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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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().
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.
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.
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.
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 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.
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.
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.
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.
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.
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.
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.
When no DEBUG_STRICT is enabled, we get this build warning:
src/stream_interface.c: In function 'stream_int_chk_snd_conn':
src/stream_interface.c:1198:28: warning: unused variable 'conn' [-Wunused-variable]
1198 | struct connection *conn = cs_conn(cs);
| ^~~~
This was the result of the simplification of the code in commit
d1480cc8a ("BUG/MEDIUM: stream-int: do not rely on the connection error
once established") which removed the last user of this variable outside
of a BUG_ON().
If the patch above is backported, this one should be backported as well.
Historically the stream-interface code used to check for connection
errors by itself. Later this was partially deferred to muxes, but
only once the mux is installed or the connection is at least in the
established state. But probably as a safety practice the connection
error tests remained.
The problem is that they are causing trouble on when a response received
from a mux is mixed with an error report. The typical case is an upload
that is interrupted by the server sending an error or redirect without
draining all data, causing an RST to be queued just after the data. In
this case the mux has the data, the CO_FL_ERROR flag is present on the
connection, and unfortunately the stream-interface refuses to retrieve
the data due to this flag, and return an error to the client.
It's about time to only rely on CS_FL_ERROR which is set by the mux, but
the stream-interface is still responsible for the connection during its
setup. However everywhere the CO_FL_ERROR is checked, CS_FL_ERROR is
also checked.
This commit addresses this by:
- adding a new function si_is_conn_error() that checks the SI state
and only reports the status of CO_FL_ERROR for states before
SI_ST_EST.
- eliminating all checks for CO_FL_ERORR in places where CS_FL_ERROR
is already checked and either the presence of a mux was already
validated or the stream-int's state was already checked as being
SI_ST_EST or higher.
CO_FL_ERROR tests on the send() direction are also inappropriate as they
may cause the loss of pending data. Now this doesn't happen anymore and
such events are only converted to CS_FL_ERROR by the mux once notified of
the problem. As such, this must not cause the loss of any error event.
Now an early error reported on a backend mux doesn't prevent the queued
response from being read and forwarded to the client (the list of syscalls
below was trimmed and epoll_ctl is not represented):
recvfrom(10, "POST / HTTP/1.1\r\nConnection: clo"..., 16320, 0, NULL, NULL) = 66
sendto(11, "POST / HTTP/1.1\r\ntransfer-encodi"..., 47, MSG_DONTWAIT|MSG_NOSIGNAL, NULL, 0) = 47
epoll_wait(3, [{events=EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLRDHUP, data={u32=11, u64=11}}], 200, 15001) = 1
recvfrom(11, "HTTP/1.1 200 OK\r\ncontent-length:"..., 16320, 0, NULL, NULL) = 57
sendto(10, "HTTP/1.1 200 OK\r\ncontent-length:"..., 57, MSG_DONTWAIT|MSG_NOSIGNAL, NULL, 0) = 57
epoll_wait(3, [{events=EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLRDHUP, data={u32=11, u64=11}}], 200, 13001) = 1
epoll_wait(3, [{events=EPOLLIN, data={u32=10, u64=10}}], 200, 13001) = 1
recvfrom(10, "A\n0123456789\r\n0\r\n\r\n", 16320, 0, NULL, NULL) = 19
shutdown(10, SHUT_WR) = 0
close(11) = 0
close(10) = 0
Above the server is an haproxy configured with the following:
listen blah
bind :8002
mode http
timeout connect 5s
timeout client 5s
timeout server 5s
option httpclose
option nolinger
http-request return status 200 hdr connection close
And the client takes care of sending requests and data in two distinct
parts:
while :; do
./dev/tcploop/tcploop 8001 C T S:"POST / HTTP/1.1\r\nConnection: close\r\nTransfer-encoding: chunked\r\n\r\n" P1 S:"A\n0123456789\r\n0\r\n\r\n" P R F;
done
With this, a small percentage of the requests will reproduce the behavior
above. Note that this fix requires the following patch to be applied for
the test above to work:
BUG/MEDIUM: mux-h1: only turn CO_FL_ERROR to CS_FL_ERROR with empty ibuf
This should be backported with after a few weeks of observation, and
likely one version at a time. During the backports, the patch might
need to be adjusted at each check of CO_FL_ERORR to follow the
principles explained above.
693b23bb1 ("MEDIUM: tree-wide: Use unsafe conn-stream API when it is
relevant") introduced a regression in DEBUG_STRICT mode because some BUG_ON
conditions were inverted. It should ok now.
In addition, ALREADY_CHECKED macro was removed from appctx_wakeup() function
because it is useless now.
This way si_*_recv() and si_*_sned() API are defined the same
way. si_sync_snd/si_sync_recv are both exported and defined in the C
file. And si_cs_send/si_cs_recv are private and only used by
stream-interface internals.
The unsafe conn-stream API (__cs_*) is now used when we are sure the good
endpoint or application is attached to the conn-stream. This avoids compiler
warnings about possible null derefs. It also simplify the code and clear up
any ambiguity about manipulated entities.
The use of co_set_data() should be strictly limited to setting the amount
of existing data to be transmitted. It ought not be used to decrement the
output after the data have left the buffer, because doing so involves
performing incorrect calculations using co_data() that still comprises
data that are not in the buffer anymore. Let's use c_rew() for this, which
is made exactly for this purpose, i.e. decrement c->output by as much as
requested. This is cleaner, faster, and will permit stricter checks.
Thanks to all previous changes, it is now possible to move the
stream-interface into the conn-stream. To do so, some SI functions are
removed and their conn-stream counterparts are added. In addition, the
conn-stream is now responsible to create and release the
stream-interface. While the stream-interfaces were inlined in the stream
structure, there is now a pointer in the conn-stream. stream-interfaces are
now dynamically allocated. Thus a dedicated pool is added. It is a temporary
change because, at the end, the stream-interface structure will most
probably disappear.
In the same way the conn-stream has a pointer to the stream endpoint , this
patch adds a pointer to the application entity in the conn-stream
structure. For now, it is a stream or a health-check. It is mandatory to
merge the stream-interface with the conn-stream.
Thanks to previous changes, it is now possible to set an appctx as endpoint
for a conn-stream. This means the appctx is no longer linked to the
stream-interface but to the conn-stream. Thus, a pointer to the conn-stream
is explicitly stored in the stream-interface. The endpoint (connection or
appctx) can be retrieved via the conn-stream.
To be able to handle applets as a conn-stream endpoint, we must be prepared
to handle different types of endpoints. First of all, the conn-strream's
connection must no longer be used directly.
The conn-stream will progressively replace the stream-interface. Thus, a
stream will have to allocate the backend conn-stream during its
creation. This means it will be possible to have a conn-stream with no
connection. To prepare this change, we test the conn-stream's connection
when we retrieve it.
In si_cs_recv(), the mux must never set CS_FL_WANT_ROOM flag on the
conn-stream if the input buffer is empty and nothing was copied. It is
important because, there is nothing the app layer can do in this case to
make some room. If this happens, this will most probably lead to a ping-pong
loop between the mux and the stream.
With this BUG_ON(), it will be easier to spot such bugs.
At many places we use construct such as:
if (objt_server(blah))
do_something(objt_server(blah));
At -O2 the compiler manages to simplify the operation and see that the
second one returns the same result as the first one. But at -O1 that's
not always the case, and the compiler is able to emit a second
expression and sees the potential null that results from it, and may
warn about a potential null deref (e.g. with gcc-6.5). There are two
solutions to this:
- either the result of the first test has to be passed to a local
variable
- or the second reference ought to be unchecked using the __objt_*
variant.
This patch fixes all occurrences at once by taking the second approach
(the least intrusive). For constructs like:
objt_server(blah) ? objt_server(blah)->name : "no name"
a macro could be useful. It would for example take the object type
(server), the field name (name) and the default value. But there
are probably not enough occurrences across the whole code for this
to really matter.
This should be backported wherever it applies.
First of all, we must be careful here because this part was modified and
each time, this introduced a bug. But, in si_update_rx(), we must not
re-enables receives if the channel buffer cannot receive more
data. Otherwise the multiplexer will be wake up for nothing. Because the
stream is woken up when the multiplexer is waiting for more room to move on,
this may lead to a ping-pong loop between the stream and the mux.
Note that for now, it does not fix any known bug. All reported issues in
this area were fixed in another way.
This patch must be backported with a special care. Technically speaking, it
may be backported as far as 2.0.
