[Python] Read Scapy (/Python) source code from file and execute

For a testing application, I've created a test file with the following contents:

packets.scapy:

Ether() / IP(dst='1.1.1.1') / Raw(load='foobar')
Ether() / IP(dst='1.1.1.2') / Raw(load='foobar')
Ether() / IP(dst='1.1.1.3') / Raw(load='foobar')


I can read this file and create an instance of each line using eval() as such:

from scapy.all import *

with open('packets.scapy') as f:
data = f.read()

objects = []
for line in data.splitlines():
objects.append(eval(line)())


But I like to extend the functionality with variables and formatting:

packets_formatted.scapy:

payload = 'foobar'

(Ether()
/ IP(dst='1.1.1.1')
/ Raw(load=payload)
)

(Ether()
/ IP(dst='1.1.1.2')
/ Raw(load=payload)
)

(Ether()
/ IP(dst='1.1.1.3')
/ Raw(load=payload)
)


Now eval() does not work anymore. How can I instantiate each object, and evaluate the payload variable?

I experimented a bit with the compile() function:

with open('packets_formatted.scapy', 'rb') as f:
data = f.read()

code = compile(data, 'packets_formatted.scapy', 'exec')


But I did not find out how to use the code object to create objects and put them in a list.

Edit:

I found that this actually works:

packets_formatted.scapy:

payload = 'foobar'

packets = []

packets.append(Ether()
/ IP(dst='1.1.1.1')
/ Raw(load=payload)
)

packets.append(Ether()
/ IP(dst='1.1.1.2')
/ Raw(load=payload)
)

packets.append(Ether()
/ IP(dst='1.1.1.3')
/ Raw(load=payload)
)


exec(open('packets_formatted.scapy').read())

This is a workable solution for me, however now the file contains more detail then I'd like.

I'm starting to realise that maybe I'm doing something very unusual.

Continue reading...