Add nghttp2_option_set_server_fallback_rfc7540_priorities. If it is
set to nonzero, and server submits SETTINGS_NO_RFC7540_PRIORITIES = 1,
but it does not receive SETTINGS_NO_RFC7540_PRIORITIES from client,
server falls back to RFC 7540 priorities. Only minimal set of
features are enabled in this fallback case.
This commit adds PRIORITY_UPDATE frame support. Applying incoming
PRIORITY_UPDATE frame to server push stream is not implemented.
Client can send PRIORITY_UPDATE frame by calling
nghttp2_submit_priority_update.
Server opts to receive PRIORITY_UPDATE frame by the call
nghttp2_option_set_builtin_recv_extension_type(option,
NGHTTP2_PRIORITY_UPDATE), and passing the option to
nghttp2_session_server_new2 or nghttp2_session_server_new3.
This commit implements RFC 9218 extensible prioritization scheme. It
is enabled when a local endpoint submits
SETTINGS_NO_RFC7540_PRIORITIES = 1. This commit only handles priority
signal in HTTP request header field. Priority header field in
PUSH_PROMISE is not supported.
HTTP messaging must be enabled to take advantage of this
prioritization scheme because HTTP fields are not parsed if HTTP
messaging is disabled.
Add the currently-unused `test_nghttp2_session_create_idle_stream()`
function to the test suite definition.
Modify the test in two places to make it pass:
* Use stream ID=10 as the priority stream ID to test automatic creation
of streams for priority specs. The code below checks against stream
ID=10 so I assume this was a typo in the test.
* Set the `last_sent_stream_id` instead of the `next_stream_id` to test
that idle streams cannot be created with smaller numbers than the
most-recently-seen stream ID. Looking at the validation path in
`session_detect_idle_stream()`, I think this was another test typo.
nghttp2_option_no_closed_streams controls whether closed streams are
retained or not. If nonzero is passed to that function's parameter
val, a session does not retain closed streams. It may hurt the shape
of priority tree, but can save memory.
Previously, in server side, we used closed streams to detect the error
that the misbehaving client sends a frame on the incoming stream it
explicitly closed. With this commit, we make a further step, and
detect one more error case. Since we retain closed streams as long as
the sum of its size and the number of opened streams are equal or less
than max concurrent streams, we can safely say that if we get a frame
which is sent on the stream that is not found in either closed or
opened stream, it is already closed or has not existed. Then we can
send GOAWAY.
The previous code shrinks closed streams when we closed another
stream, but now it is removed. It is enough to adjust closed streams
when new incoming stream is created.
While creating this commit, we noticed that
NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS is defined as INT32_MAX. But
since SETTINGS can contain value up to UINT32_MAX, it is not enough.
However, since the stream ID space is limited to INT32_MAX, it is high
enough. We could keep this value, but this time we deprecate
NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS macro. While it is in public
header, the effect of deprecating it is negligible because of the
reason we wrote above, and usually application sets much smaller value
(say, 100) as SETTINGS_MAX_CONCURRENT_STREAMS.
This function sets the maximum length of header block (a set of header
fields per HEADERS frame) to send. The length of given set of header
fields is calculated using nghttp2_hd_deflate_bound(). Previously,
this is hard-coded, and is 64KiB.
With the presence of idle stream related API (e.g.,
nghttp2_create_idle_stream()), it is more predictable for client to
create idle streams with its dependency to another idle stream.
Previously, we didn't create complete parent idle stream in this case.
Now we create idle streams as we do on server side.
Previously, nghttp2_session_end_request_headers_received assumes
stream is still writable (in other words, local endpoint has not sent
END_STREAM). But this assumption is false, because application can
send response in nghttp2_on_begin_frame_callback. Probably, this
assumption was made before the callback was introduced. This commit
addresses this issue. Since all
nghttp2_session_end_*_headers_received functions are identical, we
refactored them into one function.
Previously, nghttp2_session_find_stream(session, 0) returned NULL
despite the fact that documentation said that it should return root
stream. Now it is corrected, and it returns root stream as
documented.
To validate actual response body length against the value declared in
content-length response header field, we first check request method.
If request method is HEAD, respose body must be 0 regardless of the
value in content-length. nghttp2_session_upgrade() has no parameter
to indicate the request method is HEAD, so we failed to validate
response body if HEAD is used with HTTP Upgrade. New
nghttp2_session_upgrade2() accepts new parameter to indicate that
request method is HEAD or not to fix this issue. Although, this issue
affects client side only, we deprecate nghttp2_session_upgrade() in
favor of nghttp2_session_upgrade2() for both client and server side.
By default, we check the length of response body matches
content-length. For HEAD request, this is not necessarily true, so we
sniff request method, and if it is HEAD, make sure that response body
length is 0. But this does not work for HTTP Upgrade, since
nghttp2_session_upgrade() has no parameter to tell the request method
was HEAD. This commit disables this response body length validation
for the stream upgraded by HTTP Upgrade. We will add new version of
nghttp2_session_upgrade with the parameter to pass the request method
information so that we can handle this situation properly.
The intention of this stream API is give server application about
stream dependency information, so that it can utilize it for better
scheduling of stream processing. We have no plan to add object
oriented API based on stream object.
We now use priority queue per stream, which contains the stream which
has ready to send a frame, or one of its descendants have a frame to
send. We maintain invariant that if a stream is queued, then its
ancestors are also queued (except for root). When we re-schedule
stream after transmission, we re-schedule all ancestors, so that
streams on the other path can get a chance to send. This is basically
the same mechanism h2o project uses, but there are differences in the
details.
Tatsuhiro Tsujikawa
James M Snell
Geoff Hill