pub fn select_next_proto<'a>(
client: &'a [u8]
) -> Option<&'a [u8]>
A standard implementation of protocol selection for Application Layer Protocol Negotiation (ALPN).
server should contain the server's list of supported protocols and
client the client's. They
must both be in the ALPN wire format. See the documentation for
SslContextBuilder::set_alpn_protos for details.
It will select the first protocol supported by the server which is also supported by the client.
This corresponds to