QUIC MUX will be responsible to drive emission with pacing. This will be
implemented via setting TASK_F_USR1 before I/O tasklet wakeup. To
prepare this, encapsulate each I/O tasklet wakeup into a new function
qcc_wakeup().
This commit is purely refactoring prior to pacing implementation into
QUIC MUX.
Extend QUIC transport emission function to support a maximum datagram
argument. The purpose is to ensure that qc_send() won't emit more than
the specified value, unless it is 0 which is considered as unlimited.
In qc_prep_pkts(), a counter of built datagram has been added to support
this. The packet building loop is interrupted if it reaches a specified
maximum value. Also, its return value has been changed to the number of
prepared datagrams. This is reused by qc_send() to interrupt its work if
a specified max datagram argument value is reached over one or several
iteration of prepared/sent datagrams.
This change is necessary to support pacing emission. Note that ideally,
the total length in bytes of emitted datagrams should be taken into
account instead of the raw number of datagrams. However, for a first
implementation, it was deemed easier to implement it with the latter.
This issue came with this commit:
f627b92 BUG/MEDIUM: quic: always validate sender address on 0-RTT
and could be easily reproduced with picoquic QUIC client with -Q option
which splits a big ClientHello TLS message into two Initial datagrams.
A second condition must be fulfilled to reprodue this issue: picoquic
must not send the token provided by haproxy (NEW_TOKEN). To do that,
haproxy must be patched to prevent it to send such tokens.
Under these conditions, if haproxy has enough time to reply to the first Initial
datagrams, when it receives the second Initial datagram it sends a Retry paquet.
Then the client ignores the Retry paquet as mentionned by RFC 9000:
17.2.5.2. Handling a Retry Packet
A client MUST accept and process at most one Retry packet for each connection
attempt. After the client has received and processed an Initial or Retry packet
from the server, it MUST discard any subsequent Retry packets that it receives.
On its side, haproxy has closed the connection. When it receives the second
Initial datagram, it open a new connection but with Initial packets it
cannot decrypt (wrong ODCID) leaving the client without response.
To fix this, as the aim of the token (NEW_TOKEN) sent by haproxy is to validate
the peer address, in place of closing the connection when no token was received
for a 0RTT connection, one leaves this validation to the handshake process.
Indeed, the peer adress is validated during the handshake when a valid handshake
packet is received by the listener. But as one does not want haproxy to process
0RTT data when no token was received, one does not accept the connection before
the successful handshake completion. In addition to this, the 0RTT packets
are not released after successful handshake completion when no token was received
to leave a chance to haproxy to process these 0RTT data in such case (see
quic_conn_io_cb()).
Must be backported as far as 2.9.
Tokens are sent when opening a connection, just after the handshake, to
be possibly reused by the peer for the next connection. They are used
to validate the peer address during the 0RTT connection openings.
But there is no reason to reserve this feature to 0RTT connections.
This patch modifies quic_build_post_handshake_frames() to do so.
This bug came with this commit:
f627b92 BUG/MEDIUM: quic: always validate sender address on 0-RTT
If an error happens in quic_build_post_handshake_frames() during the
code exexuted for th NEW_TOKEN frame allocation, some could leak because
of the wrong label used to interrupt this function asap.
Replace the "goto leave" by "goto err" to deallocated such frames to fix
this issue.
Must be backported as far as 2.9.
Wake up connection layer on QUIC handshake completion via
quic_conn_io_cb. Select SUB_RETRY_RECV as this was previously unused by
QUIC MUX layer.
For the moment, QUIC MUX never subscribes for handshake completion.
However, this will be necessary for features such as the delaying of
early data forwarding via wait-for-handshake.
This patch will be necessary to implement wait-for-handshake support for
QUIC. As such, it must be backported with next commits up to 2.6,
after a mandatory period of observation.
It has been reported by Wedl Michael, a student at the University of Applied
Sciences St. Poelten, a potential vulnerability into haproxy as described below.
An attacker could have obtained a TLS session ticket after having established
a connection to an haproxy QUIC listener, using its real IP address. The
attacker has not even to send a application level request (HTTP3). Then
the attacker could open a 0-RTT session with a spoofed IP address
trusted by the QUIC listen to bypass IP allow/block list and send HTTP3 requests.
To mitigate this vulnerability, one decided to use a token which can be provided
to the client each time it successfully managed to connect to haproxy. These
tokens may be reused for future connections to validate the address/path of the
remote peer as this is done with the Retry token which is used for the current
connection, not the next one. Such tokens are transported by NEW_TOKEN frames
which was not used at this time by haproxy.
So, each time a client connect to an haproxy QUIC listener with 0-RTT
enabled, it is provided with such a token which can be reused for the
next 0-RTT session. If no such a token is presented by the client,
haproxy checks if the session is a 0-RTT one, so with early-data presented
by the client. Contrary to the Retry token, the decision to refuse the
connection is made only when the TLS stack has been provided with
enough early-data from the Initial ClientHello TLS message and when
these data have been accepted. Hopefully, this event arrives fast enough
to allow haproxy to kill the connection if some early-data have been accepted
without token presented by the client.
quic_build_post_handshake_frames() has been modified to build a NEW_TOKEN
frame with this newly implemented token to be transported inside.
quic_tls_derive_retry_token_secret() was renamed to quic_do_tls_derive_token_secre()
and modified to be reused and derive the secret for the new token implementation.
quic_token_validate() has been implemented to validate both the Retry and
the new token implemented by this patch. When this is a non-retry token
which could not be validated, the datagram received is marked as requiring
a Retry packet to be sent, and no connection is created.
When the Initial packet does not embed any non-retry token and if 0-RTT is enabled
the connection is marked with this new flag: QUIC_FL_CONN_NO_TOKEN_RCVD. As soon
as the TLS stack detects that some early-data have been provided and accepted by
the client, the connection is marked to be killed (QUIC_FL_CONN_TO_KILL) from
ha_quic_add_handshake_data(). This is done calling qc_ssl_eary_data_accepted()
new function. The secret TLS handshake is interrupted as soon as possible returnin
0 from ha_quic_add_handshake_data(). The connection is also marked as
requiring a Retry packet to be sent (QUIC_FL_CONN_SEND_RETRY) from
ha_quic_add_handshake_data(). The the handshake I/O handler (quic_conn_io_cb())
knows how to behave: kill the connection after having sent a Retry packet.
About TLS stack compatibility, this patch is supported by aws-lc. It is
disabled for wolfssl which does not support 0-RTT at this time thanks
to HAVE_SSL_0RTT_QUIC.
This patch depends on these commits:
MINOR: quic: Add trace for QUIC_EV_CONN_IO_CB event.
MINOR: quic: Implement qc_ssl_eary_data_accepted().
MINOR: quic: Modify NEW_TOKEN frame structure (qf_new_token struct)
BUG/MINOR: quic: Missing incrementation in NEW_TOKEN frame builder
MINOR: quic: Token for future connections implementation.
MINOR: quic: Implement quic_tls_derive_token_secret().
MINOR: tools: Implement ipaddrcpy().
Must be backported as far as 2.6.
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.
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.
qc_stream_desc had a field <release> used as a boolean. Convert it with
a new <flags> field and QC_SD_FL_RELEASE value as equivalent.
The purpose of this patch is to be able to extend qc_stream_desc by
adding newer flags values. This patch is required for the following
patch
BUG/MEDIUM: quic: handle retransmit for standalone FIN STREAM
As such, it must be backported prior to it.
Received QUIC packets are stored in quic_conn Rx buffer after header
protection removal in qc_rx_pkt_handle(). These packets are then removed
after quic_conn IO handler via qc_treat_rx_pkts().
If HP cannot be removed, packets are still copied into quic_conn Rx
buffer. This can happen if encryption level TLS keys are not yet
available. The packet remains in the buffer until HP can be removed and
its content processed.
An issue occurs if client emits a 0-RTT packet but haproxy does not have
the shared secret, for example after a haproxy process restart. In this
case, the packet is copied in quic_conn Rx buffer but its HP won't ever
be removed. This prevents the buffer to be purged. After some time, if
the client has emitted enough packets, Rx buffer won't have any space
left and received packets are dropped. This will cause the connection to
freeze.
To fix this, remove any 0-RTT buffered packets on handshake completion.
At this stage, 0-RTT packets are unnecessary anymore. The client is
expected to reemit its content in 1-RTT packet which are properly
deciphered.
This can easily reproduce with HTTP/3 POST requests or retrieving a big
enough object, which will fill the Rx buffer with ACK frames. Here is a
picoquic command to provoke the issue on haproxy startup :
$ picoquicdemo -Q -v 00000001 -a h3 <hostname> 20443 "/?s=1g"
Note that allow-0rtt must be present on the bind line to trigger the
issue. Else haproxy will reject any 0-RTT packets.
This must be backported up to 2.6.
This could be one of the reason for github issue #2549 but it's unsure
for now.
This bug arrived with this commit:
b068e758f MINOR: quic: simplify rescheduling for handshake
This commit introduced a bad side effect. Haproxy always replied by an ACK-only
datagram when it received the first client Initial packet. Then it handled
the CRYPTO data insided. And finally, it sent its own CRYPTO data. This broke
the packet coalescing rule whose aim is to optimally build and send as more
as QUIC packets by datagram.
To fix this, simply partially reverts this commit, to make the low level I/O
task return again if some CRYPTO were received. This will delay the
acknowledgement which will be sent with the CRYPTO data from the same
datagram again.
Must be backported to 3.0.
This commit is the renaming counterpart of the previous one, this time
for quic_conn module. Several elements related to TID affinity update
from quic_conn has been renamed : public functions, but also flag
renamed to QUIC_FL_CONN_TID_REBIND and trace event to
QUIC_EV_CONN_BIND_TID.
This should be backported with the same instruction as the previous
commit.
Add <gso_size> parameter to qc_snd_buf(). When non-null, this specifies
the value for socket option SOL_UDP/UDP_SEGMENT. This allows to send
several datagrams in a single call by splitting data multiple times at
<gso_size> boundary.
For now, <gso_size> remains set to 0 by caller, as such there should not
be any functional change.
SSL status is reported each time quic_conn_io_cb() is finished via a
trace. Change the trace label from "ssl error" to "ssl status". This
allows to search for errors easier without being distracted by this
trace.
Handshake for quic_conn instances runs on a single non-chosen thread. On
completion, listener_accept() is performed to select the less loaded
thread before initializing connection instance. As such, quic_conn
instance is migrated to the thread with its upper connection.
In case accept queue is full, listener_accept() fallback to local accept
mode, which cause the connection to be assigned to the current thread.
However, this is not supported by QUIC as quic_conn instance is left on
the previously selected thread. In most cases, this will cause a
BUG_ON() due to a task manipulation from an outside thread.
To fix this, handle quic_conn thread rebind in multiple steps using the
new extended protocol API. Several operations have been moved from
qc_set_tid_affinity1() to newly defined qc_set_tid_affinity2(), in
particular CID TID update. This ensures that quic_conn instance is not
prematurely accessed on the new thread until accept queue push is
guaranteed to succeed.
qc_reset_tid_affinity() is also newly defined to reassign the newly
created tasks and tasklets to the current thread. This is necessary to
prevent the BUG_ON() crash described above.
This must be backported up to 2.8 after a period of observation. Note
that it depends on previous patch :
MINOR: proto: extend connection thread rebind API
MINOR: listener: define callback for accept queue push
Extend API for connection thread rebind API by replacing single callback
set_affinity by three different ones. Each one of them is used at a
different stage of the operation :
* set_affinity1 is used similarly to previous set_affinity
* set_affinity2 is called directly from accept_queue_push_mp() when an
entry has been found in accept ring. This operation cannot fail.
* reset_affinity is called after set_affinity1 in case of failure from
accept_queue_push_mp() due to no space left in accept ring. This is
necessary for protocols which must reconfigure resources before
fallback on the current tid.
This patch does not have any functional changes. However, it will be
required to fix crashes for QUIC connections when accept queue ring is
full. As such, it must be backported with it.
On accept, quic_conn instance is migrated from its original thread to a
new one. This operation is conducted in two steps, on the original than
the new thread instance. During the interval, quic_conn is artificially
rendered inactive. It must never be accessed nor removed until migration
is completed via qc_finalize_affinity_rebind(). This new BUG_ON() will
enforce that removal is never conducted until migration is completed.
haproxy generates for each QUIC connection a set of CID. The peer must
reuse them as DCID for its emitted packet. On datagram reception, DCID
field serves as identifier to dispatch them on their correct thread.
These CIDs are stored in a global CID tree. Access to this data
structure must always be protected with CID_LOCK. This commit is a
refactoring to regroup all CID tree access in quic_cid module. Several
code parts are ajusted :
* quic_cid_insert() is extended to check for insertion race-condition.
This is useful on quic_conn instantiation. Code where such race cannot
happen can use unsafe _quic_cid_insert() instead.
* on RETIRE_CONNECTION_ID frame reception, existing quic_cid_delete()
function is used.
* remove tree lookup from qc_check_dcid(), extracted in the new
quic_cmp_cid_conn() function. Ultimately, the latter should be removed
as CID lookup could be conducted on quic_conn owned tree without
locking.
Locking of the CID tree was extended in qc_check_dcid() by recent commit
05f59a5 ("BUG/MINOR: quic: fix race condition in qc_check_dcid()") but
there was a direct return from the middle of the function which was not
covered by the unlock, resulting in the function keeping the lock on
success return.
Let's just remove this return and replace it with a variable to merge all
exit paths.
This must be backported wherever the fix above is backported.
qc_check_dcid() is a function which check that a DCID is associated to
the expected quic_conn instance. This is used for quic_conn socket
receive handler as there is a tiny risk that a datagram to another
connection was received on this socket.
As other operations on global CID tree, a lock must be used to protect
against race condition. However, as previous commit, lock was not held
long enough as CID tree node is accessed outside of the lock region. To
fix this, increase critical section until CID dereferencement is done.
The impact of this bug should be similar to the previous one. However,
risk of crash are even less reduced as it should be extremely rare to
receive datagram for other connections on a quic_conn socket. As such,
most of the time first check condition of qc_check_dcid() is enough.
This may fix first crash of issue github #2607.
This must be backported up to 2.8.
quic_conn API for sending was recently refactored. The main objective
was to regroup the different functions present for both handshake and
application emission.
After this refactoring, an optimization was introduced to avoid calling
qc_send() if there was nothing new to emit. However, this prevent the Tx
buffer to be purged if previous sending was interrupted, until new
frames are finally available.
To fix this, simply remove the optimization. qc_send() is thus now
always called in quic_conn IO handlers.
The impact of this bug should be minimal as it happens only on sending
temporary error. However in this case, this could cause extra latency or
even a complete sending freeze in the worst scenario.
This must be backported up to 3.0.
Ensure idle_timer task is allocated in qc_kill_conn() before waking it
up. It can be NULL if idle timer has already fired but MUX layer is
still present, which prevents immediate quic_conn release.
qc_kill_conn() is only used on send() syscall fatal error to notify
upper layer of an error and close the whole connection asap.
This crash occurence is pretty rare as it relies on timing issues. It
happens only if idle timer occurs before the MUX release (a bigger
client timeout is thus required) and any send() syscall detected error.
For now, it was only reproduced using GDB to interrupt haproxy longer
than the idle timeout.
This should be backported up to 2.6.
Rename enum values used for HTTP/3 and QPACK RFC defined codes. First
uses a prefix H3_ERR_* which serves as identifier between them. Also
separate QPACK values in a new dedicated enum qpack_err. This is deemed
cleaner.
qc_send() was systematically called by quic_conn IO handlers with all
instantiated quic_enc_level. Change this to only register quic_enc_level
for send if needed. Do not call at all qc_send() if no qel registered.
A new function qel_need_sending() is defined to detect if sending is
required. First, it checks if quic_enc_level has prepared frames or
probing is set. It can also returns true if ACK required either on
quic_enc_level itself or because of quic_conn ack timer fired. Finally,
a CONNECTION_CLOSE emission for quic_conn is also a valid case.
This should reduce the number of invocations of qc_send(). This could
improve slightly performance, as well as simplify traces debugging.
A series of previous patches have clean up sending function for
handshake case. Their new exposed API is now flexible enough to convert
app case to use the same functions.
As such, qc_send_hdshk_pkts() is renamed qc_send() and become the single
entry point for QUIC emission. It is used during application packets
emission in quic_conn_app_io_cb(), qc_send_mux(). Also the internal
function qc_prep_hpkts() is renamed qc_prep_pkts().
Remove the new unneeded qc_send_app_pkts() and qc_prep_app_pkts().
Also removed qc_send_app_probing(). It was a simple wrapper over other
application send functions. Now, default qc_send() can be reuse for such
cases with <old_data> argument set to true.
An adjustment was needed when converting qc_send_hdshk_pkts() to the
general qc_send() version. Previously, only a single packets
encoding/emission cycle was performed. This was enough as handshake
packets are always smaller than Tx buffer. However, it may be possible
to emit more application data. As such, a loop is necessary to perform
multiple encoding/emission cycles, as this was already the case in
qc_send_app_pkts().
No functional difference should happen with this commit. However, as
these are critcal functions with a lot of changes, this patch is
labelled as medium.
quic_conn_io_cb() manually implements emission by using lower level
functions qc_prep_pkts() and qc_send_ppkts(). Replace this by using the
higher level function qc_send_hdshk_pkts() which notably handle buffer
allocation and purging.
This allows to clean up send API by flagging qc_prep_pkts() and
qc_send_ppkts() as static. They are now used in a single location inside
qc_send_hdshk_pkts().
qc_send_hdshk_pkts() is a wrapper for qc_prep_hpkts() used on
retransmission. It was restricted to use two quic_enc_level pointers as
distinct arguments. Adapt it to directly use the same list of
quic_enc_level which is passed then to qc_prep_hpkts().
Now for retransmission quic_enc_level send list is built directly into
qc_dgrams_retransmit() which calls qc_send_hdshk_pkts().
Along this change, a new utility function qel_register_send() is
defined. It is an helper to build the quic_enc_level send list. It
enfores that each quic_enc_level instance is only registered in a single
list to prevent memory issues. It is both used in qc_dgrams_retransmit()
and quic_conn_io_cb().
Emission of packets during handshakes was implemented via an API which
uses two alternative ways to specify the list of frames.
The first one uses a NULL list of quic_enc_level as argument for
qc_prep_hpkts(). This was an implicit method to iterate on all qels
stored in quic_conn instance, with frames already inserted in their
corresponding quic_pktns.
The second method was used for retransmission. It uses a custom local
quic_enc_level list specified by the caller as input to qc_prep_hpkts().
Frames were accessible through <retransmit> list pointers of each
quic_enc_level used in an implicit mechanism.
This commit clarifies the API by using a single common method. Now
quic_enc_level list must always be specified by the caller. As for
frames list, each qels must set its new field <send_frms> pointer to the
list of frames to send. Callers of qc_prep_hpkts() are responsible to
always clear qels send list. This prevent a single instance of
quic_enc_level to be inserted while being attached to another list.
This allows notably to clean up some unnecessary code. First,
<retransmit> list of quic_enc_level is removed as it is replaced by new
<send_frms>. Also, it's now possible to use proper list_for_each_entry()
inside qc_prep_hpkts() to loop over each qels. Internal functions for
quic_enc_level selection is now removed.
On CRYPTO frames reception, tasklet is rescheduled with TASK_HEAVY to
limit CPU consumption. This commit slighly simplifies this by regrouping
TASK_HEAVY setting and tasklet_wakeup() instructions in a single
location in qc_handle_crypto_frm(). All other unnecessary
tasklet_wakeup() are removed.
After handshake completion, QUIC server is responsible to emit
HANDSHAKE_DONE frame. Some clients wait for it to begin STREAM
transfers.
Previously, there was no explicit tasklet_wakeup() after handshake
completion, which is necessary to emit post-handshake frames. In most
cases, this was undetected as most client continue emission which will
reschedule the tasklet. However, as there is no tasklet_wakeup(), this
is not a consistent behavior. If this bug occurs, it causes a connection
freeze, preventing the client to emit any request. The connection is
finally closed on idle timeout.
To fix this, add an explicit tasklet_wakeup() after handshake
completion. It sounds simple enough but in fact it's difficult to find
the correct location efor tasklet_wakeup() invocation, as post-handshake
is directly linked to connection accept, with different orderings.
Notably, if 0-RTT is used, connection can be accepted prior handshake
completion. Another major point is that along HANDSHAKE_DONE frame, a
series of NEW_CONNECTION_ID frames are emitted. However, these new CIDs
allocation must occur after connection is migrated to its new thread as
these CIDs are tied to it. A BUG_ON() is present to check this in
qc_set_tid_affinity().
With all this in mind, 2 locations were selected for the necessary
tasklet_wakeup() :
* on qc_xprt_start() : this is useful for standard case without 0-RTT.
This ensures that this is done only after connection thread migration.
* on qc_ssl_provide_all_quic_data() : this is done on handshake
completion with 0-RTT used. In this case only, connection is already
accepted and migrated, so tasklet_wakeup() is safe.
Note that as a side-change, quic_accept_push_qc() API has evolved to
better reflect differences between standard and 0-RTT usages. It is now
forbidden to call it multiple times on a single quic_conn instance. A
BUG_ON() has been added.
This issue is labelled as medium even though it seems pretty rare. It
was only reproducible using QUIC interop runner, with haproxy compiled
with LibreSSL with quic-go as client. However, affected code parts are
pretty sensible, which justify the chosen severity.
This should fix github issue #2418.
It should be backported up to 2.6, after a brief period of observation.
Note that the extra comment added in qc_set_tid_affinity() can be
removed in 2.6 as thread migration is not implemented for this version.
Other parts should apply without conflict.
Move qc_notify_send() from quic_tx.c to quic_conn.c. Note that it was already
exported from both quic_conn.h and quic_tx.h. Modify this latter header
to fix the duplication.
Move quic_path struct from quic_conn-t.h to quic_cc-t.h and rename it to quic_cc_path.
Update the code consequently.
Also some inlined functions in relation with QUIC path to quic_cc.h
Move quic_cstream struct definition from quic_conn-t.h to quic_tls-t.h.
Its pool is also moved from quic_conn module to quic_tls. Same thing for
quic_cstream_new() and quic_cstream_free().
Move quic_cid and quic_connnection_id from quic_conn-t.h to new quic_cid-t.h header.
Move defintions of quic_stateless_reset_token_init(), quic_derive_cid(),
new_quic_cid(), quic_get_cid_tid() and retrieve_qc_conn_from_cid() to quic_cid.c
new C file.
On CONNECTION_CLOSE reception/emission, QUIC connections enter CLOSING
state. At this stage, only CONNECTION_CLOSE can be reemitted and all
other exchanges are stopped.
Previously, on haproxy process stopping, if all QUIC connections were in
CLOSING state, they were released before their closing timer expiration
to not block the process shutdown. However, since a recent commit, the
closing timer has been shorten to a more reasonable delay. It is now
consider viable to respect connections closing state even on process
shutdown. As such, stopping specific code in QUIC connections idle timer
task was removed.
A specific function quic_handle_stopping() was implemented to notify
QUIC connections on shutdown from main() function. It should have been
deleted along the removal in QUIC idle timer task. This patch just does
this.
The connections are flagged as "to be killed" asap when the peer has left
(detected by sendto() "Connection refused" errno) by qc_kill_conn(). This
function has to wakeup the idle timer task to release the connection (and the idle
timer and the idle timer task itself). Then if in the meantime the connection
was flagged as having to process some retransmissions, some packet could lead
to sendto() errors again with a call to qc_kill_conn(), this time with a released
idle timer task.
This bug could be detected by libasan as follows:
.AddressSanitizer:DEADLYSIGNAL
=================================================================
==21018==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x 560b5d898717 bp 0x7f9aaac30000 sp 0x7f9aaac2ff80 T3)
==21018==The signal is caused by a READ memory access.
==21018==Hint: address points to the zero page.
. #0 0x560b5d898717 in _task_wakeup include/haproxy/task.h:209
#1 0x560b5d8a563c in qc_kill_conn src/quic_conn.c:171
#2 0x560b5d97f832 in qc_send_ppkts src/quic_tx.c:636
#3 0x560b5d981b53 in qc_send_app_pkts src/quic_tx.c:876
#4 0x560b5d987122 in qc_send_app_probing src/quic_tx.c:910
#5 0x560b5d987122 in qc_dgrams_retransmit src/quic_tx.c:1397
#6 0x560b5d8ab250 in quic_conn_app_io_cb src/quic_conn.c:712
#7 0x560b5de41593 in run_tasks_from_lists src/task.c:596
#8 0x560b5de4333c in process_runnable_tasks src/task.c:876
#9 0x560b5dd6f2b0 in run_poll_loop src/haproxy.c:2966
#10 0x560b5dd700fb in run_thread_poll_loop src/haproxy.c:3165
#11 0x7f9ab9188ea6 in start_thread nptl/pthread_create.c:477
#12 0x7f9ab90a8a2e in __clone (/lib/x86_64-linux-gnu/libc.so.6+0xfba2e)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV include/haproxy/task.h:209 in _task_wakeup
Thread T3 created by T0 here:
#0 0x7f9ab97ac2a2 in __interceptor_pthread_create ../../../../src/libsaniti zer/asan/asan_interceptors.cpp:214
#1 0x560b5df4f3ef in setup_extra_threads src/thread.c:252 o
#2 0x560b5dd730c7 in main src/haproxy.c:3856
#3 0x7f9ab8fd0d09 in __libc_start_main ../csu/libc-start.c:308 i
==21018==ABORTING
AddressSanitizer:DEADLYSIGNAL
Aborted (core dumped)
To fix, simply reset the connection flag QUIC_FL_CONN_RETRANS_NEEDED to cancel
the retransmission when qc_kill_conn is called.
Note that this new bug arrived with this fix which is correct and flagged as to be
backported as far as 2.6.
BUG/MINOR: quic: idle timer task requeued in the past
Must be backported as far as 2.6.
The idle timer task may be used to trigger the client handshake timeout.
The hanshake timeout expiration date (qc->hs_expire) is initialized when the
connection is allocated. Obviously, this timeout is taken into an account only
during the handshake by qc_idle_timer_do_rearm() whose job is to rearm the idle timer.
The idle timer expiration date could be initialized only one time, then
never updated until the hanshake completes. But this only works if the
handshake timeout is smaller than the idle timer task timeout. If the handshake
timeout is set greater than the idle timeout, this latter may expire before the
handshake timeout.
This patch may have an impact on the L1/C1 interop tests (with heavy packet loss
or corruption). This is why I guess some implementations with a hanshake timeout
support set a big timeout during this test. This is at least the case for ngtcp2
which sets a 180s hanshake timeout! haproxy will certainly have to proceed the
same way if it wants to have a chance to pass this test as before this handshake
timeout.
