[Webpush] Composite Crypto-Key composition issue

[JR Conlin <[e-mail]>]

I believe there may be some confusion about how to create a composite
Crypto-Key header.

The Crypto-Key Header is used by several supporting protocols of WebPush
(ECE, VAPID). The respective specifications state that the field uses RFCs
7230 & 7231 where each parameter list set is divided by commas, and each
individual parameter is divided by a semicolon.

The confusion arises in whether or not each list set should contain items
specific for a given sub-protocol.

For instance, our autopush server treats ECE and VAPID as separate entities
and divides the set containing the dh= parameter from the set containing
p256ecdsa=. It's my understanding that FCM does not follow this practice
and will generate an error if a "," appears in the Crypto-Key parameter
lists.

Since this is a point of confusion and conflict, I believe it would be in
the best interests of all if this was addressed in some manner so that
future conflict and confusion can be avoided.

(For what it's worth, I really don't care what the answer is; keep protocol
parameter sets distinct to avoid potential future conflicts or combine all
parameters into one big ol' hash. Just want to prevent future folk from
swearing at us.)