Load manuf file from Wireshark.
    param:
     - filename: the file to load the manuf file from

def load_manuf(filename):
    """Load manuf file from Wireshark.
    param:
     - filename: the file to load the manuf file from"""
    manufdb = ManufDA(_name=filename)
    with open(filename, "rb") as fdesc:
        for line in fdesc:
            try:
                line = line.strip()
                if not line or line.startswith(b"#"):
                    continue
                parts = line.split(None, 2)
                oui, shrt = parts[:2]
                lng = parts[2].lstrip(b"#").strip() if len(parts) > 2 else ""
                lng = lng or shrt
                manufdb[oui] = plain_str(shrt), plain_str(lng)
            except Exception:
                log_loading.warning("Couldn't parse one line from [%s] [%r]",
                                    filename, line, exc_info=True)
    return manufdb