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47 lines
1.3 KiB
Python
47 lines
1.3 KiB
Python
# IBM (c) 2013
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# Various utility functions that do not neatly fit into one category or another
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import base64
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import os
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import struct
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def randomstring(length=20):
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"""Generate a random string of requested length
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:param length: The number of characters to produce, defaults to 20
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"""
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chunksize = length / 4
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if (length % 4 > 0):
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chunksize += 1
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strval = base64.urlsafe_b64encode(os.urandom(chunksize * 3))
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return strval[0:length-1]
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def securerandomnumber(min=0, max=4294967295):
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"""Return a random number within requested range
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Note that this function will not return smaller than 0 nor larger
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than 2^32-1 no matter what is requested.
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The python random number facility does not provide charateristics
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appropriate for secure rng, go to os.urandom
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:param min: Smallest number to return (defaults to 0)
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:param max: largest number to return (defaults to 2^32-1)
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"""
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number = -1
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while number < min or number > max:
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number = struct.unpack("I",os.urandom(4))[0]
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return number
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def monotonic_time():
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"""Return a monotoc time value
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In scenarios like timeouts and such, monotonic timing is preferred.
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"""
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if (os.name == "posix"):
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return os.times()[4]
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else:
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return time.time()
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#TODO: windows?
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