Function parse_client_hello_handshake_prefix 

pub fn parse_client_hello_handshake_prefix(
    i: &[u8],
) -> ClientHelloHandshakePrefix

Available on crate feature tls only.

Incrementally classify a (possibly partial) TLS ClientHello handshake.

This is the fail-fast counterpart of parse_client_hello_handshake: the underlying streaming parser reports Incomplete when the bytes so far are a valid prefix that simply needs more data, and a hard parse error when they can never form a valid ClientHello. This surfaces that distinction as ClientHelloHandshakePrefix so a peeker only keeps waiting while the prefix remains possibly-valid, and rejects immediately otherwise.