Question

我正在使用scapy来阅读和打印跟踪文件。我正在阅读的PDU（My_Packet）具有以下格式：

| header | payload | crc |
--------------------------

有效负载字段包含另一个PDU。我正在使用以下代码去除crc部分，但遗憾的是有些东西没有按预期工作（我无法弄清楚是什么问题）。

#!/usr/bin/env python

from scapy.all import *

class My_Packet(Packet):
    '''My_Packet PDU'''

    name = "My Packet"
    CRC_SIZE = 4

    fields_desc=[ LEShortField("len", 0) ]

    def __init__(self, *args, **kargs):
        """Build My_Packet"""
        self.crc = []
        super(My_Packet, self).__init__(*args, **kargs)

    def get_crc(self):
        """Get the CRC"""
        return self.crc

    def post_dissect(self, p):
        """Remove trailer/CRC"""
        self.crc = p[-self.CRC_SIZE:]
        return p[:self.len - self.CRC_SIZE]

    def extract_padding(self, p):
        """Remove trailer for the upper layer"""
        return p[:self.len - self.CRC_SIZE], p[self.len - self.CRC_SIZE:]

if __name__ == '__main__':

    bind_layers(UDP, My_Packet, sport=5001, dport=5001)

    packets = rdpcap("./tcpdump_5501.bin")

    # iterate through PDUs
    for pkt in packets:
        if pkt.haslayer(UDP):
            pld = pkt[My_Packet].load
            print("PDU: 0x{}".format(pld.encode("hex")))

            crc = pkt[My_Packet].get_crc()
            print("CRC: 0x{}".format(crc.encode("hex")))

运行时错误是：

Traceback (most recent call last):
  File "./so.py", line 41, in <module>
    pld = pkt[My_Packet].load
  File "/usr/local/lib/python2.7/dist-packages/scapy/packet.py", line 964, in __getitem__
    raise IndexError("Layer [%s] not found" % lname)
IndexError: Layer [My_Packet] not found

Scapy版本：版本git-archive.dev9fc949739
Python版本：Python 2.7.12

Scapy：在解剖器中获取拖车区域

0 个答案: