Live with that "the hardware address" is an ill-defined

concept, and that different ways of trying to find "the
hardware address" may return different results.  Certainly
true on both of my Windows boxes, and in different ways
(see whining on python-dev).

Doc/lib/libuuid.tex

@@ -32,7 +32,7 @@ fields\optional{, int\optional{, version}}}}}}
 
 Create a UUID from either a string of 32 hexadecimal digits,
 a string of 16 bytes as the \var{bytes} argument, a tuple of six
-integers (32-bit \var{time_low}, 16-bit \var{time_mid}, 
+integers (32-bit \var{time_low}, 16-bit \var{time_mid},
 16-bit \var{time_hi_version},
 8-bit \var{clock_seq_hi_variant}, 8-bit \var{clock_seq_low}, 48-bit \var{node})
 as the \var{fields} argument, or a single 128-bit integer as the \var{int}
@@ -109,10 +109,13 @@ when the variant is \constant{RFC_4122}).
 The \module{uuid} module defines the following functions
 
 \begin{funcdesc}{getnode}{}
-Get the hardware address as a 48-bit integer.  The first time this runs,
-it may launch a separate program, which could be quite slow.  If all
+Get the hardware address as a 48-bit positive integer.  The first time this
+runs, it may launch a separate program, which could be quite slow.  If all
 attempts to obtain the hardware address fail, we choose a random 48-bit
-number with its eighth bit set to 1 as recommended in RFC 4122.
+number with its eighth bit set to 1 as recommended in RFC 4122.  "Hardware
+address" means the MAC address of a network interface, and on a machine
+with multiple network interfaces the MAC address of any one of them may
+be returned.
 \end{funcdesc}
 \index{getnode}
 
@@ -126,10 +129,10 @@ otherwise a random 14-bit sequence number is chosen.
 \index{uuid1}
 
 \begin{funcdesc}{uuid3}{namespace, name}
-Generate a UUID based upon a MD5 hash of the \var{name} string value 
-drawn from a specified namespace.   \var{namespace} 
+Generate a UUID based upon a MD5 hash of the \var{name} string value
+drawn from a specified namespace.   \var{namespace}
 must be one of \constant{NAMESPACE_DNS},
-\constant{NAMESPACE_URL}, \constant{NAMESPACE_OID}, 
+\constant{NAMESPACE_URL}, \constant{NAMESPACE_OID},
 or \constant{NAMESPACE_X500}.
 \end{funcdesc}
 \index{uuid3}
@@ -140,15 +143,15 @@ Generate a random UUID.
 \index{uuid4}
 
 \begin{funcdesc}{uuid5}{namespace, name}
-Generate a UUID based upon a SHA-1 hash of the \var{name} string value 
-drawn from a specified namespace.   \var{namespace} 
+Generate a UUID based upon a SHA-1 hash of the \var{name} string value
+drawn from a specified namespace.   \var{namespace}
 must be one of \constant{NAMESPACE_DNS},
-\constant{NAMESPACE_URL}, \constant{NAMESPACE_OID}, 
+\constant{NAMESPACE_URL}, \constant{NAMESPACE_OID},
 or \constant{NAMESPACE_X500}.
 \end{funcdesc}
 \index{uuid5}
 
-The \module{uuid} module defines the following namespace constants 
+The \module{uuid} module defines the following namespace constants
 for use with \function{uuid3()} or \function{uuid5()}.
 
 \begin{datadesc}{NAMESPACE_DNS}
@@ -167,7 +170,7 @@ ISO OID namespace UUID.
 X.500 DN namespace UUID.
 \end{datadesc}
 
-The \module{uuid} module defines the following constants 
+The \module{uuid} module defines the following constants
 for the possible values of the \member{variant} attribute:
 
 \begin{datadesc}{RESERVED_NCS}

Lib/test/test_uuid.py

@@ -284,7 +284,11 @@ class TestUUID(TestCase):
                 msg = "different sources disagree on node:\n"
                 for s, n in TestUUID.source2node.iteritems():
                     msg += "    from source %r, node was %012x\n" % (s, n)
-                self.fail(msg)
+                # There's actually no reason to expect the MAC addresses
+                # to agree across various methods -- e.g., a box may have
+                # multiple network interfaces, and different ways of getting
+                # a MAC address may favor different HW.
+                ##self.fail(msg)
         else:
             TestUUID.last_node = node
 
@@ -309,7 +313,7 @@ class TestUUID(TestCase):
     def test_random_getnode(self):
         node = uuid._random_getnode()
         self.assert_(0 <= node)
-        self.assert_(node < 1<<48L)
+        self.assert_(node < (1L <<48))
 
     def test_unixdll_getnode(self):
         import os
@@ -322,10 +326,14 @@ class TestUUID(TestCase):
             self.check_node(uuid._windll_getnode(), 'windll')
 
     def test_getnode(self):
-        self.check_node(uuid.getnode(), "getnode1")
+        node1 = uuid.getnode()
+        self.check_node(node1, "getnode1")
 
         # Test it again to ensure consistency.
-        self.check_node(uuid.getnode(), "getnode2")
+        node2 = uuid.getnode()
+        self.check_node(node2, "getnode2")
+
+        self.assertEqual(node1, node2)
 
     def test_uuid1(self):
         equal = self.assertEqual

Lib/uuid.py

@@ -362,6 +362,10 @@ try:
     # hardware address.  On Windows 2000 and later, UuidCreate makes a
     # random UUID and UuidCreateSequential gives a UUID containing the
     # hardware address.  These routines are provided by the RPC runtime.
+    # NOTE:  at least on Tim's WinXP Pro SP2 desktop box, while the last
+    # 6 bytes returned by UuidCreateSequential are fixed, they don't appear
+    # to bear any relationship to the MAC address of any network device
+    # on the box.
     try:
         lib = ctypes.windll.rpcrt4
     except:
@@ -389,10 +393,13 @@ def _random_getnode():
 _node = None
 
 def getnode():
-    """Get the hardware address as a 48-bit integer.  The first time this
-    runs, it may launch a separate program, which could be quite slow.  If
-    all attempts to obtain the hardware address fail, we choose a random
-    48-bit number with its eighth bit set to 1 as recommended in RFC 4122."""
+    """Get the hardware address as a 48-bit positive integer.
+
+    The first time this runs, it may launch a separate program, which could
+    be quite slow.  If all attempts to obtain the hardware address fail, we
+    choose a random 48-bit number with its eighth bit set to 1 as recommended
+    in RFC 4122.
+    """
 
     global _node
     if _node is not None: