Copy the SNI hostname to buf which can hold up to count bytes,
and the length of that hostname in out_n. The string is stored in UTF-8
with no terminating NUL byte.
Returns RUSTLS_RESULT_INSUFFICIENT_SIZE if the SNI hostname is longer than count.
Returns Ok with *out_n == 0 if there is no SNI hostname available on this connection
because it hasn't been processed yet, or because the client did not send SNI.
<https://docs.rs/rustls/0.20.0/rustls/server/struct.ServerConnection.html#method.sni_hostname>
Copy the SNI hostname to buf which can hold up to count bytes, and the length of that hostname in out_n. The string is stored in UTF-8 with no terminating NUL byte. Returns RUSTLS_RESULT_INSUFFICIENT_SIZE if the SNI hostname is longer than count. Returns Ok with *out_n == 0 if there is no SNI hostname available on this connection because it hasn't been processed yet, or because the client did not send SNI. <https://docs.rs/rustls/0.20.0/rustls/server/struct.ServerConnection.html#method.sni_hostname>