This commit adds an initial implementation of isc_nm_streamdnssocket
transport: a unified transport for DNS over stream protocols messages,
which is capable of replacing both TCP DNS and TLS DNS
transports. Currently, the interface it provides is a unified set of
interfaces provided by both of the transports it attempts to replace.
The transport is built around "isc_dnsbuffer_t" and
"isc_dnsstream_assembler_t" objects and attempts to minimise both the
number of memory allocations during network transfers as well as
memory usage.
The added function provides the interface for getting an ALPN tag
negotiated during TLS connection establishment.
The new function can be used by higher level transports.
This commit adds manual read timer control mode, similarly to TCP.
This way the read timer can be controlled manually using:
* isc__nmsocket_timer_start();
* isc__nmsocket_timer_stop();
* isc__nmsocket_timer_restart().
The change is required to make it possible to implement more
sophisticated read timer control policies in DNS transports, built on
top of TLS.
This commit adds a manual read timer control mode to the TCP
code (adding isc__nmhandle_set_manual_timer() as the interface to it).
Manual read timer control mode suppresses read timer restarting the
read timer when receiving any amount of data. This way the read timer
can be controlled manually using:
* isc__nmsocket_timer_start();
* isc__nmsocket_timer_stop();
* isc__nmsocket_timer_restart().
The change is required to make it possible to implement more
sophisticated read timer control policies in DNS transports, built on
top of TCP.
This commit adds implementation of isc__nmsocket_timer_restart() and
isc__nmsocket_timer_stop() for generic TLS code in order to make its
interface more compatible with that of TCP.
This commit adds implementations of isc_nm_bad_request() and
isc__nmsocket_reset() to the generic TLS stream code in order to make
it more compatible with TCP code.
Add internal logging functions isc__netmgr_log, isc__nmsocket_log(), and
isc__nmhandle_log() that can be used to add logging messages to the
netmgr, and change all direct use of isc_log_write() to use those
logging functions to properly prefix them with netmgr, nmsocket and
nmsocket+nmhandle.
Previously, the send callback would be synchronous only on success. Add
an option (similar to what other callbacks have) to decide whether we
need the asynchronous send callback on a higher level.
On a general level, we need the asynchronous callbacks to happen only
when we are invoking the callback from the public API. If the path to
the callback went through the libuv callback or netmgr callback, we are
already on asynchronous path, and there's no need to make the call to
the callback asynchronous again.
For the send callback, this means we need the asynchronous path for
failure paths inside the isc_nm_send() (which calls isc__nm_udp_send(),
isc__nm_tcp_send(), etc...) - all other invocations of the send callback
could be synchronous, because those are called from the respective libuv
send callbacks.
Previously, the read callback would be synchronous only on success or
timeout. Add an option (similar to what other callbacks have) to decide
whether we need the asynchronous read callback on a higher level.
On a general level, we need the asynchronous callbacks to happen only
when we are invoking the callback from the public API. If the path to
the callback went through the libuv callback or netmgr callback, we are
already on asynchronous path, and there's no need to make the call to
the callback asynchronous again.
For the read callback, this means we need the asynchronous path for
failure paths inside the isc_nm_read() (which calls isc__nm_udp_read(),
isc__nm_tcp_read(), etc...) - all other invocations of the read callback
could be synchronous, because those are called from the respective libuv
or netmgr read callbacks.
This commit introduces a primitive isc__nmsocket_stop() which performs
shutting down on a multilayered socket ensuring the proper order of
the operations.
The shared data within the socket object can be destroyed after the
call completed, as it is guaranteed to not be used from within the
context of other worker threads.
This commit fixes TLS DNS verification error message reporting which
we probably broke during one of the recent networking code
refactorings.
This prevent e.g. dig from producing useful error messages related to
TLS certificates verification.
After the loopmgr work has been merged, we can now cleanup the TCP and
TLS protocols a little bit, because there are stronger guarantees that
the sockets will be kept on the respective loops/threads. We only need
asynchronous call for listening sockets (start, stop) and reading from
the TCP (because the isc_nm_read() might be called from read callback
again.
This commit does the following changes (they are intertwined together):
1. Cleanup most of the asynchronous events in the TCP code, and add
comments for the events that needs to be kept asynchronous.
2. Remove isc_nm_resumeread() from the netmgr API, and replace
isc_nm_resumeread() calls with existing isc_nm_read() calls.
3. Remove isc_nm_pauseread() from the netmgr API, and replace
isc_nm_pauseread() calls with a new isc_nm_read_stop() call.
4. Disable the isc_nm_cancelread() for the streaming protocols, only the
datagram-like protocols can use isc_nm_cancelread().
5. Add isc_nmhandle_close() that can be used to shutdown the socket
earlier than after the last detach. Formerly, the socket would be
closed only after all reading and sending would be finished and the
last reference would be detached. The new isc_nmhandle_close() can
be used to close the underlying socket earlier, so all the other
asynchronous calls would call their respective callbacks immediately.
Co-authored-by: Ondřej Surý <ondrej@isc.org>
Co-authored-by: Artem Boldariev <artem@isc.org>
The network manager UDP code was misinterpreting when the libuv called
the udp_recv_cb with nrecv == 0 and addr == NULL -> this doesn't really
mean that the "stream" has ended, but the libuv indicates that the
receive buffer can be freed. This could lead to assertion failure in
the code that calls isc_nm_read() from the network manager read callback
due to the extra spurious callbacks.
Properly handle the extra callback calls from the libuv in the client
read callback, and refactor the UDP isc_nm_read() implementation to be
synchronous, so no datagram is lost between the time that we stop the
reading from the UDP socket and we restart it again in the asychronous
udpread event.
Add a unit test that tests the isc_nm_read() call from the read
callback to receive two datagrams.
Commit b69e783164cd50e3306364668558e460617ee8fc inadvertently caused
builds using the --disable-doh switch to fail, by putting the
declaration of the isc__nm_async_settlsctx() function inside an #ifdef
block that is only evaluated when DNS-over-HTTPS support is enabled.
This results in the following compilation errors being triggered:
netmgr/netmgr.c:2657:1: error: no previous prototype for 'isc__nm_async_settlsctx' [-Werror=missing-prototypes]
2657 | isc__nm_async_settlsctx(isc__networker_t *worker, isc__netievent_t *ev0) {
| ^~~~~~~~~~~~~~~~~~~~~~~
Fix by making the declaration of the isc__nm_async_settlsctx() function
in lib/isc/netmgr/netmgr-int.h visible regardless of whether
DNS-over-HTTPS support is enabled or not.
When we are closing the listening sockets, there's a time window in
which the TCP connection could be accepted although the respective
stoplistening function has already returned to control to the caller.
Clear the accept callback function early, so it doesn't get called when
we are not interested in the incoming connections anymore.
Previously:
* applications were using isc_app as the base unit for running the
application and signal handling.
* networking was handled in the netmgr layer, which would start a
number of threads, each with a uv_loop event loop.
* task/event handling was done in the isc_task unit, which used
netmgr event loops to run the isc_event calls.
In this refactoring:
* the network manager now uses isc_loop instead of maintaining its
own worker threads and event loops.
* the taskmgr that manages isc_task instances now also uses isc_loopmgr,
and every isc_task runs on a specific isc_loop bound to the specific
thread.
* applications have been updated as necessary to use the new API.
* new ISC_LOOP_TEST macros have been added to enable unit tests to
run isc_loop event loops. unit tests have been updated to use this
where needed.
On FreeBSD (and perhaps other *BSD) systems, the TCP connect() call (via
uv_tcp_connect()) can fail with transient UV_EADDRINUSE error. The UDP
code already handles this by trying three times (is a charm) before
giving up. Add a code for the TCP, TCPDNS and TLSDNS layers to also try
three times before giving up by calling uv_tcp_connect() from the
callback two more time on UV_EADDRINUSE error.
Additionally, stop the timer only if we succeed or on hard error via
isc__nm_failed_connect_cb().
Under specific rare timing circumstances the uv_read_start() could
fail with UV_EINVAL when the connection is reset between the connect (or
accept) and the uv_read_start() call on the nmworker loop. Handle such
situation gracefully by propagating the errors from uv_read_start() into
upper layers, so the socket can be internally closed().
Since the fctx hash table is now self-resizing, and resolver tasks are
selected to match the thread that created the fetch context, there
shouldn't be any significant advantage to having multiple tasks per CPU;
a single task per thread should be sufficient.
Additionally, the fetch context is always pinned to the calling netmgr
thread to minimize the contention just to coalesced fetches - if two
threads starts the same fetch, it will be pinned to the first one to get
the bucket.
This commit fixes a crash in generic TLS stream code, which could be
reproduced during some runs of the 'sslyze' tool.
The intention of this commit is twofold.
Firstly, it ensures that the TLS socket object cannot be destroyed too
early. Now it is being deleted alongside the underlying TCP socket
object.
Secondly, it ensures that the TLS socket object cannot be destroyed as
a result of calling 'tls_do_bio()' (the primary function which
performs encryption/decryption during the IO) as the code did not
expect that. This code path is fixed now.
As we are going to use libuv outside of the netmgr, we need the shims to
be readily available for the rest of the codebase.
Move the "netmgr/uv-compat.h" to <isc/uv.h> and netmgr/uv-compat.c to
uv.c, and as a rule of thumb, the users of libuv should include
<isc/uv.h> instead of <uv.h> directly.
Additionally, merge netmgr/uverr2result.c into uv.c and rename the
single function from isc__nm_uverr2result() to isc_uverr2result().
Move the netmgr socket related functions from netmgr/netmgr.c and
netmgr/uv-compat.c to netmgr/socket.c, so they are all present all in
the same place. Adjust the names of couple interal functions
accordingly.
This commit ensures that write callbacks are getting called only after
the data has been sent via the network.
Without this fix, a situation could appear when a write callback could
get called before the actual encrypted data would have been sent to
the network. Instead, it would get called right after it would have
been passed to the OpenSSL (i.e. encrypted).
Most likely, the issue does not reveal itself often because the
callback call was asynchronous, so in most cases it should have been
called after the data has been sent, but that was not guaranteed by
the code logic.
Also, this commit removes one memory allocation (netievent) from a hot
path, as there is no need to call this callback asynchronously
anymore.
This commit adds isc_nmsocket_set_tlsctx() - an asynchronous function
that replaces the TLS context within a given TLS-enabled listener
socket object. It is based on the newly added reference counting
functionality.
The intention of adding this function is to add functionality to
replace a TLS context without recreating the whole socket object,
including the underlying TCP listener socket, as a BIND process might
not have enough permissions to re-create it fully on reconfiguration.
Previously, HAVE_SO_REUSEPORT_LB has been defined only in the private
netmgr-int.h header file, making the configuration of load balanced
sockets inoperable.
Move the missing HAVE_SO_REUSEPORT_LB define the isc/netmgr.h and add
missing isc_nm_getloadbalancesockets() implementation.
Previously, the option to enable kernel load balancing of the sockets
was always enabled when supported by the operating system (SO_REUSEPORT
on Linux and SO_REUSEPORT_LB on FreeBSD).
It was reported that in scenarios where the networking threads are also
responsible for processing long-running tasks (like RPZ processing, CATZ
processing or large zone transfers), this could lead to intermitten
brownouts for some clients, because the thread assigned by the operating
system might be busy. In such scenarious, the overall performance would
be better served by threads competing over the sockets because the idle
threads can pick up the incoming traffic.
Add new configuration option (`load-balance-sockets`) to allow enabling
or disabling the load balancing of the sockets.
Previously, the task privileged mode has been used only when the named
was starting up and loading the zones from the disk as the "first" thing
to do. The privileged task was setup with quantum == 2, which made the
taskmgr/netmgr spin around the privileged queue processing two events at
the time.
The same effect can be achieved by setting the quantum to UINT_MAX (e.g.
practically unlimited) for the loadzone task, hence the privileged task
mode was removed in favor of just processing all the events on the
loadzone task in a single task_run().
This commit adds support for ISC_R_TLSBADPEERCERT error code, which is
supposed to be used to signal for TLS peer certificates verification
in dig and other code.
The support for this error code is added to our TLS and TLS DNS
implementations.
This commit also adds isc_nm_verify_tls_peer_result_string() function
which is supposed to be used to get a textual description of the
reason for getting a ISC_R_TLSBADPEERCERT error.
Previously, it was possible to assign a bit of memory space in the
nmhandle to store the client data. This was complicated and prevents
further refactoring of isc_nmhandle_t caching (future work).
Instead of caching the data in the nmhandle, allocate the hot-path
ns_client_t objects from per-thread clientmgr memory context and just
assign it to the isc_nmhandle_t via isc_nmhandle_set().
Previously, there was a single per-socket write timer that would get
restarted for every new write. This turned out to be insufficient
because the other side could keep reseting the timer, and never reading
back the responses.
Change the single write timer to per-send timer which would in turn
reset the TCP connection on the first send timeout.
Previously the socket code would set the TCPv6 maximum segment size to
minimum value to prevent IP fragmentation for TCP. This was not yet
implemented for the network manager.
Implement network manager functions to set and use minimum MTU socket
option and set the TCP_MAXSEG socket option for both IPv4 and IPv6 and
use those to clamp the TCP maximum segment size for TCP, TCPDNS and
TLSDNS layers in the network manager to 1220 bytes, that is 1280 (IPv6
minimum link MTU) minus 40 (IPv6 fixed header) minus 20 (TCP fixed
header)
We already rely on a similar value for UDP to prevent IP fragmentation
and it make sense to use the same value for IPv4 and IPv6 because the
modern networks are required to support IPv6 packet sizes. If there's
need for small TCP segment values, the MTU on the interfaces needs to be
properly configured.
The IPV6_USE_MIN_MTU socket option directs the IP layer to limit the
IPv6 packet size to the minimum required supported MTU from the base
IPv6 specification, i.e. 1280 bytes. Many implementations of TCP
running over IPv6 neglect to check the IPV6_USE_MIN_MTU value when
performing MSS negotiation and when constructing a TCP segment despite
MSS being defined to be the MTU less the IP and TCP header sizes (60
bytes for IPv6). This leads to oversized IPv6 packets being sent
resulting in unintended Path Maximum Transport Unit Discovery (PMTUD)
being performed and to fragmented IPv6 packets being sent.
Add and use a function to set socket option to limit the MTU on IPv6
sockets to the minimum MTU (1280) both for UDP and TCP.
The current implementation of isc_queue uses Michael-Scott lock-free
queue that in turn uses hazard pointers. It was discovered that the way
we use the isc_queue, such complicated mechanism isn't really needed,
because most of the time, we either execute the work directly when on
nmthread (in case of UDP) or schedule the work from the matching
nmthreads.
Replace the current implementation of the isc_queue with a simple locked
ISC_LIST. There's a slight improvement - since copying the whole list
is very lightweight - we move the queue into a new list before we start
the processing and locking just for moving the queue and not for every
single item on the list.
NOTE: There's a room for future improvements - since we don't guarantee
the order in which the netievents are processed, we could have two lists
- one unlocked that would be used when scheduling the work from the
matching thread and one locked that would be used from non-matching
thread.
The isc__nmsocket_t has locked array of isc_nmhandle_t that's not used
for anything. The isc__nmhandle_get() adds the isc_nmhandle_t to the
locked array (and resized if necessary) and removed when
isc_nmhandle_put() finally destroys the handle. That's all it does, so
it serves no useful purpose.
Remove the .ah_handles, .ah_size, and .ah_frees members of the
isc__nmsocket_t and .ah_pos member of the isc_nmhandle_t struct.
When the TCP, TCPDNS or TLSDNS connection times out, the isc__nm_uvreq_t
would be pushed into sock->inactivereqs before the uv_tcp_connect()
callback finishes. Because the isc__nmsocket_t keeps the list of
inactive isc__nm_uvreq_t, this would cause use-after-free only when the
sock->inactivereqs is full (which could never happen because the failure
happens in connection timeout callback) or when the sock->inactivereqs
mechanism is completely removed (f.e. when running under Address or
Thread Sanitizer).
Delay isc__nm_uvreq_t deallocation to the connection callback and only
signal the connection callback should be called by shutting down the
libuv socket from the connection timeout callback.
The keep-response-order option has been obsoleted, and in this commit,
remove the keep-response-order ACL map rendering the option no-op, the
call the isc_nm_sequential() and the now unused isc_nm_sequential()
function itself.
There was an artificial limit of 23 on the number of simultaneous
pipelined queries in the single TCP connection. The new network
managers is capable of handling "unlimited" (limited only by the TCP
read buffer size ) queries similar to "unlimited" handling of the DNS
queries receive over UDP.
Don't limit the number of TCP queries that we can process within a
single TCP read callback.
When invalid DNS message is received, there was a handling mechanism for
DoH that would be called to return proper HTTP response.
Reuse this mechanism and reset the TCP connection when the client is
blackholed, DNS message is completely bogus or the ns_client receives
response instead of query.
When the outgoing TCP write buffers are full because the other party is
not reading the data, the uv_write() could wait indefinitely on the
uv_loop and never calling the callback. Add a new write timer that uses
the `tcp-idle-timeout` value to interrupt the TCP connection when we are
not able to send data for defined period of time.
