We currently attach HTTP cookie headers from LibWeb within Fetch. This
has the downside that the cookie IPC, and the infrastructure around it,
are all synchronous. This blocks the WebContent process entirely while
the cookie is being retrieved, for every request on a page.
We now attach cookie headers from RequestServer. The state machine in
RequestServer::Request allows us to easily do this work asynchronously.
We can also skip this work entirely when the response is served from
disk cache.
Note that we will continue to parse cookies in the WebContent process.
If something goes awry during parsing. we limit the damage to that
process, instead of the UI or RequestServer.
Also note that WebSocket requests still have cookie headers attached
attached from LibWeb. This will be handled in a future patch.
In the future, we may want to introduce a memory cache for cookies in
RequestServer to avoid IPC altogether as able.
The end goal here is for LibHTTP to be the home of our RFC 9111 (HTTP
caching) implementation. We currently have one implementation in LibWeb
for our in-memory cache and another in RequestServer for our disk cache.
The implementations both largely revolve around interacting with HTTP
headers. But in LibWeb, we are using Fetch's header infra, and in RS we
are using are home-grown header infra from LibHTTP.
So to give these a common denominator, this patch replaces the LibHTTP
implementation with Fetch's infra. Our existing LibHTTP implementation
was not particularly compliant with any spec, so this at least gives us
a standards-based common implementation.
This migration also required moving a handful of other Fetch AOs over
to LibHTTP. (It turns out these AOs were all from the Fetch/Infra/HTTP
folder, so perhaps it makes sense for LibHTTP to be the implementation
of that entire set of facilities.)
