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.
