MEDIUM: stream: Don't use the stream-int anymore in process_stream()
process_stream() and all associated functions now manipulate conn-streams.
stream-interfaces are no longer used. In addition, function to dump info
about a stream no longer print info about stream-interfaces.
MEDIUM: stream-int/conn-stream: Move I/O functions to conn-stream
cs_conn_io_cb(), cs_conn_sync_recv() and cs_conn_sync_send() are moved in
conn_stream.c. Associated functions are moved too (cs_notify, cs_conn_read0,
cs_conn_recv, cs_conn_send and cs_conn_process).
MEDIUM: stream-int/conn-stream: Move blocking flags from SI to CS
Remaining flags and associated functions are move in the conn-stream
scope. These flags are added on the endpoint and not the conn-stream
itself. This way it will be possible to get them from the mux or the
applet. The functions to get or set these flags are renamed accordingly with
the "cs_" prefix and updated to manipualte a conn-stream instead of a
stream-interface.
MINOR: conn-stream: Move si_conn_cb in the conn-stream scope
si_conn_cb variable is renamed cs_data_conn_cb. In addtion, its associated
functions are also renamed. si_cs_recv(), si_cs_send() and si_cs_process() are
renamed cs_conn_recv(), cs_conn_send and cs_conn_process(). These functions are
updated to manipulate conn-streams instead of stream-interfaces.
MEDIUM: conn-stream/applet: Add a data callback for applets
data callbacks were only used for streams attached to a connection and
for health-checks. However there is a callback used by task_run_applet. So,
si_applet_wake_cb() is first renamed to cs_applet_process() and it is
defined as the data callback for streams attached to an applet. This way,
this part now manipulates a conn-stream instead of a stream-interface. In
addition, applets are no longer handled as an exception for this part.
MINOR: stream-int/stream: Move si_update_both in stream scope
si_update_both() is renamed stream_update_both_cs() and moved in stream.c.
The function is slightly changed to manipulate the stream instead the front
and back conn-streams.
MINOR: stream-int-conn-stream: Move si_update_* in conn-stream scope
si_update_rx(), si_update_tx() and si_update() are renamed cs_update_rx(),
cs_upate_tx() and cs_update() and updated to manipulate a conn-stream
instead of a stream-interface.
REORG: stream-int: Export si_cs_recv(), si_cs_send() and si_cs_process()
It is a transient commit. It should ease next changes about the conn-stream
refactoring. At the end these functions will be moved in the conn-stream
scope.
MINOR: applet: Use the CS to register and release applets instead of SI
si_register_applet() and si_applet_release() are renamed
cs_register_applet() and cs_applet_release() and now manipulate a
conn-stream instead of a stream-inteface.
MINOR: stream-int/conn-stream: Move si_shut* and si_chk* in conn-stream scope
si_shutr(), si_shutw(), si_chk_rcv() and si_chk_snd() are moved in the
conn-stream scope and renamed, respectively, cs_shutr(), cs_shutw(),
cs_chk_rcv(), cs_chk_snd() and manipulate a conn-stream instead of a
stream-interface.
MINOR: conn-stream: Rename CS functions dedicated to connections
Some conn-stream functions are only used when there is a connection. Thus,
they was renamed with "cs_conn_" prefix. In addition, we expect to have a
connection, so a BUG_ON is added to be sure the functions are never called
in another context.
MEDIUM: stream-int/conn-stream: Handle I/O subscriptions in the conn-stream
wait_event structure is moved in the conn-stream. The tasklet is only
created if the conn-stream is attached to a mux and released when the mux is
detached. This implies a subtle change. In stream_int_chk_rcv() function,
the wakeup of the tasklet was removed because there is no longer tasklet at
this stage (stream_int_chk_rcv() is a callback function of si_embedded_ops).
MEDIUM: conn-stream: Be prepared to fail to attach a cs to a mux
To be able to move wait_event from the stream-interface to the conn-stream,
we must be prepare to handle errors when a mux is attached to a conn-stream.
Indeed, the wait_event's tasklet will be allocated when both a mux and a
stream will be both attached to a stream. So, we must be prepared to handle
allocation errors.
MINOR: conn-stream/connection: Move SHR/SHW modes in the connection scope
These flags only concerns the connection part. In addition, it is required
for a next commit, to avoid circular deps. Thus CS_SHR_* and CS_SHW_* were
renamed with the "CO_" prefix.
MINOR: stream-int/backend: Move si_connect() in the backend scope
si_connect() is moved in backend.c and renamed as do_connect_server(). In
addition, the function now manipulate a stream instead of a
stream-interface.
MINOR: stream-int/stream: Move si_retnclose() in the stream scope
si_retnclose() is used to send a reply to a client before closing. There is
no use on the server side, in spite of the function is generic. Thus, it is
renamed stream_retnclose() and moved into the stream scope. The function now
handle a stream and explicitly send a message to the client.
MEDIUM: stream-int/conn-stream: Move stream-interface state in the conn-stream
The stream-interface state (SI_ST_*) is now in the conn-stream. It is a
mechanical replacement for now. Nothing special. SI_ST_* and SI_SB_* were
renamed accordingly. Utils functions to manipulate these infos were moved
under the conn-stream scope.
But it could be good to keep in mind that this part should be
reworked. Indeed, at the CS level, we only need to know if it is ready to
receive or to send. The state of conn-stream from INI to EST is only used on
the server side. The client CS is immediately set to EST. Thus current
SI_ST_* states should probably be moved to the stream to reflect the server
connection state during the establishment stage.
MEDIUM: stream-int: Move SI err_type in the stream
Only the server side is concerned by the stream-interface error type. It is
useless to have an err_type field on the client side. So, it is now move to
the stream. SI_ET_* are renames STRM_ET_* and moved in stream-t.h header
file.
MINOR: stream: Only save previous connection state for the server side
The previous connection state on the client side was only used for debugging
purpose to report client close. But this may be handled when the client
stream-interface is switched from SI_ST_DIS to SI_ST_CLO.
So, there only remains the previous connection state on the server side that
is used by the stream, in process_stream(), to be able to set the correct
termination flags. Thus, instead of keeping this info in the
stream-interface for only one side, the info is now stored in the stream
itself.
MINOR: stream-int: Remove SI_FL_SRC_ADDR to rely on stream flags instead
Flag to get the source ip/port with getsockname is now handled at the stream
level. Thus SI_FL_SRC_ADDR stream-int flag is replaced by SF_SRC_ADDR stream
flag.
MINOR: stream-int: Remove SI_FL_INDEP_STR to rely on CS flags instead
Flag to consider a stream as indepenent is now handled at the conn-stream
level. Thus SI_FL_INDEP_STR stream-int flag is replaced by CS_FL_INDEP_STR
conn-stream flags.
MINOR: stream-int: Remove SI_FL_DONT_WAKE to rely on CS flags instead
Flag to not wake the stream up on I/O is now handled at the conn-stream
level. Thus SI_FL_DONT_WAKE stream-int flag is replaced by CS_FL_DONT_WAKE
conn-stream flags.
MINOR: stream-int: Remove SI_FL_NOLINGER/NOHALF to rely on CS flags instead
Flags to disable lingering and half-close are now handled at the conn-stream
level. Thus SI_FL_NOLINGER and SI_FL_NOHALF stream-int flags are replaced by
CS_FL_NOLINGER and CS_FL_NOHALF conn-stream flags.
MINOR: stream-int: Remove SI_FL_KILL_CON to rely on conn-stream endpoint only
Instead of setting a stream-interface flag to then set the corresponding
conn-stream endpoint flag, we now only rely the conn-stream endoint. Thus
SI_FL_KILL_CON is replaced by CS_EP_KILL_CONN.
In addition si_must_kill_conn() is replaced by cs_must_kill_conn().
MEDIUM: conn-stream: Use endpoint error instead of conn-stream error
Instead of relying on the conn-stream error, via CS_FL_ERR flags, we now
directly use the error at the endpoint level with the flag CS_EP_ERROR. It
should be safe to do so. But we must be careful because it is still possible
that an error is processed too early. Anyway, a conn-stream has always a
valid endpoint, maybe detached from any endpoint, but valid.
MINOR: stream-int/conn-stream: Report error to the CS instead of the SI
SI_FL_ERR is removed and replaced by CS_FL_ERROR. It is a transient patch
because the idea is to rely on the endpoint to handle errors at this
level. But if for any reason it is not possible, the stream-interface flags
will still be replaced.
MEDIUM: stream-int/stream: Use connect expiration instead of SI expiration
The expiration date in the stream-interface was only used on the server side
to set the connect, queue or turn-around timeout. It was checked on the
frontend stream-interface, but never used concretely. So it was removed and
replaced by a connect expiration date in the stream itself. Thus, SI_FL_EXP
flag in stream-interfaces is replaced by a stream flag, SF_CONN_EXP.
MEDIUM: stream-int/conn-stream: Move src/dst addresses in the conn-stream
The source and destination addresses at the applicative layer are moved from
the stream-interface to the conn-stream. This simplifies a bit the code and
it is a logicial step to remove the stream-interface.
The conn_retries counter was set to the max value and decremented at each
connection retry. Thus the counter reflected the number of retries left and
not the real number of retries. All calculations of redispatch or reporting
of number of retries experienced were made using subtracts from the
configured retries, which was complicated and didn't bring any benefit.
Now, this counter is set to 0 and incremented at each retry. We know we've
reached the maximum allowed connection retries by comparing it to the
configured value. In all other cases, we directly use the counter.
This patch should address the feature request #1608.
MINOR: stream-int/stream: Move conn_retries counter in the stream
The conn_retries counter may be moved into the stream structure. It only
concerns the connection establishment. The frontend stream-interface does not
use it. So it is a logical change.
MINOR: stream-int/txn: Move buffer for L7 retries in the HTTP transaction
The L7 retries only concerns the stream when a server connection is
established. Thus instead of storing the L7 buffer into the
stream-interface, it may be moved to the stream. And because it is only
available for HTTP streams, it may be moved in the HTTP transaction.
Associated flags are also moved into the HTTP transaction.
MEDIUM: tree-wide: Use CS util functions instead of SI ones
At many places, we now use the new CS functions to get a stream or a channel
from a conn-stream instead of using the stream-interface API. It is the
first step to reduce the scope of the stream-interfaces. The main change
here is about the applet I/O callback functions. Before the refactoring, the
stream-interface was the appctx owner. Thus, it was heavily used. Now, as
far as possible,the conn-stream is used. Of course, it remains many calls to
the stream-interface API.
MINOR: conn-stream: Add header file with util functions related to conn-streams
cs_utils.h header file will contain all util functions related to the
conn_streams. For now, few functions were added, all are equivalent to SI
functions. Idea is to progressively replace SI functions by CS ones.
CS_FL_ISBACK is a new flag, set on backend conn-streams. We must just be
careful to preserve this flag when the endpoint is detached from the
conn-stream.
MINOR: mux-pt: Rely on the endpoint instead of the conn-stream when possible
Instead of testing if a conn-stream exists or not, we rely on CS_EP_ORPHAN
endpoint flag. In addition, if possible, we access the endpoint from the
mux_pt context. Finally, the endpoint flags are now reported in trace
messages.
MEDIUM: conn-stream: Move remaning flags from CS to endpoint
All old flags CS_FL_* are now moved in the endpoint scope and renamed
CS_EP_* accordingly. It is a systematic replacement. There is no true change
except for the health-check and the endpoint reset. Here it is a bit special
because the same conn-stream is reused. Thus, we must handle endpoint
allocation errors. To do so, cs_reset_endp() has been adapted.
Thanks to this last change, it will now be possible to simplify the
multiplexer and probably the applets too. A review must also be performed to
remove some flags in the channel or the stream-interface. The HTX will
probably be simplified too. Finally, there is now some place in the
conn-stream to move info from the stream-interface.
MAJOR: conn-stream: Share endpoint struct between the CS and the mux/applet
The conn-stream endpoint is now shared between the conn-stream and the
applet or the multiplexer. If the mux or the applet is created first, it is
responsible to also create the endpoint and share it with the conn-stream.
If the conn-stream is created first, it is the opposite.
When the endpoint is only owned by an applet or a mux, it is called an
orphan endpoint (there is no conn-stream). When it is only owned by a
conn-stream, it is called a detached endpoint (there is no mux/applet).
The last entity that owns an endpoint is responsible to release it. When a
mux or an applet is detached from a conn-stream, the conn-stream
relinquishes the endpoint to recreate a new one. This way, the endpoint
state is never lost for the mux or the applet.
MEDIUM: conn-stream: Pre-allocate endpoint to create CS from muxes and applets
It is a transient commit to prepare next changes. Now, when a conn-stream is
created from an applet or a multiplexer, an endpoint is always provided. In
addition, the API to create a conn-stream was specialized to have one
function per type.
The next step will be to share the endpoint structure.
MEDIUM: conn-stream: Be able to pass endpoint to create a conn-stream
It is a transient commit to prepare next changes. It is possible to pass a
pre-allocated endpoint to create a new conn-stream. If it is NULL, a new
endpoint is created, otherwise the existing one is used. There no more
change at the conn-stream level.
In the applets, all conn-stream are created with no pre-allocated
endpoint. But for multiplexers, an endpoint is systematically created before
creating the conn-stream.
MINOR: conn-stream: Move some CS flags to the endpoint
Some CS flags, only related to the endpoint, are moved into the endpoint
struct. More will probably moved later. Those ones are not critical. So it
is pretty safe to move them now and this will ease next changes.
MEDIUM: conn-stream: Add an endpoint structure in the conn-stream
Group the endpoint target of a conn-stream, its context and the associated
flags in a dedicated structure in the conn-stream. It is not inlined in the
conn-stream structure. There is a dedicated pool.
For now, there is no complexity. It is just an indirection to get the
endpoint or its context. But the purpose of this structure is to be able to
share a refcounted context between the mux and the conn-stream. This way, it
will be possible to preserve it when the mux is detached from the
conn-stream.
REORG: Initialize the conn-stream by hand in cs_init()
The function cs_init() is only called by cs_new(). The conn-stream
initialization will be reviewed. It is easier to do it in cs_new() instead
of using a dedicated function. cs_new() is pretty simple, there is no reason
to split the code in this case.
MAJOR: conn-stream: Invert conn-stream endpoint and its context
This change is only significant for the multiplexer part. For the applets,
the context and the endpoint are the same. Thus, there is no much change. For
the multiplexer part, the connection was used to set the conn-stream
endpoint and the mux's stream was the context. But it is a bit strange
because once a mux is installed, it takes over the connection. In a
wonderful world, the connection should be totally hidden behind the mux. The
stream-interface and, in a lesser extent, the stream, still access the
connection because that was inherited from the pre-multiplexer era.
Now, the conn-stream endpoint is the mux's stream (an opaque entity for the
conn-stream) and the connection is the context. Dedicated functions have
been added to attached an applet or a mux to a conn-stream.
MEDIUM: applet: Set the appctx owner during allocation
The appctx owner is now always a conn-stream. Thus, it can be set during the
appctx allocation. But, to do so, the conn-stream must be created first. It
is not a problem on the server side because the conn-stream is created with
the stream. On the client side, we must take care to create the conn-stream
first.
This change should ease other changes about the applets bootstrapping.
MINOR: conn-stream: Add flags to set the type of the endpoint
This patch is mandatory to invert the endpoint and the context in the
conn-stream. There is no common type (at least for now) for the entity
representing a mux (h1s, h2s...), thus we must set its type when the
endpoint is attached to a conn-stream. There is 2 types for the conn-stream
endpoints: the mux (CS_FL_ENDP_MUX) and the applet (CS_FL_ENDP_APP).
For now there is no much change. Only the appctx is passed as argument when
the .init callback function is called. And it is not possible to yield at
this stage. It is not a problem because the feature is not used. Only the
lua defines this callback function for the lua TCP/HTTP services. The idea
is to be able to use it for all applets to initialize the appctx context.
BUG/MINOR: mux-h1: Don't release unallocated CS on error path
cs_free() must not be called when we fail to allocate the conn-stream in
h1s_new_cs() function. This bug was introduced by the commit cda94accb
("MAJOR: stream/conn_stream: Move the stream-interface into the
conn-stream").
BUG/MINOR: cache: do not display expired entries in "show cache"
It was mentioned in issue #12 that expired entries would appear with a
negative expire delay in "show cache". Instead of listing them, let's
just evict them.
This could be backported to all versions since this was reported on
1.8 already.
BUG/MINOR: mux-h2: do not send GOAWAY if SETTINGS were not sent
It was reported in issue #13 that a GOAWAY frame was sent on timeout even
if no SETTINGS frame was sent. The approach imagined by then was to track
the fact that a SETTINGS frame was already sent to avoid this, but that's
already what is done through the state, though it doesn't stand due to the
fact that we switch the frame to the error state. Thus instead what we're
doing here is to instead set the GOAWAY_FAILED flag in h2c_error() before
switching to the ERROR state when the state indicates we've not yet sent
settings, and refrain from sending anything from the h2c_send_goaway_error()
function for such states.
This could be backported to all versions where it applies well.
qcs by_id field has been replaced by a new field named "id". Adjust the
h3_debug_printf traces. This is the case since the introduction of the
qc_stream_desc type.
BUILD: halog: fix some incorrect signs in printf formats for integers
In issue #1184, cppcheck found several issues in the printf formats
used to display integers, some of which are unsigned but which used to
still rely on "%d".
BUILD/DEBUG: hpack-tbl: fix format string in standalone debug code
In issue #1184, cppcheck reports that an incorrect format "%d" was
used to print an unsigned in the debug code, though values are always
very small and this will never be an issue.
BUILD: peers: adjust some printf format to silence cppcheck
In issue #1184, cppcheck complains about some inconsistent printf
formats. At least the one in peer_prepare_hellomsg() that uses "%u"
for the int "min_ver" is wrong. Let's force other types to make it
happy, though constants cannot cause trouble.
cppcheck reports in issue #1184 a type mismatch between "%d" and the
unsigned int "misses" in the standalone debug code of lru.c. Let's
switch to "%u".
MINOR: log: add '~' to frontend when the transport layer provides SSL
We used to check if the transport layer was ssl_sock to decide to log
"~" after a frontend's name. Now that QUIC is present, this doesn't work
anymore. Better rely on the transport layer's get_ssl_sock_ctx() method.
BUG/MINOR: sock: do not double-close the accepted socket on the error path
Coverity found in issue #1646 that I added a double-close bug in last
commit e4d09cedb ("MINOR: sock: check configured limits at the sock layer,
not the listener's") because the error path already closes the FD. No
backport needed.
MINOR: ssl: refine the error testing for fc_err and fc_err_str
In issue #1645, coverity suspects some dead code due to a pair of
remaining tests on "if (!ctx)". While all other functions test the
context earlier, these ones used to only test the connection and the
transport. It's still not very clear to me if there are certain error
cases that can lead to no SSL being initially set while the rest is
ready, and the SSL arriving later, but better preserve this original
construct by testing first the connection and only later the context.
BUILD: ssl: add an unchecked version of __conn_get_ssl_sock_ctx()
First gcc, then now coverity report possible null derefs in situations
where we know these cannot happen since we call the functions in
contexts that guarantee the existence of the connection and the method
used. Let's introduce an unchecked version of the function for such
cases, just like we had to do with objt_*. This allows us to remove the
ALREADY_CHECKED() statements (which coverity doesn't see), and addresses
github issues #1643, #1644, #1647.
BUILD: ssl: fix build warning with previous changes to ssl_sock_ctx
Some compilers see a possible null deref after conn_get_ssl_sock_ctx()
in ssl_sock_parse_heartbeat, which cannot happen there, so let's mark
it as safe. No backport needed.
It was supposed to be there, and probably was not placed there due to
historic limitations in listener_accept(), but now there does not seem
to be a remaining valid reason for keeping the quic_conn out of the
handle. In addition in new_quic_cli_conn() the handle->fd was incorrectly
set to the listener's FD.
By being able to return the ssl_sock_ctx, we're now enabling the whole
set of SSL sample fetch methods to work on the current SSL context of
the QUIC connection, as seen in the following test showing a request
forwarded to an HTTP/1 server with plenty of SSL headers filled:
The code is trivial, but this is marked as medium as there's always
the risk that some of the callable functions do not like being called
on such SSL contexts.
MEDIUM: ssl: stop using conn->xprt_ctx to access the ssl_sock_ctx
The SSL functions must not use conn->xprt_ctx anymore but find the context
by calling conn_get_ssl_sock_ctx(), which will properly pass through the
transport layers to retrieve the desired information. Otherwise when the
functions are called on a QUIC connection, they refuse to work for not
being called on the proper transport.
MEDIUM: ssl: improve retrieval of ssl_sock_ctx and SSL detection
Historically there was a single way to have an SSL transport on a
connection, so detecting if the transport layer was SSL and a context
was present was sufficient to detect SSL. With QUIC, things have changed
because QUIC also relies on SSL, but the context is embedded inside the
quic_conn and the transport layer doesn't match expectations outside,
making it difficult to detect that SSL is in use over the connection.
The approach taken here to improve this consists in adding a new method
at the transport layer, get_ssl_sock_ctx(), to retrieve this often needed
ssl_sock_ctx, and to use this to detect the presence of SSL. This will
even allow some simplifications and cleanups to be made in the SSL code
itself, and QUIC will be able to provide one to export its ssl_sock_ctx.
MINOR: quic-sock: provide a pair of get_src/get_dst functions
These functions will allow the connection layer to retrieve a quic_conn's
source or destination when possible. The quic_conn holds the peer's address
but not the local one, and the sockets API doesn't always makes that easy
for datagrams. Thus for frontend connection what we're doing here is to
retrieve the listener's address when the destination address is desired.
Now it finally becomes possible to fetch the source and destination using
"src" and "dst", and to pass an incoming connection's endpoints via the
proxy protocol.
MINOR: protocol: add get_src() and get_dst() at the protocol level
Right now the proto_fam descriptor provides a family-specific
get_src() and get_dst() pair of calls to retrieve a socket's source
or destination address. However this only works for connected mode
sockets. QUIC provides its own stream protocol, which relies on a
datagram protocol underneath, so the get_src()/get_dst() at that
protocol's family will not work, and QUIC would need to provide its
own.
This patch implements get_src() and get_dst() at the protocol level
from a connection, and makes sure that conn_get_src()/conn_get_dst()
will automatically use them if defined before falling back to the
family's pair of functions.
MINOR: connection: rearrange conn_get_src/dst to be a bit more extensible
We'll want conn_get_src/dst to support other means of retrieving these
respective IP addresses, but the functions as they're designed are a bit
too restrictive for now.
This patch arranges them to have a default error fallback allowing to
test different mechanisms. In addition we now make sure the underlying
protocol is of type stream before calling the family's get_src/dst as
it makes no sense to do that on dgram sockets for example.
MINOR: mux-quic: properly set the flags and name fields
The mux didn't have its flags nor name set, as seen in this output of
"haproxy -vv":
Available multiplexer protocols :
(protocols marked as <default> cannot be specified using 'proto' keyword)
quic : mode=HTTP side=FE mux= flags=
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|CLEAN_ABRT|HOL_RISK|NO_UPG
This might have random impacts at certain points like forcing some
connections to close instead of aborting a stream, or not always
handling certain streams as fully HTX-compliant.
MEDIUM: connection: panic when calling FD-specific functions on FD-less conns
Certain functions cannot be called on an FD-less conn because they are
normally called as part of the protocol-specific setup/teardown sequence.
Better place a few BUG_ON() to make sure none of them is called in other
situations. If any of them would trigger in ambiguous conditions, it would
always be possible to replace it with an error.
MINOR: connection: skip FD-based syscalls for FD-less connections
Some syscalls at the TCP level act directly on the FD. Some of them
are used by TCP actions like set-tos, set-mark, silent-drop, others
try to retrieve TCP info, get the source or destination address. These
ones must not be called with an invalid FD coming from an FD-less
connection, so let's add the relevant tests for this. It's worth
noting that all these ones already have fall back plans (do nothing,
error, or switch to alternate implementation).
MINOR: connection: add conn_fd() to retrieve the FD only when it exists
There are plenty of places (particularly in debug code) where we try to
dump the connection's FD only when the connection is defined. That's
already a pain but now it gets one step further with QUIC because we do
*not* want to dump this FD in this case.
conn_fd() checks if the connection exists, is ready and is not fd-less,
and returns the FD only in this case, otherwise returns -1. This aims at
simplifying most of these conditions.
MINOR: connection: add a new flag CO_FL_FDLESS on fd-less connections
QUIC connections do not use a file descriptor, instead they use the
quic equivalent which is the quic_conn. A number of our historical
functions at the connection level continue to unconditionally touch
the file descriptor and this may have consequences once QUIC starts
to be used.
This patch adds a new flag on QUIC connections, CO_FL_FDLESS, to
mention that the connection doesn't have a file descriptor, hence the
FD-based API must never be used on them.
From now on it will be possible to intrument existing functions to
panic when this flag is present.