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.
This can happen normally when Cowboy is restarted, for example.
Instead of failing requests when that happens, we degrade
gracefully and do a little more work to provide the current
date header.
Also {switch_handler, Module, Opts}.
Allows switching to a different handler type. This is
particularly useful for processing most of the request
with cowboy_rest and then streaming the response body
using cowboy_loop.
Sending data of size 0 with the fin flag set resulted in nothing
being sent to the client and still considering the response to
be finished for HTTP/1.1.
For both HTTP/1.1 and HTTP/2, the final chunk of body that is
sent automatically by Cowboy at the end of a response that the
user did not properly terminate was not passing through stream
handlers. This resulted in issues like compression being incorrect.
Some tests still fail under 20.1.3. They are due to recent zlib
changes and should be fixed in a future patch release. Unfortunately
it does not seem to be any 20.1 version that is safe to use for
Cowboy, although some will work better than others.
