/usr/lib/python2.7/dist-packages/dns/entropy.py is in python-dnspython 1.15.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | # Copyright (C) 2009, 2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
import os
import random
import time
from ._compat import long, binary_type
try:
import threading as _threading
except ImportError:
import dummy_threading as _threading
class EntropyPool(object):
def __init__(self, seed=None):
self.pool_index = 0
self.digest = None
self.next_byte = 0
self.lock = _threading.Lock()
try:
import hashlib
self.hash = hashlib.sha1()
self.hash_len = 20
except ImportError:
try:
import sha
self.hash = sha.new()
self.hash_len = 20
except ImportError:
import md5 # pylint: disable=import-error
self.hash = md5.new()
self.hash_len = 16
self.pool = bytearray(b'\0' * self.hash_len)
if seed is not None:
self.stir(bytearray(seed))
self.seeded = True
self.seed_pid = os.getpid()
else:
self.seeded = False
self.seed_pid = 0
def stir(self, entropy, already_locked=False):
if not already_locked:
self.lock.acquire()
try:
for c in entropy:
if self.pool_index == self.hash_len:
self.pool_index = 0
b = c & 0xff
self.pool[self.pool_index] ^= b
self.pool_index += 1
finally:
if not already_locked:
self.lock.release()
def _maybe_seed(self):
if not self.seeded or self.seed_pid != os.getpid():
try:
seed = os.urandom(16)
except Exception:
try:
r = open('/dev/urandom', 'rb', 0)
try:
seed = r.read(16)
finally:
r.close()
except Exception:
seed = str(time.time())
self.seeded = True
self.seed_pid = os.getpid()
self.digest = None
seed = bytearray(seed)
self.stir(seed, True)
def random_8(self):
self.lock.acquire()
try:
self._maybe_seed()
if self.digest is None or self.next_byte == self.hash_len:
self.hash.update(binary_type(self.pool))
self.digest = bytearray(self.hash.digest())
self.stir(self.digest, True)
self.next_byte = 0
value = self.digest[self.next_byte]
self.next_byte += 1
finally:
self.lock.release()
return value
def random_16(self):
return self.random_8() * 256 + self.random_8()
def random_32(self):
return self.random_16() * 65536 + self.random_16()
def random_between(self, first, last):
size = last - first + 1
if size > long(4294967296):
raise ValueError('too big')
if size > 65536:
rand = self.random_32
max = long(4294967295)
elif size > 256:
rand = self.random_16
max = 65535
else:
rand = self.random_8
max = 255
return first + size * rand() // (max + 1)
pool = EntropyPool()
try:
system_random = random.SystemRandom()
except Exception:
system_random = None
def random_16():
if system_random is not None:
return system_random.randrange(0, 65536)
else:
return pool.random_16()
def between(first, last):
if system_random is not None:
return system_random.randrange(first, last + 1)
else:
return pool.random_between(first, last)
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