It would be really helpful if we could extend the client's options structure / API to include an optional SNI hostname. The implementation would reach into the native handle for ASIO's SSL context and call OpenSSL's SSL_set_tlsext_host_name on the context with the input hostname.

From a quick look, I think this is possible with a minimal amount of code. If I'm not missing something complex/obvious there should be a PoC PR soon. 💃