func parseUdpHeader(buf *streambuf.Buffer) (mcUdpHeader, error) {
var h mcUdpHeader
h.requestId, _ = buf.ReadNetUint16()
h.seqNumber, _ = buf.ReadNetUint16()
h.numDatagrams, _ = buf.ReadNetUint16()
buf.Advance(2) // ignore reserved
return h, buf.Err()
}