如果字段名称是字符串变量，如何从数据包层获取字段值？

Question

我有 layer 和 field 作为变量。如何获取字段值？

#packet is just a sniff() packet

layer = "IP"
field = "src"

# I need something like
fieldValue = packet[layer].field

# or
fieldValue = packet[layer].getfieldval(field)


print("Layer: ", layer, " Field: ", field, " Value: ", fieldValue)
#Output- Layer: IP Field: src Value: 192.168.1.1

Answer 1

假设我们正在用 scapy 嗅探数据包，想看看里面的值。其中大部分是使用 scapy documentation 查找每个层具有的属性的问题。您也可以在 python/scapy 解释器中使用 dir(packet) 执行此操作，以查看它具有哪些属性和方法。例如：

>>> dir(packet)
...
 'show',
 'show2',
 'show_indent',
 'show_summary',
 'sniffed_on',
 'sprintf',
 'src',
...

要从数据包中动态获取源属性，我们需要使用getattr function，它可以从对象中获取方法和属性。

# Required if you are not using the scapy interpreter
from scapy.all import sniff, IP

layer = "IP"
field = "src"

# Sniff 4 packets, filtering for packets with an IP layer
packet_list = sniff(filter="ip", count=4)
# Choose first packet arbitrarily
packet0 = packet_list[0]
# We can get the attribute reflexively because python allows it
field_value = getattr(packet0[layer], field)

# Print this information
print("Layer: ", layer, " Field: ", field, " Value: ", field_value)
---
> Layer:  IP  Field:  src  Value:  192.168.1.246

如果字段名称是字符串变量，如何从数据包层获取字段值？

How to get a field value from a packet layer if the field name is a string variable?

python

layer

scapy

packet

packet-sniffers