79 lines
3.7 KiB
Python
79 lines
3.7 KiB
Python
#!/usr/bin/env python2
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import os.path as path
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import time
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from distutils.util import strtobool
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class Module:
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def __init__(self, incoming=False, verbose=False, options=None):
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# extract the file name from __file__. __file__ is proxymodules/name.py
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self.name = path.splitext(path.basename(__file__))[0]
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self.description = 'Change HTTP responses of a certain size to 404.'
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self.incoming = incoming # incoming means module is on -im chain
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self.size = 2392 # if a response has this value as content-length, it will become a 404
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self.verbose = False
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self.custom = False
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self.rewriteall = False # will we block the first occurence?
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self.firstfound = False # have we found the first occurence yet?
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self.resetinterval = None # if we haven't found a fitting response in this many seconds, reset the state and set first to False again
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self.timer = time.time()
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if options is not None:
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if 'size' in options.keys():
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try:
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self.size = int(options['size'])
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except ValueError:
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pass # use the default if you can't parse the parameter
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if 'verbose' in options.keys():
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self.verbose = bool(strtobool(options['verbose']))
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if 'custom' in options.keys():
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try:
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with open(options['custom'], 'rb') as handle:
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self.custom = handle.read()
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except Exception:
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print('Can\'t open custom error file, not using it.')
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self.custom = False
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if 'rewriteall' in options.keys():
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self.rewriteall = bool(strtobool(options['rewriteall']))
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if 'reset' in options.keys():
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try:
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self.resetinterval = float(options['reset'])
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except ValueError:
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pass # use the default if you can't parse the parameter
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def execute(self, data):
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contentlength = b'content-length: ' + bytes(str(self.size), 'ascii')
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if data.startswith(b'HTTP/1.1 200 OK') and contentlength in data.lower():
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if self.resetinterval is not None:
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t = time.time()
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if t - self.timer >= self.resetinterval:
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if self.verbose:
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print('Timer elapsed')
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self.firstfound = False
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self.timer = t
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if self.rewriteall is False and self.firstfound is False:
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# we have seen this response size for the first time and are not blocking the first one
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self.firstfound = True
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if self.verbose:
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print('Letting this response through')
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return data
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if self.custom is not False:
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data = self.custom
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if self.verbose:
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print('Replaced response with custom response')
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else:
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data = data.replace(b'200 OK', b'404 Not Found', 1)
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if self.verbose:
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print('Edited return code')
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return data
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def help(self):
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h = '\tsize: if a response has this value as content-length, it will become a 404\n'
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h += ('\tverbose: print a message if a string is replaced\n'
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'\tcustom: path to a file containing a custom response, will replace the received response\n'
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'\trewriteall: if set, it will rewrite all responses. Default is to let the first on through'
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'\treset: number of seconds after which we will reset the state and will let the next response through.')
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return h
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if __name__ == '__main__':
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print('This module is not supposed to be executed alone!')
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