It is very hard to support multiple protocols in backend while
retaining multiple mode settings. Therefore, we dropped modes except
for default and HTTP/2 proxy mode. The other removed modes can be
emulated using combinations of options. Now the backend connection is
not encrypted by default. To enable encryption on backend connection,
use --backend-tls option.
By default, as RFC 7540 calls for, pushed stream depends on its
associated (parent) stream. There are some situations that this is
sub-optimal. For example, if associated stream is HTML, and server is
configured to push css and javascript files which are in critical
rendering path. Then the default priority scheme is sub-optimal,
since browser typically blocks rendering while waiting for critical
resources. In this case, it is better to at least give pushed stream
the same priority of associated stream, and interleave these streams.
This change gives pushed stream the same priority of associated stream
if pushed stream has content-type "application/javascript" or
"text/css". The pushed stream now depends on the stream which
associated stream depends on. We use the same weight of associated
stream.
This might help throughput, but it interfere stream priority. The
throughput issue is generally caused by the small buffer size to store
response body, which was 16K. We increased it to 128K to compensate
this change.
RFC 7540 says that proxy should not emit :authority when translating
HTTP/1 request in origin or asterisk form to HTTP/2. To keep this
semantics in tact, we should also refrain from emitting :authority if
it is missing (host header field is required in this case).
Header field related functions are now gathered into FieldStore class.
This commit only handles request. Subsequent commit will do the same
thing for response.
This commits enables HTTP/2 server push from HTTP/2 backend to be
relayed to HTTP/2 frontend. To use this feature, --http2-bridge or
--client is required. Server push via Link header field contiues to
work.
Tatsuhiro Tsujikawa