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.
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, this field was not set while creating a QUIC stream connection.
As a result, calling ngx_connection_local_sockaddr() led to getsockname()
bad descriptor error.
If client acknowledged an Initial packet with CRYPTO frame and then
sent another Initial packet containing duplicate CRYPTO again, this
could result in resending frames off the empty send queue.
