Previously, computing rttvar used an updated smoothed_rtt value as per
RFC 9002, section 5.3, which appears to be specified in a wrong order.
A technical errata ID 7539 is reported.
Although it has better implementation status than HTTP/3 server push,
it remains of limited use, with adoption numbers seen as negligible.
Per IETF 102 materials, server push was used only in 0.04% of sessions.
It was considered to be "difficult to use effectively" in RFC 9113.
Its use is further limited by badly matching to fetch/cache/connection
models in browsers, see related discussions linked from [1].
Server push was disabled in Chrome 106 [2].
The http2_push, http2_push_preload, and http2_max_concurrent_pushes
directives are made obsolete. In particular, this essentially reverts
7201:641306096f5b and 7207:3d2b0b02bd3d.
[1] https://jakearchibald.com/2017/h2-push-tougher-than-i-thought/
[2] https://chromestatus.com/feature/6302414934114304
It has been deprecated since 7270:46c0c7ef4913 (1.15.0) in favour of
the "ssl" parameter of the "listen" directive, which has been available
since 2224:109849282793 (0.7.14).
The directive enables HTTP/2 in the current server. The previous way to
enable HTTP/2 via "listen ... http2" is now deprecated. The new approach
allows to share HTTP/2 and HTTP/0.9-1.1 on the same port.
For SSL connections, HTTP/2 is now selected by ALPN callback based on whether
the protocol is enabled in the virtual server chosen by SNI. This however only
works since OpenSSL 1.0.2h, where ALPN callback is invoked after SNI callback.
For older versions of OpenSSL, HTTP/2 is enabled based on the default virtual
server configuration.
For plain TCP connections, HTTP/2 is now auto-detected by HTTP/2 preface, if
HTTP/2 is enabled in the default virtual server. If preface is not matched,
HTTP/0.9-1.1 is assumed.
Previously, rec.level field was not uninitialized in SSL_provide_quic_data().
As a result, its value was always ssl_encryption_initial. Later in
ngx_quic_ciphers() such level resulted in resetting the cipher to
TLS1_3_CK_AES_128_GCM_SHA256 and using AES128 to encrypt the packet.
Now the level is initialized and the right cipher is used.
The layer is enabled as a fallback if the QUIC support is configured and the
BoringSSL API wasn't detected, or when using the --with-openssl option, also
compatible with QuicTLS and LibreSSL. For the latter, the layer is assumed
to be present if QUIC was requested, so it needs to be undefined to prevent
QUIC API redefinition as appropriate.
A previously used approach to test the TLSEXT_TYPE_quic_transport_parameters
macro doesn't work with OpenSSL 3.2 master branch where this macro appeared
with incompatible QUIC API. To fix the build there, the test is revised to
pass only for QuicTLS and LibreSSL.
Previously, ngx_quic_close_connection() could be called in a way that QUIC
connection was accessed after the call. In most cases the connection is not
closed right away, but close timeout is scheduled. However, it's not always
the case. Also, if the close process started earlier for a different reason,
calling ngx_quic_close_connection() may actually close the connection. The
connection object should not be accessed after that.
Now, when possible, return statement is added to eliminate post-close connection
object access. In other places ngx_quic_close_connection() is substituted with
posting close event.
Also, the new way of closing connection in ngx_quic_stream_cleanup_handler()
fixes another problem in this function. Previously it passed stream connection
instead of QUIC connection to ngx_quic_close_connection(). This could result
in incomplete connection shutdown. One consequence of that could be that QUIC
streams were freed without shutting down their application contexts. This could
result in another use-after-free.
Found by Coverity (CID 1530402).
The qsock->sockaddr field is a ngx_sockaddr_t union, and therefore can hold
any sockaddr (and union members, such qsock->sockaddr.sockaddr, can be used
to access appropriate variant of the sockaddr). It is better to set it via
qsock->sockaddr itself though, and not qsock->sockaddr.sockaddr, so static
analyzers won't complain about out-of-bounds access.
Prodded by Coverity (CID 1530403).
Previously, ngx_udp_rbtree_insert_value() was used for plain UDP and
ngx_quic_rbtree_insert_value() was used for QUIC. Because of this it was
impossible to initialize connection tree in ngx_create_listening() since
this function is not aware what kind of listening it creates.
Now ngx_udp_rbtree_insert_value() is used for both QUIC and UDP. To make
is possible, a generic key field is added to ngx_udp_connection_t. It keeps
client address for UDP and connection ID for QUIC.
The directive used to set the value of the "max_udp_payload_size" transport
parameter. According to RFC 9000, Section 18.2, the value specifies the size
of buffer for reading incoming datagrams:
This limit does act as an additional constraint on datagram size in
the same way as the path MTU, but it is a property of the endpoint
and not the path; see Section 14. It is expected that this is the
space an endpoint dedicates to holding incoming packets.
Current QUIC implementation uses the maximum possible buffer size (65527) for
reading datagrams.
HTTP and Stream variables $remote_addr and $binary_remote_addr rely on
constant client address, particularly because they are cacheable.
However, QUIC client may migrate to a new address. While there's no perfect
way to handle this, the proposed solution is to copy client address to QUIC
stream at stream creation.
The change also fixes truncated $remote_addr if migration happened while the
stream was active. The reason is addr_text string was copied to stream by
value.
The existing logic to evaluate multi header "$sent_http_*" variables,
such as $sent_http_cache_control, as previously introduced in 1.23.0,
doesn't take into account that one or more elements can be cleared,
yet still present in a linked list, pointed to by the next field.
Such elements don't contribute to the resulting variable length, an
attempt to append a separator for them ends up in out of bounds write.
This is not possible with standard modules, though at least one third
party module is known to override multi header values this way, so it
makes sense to harden the logic.
The fix restores a generic boundary check.
Previously, the value was not set and remained zero. While in nginx code the
value of c->sockaddr is accessed without taking c->socklen into account,
invalid c->socklen could lead to unexpected results in third-party modules.
Previously, the post-migration value of addr_text could be truncated, if
it was longer than the previous one. Also, the new value always included
port, which should not be there.
According to RFC 9000, 8.2.4. Failed Path Validation,
the following value is recommended as a validation timeout:
A value of three times the larger of the current PTO
or the PTO for the new path (using kInitialRtt, as
defined in [QUIC-RECOVERY]) is RECOMMENDED.
The change adds PTO of the new path to the equation as the lower bound.
Path validation packets containing PATH_CHALLENGE frames are sent separately
from regular frame queue, because of the need to use a decicated path and pad
the packets. The packets are sent periodically, separately from the regular
probe/lost detection mechanism. A path validation packet is resent up to 3
times, each time after PTO expiration, with increasing per-path PTO backoff.
The check is needed for clients in order to unblock a server due to
anti-amplification limits, and it seems to make no sense for servers.
See RFC 9002, A.6 and A.8 for a further explanation.
This makes max_ack_delay to now always account, notably including
PATH_CHALLENGE timers as noted in the last paragraph of 9000, 9.4,
unlike when it was only used when there are packets in flight.
While here, fixed nearby style.
Previously, ssl_encryption_application was hardcoded. Before 9553eea74f2a,
ngx_quic_frame_sendto() was used only for PATH_CHALLENGE/PATH_RESPONSE sent
at the application level only. Since 9553eea74f2a, ngx_quic_frame_sendto()
is also used for CONNECTION_CLOSE, which can be sent at initial level after
SSL handshake error or rejection. This resulted in packet encryption error.
Now level is copied from frame, which fixes the error.
Previously, before sending CONNECTION_CLOSE to client, all pending frames
were sent. This is redundant and could prevent CONNECTION_CLOSE from being
sent due to congestion control. Now pending frames are freed and
CONNECTION_CLOSE is sent without congestion control, as advised by RFC 9002:
Packets containing frames besides ACK or CONNECTION_CLOSE frames
count toward congestion control limits and are considered to be in flight.
Do not corrupt frame data chain pointer on ngx_quic_read_buffer() error.
The error leads to closing a QUIC connection where the frame may be used
as part of the QUIC connection tear down, which envolves writing pending
frames, including this one.
The rcf->studies list is unconditionally accessed by ngx_regex_cleanup(),
and this used to cause NULL pointer dereference if allocation
failed. Fix is to set cleanup handler only when allocation succeeds.
Previously, waiting on a shared connection was not allowed, because the only
type of such connection was plain UDP. However, QUIC stream connections are
also shared since they share socket descriptor with the listen connection.
Meanwhile, it's perfectly normal to wait on such connections.
The issue manifested itself with stream write errors when the amount of data
exceeded stream buffer size or flow control. Now no error is triggered
and Stream write module is allowed to wait for buffer space to become available.
When a stream is created by client, it's often the case that nginx will send
immediate response on that stream. An example is HTTP/3 request stream, which
in most cases quickly replies with at least HTTP headers.
QUIC stream init handlers are called from a posted event. Output QUIC
frames are also sent to client from a posted event, called the push event.
If the push event is posted before the stream init event, then output produced
by stream may trigger sending an extra UDP datagram. To address this, push
event is now re-posted when a new stream init event is posted.
An example is handling 0-RTT packets. Client typically sends an init packet
coalesced with a 0-RTT packet. Previously, nginx replied with a padded CRYPTO
datagram, followed by a 1-RTT stream reply datagram. Now CRYPTO and STREAM
packets are coalesced in one reply datagram, which saves bandwidth.
Other examples include coalescing 1-RTT first stream response, and
MAX_STREAMS/STREAM sent in response to ACK/STREAM.
It now uses custom alloc_aligned() wrapper for all allocations,
therefore all allocations are larger than expected by (64 + sizeof(void*)).
Further, they are seen as allocations of 1 element. Relevant calculations
were adjusted to reflect this, and state allocation is now protected
with a flag to avoid misinterpreting other allocations as the zlib
deflate_state allocation.
Further, it no longer forces window bits to 13 on compression level 1,
so the comment was adjusted to reflect this.
When establishing a connection to the backend, nginx blocks reading
from the client with ngx_mail_proxy_block_read(). Previously, such
events were lost, and in some cases this resulted in connection hangs.
Notably, this affected mail_imap_ssl.t on Windows, since the test
closes connections after requesting authentication, but without
waiting for any responses (so the connection close events might be
lost).
Fix is to post an event to read from the client after connecting to
the backend if there were blocked events.
