the means of encryption offloading to third-party
software (as might be desirable in some environments to simplify TLS
certificates management).
This commit includes work-in-progress implementation of
DNS-over-HTTP(S).
Server-side code remains mostly untested, and there is only support
for POST requests.
This commit resurrects the old TLS code from
8f73c70d23e26954165fd44ce5617a95f112bcff.
It also includes numerous stability fixes and support for
isc_nm_cancelread() for the TLS layer.
The code was resurrected to be used for DoH.
* Following the example set in 634bdfb16d8, the tlsdns netmgr
module now uses libuv and SSL primitives directly, rather than
opening a TLS socket which opens a TCP socket, as the previous
model was difficult to debug. Closes#2335.
* Remove the netmgr tls layer (we will have to re-add it for DoH)
* Add isc_tls API to wrap the OpenSSL SSL_CTX object into libisc
library; move the OpenSSL initialization/deinitialization from dstapi
needed for OpenSSL 1.0.x to the isc_tls_{initialize,destroy}()
* Add couple of new shims needed for OpenSSL 1.0.x
* When LibreSSL is used, require at least version 2.7.0 that
has the best OpenSSL 1.1.x compatibility and auto init/deinit
* Enforce OpenSSL 1.1.x usage on Windows
* Added a TLSDNS unit test and implemented a simple TLSDNS echo
server and client.
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.
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.
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.
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.
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
When calling the high level netmgr functions, the callback would be
sometimes called synchronously if we catch the failure directly, or
asynchronously if it happens later. The synchronous call to the
callback could create deadlocks as the caller would not expect the
failed callback to be executed directly.
This commit adds couple of additional safeguards against running
sends/reads on inactive sockets. The changes was modeled after the
changes we made to netmgr/tcpdns.c
Parse the configuration of tls objects into SSL_CTX* objects. Listen on
DoT if 'tls' option is setup in listen-on directive. Use DoT/DoH ports
for DoT/DoH.
Add server-side TLS support to netmgr - that includes moving some of the
isc_nm_ functions from tcp.c to a wrapper in netmgr.c calling a proper
tcp or tls function, and a new isc_nm_listentls() function.
Add DoT support to tcpdns - isc_nm_listentlsdns().
there were two failures during observed in testing, both occurring
when 'rndc halt' was run rather than 'rndc stop' - the latter dumps
zone contents to disk and presumably introduced enough delay to
prevent the races:
- a failure when the zone was shut down and called dns_xfrin_detach()
before the xfrin had finished connecting; the connect timeout
terminated without detaching its handle
- a failure when the tcpdns socket timer fired after the outerhandle
had already been cleared.
this commit incidentally addresses a failure observed in mutexatomic
due to a variable having been initialized incorrectly.
socket() call can return an error - e.g. EMFILE, so we need to handle
this nicely and not crash.
Additionally wrap the socket() call inside a platform independent helper
function as the Socket data type on Windows is unsigned integer:
> This means, for example, that checking for errors when the socket and
> accept functions return should not be done by comparing the return
> value with –1, or seeing if the value is negative (both common and
> legal approaches in UNIX). Instead, an application should use the
> manifest constant INVALID_SOCKET as defined in the Winsock2.h header
> file.
Because we use result earlier for setting the loadbalancing on the
socket, we could be left with a ISC_R_NOTIMPLEMENTED value stored in the
variable and when the UDP connection would succeed, we would
errorneously return this value instead of ISC_R_SUCCESS.
this function sets the read timeout for the socket associated
with a netmgr handle and, if the timer is running, resets it.
for TCPDNS sockets it also sets the read timeout and resets the
timer on the outer TCP socket.
When we are operating on the tcpdns socket, we need to double check
whether the socket or its outerhandle or its listener or its mgr is
still active and when not, bail out early.
If dnslisten_readcb gets a read callback it needs to verify that the
outer socket wasn't closed in the meantime, and issue a CANCELED callback
if it was.
There were more races that could happen while connecting to a
socket while closing or shutting down the same socket. This
commit introduces a .closing flag to guard the socket from
being closed twice.
There was a data race where a new event could be scheduled after
isc__nm_async_shutdown() had cleaned up all the dangling UDP/TCP
sockets from the loop.
- more logical code flow.
- propagate errors back to the caller.
- add a 'reading' flag and call the callback from failed_read_cb()
only when it the socket was actively reading.
- don't bother closing sockets that are already closing.
- UDP read timeout timer was not stopped after reading.
- improve handling of TCP connection failures.
- isc_nm_tcpdnsconnect() sets up up an outgoing TCP DNS connection.
- isc_nm_tcpconnect(), _udpconnect() and _tcpdnsconnect() now take a
timeout argument to ensure connections time out and are correctly
cleaned up on failure.
- isc_nm_read() now supports UDP; it reads a single datagram and then
stops until the next time it's called.
- isc_nm_cancelread() now runs asynchronously to prevent assertion
failure if reading is interrupted by a non-network thread (e.g.
a timeout).
- isc_nm_cancelread() can now apply to UDP sockets.
- added shim code to support UDP connection in versions of libuv
prior to 1.27, when uv_udp_connect() was added
all these functions will be used to support outgoing queries in dig,
xfrin, dispatch, etc.
If the connection is closed while we're processing the request
we might access TCPDNS outerhandle which is already reset. Check
for this condition and call the callback with ISC_R_CANCELED result.
When client disconnects before the connection can be accepted, the named
would log a spurious log message:
error: Accepting TCP connection failed: socket is not connected
We now ignore the ISC_R_NOTCONNECTED result code and log only other
errors
1. The isc__nm_tcp_send() and isc__nm_tcp_read() was not checking
whether the socket was still alive and scheduling reads/sends on
closed socket.
2. The isc_nm_read(), isc_nm_send() and isc_nm_resumeread() have been
changed to always return the error conditions via the callbacks, so
they always succeed. This applies to all protocols (UDP, TCP and
TCPDNS).
There were two problems how tcp_send_direct() was used:
1. The tcp_send_direct() can return ISC_R_CANCELED (or translated error
from uv_tcp_send()), but the isc__nm_async_tcpsend() wasn't checking
the error code and not releasing the uvreq in case of an error.
2. In isc__nm_tcp_send(), when the TCP send is already in the right
netthread, it uses tcp_send_direct() to send the TCP packet right
away. When that happened the uvreq was not freed, and the error code
was returned to the caller. We need to return ISC_R_SUCCESS and
rather use the callback to report an error in such case.
When closing the socket that is actively reading from the stream, the
read_cb() could be called between uv_close() and close callback when the
server socket has been already detached hence using sock->statichandle
after it has been already freed.
There were two problems how udp_send_direct() was used:
1. The udp_send_direct() can return ISC_R_CANCELED (or translated error
from uv_udp_send()), but the isc__nm_async_udpsend() wasn't checking
the error code and not releasing the uvreq in case of an error.
2. In isc__nm_udp_send(), when the UDP send is already in the right
netthread, it uses udp_send_direct() to send the UDP packet right
away. When that happened the uvreq was not freed, and the error code
was returned to the caller. We need to return ISC_R_SUCCESS and
rather use the callback to report an error in such case.
