import struct

class FileConvert(object):

    ''' test python file'''

    def __init__(self):

        self.aa = 0

        self.bb = 0

    def convertPcapToHex(self,debugFlg=0):

        infile = open("test.pcap",'rb')

        outfile = open("testRslt.txt",'w')

        a = int(0)

        while True:

            a = int(0)

            a = infile.read(4)

            #print(type(a))

            #print(len(a))

            dataSaveNum = len(a)

            if not a:

                break

            if(len(a) == 4):

                pass

            elif(len(a) != 0):

                loopTime = 4 - len(a)

                while (loopTime > 0):

                    loopTime = loopTime - 1

                    a = a + b'\x00'

            z = struct.unpack('i',a)

            unNeg = z[0] & 0xFFFFFFFF #负数的验证

            if(dataSaveNum == 4):

                outfile.write("%08x"%unNeg)

                dataSaveNum = 0

            while(dataSaveNum > 0):

                saveData = unNeg&0xFF

                #保留单个字节

                #outfile.write("%08x"%unNeg)

                unNeg = unNeg >> 8

                dataSaveNum = dataSaveNum - 1

                outfile.write("%02x"%saveData)

            if(debugFlg == 1):

                outfile.write("\n")

        infile.close()

        outfile.close()

    def convertHexToPcap(self):

        infile = open("testRslt.txt",'r')

        outfile = open("another.pcap",'wb')

        #for a in infile.read():

        while True:

            a = infile.read(8)

            #print(type(a))

            #print(b);

            if not a:

                break

            if(len(a)!= 0):

                #16进制转换10进制数

                b=int(a,16)

                covertValue = struct.pack("L",b)

                outfile.write(covertValue)

            #outfile.write("%s"%a)

            #outfile.write("\n")

        infile.close()

        outfile.close()

if __name__ == '__main__':

    fileCvrt = FileConvert()

    fileCvrt.convertPcapToHex()

    fileCvrt.convertHexToPcap()