On Tue, 15 Mar 2022 14:54:35 GMT, Conor Cleary <ccle...@openjdk.org> wrote:
>> **Problem**
>> When a Continuation Frame is received by the httpclient using HTTP/2 after a
>> Push Promise frame (can happen if the amount of headers to be sent in a
>> single Push Promise frame exceeds the maximum frame size, so a Continuation
>> frame is required), the following exception occurs:
>>
>>
>> java.io.IOException: no statuscode in response
>> at
>> java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:565)
>> at
>> java.net.http/jdk.internal.net.http.HttpClientFacade.send(HttpClientFacade.java:119)
>> ...
>>
>> This exception occurs because there is no existing flow in
>> `jdk/internal/net/http/Http2Connection.java` which accounts for the case
>> where a PushPromiseFrame is received with the END_HEADERS flag set to 0x0.
>> When this occurs, the only acceptable frame/s (as multiple continuations are
>> also acceptable) that can be received by the client on the same stream is a
>> continuation frame.
>>
>> **Fix**
>> To ensure correct behavior, the following changes were made to
>> `jdk/internal/net/http/Http2Connection.java`.
>>
>> - The existing method `handlePushPromise()` was modified so that if the
>> END_HEADERS flag is _unset_ (flags equal to 0x0), then a record used to
>> track the state of the Push Promise containing a shared `HeaderDecoder` and
>> the received `PushPromiseFrame` is initialised.
>> - When the subsequent `ContinuationFrame` is received in `processFrame()`,
>> the method `handlePushContinuation()` is called instead of the default flow
>> resulting in `stream.incoming(frame)` being called (the source of the
>> incorrect behaviour originally).
>> - In `handlePushContinuation()`, the shared decoder is used to decode the
>> received `ContinuationFrame` headers and if the `END_HEADERS` flag is set
>> (flags equal to 0x4), the `HttpHeaders` object for the Push Promise as a
>> whole is constructed which serves to combine the headers from both the
>> `PushPromiseFrame` and the `ContinuationFrame`.
>>
>> A regression test was included which verifies that the exception is not
>> thrown and that the headers arrive correctly.
>
> Conor Cleary has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - 8263031: Cleanup of changes in Http2Connection
> - 8263031: Added test for multiple Continuation Frames
src/java.net.http/share/classes/jdk/internal/net/http/Http2Connection.java line
814:
> 812: // TODO: Maybe say what kind of frame was received
> instead
> 813: pushContinuationState = null;
> 814: protocolError(ErrorFrame.PROTOCOL_ERROR, "Expected a
> Continuation frame but received " + frame);
In all other places in this method we have `return;` just after a call to
`protocolError`, except in the two places where your changes added one. For
consistency you should probably add this `return;` statement, even if it's not
strictly needed. It would avoid having to have to analyze the whole structure
of the nested `if - then - else` to figure out that it's actually not needed.
src/java.net.http/share/classes/jdk/internal/net/http/Http2Connection.java line
880:
> 878: private <T> void handlePushContinuation(Stream<T> parent,
> ContinuationFrame cf)
> 879: throws IOException {
> 880: decodeHeaders(cf, pushContinuationState.pushContDecoder);
I suggest declaring a local variable here to avoid reading
pushContinuationState more than once.
Something like:
var pcs = pushContinuationState;
then use `pcs` wherever needed in that method.
test/jdk/java/net/httpclient/http2/PushPromiseContinuation.java line 75:
> 73: static HttpHeaders testHeaders;
> 74: static HttpHeadersBuilder testHeadersBuilder;
> 75: static int continuationCount;
Since these three static variables are set by one thread and read by another -
they should all be volatile.
-------------
PR: https://git.openjdk.java.net/jdk/pull/7696
