Callbacks can ask the caller to, eg, destroy the ss handle now. But some
callback returns are handled and produced inside other helper apis, eg
lws_ss_backoff() may have to had fulfilled the callback request to destroy
the ss... therefore it has to signal to its caller, and its callers have
to check and exit their flow accordingly.
Allow usage of ${metadata} string substitution in more policy elements
for MQTT:
- associated subscription topic in policy
- associated publish topic in policy
- associated will topic in policy
- associated will message in policy
Tested against lws-minimal-mqtt-client-multi / mosquitto
It's not safe to destroy objects inside a callback from a parent that
still has references to the object.
Formalize what the user code can indicate by its return code from the
callback functions and provide the implementations at the parents.
- LWSSSSRET_OK: no action, OK
- LWSSSSRET_DISCONNECT_ME: disconnect the underlying connection
- LWSSSSRET_DESTROY_ME: destroy the ss object
- LWSSSSRET_TX_DONT_SEND: for tx, give up the tx opportunity since nothing to send
Some streamtypes do not pass or receive payload meaningfully. Allow them
to just leave their related cb NULL. Ditto for state, although I'm not sure
how useful such a streamtype can be.
Adapt the pt sul owner list to be an array, and define two different lists,
one that acts like before and is the default for existing users, and another
that has the ability to cooperate with systemwide suspend to restrict the
interval spent suspended so that it will wake in time for the earliest
thing on this wake-suspend sul list.
Clean the api a bit and add lws_sul_cancel() that only needs the sul as the
argument.
Add a flag for client creation info to indicate that this client connection
is important enough that, eg, validity checking it to detect silently dead
connections should go on the wake-suspend sul list. That flag is exposed in
secure streams policy so it can be added to a streamtype with
"swake_validity": true
Deprecate out the old vhost timer stuff that predates sul. Add a flag
LWS_WITH_DEPRECATED_THINGS in cmake so users can get it back temporarily
before it will be removed in a v4.2.
Adapt all remaining in-tree users of it to use explicit suls.
When most of ss-h2 was combined into ss-h1 during development, the h2 difference
about needing HTTP_FINAL to signal h2 FIN flag was accidentally dropped. In
many cases the peer can infer it, from, eg, content-length reached. But we need
to replace explicitly doing it to cover all cases.
You can disconnect the stream by returning -1 from tx(). You can
give up your chance to send anything by returning 1 from tx().
Returning 0 sends `*len` amount of the provided buffer.
Returning <0 from rx() also disconnects the stream.
The endpoint field in streamtype policy may continue to just be the
hostname, like "warmcat.com".
But it's also possible now to be a url-formatted string, like, eg,
"https://warmcat.com:444/mailman/listinfo"
If so (ie, if it contains a : ) then the decoded elements may override
if tls is enabled, the endpoint address, the port, and the url path.
No ABI change.
Implement Captive Portal detection support in lws, with the actual
detection happening in platform code hooked up by lws_system_ops_t.
Add an implementation using Secure Streams as well, if the policy
defines captive_portal_detect streamtype, a SS using that streamtype
is used to probe if it's behind a captive portal.
Secure Streams is an optional layer on top of lws that separates policy
like endpoint selection and tls cert validation into a device JSON
policy document.
Code that wants to open a client connection just specifies a streamtype name,
and no longer deals with details like the endpoint, the protocol (!) or anything
else other than payloads and optionally generic metadata; the JSON policy
contains all the details for each streamtype. h1, h2, ws and mqtt client
connections are supported.
Logical secure streams outlive any particular connection and supports "nailed-up"
connectivity regardless of underlying connection stability.
