How to use the scapy.fields.ShortField function in scapy

FlagsField("flags", 0, 8, _peer_flags),
        IntField("v6_flag", 0),
        IntField("unused1", 0),
        IP6Field("addr6", "::")
    ]


class NTPInfoPeerSummary(Packet):
    """
    Sort of the info that ntpdc returns by default.
    """
    name = "info_peer_summary"
    fields_desc = [
        IPField("dstaddr", "0.0.0.0"),
        IPField("srcaddr", "0.0.0.0"),
        ShortField("srcport", 0),
        ByteField("stratum", 0),
        ByteField("hpoll", 0),
        ByteField("ppoll", 0),
        ByteField("reach", 0),
        FlagsField("flags", 0, 8, _peer_flags),
        ByteField("hmode", _ntp_modes),
        FixedPointField("delay", 0, size=32, frac_bits=16),
        TimeStampField("offset", 0),
        FixedPointField("dispersion", 0, size=32, frac_bits=16),
        IntField("v6_flag", 0),
        IntField("unused1", 0),
        IP6Field("dstaddr6", "::"),
        IP6Field("srcaddr6", "::")
    ]

# DIAG_DGOTYP_FNAME
        ConditionalField(StrLenField("name_text", "", length_from=lambda pkt:pkt.atom_length - 13), lambda pkt:pkt.etype == 114),
        # DIAG_DGOTYP_PUSHBUTTON_2 */
        ConditionalField(ByteField("pushbutton_v_length", 0), lambda pkt:pkt.etype in [115]),
        ConditionalField(ByteField("pushbutton_v_height", 0), lambda pkt:pkt.etype in [115]),
        ConditionalField(ShortField("pushbutton_function_code_offset", 0), lambda pkt:pkt.etype in [115]),
        ConditionalField(ShortField("pushbutton_text_offset", 0), lambda pkt:pkt.etype in [115]),
        ConditionalField(StrField("pushbutton_text", ""), lambda pkt:pkt.etype in [115]),
        ConditionalField(StrField("pushbutton_function_code", ""), lambda pkt:pkt.etype in [115]),
        # DIAG_DGOTYP_TABSTRIP_BUTTON
        ConditionalField(ByteField("tabstripbutton_v_length", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(ByteField("tabstripbutton_v_height", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(ByteField("tabstripbutton_page_id", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(ShortField("tabstripbutton_function_code_offset", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(ShortField("tabstripbutton_text_offset", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(ShortField("tabstripbutton_id_offset", 0), lambda pkt:pkt.etype in [116]),
        ConditionalField(StrNullField("tabstripbutton_text", ""), lambda pkt:pkt.etype in [116]),
        ConditionalField(StrNullField("tabstripbutton_function_code", ""), lambda pkt:pkt.etype in [116]),
        ConditionalField(StrNullField("tabstripbutton_id", ""), lambda pkt:pkt.etype in [116]),
        # DIAG_DGOTYP_XMLPROP
        ConditionalField(StrLenField("xmlprop_text", "", length_from=lambda pkt:pkt.atom_length - 13), lambda pkt:pkt.etype == 120),
        # DIAG_DGOTYP_EFIELD_1 or DIAG_DGOTYP_OFIELD_1 or DIAG_DGOTYP_KEYWORD_1
        ConditionalField(ByteField("field1_flag1", 0), lambda pkt:pkt.etype in [121, 122, 123]),
        ConditionalField(FieldLenField("field1_dlen", None, fmt="B", length_of="field1_text"), lambda pkt:pkt.etype in [121, 122, 123]),
        ConditionalField(ByteField("field1_mlen", 0), lambda pkt:pkt.etype in [121, 122, 123]),
        ConditionalField(ShortField("field1_maxnrchars", 0), lambda pkt:pkt.etype in [121, 122, 123]),
        ConditionalField(StrLenField("field1_text", "", length_from=lambda pkt:pkt.field1_dlen), lambda pkt:pkt.etype in [121, 122, 123]),
        # DIAG_DGOTYP_FRAME_1
        ConditionalField(ShortField("frame_drows", 0), lambda pkt:pkt.etype in [127]),
        ConditionalField(ShortField("frame_dcols", 0), lambda pkt:pkt.etype in [127]),
        ConditionalField(StrLenField("frame_text", "", length_from=lambda pkt:pkt.atom_length - 17), lambda pkt:pkt.etype in [127]),
        # DIAG_DGOTYP_RADIOBUTTON_3

2: "FRAG_REASM",
                                               3: "FRAG_MASK"}),
                   ShortField("miss_send_len", 0)]


class OFPTSetConfig(_ofp_header):
    name = "OFPT_SET_CONFIG"
    fields_desc = [ByteEnumField("version", 0x01, ofp_version),
                   ByteEnumField("type", 9, ofp_type),
                   ShortField("len", None),
                   IntField("xid", 0),
                   ShortEnumField("flags", 0, {0: "FRAG_NORMAL",
                                               1: "FRAG_DROP",
                                               2: "FRAG_REASM",
                                               3: "FRAG_MASK"}),
                   ShortField("miss_send_len", 128)]


class OFPTPacketIn(_ofp_header):
    name = "OFPT_PACKET_IN"
    fields_desc = [ByteEnumField("version", 0x01, ofp_version),
                   ByteEnumField("type", 10, ofp_type),
                   ShortField("len", None),
                   IntField("xid", 0),
                   IntEnumField("buffer_id", "NO_BUFFER", ofp_buffer),
                   ShortField("total_len", 0),
                   ShortEnumField("in_port", 0, ofp_port_no),
                   ByteEnumField("reason", 0, {0: "OFPR_NO_MATCH",
                                               1: "OFPR_ACTION"}),
                   XByteField("pad", 0),
                   PacketField("data", None, Ether)]

fields_desc = [ShortField("count", 0),
                   IntField("sysUptime", 0),
                   UTCTimeField("unixSecs", 0),
                   UTCTimeField("unixNanoSeconds", 0, use_nano=True),
                   IntField("flowSequence", 0),
                   ByteField("engineType", 0),
                   ByteField("engineID", 0),
                   ShortField("samplingInterval", 0)]


class NetflowRecordV5(Packet):
    name = "Netflow Record v5"
    fields_desc = [IPField("src", "127.0.0.1"),
                   IPField("dst", "127.0.0.1"),
                   IPField("nexthop", "0.0.0.0"),
                   ShortField("input", 0),
                   ShortField("output", 0),
                   IntField("dpkts", 1),
                   IntField("dOctets", 60),
                   IntField("first", 0),
                   IntField("last", 0),
                   ShortField("srcport", 0),
                   ShortField("dstport", 0),
                   ByteField("pad1", 0),
                   FlagsField("tcpFlags", 0x2, 8, "FSRPAUEC"),
                   ByteEnumField("prot", IP_PROTOS["tcp"], IP_PROTOS),
                   ByteField("tos", 0),
                   ShortField("src_as", 0),
                   ShortField("dst_as", 0),
                   ByteField("src_mask", 0),
                   ByteField("dst_mask", 0),
                   ShortField("pad2", 0)]

ConditionalField(ShortField("pad2", 0xffff), lambda pkt:pkt.id in [0x02]),

        # MS_PROPERTY_IPADR
        ConditionalField(IPField("address", "0.0.0.0"), lambda pkt:pkt.id in [0x03]),
        ConditionalField(IP6Field("address6", "::"), lambda pkt:pkt.id in [0x03]),

        # MS_PROPERTY_PARAM
        ConditionalField(FieldLenField("param_len", 0, length_of="param", fmt="I"), lambda pkt:pkt.id in [0x04]),
        ConditionalField(StrLenField("param", "", length_from=lambda pkt: pkt.param_len), lambda pkt:pkt.id in [0x04]),
        ConditionalField(StrLenField("param_padding", "", length_from=lambda pkt: 100 - pkt.param_len), lambda pkt:pkt.id in [0x04]),
        ConditionalField(ShortField("pad3", 0), lambda pkt:pkt.id in [0x04]),
        ConditionalField(FieldLenField("value_len", 0x0, length_of="value", fmt="H"), lambda pkt:pkt.id in [0x04]),
        ConditionalField(StrLenField("value", "", length_from=lambda pkt:pkt.value_len), lambda pkt:pkt.id in [0x04]),

        # MS_PROPERTY_SERVICE
        ConditionalField(ShortField("service", 0), lambda pkt:pkt.id in [0x05]),
        ConditionalField(ByteField("value", 0), lambda pkt:pkt.id in [0x05]),

        # Release Information fields
        ConditionalField(StrNullFixedLenField("release", "720", length=10), lambda pkt:pkt.id in [0x07]),
        ConditionalField(IntField("patchno", 0), lambda pkt:pkt.id in [0x07]),
        ConditionalField(IntField("supplvl", 0), lambda pkt:pkt.id in [0x07]),
        ConditionalField(IntField("platform", 0), lambda pkt:pkt.id in [0x07]),
    ]


class SAPMSJ2EECluster(Packet):
    """SAP Message Server J2EE Cluster packet

    This packet is used for the Message Server protocol for J2EE cluster nodes.
    """
    name = "SAP Message Server J2EE Cluster"

"""Generate the response block of this request.
        Careful: it only sets the fields which can be set from the request
        """
        res = ARBlockRes()
        for field in ["ARType", "ARUUID", "SessionKey"]:
            res.setfieldval(field, self.getfieldval(field))
        return res


class ARBlockRes(Block):
    """Application relationship block response"""
    fields_desc = [
        BlockHeader,
        XShortEnumField("ARType", 1, AR_TYPE),
        UUIDField("ARUUID", None),
        ShortField("SessionKey", 0),
        MACField("CMResponderMacAdd", None),
        ShortField("CMResponderUDPRTPort", 0x8892),
    ]
    # default block_type value
    block_type = 0x8101


#     IOCRBlockRe{q,s}
class IOCRAPIObject(Packet):
    """API item descriptor used in API description of IOCR blocks"""
    name = "API item"
    fields_desc = [
        XShortField("SlotNumber", 0),
        XShortField("SubslotNumber", 0),
        ShortField("FrameOffset", 0),
    ]

IntField("ip_addr", 0),
        ShortField("value", 0)
    ]


class BGPPAExtCommRedirectAS4Byte(Packet):
    """
    Packet handling the (FlowSpec) "redirect AS-4byte" extended community.
    (RFC 7674).
    References: RFC 7674
    """

    name = "FlowSpec redirect AS-4byte extended community"
    fields_desc = [
        IntField("asn", 0),
        ShortField("value", 0)
    ]


class BGPPAExtCommTrafficMarking(Packet):
    """
    Packet handling the (FlowSpec) "traffic-marking" extended community.
    References: RFC 5575
    """

    name = "FlowSpec traffic-marking extended community"
    fields_desc = [
        BitEnumField("dscp", 48, 48, _ext_comm_traffic_action_fields)
    ]


_ext_high_low_dict = {

]

    def to_json(self):
        return json.dumps(self.fields, separators=(',', ':'))


class AccessControlRow1(Packet):
    name = "AccessControlRow1"
    fields_desc = [
        BitField("set_ctrl", 0, 2),
        BitField("row_part_id", 0, 3),
        BitField("test", 0, 1),
        BitField("row_key", 0, 10),

        StrFixedLenField("ipv6_src_addr_start_bytes", None, 12),
        ShortField("preview_length", None),
        ShortField("preview_repeat_time", None),
        ShortField("preview_repeat_count", None),
        ShortField("preview_reset_time", None),
        ShortField("reserved1", 0)
    ]

    def to_json(self):
        return json.dumps(self.fields, separators=(',', ':'))


class AccessControlRow2(Packet):
    name = "AccessControlRow2"
    fields_desc = [
        BitField("set_ctrl", 0, 2),
        BitField("row_part_id", 0, 3),
        BitField("test", 0, 1),

ByteField("domnamelen", None),
        StrFixedLenField("domname", "manbearpig", 32),
        ConditionalField(SignedIntField("rev", 0),
                         lambda pkt:pkt.code == 1 or
                         pkt.code == 2),
        # updater identity
        ConditionalField(IPField("uid", "192.168.0.1"),
                         lambda pkt:pkt.code == 1),
        ConditionalField(VTPTimeStampField("timestamp", '930301000000'),
                         lambda pkt:pkt.code == 1),
        ConditionalField(StrFixedLenField("md5", b"\x00" * 16, 16),
                         lambda pkt:pkt.code == 1),
        ConditionalField(
            PacketListField("vlaninfo", [], VTPVlanInfo),
            lambda pkt: pkt.code == 2),
        ConditionalField(ShortField("startvalue", 0),
                         lambda pkt:pkt.code == 3)
    ]

    def post_build(self, p, pay):
        if self.domnamelen is None:
            domnamelen = len(self.domname.strip(b"\x00"))
            p = p[:3] + chr(domnamelen & 0xff) + p[4:]

        p += pay

        return p


bind_layers(SNAP, VTP, code=0x2003)

if __name__ == '__main__':

"""SAP Dispatcher Info packet

    This packet is encapsulated inside SAPMS packet
    and before the MS ADM payload. Kernel 749.
    """
    name = "SAP Dispatcher Info v3"
    fields_desc = [
        IntField("dp_padd1", 185),

        ByteEnumKeysField("dp_req_prio", 0x1, dp_prio_values),
        ShortField("dp_padd2", 0x0),
        ByteField("dp_padd3", 0x0),

        ByteField("dp_padd4", 0x0),
        IntField("dp_req_len", 0x0),
        ShortField("dp_padd5", 0x0),
        ByteField("dp_padd6", 0x0),
        ByteEnumKeysField("dp_type_from", 0x2, dp_type_values),
        StrFixedLenField("dp_fromname", " "*40, 40),
        ShortField("dp_padd7", 0x0),
        ByteField("dp_padd8", 0x0),
        ByteEnumKeysField("dp_agent_type_from", 0x6, dp_agent_type_values),
        ShortField("dp_padd9", 0x0),
        ByteField("dp_padd10", 0x0),

        ByteField("dp_padd12", 0xff),
        ShortField("dp_padd13", 0x0),
        ByteEnumKeysField("dp_worker_type_from", 0x1, dp_worker_type_values),

        ByteField("dp_worker_from_num", 0x0),
        ByteField("dp_padd133", 0x0),
        ShortField("dp_padd111", 0x0000),