class RawPcapNgReader(RawPcapReader):
"""A stateful pcapng reader. Each packet is returned as
bytes.

"""

alternative = RawPcapReader

PacketMetadata = collections.namedtuple("PacketMetadata",
                                        ["linktype", "tsresol",
                                         "tshigh", "tslow", "wirelen"])

def __init__(self, filename, fdesc, magic):
    self.filename = filename
    self.f = fdesc
    # A list of (linktype, snaplen, tsresol); will be populated by IDBs.
    self.interfaces = []
    self.default_options = {
        "tsresol": 1000000
    }
    self.blocktypes = {
        1: self.read_block_idb,
        2: self.read_block_pkt,
        3: self.read_block_spb,
        6: self.read_block_epb,
    }
    if magic != b"\x0a\x0d\x0d\x0a":  # PcapNg:
        raise Scapy_Exception(
            "Not a pcapng capture file (bad magic: %r)" % magic
        )
    # see https://github.com/pcapng/pcapng
    blocklen, magic = self.f.read(4), self.f.read(4)  # noqa: F841
    if magic == b"\x1a\x2b\x3c\x4d":
        self.endian = ">"
    elif magic == b"\x4d\x3c\x2b\x1a":
        self.endian = "<"
    else:
        raise Scapy_Exception("Not a pcapng capture file (bad magic)")
    self.f.read(12)
    #blocklen = struct.unpack("!I", blocklen)[0]
    blocklen = struct.unpack(self.endian + "I", blocklen)[0]

    # Read default options
    self.default_options = self.read_options(
        self.f.read(blocklen - 24)
    )
    try:
        self.f.seek(0)
    except Exception:
        pass