s4-python: import a copy of the python dns library

This library is not installed on enough systems for us to rely
on it being available. We use the system copy if possible, and
fallback to this local copy

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/source4/scripting/python/samba_external/dnspython/dns/entropy.py b/source4/scripting/python/samba_external/dnspython/dns/entropy.py
new file mode 100644
index 0000000000..fd9d4f8cdf
--- /dev/null
+++ b/source4/scripting/python/samba_external/dnspython/dns/entropy.py
@@ -0,0 +1,123 @@
+# Copyright (C) 2009 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 time
+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:
+            try:
+                import sha
+                self.hash = sha.new()
+                self.hash_len = 20
+            except:
+                import md5
+                self.hash = md5.new()
+                self.hash_len = 16
+        self.pool = '\0' * self.hash_len
+        if not seed is None:
+            self.stir(seed)
+            self.seeded = True
+        else:
+            self.seeded = False
+
+    def stir(self, entropy, already_locked=False):
+        if not already_locked:
+            self.lock.acquire()
+        try:
+            bytes = [ord(c) for c in self.pool]
+            for c in entropy:
+                if self.pool_index == self.hash_len:
+                    self.pool_index = 0
+                b = ord(c) & 0xff
+                bytes[self.pool_index] ^= b
+                self.pool_index += 1
+            self.pool = ''.join([chr(c) for c in bytes])
+        finally:
+            if not already_locked:
+                self.lock.release()
+
+    def _maybe_seed(self):
+        if not self.seeded:
+            try:
+                seed = os.urandom(16)
+            except:
+                try:
+                    r = file('/dev/urandom', 'r', 0)
+                    try:
+                        seed = r.read(16)
+                    finally:
+                        r.close()
+                except:
+                    seed = str(time.time())
+            self.seeded = True
+            self.stir(seed, True)
+
+    def random_8(self):
+        self.lock.acquire()
+        self._maybe_seed()
+        try:
+            if self.digest is None or self.next_byte == self.hash_len:
+                self.hash.update(self.pool)
+                self.digest = self.hash.digest()
+                self.stir(self.digest, True)
+                self.next_byte = 0
+            value = ord(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 > 4294967296L:
+            raise ValueError('too big')
+        if size > 65536:
+            rand = self.random_32
+            max = 4294967295L
+        elif size > 256:
+            rand = self.random_16
+            max = 65535
+        else:
+            rand = self.random_8
+            max = 255
+	return (first + size * rand() // (max + 1))
+
+pool = EntropyPool()
+
+def random_16():
+    return pool.random_16()
+
+def between(first, last):
+    return pool.random_between(first, last)