Previously, tx ACK frames held ranges in an array of ngx_quic_ack_range_t,
while rx ACK frames held ranges in the serialized format. Now serialized format
is used for both types of frames.
The patch resets ctx->frames queue, which may contain frames. It was possible
that congestion or amplification limits prevented all frames to be sent.
Retransmitted frames could be accounted twice as inflight: first time in
ngx_quic_congestion_lost() called from ngx_quic_resend_frames(), and later
from ngx_quic_discard_ctx().
This accounts for the following change:
* Require expansion of datagrams to ensure that a path supports at
least 1200 bytes:
- During the handshake ack-eliciting Initial packets from the
server need to be expanded
All values are prefixed with name and separated from it using colon.
Multiple values are listed without commas in between.
Rationale: this greatly simplifies log parsing for analysis.
For application level packets, only every second packet is now acknowledged,
respecting max ack delay.
13.2.1 Sending ACK Frames
In order to assist loss detection at the sender, an endpoint SHOULD
generate and send an ACK frame without delay when it receives an ack-
eliciting packet either:
* when the received packet has a packet number less than another
ack-eliciting packet that has been received, or
* when the packet has a packet number larger than the highest-
numbered ack-eliciting packet that has been received and there are
missing packets between that packet and this packet.
13.2.2. Acknowledgement Frequency
A receiver SHOULD send an ACK frame after receiving at least two
ack-eliciting packets.
In some cases it might be needed to reject SSL handshake based on SNI
server name provided, for example, to make sure an invalid certificate
is not returned to clients trying to contact a name-based virtual server
without SSL configured. Previously, a "ssl_ciphers aNULL;" was used for
this. This workaround, however, is not compatible with TLSv1.3, in
particular, when using BoringSSL, where it is not possible to configure
TLSv1.3 ciphers at all.
With this change, the ssl_reject_handshake directive is introduced,
which instructs nginx to reject SSL handshakes with an "unrecognized_name"
alert in a particular server block.
For example, to reject handshake with names other than example.com,
one can use the following configuration:
server {
listen 443 ssl;
ssl_reject_handshake on;
}
server {
listen 443 ssl;
server_name example.com;
ssl_certificate example.com.crt;
ssl_certificate_key example.com.key;
}
The following configuration can be used to reject all SSL handshakes
without SNI server name provided:
server {
listen 443 ssl;
ssl_reject_handshake on;
}
server {
listen 443 ssl;
server_name ~^;
ssl_certificate example.crt;
ssl_certificate_key example.key;
}
Additionally, the ssl_reject_handshake directive makes configuring
certificates for the default server block optional. If no certificates
are configured in the default server for a given listening socket,
certificates must be defined in all non-default server blocks with
the listening socket in question.
Similarly to ssl_conf_command, proxy_ssl_conf_command can be used to
set arbitrary OpenSSL configuration parameters as long as nginx is
compiled with OpenSSL 1.0.2 or later, when connecting to upstream
servers with SSL. Full list of available configuration commands
can be found in the SSL_CONF_cmd manual page
(https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html).
Similarly to ssl_conf_command, proxy_ssl_conf_command (grpc_ssl_conf_command,
uwsgi_ssl_conf_command) can be used to set arbitrary OpenSSL configuration
parameters as long as nginx is compiled with OpenSSL 1.0.2 or later,
when connecting to upstream servers with SSL. Full list of available
configuration commands can be found in the SSL_CONF_cmd manual page
(https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html).
With the ssl_conf_command directive it is now possible to set
arbitrary OpenSSL configuration parameters as long as nginx is compiled
with OpenSSL 1.0.2 or later. Full list of available configuration
commands can be found in the SSL_CONF_cmd manual page
(https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html).
In particular, this allows configuring PrioritizeChaCha option
(ticket #1445):
ssl_conf_command Options PrioritizeChaCha;
It can be also used to configure TLSv1.3 ciphers in OpenSSL,
which fails to configure them via the SSL_CTX_set_cipher_list()
interface (ticket #1529):
ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256;
Configuration commands are applied after nginx own configuration
for SSL, so they can be used to override anything set by nginx.
Note though that configuring OpenSSL directly with ssl_conf_command
might result in a behaviour nginx does not expect, and should be
done with care.
With this change, it is now possible to use ngx_conf_merge_ptr_value()
to merge keyval arrays. This change actually follows much earlier
changes in ngx_conf_merge_ptr_value() and ngx_conf_set_str_array_slot()
in 1452:cd586e963db0 (0.6.10) and 1701:40d004d95d88 (0.6.22).
To preserve compatibility with existing 3rd party modules, both NULL
and NGX_CONF_UNSET_PTR are accepted for now.
13.2.4. Limiting Ranges by Tracking ACK Frames
When a packet containing an ACK frame is sent, the largest
acknowledged in that frame may be saved. When a packet containing an
ACK frame is acknowledged, the receiver can stop acknowledging
packets less than or equal to the largest acknowledged in the sent
ACK frame.
The history of acknowledged packet is kept in send context as ranges.
Up to NGX_QUIC_MAX_RANGES ranges is stored.
As a result, instead of separate ack frames, single frame with ranges
is sent.
Per draft-ietf-quic-transport-32 on the topic:
: Similarly, a server MUST expand the payload of all UDP datagrams carrying
: ack-eliciting Initial packets to at least the smallest allowed maximum
: datagram size of 1200 bytes.
The history of acknowledged packet is kept in send context as ranges.
Up to NGX_QUIC_MAX_RANGES ranges is stored.
As a result, instead of separate ack frames, single frame with ranges
is sent.
Previously, if there were multiple limits configured, errors in
ngx_http_complex_value() during processing of a non-first limit
resulted in reference count leak in shared memory nodes of already
processed limits. Fix is to explicity unlock relevant nodes, much
like we do when rejecting requests.
The proxy_smtp_auth directive instructs nginx to authenticate users
on backend via the AUTH command (using the PLAIN SASL mechanism),
similar to what is normally done for IMAP and POP3.
If xclient is enabled along with proxy_smtp_auth, the XCLIENT command
won't try to send the LOGIN parameter.
In 7717:e3e8b8234f05, the 1st bit was incorrectly used. It shouldn't
be used for bitmask values, as it is used by NGX_CONF_BITMASK_SET.
Additionally, special value "off" added to make it possible to clear
inherited userid_flags value.
