Add a helper to simplify passing smd ss rx traffic into the local
smd participants, excluding the rx that received it externally to
avoid looping.
Make the smd readme clearer with three diagrams and more explanation
of how the ss proxying works.
This adds some new objects and helpers for keeping and logging
info on grouped allocations, a group is, eg, SS handles or client
wsis.
Allocated objects get a context-unique "tag" string intended to replace
%p / wsi pointers etc. Pointers quickly become confusing when
allocations are freed and reused, the tag string won't repeat
until you produce 2^64 objects in a context.
In addition the tag string documents the object group, with prefixes
like "wsi-" or "vh-" and contain object-specific additional
information like the vhost name, address / port or the role of the wsi.
At creation time the lws code can use a format string and args
to add whatever group-specific info makes sense, eg, a wsi bound
to a secure stream can also append the guid of the secure stream,
it's copied into the new object tag and so is still available
cleanly after the stream is destroyed if the wsi outlives it.
Since client_connect and request_tx can be called from code that expects
the ss handle to be in scope, these calls can't deal with destroying the
ss handle and must pass the lws_ss_state_return_t disposition back to
the caller to handle.
At the moment you can define and set per-stream metadata at the client,
which will be string-substituted and if configured in the policy, set in
related outgoing protocol specific content like h1 headers.
This patch extends the metadata concept to also check incoming protocol-
specific content like h1 headers and where it matches the binding in the
streamtype's metadata entry, make it available to the client by name, via
a new lws_ss_get_metadata() api.
Currently warmcat.com has additional headers for
server: lwsws (well-known header name)
test-custom-header: hello (custom header name)
minimal-secure-streams test is updated to try to recover these both
in direct and -client (via proxy) versions. The corresponding metadata
part of the "mintest" stream policy from warmcat.com is
{
"srv": "server:"
}, {
"test": "test-custom-header:"
},
If built direct, or at the proxy, the stream has access to the static
policy metadata definitions and can store the rx metadata in the stream
metadata allocation, with heap-allocated a value. For client side that
talks to a proxy, only the proxy knows the policy, and it returns rx
metadata inside the serialized link to the client, which stores it on
the heap attached to the stream.
In addition an optimization for mapping static policy metadata definitions
to individual stream handle metadata is changed to match by name.
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.
Formalize the LWSSSSRET_ enums into a type "lws_ss_state_return_t"
returned by the rx, tx and state callbacks, and some private helpers
lws_ss_backoff() and lws_ss_event_helper().
Remove LWSSSSRET_SS_HANDLE_DESTROYED concept... the two helpers that could
have destroyed the ss and returned that, now return LWSSSSRET_DESTROY_ME
to the caller to perform or pass up to their caller instead.
Handle helper returns in all the ss protocols and update the rx / tx
calls to have their returns from rx / tx / event helper and ss backoff
all handled by unified code.
You may use separate rx or tx handlers to neatly isolate different
rx or tx state handling, for example if the connection enters some
mode where you may send a variety of possibly large things, it can
be advantageous to have different code handling each of the
different things.
This allows you to change the rx, tx and / or state handlers to
different ones suitable for the user protocol state, if it's helpful.
With upcoming SS Server support, this has another use when SS
indicates that the underlying protocol upgraded, eg, http -> ws,
you may want to change the handlers for the different sort of
payloads expected after that, according to your user protocol.
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.
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.
