If a small request is received on QUIC MUX frontend, it can be
transmitted directly with the FIN on attach operation. rcv_buf is
skipped by the stream layer. Thus, it is necessary to ensure that there
is similar behavior when FIN is reported either on attach or rcv_buf.
One difference was that se_expect_data() was called only for rcv_buf but
not on attach. This most obvious effect is that stream timeout was
deactivated for this request : client timeout was disabled on EOI but
server one not armed due to previous se_expect_no_data(). This prevents
the early closure of too long requests.
To fix this, add an invokation of se_expect_data() on attach operation.
This bug can simply be detected using httpterm with delay request (for
example /?t=10000) and using smaller client/server timeouts. The bug is
present if the request is not aborted on timeout but instead continue
until its proper HTTP 200 termination.
This has been introduced by the following commit :
85eabfbf672c57e4ed082da1b96c95348b331320
MEDIUM: mux-quic: Don't expect data from server as long as request is unfinished
This must be backported up to 2.8.
QUIC streamdesc layer is responsible to handle reception of ACK for
streams. It removes stream data from the underlying buffers on ACK
reception.
Streamdesc layer treats ACK in order at the stream level. Out of order
ACKs are buffered in a tree until they can be handled on older data
acknowledgement reception. Previously, qf_stream instance which comes
from the quic_tx_packet was used as tree node to buffer such ranges.
Introduce a new type dedicated to represent out of order stream ack data
range. This type is named qc_stream_ack. It contains minimal infos only
relative to the acknowledged stream data range.
This allows to reduce size of frequently used quic_frame with the
removal of tree node from qf_stream. Another side effect of this change
is that now quic_frame are always released immediately on ACK reception,
both in-order and out-of-order. This allows to also release the
quic_tx_packet instance which should reduce memory consumption.
The drawback of this change is that qc_stream_ack instance must be
allocated on out-of-order ACK reception. As such, qc_stream_desc_ack()
may fail if an error happens on allocation. For the moment, such error
is silenly recovered up to qc_treat_rx_pkts() with the dropping of the
received packet containing the ACK frame. In the future, it may be
useful to close the connection as this error may only happens on low
memory usage.
Most of the time STREAM frames emitted by QUIC MUX have some data in it.
However, it is possible to use an empty frame when a delayed FIN must be
transferred.
Recently, QUIC MUX send callback notification has been refactored. Now,
this callback is blindly called by quic_conn lower layer each time a
STREAM frame is built into a newly Tx packet. QUIC MUX is responsible to
ensure the notified frame corresponds to newly emitted data or
retransmission. Offsets are used for this comparison, but this requires
special care for empty FIN frames.
Sadly, the comparison written to determine if an empty FIN frame was
sent for the first time or retransmitted is not correct. This caused
such frame to always be dismissed as retransmission in QUIC MUX sent
callback. This prevented the related QCS instance to be removed from the
send_list, causing qcc_io_send() to retry a new emission. This was
finally interrupted by the BUG_ON() assertion to prevent an infinite
loop.
Fix this crash by updating the condition in QUIC MUX send callback. For
empty STREAM frame, it is sufficient to check if QC_SF_FIN_STREAM was
already removed or not to detect a retransmission. Indeed, empty STREAM
frames are never used outside of delayed FIN reporting.
No need to backport. This crash was introduced in the current dev branch
by the following commit.
d7f4e5abf0b7129329d0ea716c104474fd934bc6
MEDIUM: quic: strengthen MUX send notification
qcc_release() may be used in case qcc_init() cannot complete. In this
case, connection instance is NULL. As such, it cannot be dereferenced
without testing it first.
This should fix github coverity report #2739.
No backport needed.
qc_stream_desc layer is used by QUIC MUX to store emitted STREAM data
until their acknowledgement. Each stream with Tx capability can allocate
its own qc_stream_desc. In turn, each stream desc can have one or
multiple data buffers. This is useful when a MUX stream releases a
buffer and allocate a new one, to preserve bandwith without waiting to
receive all acknowledgement of the previous buffer.
Each buffer is encapsulated in a qc_stream_buf structure. Previously, it
was stored as a list into qc_stream_desc. Change this storage to use a
tree instead. Each buffer is indexed by their offset.
This commit does not introduce functional changes. However, this
rearchitecture will be necessary for future commit to extend ACK
management which require fetching individual buffer instance, not just
the first or last element of a streamdesc, by their offset.
qc_stream_desc is an intermediary layer between QUIC MUX and quic_conn.
It is a facility which permits to store data to emit and keep them for
retransmission until acknowledgment. This layer is responsible to notify
QUIC MUX each time a buffer is freed. This is necessary as MUX buffer
allocation is limited by the underlying congestion window size.
Refactor this to use a mechanism similar to send notification. A new
callback notify_room can now be registered to qc_stream_desc instance.
This is set by QUIC MUX to qmux_ctrl_room(). On MUX QUIC free, special
care is now taken to reset notify_room callback to NULL.
Thanks to this refactoring, further adjustment have been made to refine
the architecture. One of them is the removal of qc_stream_desc
QC_SD_FL_OOB_BUF, which is now converted to a MUX layer flag
QC_SF_TXBUF_OOB.
Previous commit implement a refactor of MUX send notification from
quic_conn layer. With this new architecture, a proper callback is
defined for each qc_stream_desc instance.
This architecture change allows to simplify notification from quic_conn
layer. First, ensure the MUX callback to properly ignore retransmission
of an already emitted frame. Luckily, this can be handled easily by
comparing offsets and FIN status. Also, each QCS instance can now be
unregistered from send notification just prior qc_stream_desc releasing.
This ensures a QCS is never manipulated from quic_conn after its
emission ending. Both these changes render the send notification more
robust. As a nice effect, flag QUIC_FL_CONN_TX_MUX_CONTEXT can be
removed as it is now unneeded.
For STREAM emission, MUX QUIC generates one or several frames and emit
them via qc_send_mux(). Lower layer may use them as-is, or split them to
lower chunk to fit in a QUIC packet. It is then responsible to notify
the MUX to report the amount of data sent.
Previously, this was done via a direct call from quic_conn to MUX using
qcc_streams_sent_done(). Modify this to have a better isolation accross
layers. Define a send callback handled by the qc_stream_desc instance.
This allows the MUX to register each QCS instance individually to the
renamved qmux_ctrl_send() which replaces qcc_streams_sent_done().
At quic_conn layer, qc_stream_desc_send() can be used now. This is a
wrapper to qc_stream_desc layer to invoke the send callback if
registered.
This mechanism of qc_stream_desc callback should be extended later to
implement other notifications accross the QUIC stack.
This function is reserved for QCS instance where no data was emitted.
A BUG_ON() ensures this by checking that streamdesc buf_list is empty.
However, this condition would not be enough if data were previously
emitted but already fully acknowledged. Thus, extend the condition by
also checking the streamdesc ack_offset is 0.
Complete debug info when a QCS instance is dumped either on traces or
show quic. Display the value of Tx offset both soft and real, along with
the current flow-control limit.
Glitch counter was implemented for QUIC/HTTP3. The counter is stored in
the QCC MUX connection instance. However, this is never reported at the
session level which is necessary if glitch counter is tracked via a
stick-table.
To fix this, use session_add_glitch_ctr() in various QUIC MUX functions
which may increment glitch counter.
This should be backported up to 3.0.
Dump <buf_in_flight> QCC field both in QUIC MUX traces and "show quic".
This could help to detect if MUX does not allocate enough buffers
compared to quic_conn current congestion window.
Previous commit switch to small buffers for HTTP/3 HEADERS emission.
This ensures that several parallel streams can allocate their own buffer
without hitting the connection buffer limit based now on the congestion
window size.
However, this prevents the transmission of responses with uncommonly
large headers. Indeed, if all headers cannot be encoded in a single
buffer, an error is reported which cause the whole connection closure.
Adjust this by implementing a realloc API exposed by QUIC MUX. This
allows application layer to switch from a small to a default buffer and
restart its processing. This guarantees that again headers not longer
than bufsize can be properly transferred.
This patch extends qc_stream_desc API to be able to allocate small
buffers. QUIC MUX API is similarly updated as ultimatly each application
protocol is responsible to choose between a default or a smaller buffer.
Internally, the type of allocated buffer is remembered via qc_stream_buf
instance. This is mandatory to ensure that the buffer is released in the
correct pool, in particular as small and standard buffers can be
configured with the same size.
This commit is purely an API change. For the moment, small buffers are
not used. This will changed in a dedicated patch.
Each QUIC MUX may allocate buffers for MUX stream emission. These
buffers are then shared with quic_conn to handle ACK reception and
retransmission. A limit on the number of concurrent buffers used per
connection has been defined statically and can be updated via a
configuration option. This commit replaces the limit to instead use the
current underlying congestion window size.
The purpose of this change is to remove the artificial static buffer
count limit, which may be difficult to choose. Indeed, if a connection
performs with minimal loss rate, the buffer count would limit severely
its throughput. It could be increase to fix this, but it also impacts
others connections, even with less optimal performance, causing too many
extra data buffering on the MUX layer. By using the dynamic congestion
window size, haproxy ensures that MUX buffering corresponds roughly to
the network conditions.
Using QCC <buf_in_flight>, a new buffer can be allocated if it is less
than the current window size. If not, QCS emission is interrupted and
haproxy stream layer will subscribe until a new buffer is ready.
One of the criticals parts is to ensure that MUX layer previously
blocked on buffer allocation is properly woken up when sending can be
retried. This occurs on two occasions :
* after an already used Tx buffer is cleared on ACK reception. This case
is already handled by qcc_notify_buf() via quic_stream layer.
* on congestion window increase. A new qcc_notify_buf() invokation is
added into qc_notify_send().
Finally, remove <avail_bufs> QCC field which is now unused.
This commit is labelled MAJOR as it may have unexpected effect and could
cause significant behavior change. For example, in previous
implementation QUIC MUX would be able to buffer more data even if the
congestion window is small. With this patch, data cannot be transferred
from the stream layer which may cause more streams to be shut down on
client timeout. Another effect may be more CPU consumption as the
connection limit would be hit more often, causing more streams to be
interrupted and woken up in cycle.
Define a new QCC counter named <buf_in_flight>. Its purpose is to
account the current sum of all allocated stream buffer size used on
emission.
For this moment, this counter is updated and buffer allocation and
deallocation. It will be used to replace <avail_bufs> once congestion
window is used as limit for buffer allocation in a future commit.
Define a new qc_stream_desc flag QC_SD_FL_OOB_BUF. This is to mark
streams which are not subject to the connection limit on allocated MUX
stream buffer.
The purpose is to simplify handling of QUIC MUX streams which do not
transfer data and as such are not driven by haproxy layer, for example
HTTP/3 control stream. These streams interacts synchronously with QUIC
MUX and cannot retry emission in case of temporary failure.
This commit will be useful once connection buffer allocation limit is
reimplemented to directly rely on the congestion window size. This will
probably cause the buffer limit to be reached more frequently, maybe
even on QUIC MUX initialization. As such, it will be possible to mark
control streams and prevent them to be subject to the buffer limit.
QUIC MUX expose a new function qcs_send_metadata(). It can be used by an
application protocol to specify which streams are used for control
exchanges. For the moment, no such stream use this mechanism.
A limit per connection is put on the number of buffers allocated by QUIC
MUX for emission accross all its streams. This ensures memory
consumption remains under control. This limit is simply explained as a
count of buffers which can be concurrently allocated for each
connection.
As such, quic_conn structure was used to account currently allocated
buffers. However, a quic_conn nevers allocates new stream buffers. This
is only done at QUIC MUX layer. As such, this commit moves buffer
accounting inside QCC structure. This simplifies the API, most notably
qc_stream_buf_alloc() usage.
Note that this commit inverts the accounting. Previously, it was
initially set to 0 and increment for each allocated buffer. Now, it is
set to the maximum value and decrement for each buf usage. This is
considered as clearer to use.
This commit simply adjusts QUIC stream buffer allocation. This operation
is conducted by QUIC MUX using qc_stream_desc layer. Previously,
qc_stream_buf_alloc() would return a qc_stream_buf instance and QUIC MUX
would finalized the buffer area allocation. Change this to perform the
buffer allocation directly into qc_stream_buf_alloc().
This patch clarifies the interaction between QUIC MUX and
qc_stream_desc. It is cleaner to allocate the buffer via qc_stream_desc
as it is already responsible to free the buffer.
It also ensures that connection buffer accounting is only done after the
whole qc_stream_buf and its buffer are allocated. Previously, the
increment operation was performed between the two steps. This was not an
issue, as this kind of error triggers the whole connection closure.
However, if in the future this is handled as a stream closure instead,
this commit ensures that the buffer remains valid in all cases.
qcc_send_frames() can be called with an empty list and returns
immediately with an error code. This is convenience to be able to call
it in a while loop.
Remove the trace with "error" when this is the case and replacing it
with a less alarming "leaving on..." message. This should help debugging
when traces are active.
QUIC stream IDs are expressed as QUIC variable integer which cover the
range for 0 to 2^62 - 1. As such, it is forbidden to send an ID for
MAX_STREAMS flow-control frame which would allow to overcome this value.
This patch fixes MAX_STREAMS emission to ensure sent value is valid.
This also ensures that the peer cannot open a stream with an invalid ID
as this would cause a flow-control violation instead.
This must be backported up to 2.6.
Logging below the developer level doesn't always yield very convenient
traces as we don't know well where streams are allocated nor released.
Let's just make that more explicit by using state-level traces for these
important steps.
In qcs_free() we're calling a few other functions after releasing
qcs->sd. None of them make use of it for now but with traces that
will change. Make sure to clear qcs->sd after releasing it.
Reuse newly defined tot_time structure to measure various values related
to a QCS lifetime.
First, a timer is used to comptabilize the total QCS lifetime. Then, two
other timers are used to account the total time during which Tx from
stream layer to MUX is blocked, either on lack of buffer or due to
flow-control.
These three timers are reported in qmux_dump_qcs_info(). Thus, they are
available in traces and for QUIC MUX debug string sample.
Define a new xprt_ops callback named dump_info. This can be used to
extend MUX debug string with infos from the lower layer.
Implement dump_info for QUIC stack. For now, only minimal info are
reported : bytes in flight and size of the sending window. This should
allow to detect if the congestion controller is fine. These info are
reported via QUIC MUX debug string sample.
Implement MUX_SCTL_DBG_STR for QUIC MUX. This returns info for the
current QCS and QCC instances, reusing qmux_dump_qc{c,s}_info functions
already used for traces, and the connection flags.
This stream operation is useful for debug string sample support.
STREAM frames have dedicated handling on retransmission. A special check
is done to remove data already acked in case of duplicated frames, thus
only unacked data are retransmitted.
This handling is faulty in case of an empty STREAM frame with FIN set.
On retransmission, this frame does not cover any unacked range as it is
empty and is thus discarded. This may cause the transfer to freeze with
the client waiting indefinitely for the FIN notification.
To handle retransmission of empty FIN STREAM frame, qc_stream_desc layer
have been extended. A new flag QC_SD_FL_WAIT_FOR_FIN is set by MUX QUIC
when FIN has been transmitted. If set, it prevents qc_stream_desc to be
freed until FIN is acknowledged. On retransmission side,
qc_stream_frm_is_acked() has been updated. It now reports false if
FIN bit is set on the frame and qc_stream_desc has QC_SD_FL_WAIT_FOR_FIN
set.
This must be backported up to 2.6. However, this modifies heavily
critical section for ACK handling and retransmission. As such, it must
be backported only after a period of observation.
This issue can be reproduced by using the following socat command as
server to add delay between the response and connection closure :
$ socat TCP-LISTEN:<port>,fork,reuseaddr,crlf SYSTEM:'echo "HTTP/1.1 200 OK"; echo ""; sleep 1;'
On the client side, ngtcp2 can be used to simulate packet drop. Without
this patch, connection will be interrupted on QUIC idle timeout or
haproxy client timeout with ERR_DRAINING on ngtcp2 :
$ ngtcp2-client --exit-on-all-streams-close -r 0.3 <host> <port> "http://<host>:<port>/?s=32o"
Alternatively to ngtcp2 random loss, an extra haproxy patch can also be
used to force skipping the emission of the empty STREAM frame :
diff --git a/include/haproxy/quic_tx-t.h b/include/haproxy/quic_tx-t.h
index efbdfe687..1ff899acd 100644
--- a/include/haproxy/quic_tx-t.h
+++ b/include/haproxy/quic_tx-t.h
@@ -26,6 +26,8 @@ extern struct pool_head *pool_head_quic_cc_buf;
/* Flag a sent packet as being probing with old data */
#define QUIC_FL_TX_PACKET_PROBE_WITH_OLD_DATA (1UL << 5)
+#define QUIC_FL_TX_PACKET_SKIP_SENDTO (1UL << 6)
+
/* Structure to store enough information about TX QUIC packets. */
struct quic_tx_packet {
/* List entry point. */
diff --git a/src/quic_tx.c b/src/quic_tx.c
index 2f199ac3c..2702fc9b9 100644
--- a/src/quic_tx.c
+++ b/src/quic_tx.c
@@ -318,7 +318,7 @@ static int qc_send_ppkts(struct buffer *buf, struct ssl_sock_ctx *ctx)
tmpbuf.size = tmpbuf.data = dglen;
TRACE_PROTO("TX dgram", QUIC_EV_CONN_SPPKTS, qc);
- if (!skip_sendto) {
+ if (!skip_sendto && !(first_pkt->flags & QUIC_FL_TX_PACKET_SKIP_SENDTO)) {
int ret = qc_snd_buf(qc, &tmpbuf, tmpbuf.data, 0, gso);
if (ret < 0) {
if (gso && ret == -EIO) {
@@ -354,6 +354,7 @@ static int qc_send_ppkts(struct buffer *buf, struct ssl_sock_ctx *ctx)
qc->cntrs.sent_bytes_gso += ret;
}
}
+ first_pkt->flags &= ~QUIC_FL_TX_PACKET_SKIP_SENDTO;
b_del(buf, dglen + QUIC_DGRAM_HEADLEN);
qc->bytes.tx += tmpbuf.data;
@@ -2066,6 +2067,17 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
continue;
}
+ switch (cf->type) {
+ case QUIC_FT_STREAM_8 ... QUIC_FT_STREAM_F:
+ if (!cf->stream.len && (qc->flags & QUIC_FL_CONN_TX_MUX_CONTEXT)) {
+ TRACE_USER("artificially drop packet with empty STREAM frame", QUIC_EV_CONN_TXPKT, qc);
+ pkt->flags |= QUIC_FL_TX_PACKET_SKIP_SENDTO;
+ }
+ break;
+ default:
+ break;
+ }
+
quic_tx_packet_refinc(pkt);
cf->pkt = pkt;
}
It is a small change, but it is cleaner to no include stconn-t.h header in
connection-t.h, mainly to avoid circular definitions.
The related issue is #2502.
BUG_ON() from qcc_set_error() is triggered on HTTP/3 control stream
allocation failure. This is caused because both h3_finalize() and
qcc_init_stream_local() call qcc_set_error() which is forbidden to
prevent error code erasure.
Fix this by removing qcc_set_error() invocation from h3_finalize() on
allocation failure. Note that this function is still responsible to use
it on SETTING frame emission failure.
This was detected using -dMfail.
This must be backported up to 3.0.
Since the following commit, sedesc are created since QCS instantiation
in qcs_new().
086e51017e7731ee9820b882fe6e8cc5f0dd5352
BUG/MEDIUM: mux-quic: Create sedesc in same time of the QUIC stream
However, sedesc is initialized before other QCS mandatory fields. If
sedesc allocation fails, a crash would occur on qcs_free() invocation
for QCS early release. To fix this, delay sedesc allocation until
function end.
This bug was detected using -dMfail.
This should be backported up to 2.6.
It may only happens when there is no data to forward but a last stream frame
must be sent with the FIN bit. It is not invalid, but it is useless to send
an empty H3 DATA frame in that case.
The previous fix (792a645ec2 ["BUG/MEDIUM: mux-quic: Unblock zero-copy
forwarding if the txbuf can be released"]) introduced a regression. The
zero-copy data forwarding must only be unblocked if it was blocked by the
producer, after a successful negotiation.
It is important because during a negotiation, the consumer may be blocked
for another reason. Because of the flow control for instance. In that case,
there is not necessarily a TX buffer. And it unexpected to try to release an
unallocated TX buf.
In addition, the same may happen while a TX buf is still in-use. In that
case, it must also not be released. So testing the TX buffer is not the
right solution.
To fix the issue, a new IOBUF flag was added (IOBUF_FL_FF_WANT_ROOM). It
must be set by the producer if it is blocked after a sucessful negotiation
because it needs more room. In that case, we know a buffer was provided by
the consummer. In done_fastfwd() callback function, it is then possible to
safely unblock the zero-copy data forwarding if this flag is set.
This patch must be backported to 3.0 with the commit above.
In done_fastfwd() callback function, if nothing was forwarding while the SD
is blocked, it means there is not enough space in the buffer to proceed. It
may be because there are data to be sent. But it may also be data already
sent waiting for an ack. In this case, no data to be sent by the mux. So the
quic stream is not woken up when data are finally removed from the
buffer. The data forwarding can thus be stuck. This happens when the stats
page is requested in QUIC/H3. Only applets are affected by this issue and
only with the QUIC multiplexer because it is the only mux with already sent
data in the TX buf.
To fix the issue, the idea is to release the txbuf if possible and then
unblock the SD to perform a new zero-copy data forwarding attempt. Doing so,
and thanks to the previous patch ("MEDIUM: applet: Be able to unblock
zero-copy data forwarding from done_fastfwd"), the applet will be woken up.
This patch should fix the issue #2584. It must be backported to 3.0.
It is a revert of cc9827bb09 ("BUG/MEDIUM: mux-quic: fix crash on
STOP_SENDING received without SD"). This fix was based on a wrong assumption
about QUIC streams that may have no stream-endpoint descriptor. However, it
must never happen. And this was fixed. So we can now safely revert the
commit above. However, it is not a bugfix because, for now, abort info are
only used by the upper layer. So it is not a big deal to not set it when
there is no SC.
Recent changes to save abort reason revealed an issue during the QUIC stream
creation. Indeed, by design, when a mux stream is created, it must always
have a valid stream-endpoint descriptor and it must remain valid till the
mux stream destruction. On frontend side, it is the multiplexer
responsibility to create it and set it as orphan. On the backend side, the
sedesc is provided by the upper layer. It is the sedesc of the back
stream-connector.
For the QUIC multiplexer, the stream-endpoint descriptor was only created
when the stream-connector was created and attached on it. It is unexpected
and some bugs may be introduced because there is no valid sedesc on a QUIC
stream. And a recent bug was introduced for this reason.
This patch must be backported as far as 2.6.
Implement basic support for glitches on QUIC multiplexer. This is mostly
identical too glitches for HTTP/2.
A new configuration option named tune.quic.frontend.glitches-threshold
is defined to limit the number of glitches on a connection before
closing it.
Glitches counter is incremented via qcc_report_glitch(). A new
qcc_app_ops callback <report_susp> is defined. On threshold reaching, it
allows to set an application error code to close the connection. For
HTTP/3, value H3_EXCESSIVE_LOAD is returned. If not defined, default
code INTERNAL_ERROR is used.
For the moment, no glitch are reported for QUIC or HTTP/3 usage. This
will be added in future patches as needed.
qcc_shutdown() is called whenever the connection must be closed. If
application protocol defined its owned shutdown callback, it is invoked
to use the correct error code. Else transport error code NO_ERROR is
used.
A bug occurs in the latter case as NO_ERROR is used with quic_err_app()
which is reserved for application errro codes. This will trigger the
emission of a CONNECTION_CLOSE of type 0x1d (Application) instead of
0x1c (Transport).
This bug is considered minor as it does not impact QUIC with HTTP/3. It
may only be visible when using experimental HTTP/0.9 protocol.
This should be backported up to 2.6. For 2.6, patch must be completed
rewritten due to code differences. Here is the change to apply :
diff --git a/src/mux_quic.c b/src/mux_quic.c
index 26fb70ddf..c48f82e27 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -1918,7 +1918,9 @@ static void qc_release(struct qcc *qcc)
qc_send(qcc);
}
else {
- qcc_emit_cc_app(qcc, QC_ERR_NO_ERROR, 0);
+ /* Duplicate from qcc_emit_cc_app() for Transport error code. */
+ if (!(qcc->conn->handle.qc->flags & QUIC_FL_CONN_IMMEDIATE_CLOSE))
+ qcc->conn->handle.qc->err = quic_err_transport(QC_ERR_NO_ERROR);
}
}
The goal is to indicate how critical the allocation is, between the
least one (growing an existing buffer ring) and the topmost one (boot
time allocation for the life of the process).
The 3 tcp-based muxes (h1, h2, fcgi) use a common allocation function
to try to allocate otherwise subscribe. There's currently no distinction
of direction nor part that tries to allocate, and this should be revisited
to improve this situation, particularly when we consider that mux-h2 can
reduce its Tx allocations if needed.
For now, 4 main levels are planned, to translate how the data travels
inside haproxy from a producer to a consumer:
- MUX_RX: buffer used to receive data from the OS
- SE_RX: buffer used to place a transformation of the RX data for
a mux, or to produce a response for an applet
- CHANNEL: the channel buffer for sync recv
- MUX_TX: buffer used to transfer data from the channel to the outside,
generally a mux but there can be a few specificities (e.g.
http client's response buffer passed to the application,
which also gets a transformation of the channel data).
The other levels are a bit different in that they don't strictly need to
allocate for the first two ones, or they're permanent for the last one
(used by compression).
Abort reason code received on STOP_SENDING is notified to upper layer
since the following commit :
367ce1ebf3e4cead319a9f01581037c9f0280e77
MINOR: mux-quic: Set tha SE abort reason when a STOP_SENDING frame is received
However, this causes a crash when a STOP_SENDING is received on a QCS
instance without any stream instantiated. Fix this by checking first if
qcs->sd is not NULL before setting abort code.
This bug can easily be reproduced by emitting a STOP_SENDING as first
frame of a stream.
This should fix github issue #2563.
This does not need to be backported.
There are 2 new ctl commands that may be used to retrieve the current number
of streams openned for a connection and its limit (the maximum number of
streams a mux connection supports).
For the PT and H1 muxes, the limit is always 1 and the current number of
streams is 0 for idle connections, otherwise 1 is returned.
For the H2 and the FCGI muxes, info are already available in the mux
connection.
For the QUIC mux, the limit is also directly available. It is the maximum
initial sub-ID of bidirectional stream allowed for the connection. For the
current number of streams, it is the number of SC attached on the connection
and the number of not already attached streams present in the "opening_list"
list.
Other muxes implement this callback function. It was not implemented for the
QUIC mux because it was useless. It will be used to retrieve the current/max
number of stream for a quic connection. So let's added it, adding the
default support for MUX_CTL_EXIT_STATUS command.
When STOP_SENDING frame is received for a quic stream, the error code is now
saved in the SE abort reason. To do so, we use the QUIC source
(SE_ABRT_SRC_MUX_QUIC). For now, this code is only set but not used on the
opposite side.
A reason is now passed as parameter to muxes shutdowns to pass additional
info about the abort, if any. No info means no abort or only generic one.
For now, the reason is composed of 2 32-bits integer. The first on represents
the abort code and the other one represents the info about the code (for
instance the source). The code should be interpreted according to the associated
info.
One info is the source, encoding on 5 bits. Other bits are reserverd for now.
For now, the muxes are the only supported source. But we can imagine to extend
it to applets, streams, health-checks...
The current design is quite simple and will most probably evolved.. But the
idea is to let the opposite side forward some errors and let's a mux know
why its stream was aborted. At first glance, a abort reason must only be
evaluated if SE_SHW_SILENT flag is set.
The main goal at short term, is to forward some H2 RST_STREAM codes because
it is mandatory for gRPC applications, mainly to forward gRPC cancellation
from an H2 client to an H2 server. But we can imagine to alter this reason
at the applicative level to enrich it. It would also be used to report more
accurate errors in logs.
mux-ops .shutr and .shutw callback functions are merged into a unique
functions, called .shut. The shutdown mode is still passed as argument,
muxes are responsible to test it. Concretly, .shut() function of each mux is
now the content of the old .shutw() followed by the content of the old
.shutr().
CO_SHR_* and CO_SHW_* modes are in fact used by the stream-connectors to
instruct the muxes how streams must be shut done. It is then the mux
responsibility to decide if it must be propagated to the connection layer or
not. And in this case, the modes above are only tested to pass a boolean
(clean or not).
So, it is not consistant to still use connection related modes for
information set at an upper layer and never used by the connection layer
itself.
These modes are thus moved at the sedesc level and merged into a single
enum. Idea is to add more modes, not necessarily mutually exclusive, to pass
more info to the muxes. For now, it is a one-for-one renaming.
QUIC MUX is freed via qcc_release(). This in turn liberate all the
remaining QCS instances. For each one of them, their corresponding
stream-desc is released via qc_stream_desc_release().
This last function may itself notifies QUIC MUX when new buffers are
available. This is useful when QCS are closed individually without the
whole connection. However, when the connection is closed through
qcc_release(), this may cause issue as some elements of QUIC MUX are
already freed.
In 2.9.6, a bug was detected directly linked to this. Indeed, QCC
instance may be woken up on stream-desc release. If called through
qcc_release(), this is an issue because QCC tasklet is freed before QCS
instances. However, this bug is not systematic and relies on prior
conditions : in particular, QUIC MUX must be under Tx buffers exhaustion
prior to the qcc_release() invocation.
The current dev tree is not impacted by this bug, thanks to QUIC MUX
refactoring. Indeed, notifying accross layers have changed and now
stream-desc release notifies individual QCS instances instead of the QCC
element, which is a safer mechanism. However, to simplify backport
process, bugfix is introduced in the current dev tree as it does not
have any impact.
Note that a proper fix would be to set quic-conn MUX state to
QC_MUX_RELEASED. However, it is not possible to call quic_close()
without having releasing all stream-desc elements first. The simpler
solution was chosen to prevent other breaking issues during backports.
This should fix github issue #2494.
It should be backported up to 2.6. Note that prior to 2.7 qcc_release()
was named qc_release().
A remote unidirectional stream can be aborted prematurely if application
layers cannot identify its type. In this case, a STOP_SENDING frame is
emitted.
Since QUIC MUX refactoring, a crash would occur in this scenario due to
2 specific characteristics of remote uni streams :
* qcs.tx.fctl was not initialized completely. This cause a crash due to
BUG_ON() statement inside qcs_destroy().
* qcs.stream is never allocated. This caused qcs_prep_bytes() to crash
inside qcc_io_send().
This bug is considered minor as it happens only on very specific QUIC
clients. It was detected when using s2n-quic over interop.
This does not need to be backported.
This is 39th iteration of typo fixes
The naming issue on the argument called "unsued" instead of "unused"
in two functions from resolvers and stick-tables was put into a second
patch so that it can be omitted if it were to cause backport issues.
Extend "show quic" to be able to dump MUX related information. This is
done via the new function qcc_show_quic(). This replaces the old streams
dumping list which was incomplete.
These info are displayed on full output or by specifying "mux" field.
