[hybi] permessage-deflate parameter negotiation

[Tobias Oberstein <[e-mail]>]

After implementing permessage-deflate client/server and with all features, I think the initial
parameter negotiation is by far the most complex part of the extension.

I still have some questions. To keep it simple, here are a couple of examples:

1)
client offers:
permessage-deflate; c2s_max_window_bits

server response:
permessage-deflate; s2c_no_context_takeover

2)
client offers:
permessage-deflate; c2s_max_window_bits

server response:
permessage-deflate; s2c_max_window_bits=10

3)
client offers:
permessage-deflate; c2s_max_window_bits ; s2c_max_window_bits=10

server response:
permessage-deflate; s2c_max_window_bits=8

4)
client offers:
permessage-deflate; c2s_max_window_bits; s2c_max_window_bits=10

server response:
permessage-deflate; s2c_max_window_bits=12

===

Chrome Canary fails 1 + 2 (bails out "Received an unexpected permessage-deflate extension parameter").

Chrome offers a fixed "permessage-deflate; c2s_max_window_bits", so I could not test 3 and 4.

The current draft (in my reading) allows 1 + 2, but not 3, and not 4.

I think 1-3 should be successful, and 4 failed by client.

As in my other mail, I also think a client should explicitly announce support for "c2s_no_context_takeover":

permessage-deflate; c2s_max_window_bits; c2s_no_context_takeover

/Tobias