TlsResult.done
bool done() const pure nothrow @safe @nogcContract for "no data": a read that produced nothing because the stream is idle returns NEED_READ — never DONE with zero bytes. DONE with bytes == 0 unambiguously means EOF, which is also signalled by eof == true. Implementations must follow this rule so callers can treat done() as "operation finished".
Returns
true if the operation completed (successfully or EOF).