REST call at TLS handshake

[Sridhar BV]

Hello, 

On of our requirement on nginx is to make a non-blocking REST call in stream context before TLS handshake ( i.e after receiving Client-Hello). Also cache the REST response index by client-ip and lookup for subsequent client connections. Post completion of REST call resume TLS handshake.  

I am new to OpenResty and based on my preliminary readings (https://github.com/openresty/stream-lua-nginx-module) it seems feasible to do.. 

Requesting to review the feasibility and also share any examples for reference. 

Thanks,

Sridhar