Until now although we can follow redirects, and they can promote the
protocol from h1->h2, we couldn't handle h2 wsi reuse since there are many
states in the wsi affected by being h2.
This wipes the related states in lws_wsi_reset() and follows the generic
wsi close flow before deviating into the redirect really close to the end,
ensuring we cleaned out evidence of our previous life properly.
h2->h2 redirects work properly after this.
The max number of redirects is increased from 3 -> 4 since this was seen in
the wild with www and then geographic-based redirects.
This is complicated by the fact extern on a function declaration implies
visibility... we have to make LWS_EXTERN empty when building static.
And, setting target_compile_definitions() doesn't work inside macros,
so it has to be set explicitly for the plugins.
Checking the symbol status needs nm -C -D as per
https://stackoverflow.com/questions/37934388/symbol-visibility-not-working-as-expected
after this patch, libwebsockets.a shows no symbols when checked like that and
the static-linked minimal examples only show -U for their other dynamic
imports.
In a handful of cases we use LWS_EXTERN on extern data declarations,
those then need to change to explicit extern.
This changes the approach of tx credit management to set the
initial stream tx credit window to zero. This is the only way
with RFC7540 to gain the ability to selectively precisely rx
flow control incoming streams.
At the time the headers are sent, a WINDOW_UPDATE is sent with
the initial tx credit towards us for that specific stream. By
default, this acts as before with a 256KB window added for both
the stream and the nwsi, and additional window management sent
as stuff is received.
It's now also possible to set a member in the client info
struct and a new option LCCSCF_H2_MANUAL_RXFLOW to precisely
manage both the initial tx credit for a specific stream and
the ongoing rate limit by meting out further tx credit
manually.
Add another minimal example http-client-h2-rxflow demonstrating how
to force a connection's peer's initial budget to transmit to us
and control it during the connection lifetime to restrict the amount
of incoming data we have to buffer.
This should be a NOP for h2 support and only affects internal
apis. But it lets us reuse the working and reliable h2 mux
arrangements directly in other protocols later, and share code
so building for h2 + new protocols can take advantage of common
mux child handling struct and code.
Break out common mux handling struct into its own type.
Convert all uses of members that used to be in wsi->h2 to wsi->mux
Audit all references to the members and break out generic helpers
for anything that is useful for other mux-capable protocols to
reuse wsi->mux related features.
Refactor everything around ping / pong handling in ws and h2, so there
is instead a protocol-independent validity lws_sul tracking how long it
has been since the last exchange that confirms the operation of the
network connection in both directions.
Clean out periodic role callback and replace the last two role users
with discrete lws_sul for each pt.
It was already correct but add helpers to isolate and deduplicate
processing adding and closing a generically immortal stream.
Change the default 31s h2 network connection timeout to be settable
by .keepalive_timeout if nonzero.
Add a public api allowing a client h2 stream to transition to
half-closed LOCAL (by sending a 0-byte DATA with END_STREAM) and
mark itself as immortal to create a read-only long-poll stream
if the server allows it.
Add a vhost server option flag LWS_SERVER_OPTION_VH_H2_HALF_CLOSED_LONG_POLL
which allows the vhost to treat half-closed remotes as immortal long
poll streams.
