utils.py 文件源码

def __init__(self, filename):
        self.filename = filename
        try:
            self.f = gzip.open(filename,"rb")
            magic = self.f.read(4)
        except IOError:
            self.f = open(filename,"rb")
            magic = self.f.read(4)
        if magic == "\xa1\xb2\xc3\xd4": #big endian
            self.endian = ">"
        elif  magic == "\xd4\xc3\xb2\xa1": #little endian
            self.endian = "<"
        else:
            raise Scapy_Exception("Not a pcap capture file (bad magic)")
        hdr = self.f.read(20)
        if len(hdr)<20:
            raise Scapy_Exception("Invalid pcap file (too short)")
        vermaj,vermin,tz,sig,snaplen,linktype = struct.unpack(self.endian+"HHIIII",hdr)

        self.linktype = linktype