The reasons why a stream may not be created by server currently include hitting
worker_connections limit and memory allocation error. Previously in these
cases the entire QUIC connection was closed and all its streams were shut down.
Now the new stream is rejected and existing streams continue working.
To reject an HTTP/3 request stream, RESET_STREAM and STOP_SENDING with
H3_REQUEST_REJECTED error code are sent to client. HTTP/3 uni streams and
Stream streams are not rejected.
As per quic-qpack-21:
When a stream is reset or reading is abandoned, the decoder emits a
Stream Cancellation instruction.
Previously the instruction was not sent. Now it's sent when closing QUIC
stream connection if dynamic table capacity is non-zero and eof was not
received from client. The latter condition means that a trailers section
may still be on its way from client and the stream needs to be cancelled.
A QUIC stream connection is treated as reusable until first bytes of request
arrive, which is also when the request object is now allocated. A connection
closed as a result of draining, is reset with the error code
H3_REQUEST_REJECTED. Such behavior is allowed by quic-http-34:
Once a request stream has been opened, the request MAY be cancelled
by either endpoint. Clients cancel requests if the response is no
longer of interest; servers cancel requests if they are unable to or
choose not to respond.
When the server cancels a request without performing any application
processing, the request is considered "rejected." The server SHOULD
abort its response stream with the error code H3_REQUEST_REJECTED.
The client can treat requests rejected by the server as though they had
never been sent at all, thereby allowing them to be retried later.
When an HTTP/3 function returns an error in context of a QUIC stream, it's
this function's responsibility now to finalize the entire QUIC connection
with the right code, if required. Previously, QUIC connection finalization
could be done both outside and inside such functions. The new rule follows
a similar rule for logging, leads to cleaner code, and allows to provide more
details about the error.
While here, a few error cases are no longer treated as fatal and QUIC connection
is no longer finalized in these cases. A few other cases now lead to
stream reset instead of connection finalization.
The PATH_RESPONSE frame must be expanded to 1200, except the case
when anti-amplification limit is in effect, i.e. on unvalidated paths.
Previously, the anti-amplification limit was always applied.
If client ID was never used, its refcount is zero. To keep things simple,
the ngx_quic_unref_client_id() function is now aware of such IDs.
If client ID was used, the ngx_quic_replace_retired_client_id() function
is supposed to find all users and unref the ID, thus ngx_quic_unref_client_id()
should not be called after it.
Previously, it was not enforced in the stream module.
Now, since b9e02e9b2f1d it is possible to specify protocols.
Since ALPN is always required, the 'require_alpn' setting is now obsolete.
The "min" and "max" arguments refer to UDP datagram size. Generating payload
requires to account properly for header size, which is variable and depends on
payload size and packet number.
Without this change, aio used with HTTP/2 can result in connection hang,
as observed with "aio threads; aio_write on;" and proxying (ticket #2248).
The problem is that HTTP/2 updates buffers outside of the output filters
(notably, marks them as sent), and then posts a write event to call
output filters. If a filter does not call the next one for some reason
(for example, because of an AIO operation in progress), this might
result in a state when the owner of a buffer already called
ngx_chain_update_chains() and can reuse the buffer, while the same buffer
is still sitting in the busy chain of some other filter.
In the particular case a buffer was sitting in output chain's ctx->busy,
and was reused by event pipe. Output chain's ctx->busy was permanently
blocked by it, and this resulted in connection hang.
Fix is to change ngx_chain_update_chains() to skip buffers from other
modules unconditionally, without trying to wait for these buffers to
become empty.
The "sendfile_max_chunk" directive is important to prevent worker
monopolization by fast connections. The 2m value implies maximum 200ms
delay with 100 Mbps links, 20ms delay with 1 Gbps links, and 2ms on
10 Gbps links. It also seems to be a good value for disks.
Previously, connections to upstream servers used sendfile() if it was
enabled, but never honored sendfile_max_chunk. This might result
in worker monopolization for a long time if large request bodies
are allowed.
On Linux starting with 2.6.16, sendfile() silently limits all operations
to MAX_RW_COUNT, defined as (INT_MAX & PAGE_MASK). This incorrectly
triggered the interrupt check, and resulted in 0-sized writev() on the
next loop iteration.
Fix is to make sure the limit is always checked, so we will return from
the loop if the limit is already reached even if number of bytes sent is
not exactly equal to the number of bytes we've tried to send.
Previously, it was checked that sendfile_max_chunk was enabled and
almost whole sendfile_max_chunk was sent (see e67ef50c3176), to avoid
delaying connections where sendfile_max_chunk wasn't reached (for example,
when sending responses smaller than sendfile_max_chunk). Now we instead
check if there are unsent data, and the connection is still ready for writing.
Additionally we also check c->write->delayed to ignore connections already
delayed by limit_rate.
This approach is believed to be more robust, and correctly handles
not only sendfile_max_chunk, but also internal limits of c->send_chain(),
such as sendfile() maximum supported length (ticket #1870).
Previously, 1 millisecond delay was used instead. In certain edge cases
this might result in noticeable performance degradation though, notably on
Linux with typical CONFIG_HZ=250 (so 1ms delay becomes 4ms),
sendfile_max_chunk 2m, and link speed above 2.5 Gbps.
Using posted next events removes the artificial delay and makes processing
fast in all cases.
The directive enables including all frames from start time to the most recent
key frame in the result. Those frames are removed from presentation timeline
using mp4 edit lists.
Edit lists are currently supported by popular players and browsers such as
Chrome, Safari, QuickTime and ffmpeg. Among those not supporting them properly
is Firefox[1].
Based on a patch by Tracey Jaquith, Internet Archive.
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1735300
The function updates the duration field of mdhd atom. Previously it was
updated in ngx_http_mp4_read_mdhd_atom(). The change makes it possible to
alter track duration as a result of processing track frames.
After fe919fd63b0b, processing QUIC streams was postponed until after handshake
completion, which means that 0-RTT is effectively off. With ssl_ocsp enabled,
it could be further delayed. This differs from how OCSP validation works with
SSL_read_early_data(). With this change, processing QUIC streams is unlocked
when obtaining 0-RTT secret.
The sent queue is sorted by packet number. It is possible to avoid
traversing full queue while handling ack ranges. It makes sense to
start traversing from the queue head (i.e. check oldest packets first).
With this patch, all traffic over a QUIC connection is compared to traffic
over QUIC streams. As long as total traffic is many times larger than stream
traffic, we consider this to be a flood.
With this patch, all traffic over HTTP/3 bidi and uni streams is counted in
the h3c->total_bytes field, and payload traffic is counted in the
h3c->payload_bytes field. As long as total traffic is many times larger than
payload traffic, we consider this to be a flood.
Request header traffic is counted as if all fields are literal. Response
header traffic is counted as is.
Checking the reset after encryption avoids false positives. More importantly,
it avoids the check entirely in the usual case where decryption succeeds.
RFC 9000, 10.3.1 Detecting a Stateless Reset
Endpoints MAY skip this check if any packet from a datagram is
successfully processed.
As per RFC 9000:
An endpoint that receives a STOP_SENDING frame MUST send a RESET_STREAM
frame if the stream is in the "Ready" or "Send" state.
An endpoint SHOULD copy the error code from the STOP_SENDING frame to
the RESET_STREAM frame it sends, but it can use any application error code.
The flag indicates that the entire response was sent to the socket up to the
last_buf flag. The flag is only usable for protocol implementations that call
ngx_http_write_filter() from header filter, such as HTTP/1.x and HTTP/3.
Similar to the previous change, a segmentation fault occurres when evaluating
SSL certificates on a QUIC connection due to an uninitialized stream session.
The fix is to adjust initializing the QUIC part of a connection until after
it has session and variables initialized.
Similarly, this appends logging error context for QUIC connections:
- client 127.0.0.1:54749 connected to 127.0.0.1:8880 while handling frames
- quic client timed out (60: Operation timed out) while handling quic input
A QUIC connection doesn't have c->log->data and friends initialized to sensible
values. Yet, a request can be created in the certificate callback with such an
assumption, which leads to a segmentation fault due to null pointer dereference
in ngx_http_free_request(). The fix is to adjust initializing the QUIC part of
a connection such that it has all of that in place.
Further, this appends logging error context for unsuccessful QUIC handshakes:
- cannot load certificate .. while handling frames
- SSL_do_handshake() failed .. while sending frames
