Rewind tls.Conn

[WeidiDeng]

tls.Conn can be rewound by using reflect to modify its internal buffer.

func RewindTlsConn(conn *tls.Conn, read []byte) {
	var (
		tlsInput, _ = reflect.TypeOf(tls.Conn{}).FieldByName("input")
		input     = (*bytes.Reader)(unsafe.Add(unsafe.Pointer(conn), tlsInput.Offset))
		remaining = input.Len()
		size      = int(input.Size())
		buffered  = len(read)
	)
	if buffered <= size {
		_, _ = input.Seek(0, 0)
	} else {
		buf := make([]byte, buffered+remaining)
		copy(buf, read)
		_, _ = input.Read(buf[buffered:])
		input.Reset(buf)
	}
}

There is no need to turn on allow h2c if caddy is using https.

[imgk]

Hi, I'm not familiar with reflect. Can you create a PR?