fix.py

import argparse
import os

SERVERBROWSE_FWERROR = b'\xff\xff\xff\xfffwer'

def make_executable(path):
	"""
	Taken from http://stackoverflow.com/a/30463972.

	Has obvious race conditions, but whatever...
	"""
	old_mode = os.stat(path).st_mode

	new_mode = old_mode | ((old_mode & 0o444) >> 2)    # copy R bits to X

	if new_mode != old_mode:
		os.chmod(path, new_mode)


def main():
	parser = argparse.ArgumentParser(description="Patch a Teeworlds server executable to work around a bug in the registering code.")
	parser.add_argument('file', metavar="FILE", help="Filename of the executable to patch")

	filename = parser.parse_args().file
	file = open(filename, 'rb')

	contents = file.read()
	fixed = contents.replace(SERVERBROWSE_FWERROR, os.urandom(len(SERVERBROWSE_FWERROR)))

	fixed_filename = filename + "_fixed.exe"
	open(fixed_filename, 'wb').write(fixed)
	make_executable(fixed_filename)


if __name__ == '__main__':
	main()