Systemsicherheit/Assignment 4 - Protokollsicherheit (Praxis)/proxy/proxymodules/removegzip.py

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2024-05-25 10:25:40 +02:00
#!/usr/bin/env python3
import os.path as path
class Module:
def __init__(self, incoming=False, verbose=False, options=None):
# extract the file name from __file__. __file__ is proxymodules/name.py
self.name = path.splitext(path.basename(__file__))[0]
self.description = 'Replace gzip in the list of accepted encodings ' \
'in a HTTP request with booo.'
self.incoming = incoming # incoming means module is on -im chain
# I chose to replace gzip instead of removing it to keep the parsing
# logic as simple as possible.
def execute(self, data):
try:
# split at \r\n\r\n to split the request into header and body
header, body = data.split(b'\r\n\r\n', 1)
except ValueError:
# no \r\n\r\n, so probably not HTTP, we can go now
return data
# now split the header string into its lines
headers = header.split(b'\r\n')
for h in headers:
if h.lower().startswith(b'accept-encoding:') and b'gzip' in h:
headers[headers.index(h)] = h.replace(b'gzip', b'booo')
break
return b'\r\n'.join(headers) + b'\r\n\r\n' + body
if __name__ == '__main__':
print('This module is not supposed to be executed alone!')