Cowboy takes a few shortcuts to avoid wasting resources when
there is a protocol error. The RFC wants us to send a different
error depending on the state of the stream at the time of the
error, and for us to maintain the connection in cases where we
would have to spend valuable resources to decode headers. In
all these cases Cowboy will simply close the connection with
an appropriate error.
In some cases we were sending a response faster than h2spec
was sending us the test case data, resulting in the request
being processed successfully instead of failing as expected.
A few more bugs detected. I'm at the end of the list. I need to
do a second reading, implement what I can, fix what I can and
then the suite should be complete.
Bad chunk sizes used to be accepted and could result in
a badly parsed body or a timeout. They are now properly
rejected.
Chunk extensions now have a hard limit of 129 characters.
I haven't heard of anyone using them and Cowboy does not
provide an interface for them, but we can always increase
or make configurable if it ever becomes necessary (but
I honestly doubt it).
Also a test from the old http suite could be removed. Yay!
It's worth noting that transfer-encoding now takes precedence
over content-length as recommended by the RFC, so that when
both headers are sent we only care about transfer-encoding
and explicitly remove content-length from the headers.
They are global for the node for all future call trace flags,
so it's not necessary to set them repeatedly with every request.
Doing it once at startup also ensures we can't have race
conditions when the user wants to change which trace patterns
should be used (because requests are concurrent and patterns
end up overwriting themselves repeatedly), and makes this
changing of trace patterns much more straightforward: the
user can just define the ones they want. The default function
traces everything.
In addition I have also added the tracer_flags option to make
the trace flags configurable, excluding the tracer pid.
If we do then we end up killing the tracer after the stream
terminates and this is not what we want. This prevents us from
getting useful information from requests that are still ongoing
(when they run concurrently) and completely prevents us from
tracing Websocket handlers.
I'm not the biggest fan of having unsupervised modules but if
this is properly documented there should be no problem.
Instead of tracking Erlang/OTP versions manually in each project,
I can just say OTP-19+ and let the plugin fill in the most recent
patch releases for each version. In addition I will configure the
CI commands to cleanup unneeded versions automatically.
