存储网络中字节列表的Python方法(big endian)字节顺序到文件(little endian)

我有一个字节列表,其中包含一段使用pythonpcapy包BTW读取和处理的P2P视频。

bytes = [14, 254, 23, 35, 34, 67, etc... ]

我正在寻找一种方法来将这些字节存储到文件中,这些字节目前保存在Python应用程序的列表中。

目前我写的作品如下:

def writePiece(self, filename, pieceindex, bytes, ipsrc, ipdst, ts): 
    file = open(filename,"ab")
    # Iterate through bytes writing them to a file if don't have piece already 
    if not self.piecemap[ipdst].has_key(pieceindex):
        for byte in bytes: 
            file.write('%c' % byte)
        file.flush()
        self.procLog.info("Wrote (%d) bytes of piece (%d) to %s" % (len(bytes), pieceindex, filename))

    # Remember we have this piece now in case duplicates arrive 
    self.piecemap[ipdst][pieceindex] = True

    # TODO: Collect stats 
    file.close()

正如您在for循环中看到的,我将字节写入文件的顺序与从线路处理字节的顺序相同(即网络顺序或大端顺序)。

我想我需要将它们转换成小端字节顺序,但不确定用Python实现这一点的最佳方法。

对我来说,解决方案是(适当地编写处理endian问题的P2P文章):

def writePiece(self, filename, pieceindex, bytes, ipsrc, ipdst, ts): 
    file = open(filename,"r+b")
    if not self.piecemap[ipdst].has_key(pieceindex):
        little = struct.pack('<'+'B'*len(bytes), *bytes) 
        # Seek to offset based on piece index 
        file.seek(pieceindex * self.piecesize)
        file.write(little)
        file.flush()
        self.procLog.info("Wrote (%d) bytes of piece (%d) to %s" % (len(bytes), pieceindex, filename))

    # Remember we have this piece now in case duplicates arrive 
    self.piecemap[ipdst][pieceindex] = True

    file.close()

解决方案的关键是使用可疑的Python struct模块,特别是:

    little = struct.pack('<'+'B'*len(bytes), *bytes)