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| author | Barry Warsaw <barry@python.org> | 2017-11-28 22:26:04 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-11-28 22:26:04 (GMT) |
| commit | 23df2d1304ece169d7e0dfc843dfb8026b413d9f (patch) | |
| tree | a7fdbffe4a5dc8e21f5b4a0734e5811451cc2aed /Doc/library | |
| parent | 71bd588646b282c9eebc390b31184a5bdb54e712 (diff) | |
| download | cpython-23df2d1304ece169d7e0dfc843dfb8026b413d9f.zip cpython-23df2d1304ece169d7e0dfc843dfb8026b413d9f.tar.gz cpython-23df2d1304ece169d7e0dfc843dfb8026b413d9f.tar.bz2 | |
bpo-32107 - Improve MAC address calculation and fix test_uuid.py (#4600)
``uuid.getnode()`` now preferentially returns universally administered MAC addresses if available, over locally administered MAC addresses. This makes a better guarantee for global uniqueness of UUIDs returned from ``uuid.uuid1()``. If only locally administered MAC addresses are available, the first such one found is returned.
Also improve internal code style by being explicit about ``return None`` rather than falling off the end of the function.
Improve the test robustness.
Diffstat (limited to 'Doc/library')
| -rw-r--r-- | Doc/library/uuid.rst | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/Doc/library/uuid.rst b/Doc/library/uuid.rst index ea9ea7d..8ec75a7 100644 --- a/Doc/library/uuid.rst +++ b/Doc/library/uuid.rst @@ -156,10 +156,18 @@ The :mod:`uuid` module defines the following functions: 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. "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. + attempts to obtain the hardware address fail, we choose a random 48-bit + number with the multicast bit (least significant bit of the first octet) + set to 1 as recommended in RFC 4122. "Hardware address" means the MAC + address of a network interface. On a machine with multiple network + interfaces, universally administered MAC addresses (i.e. where the second + least significant bit of the first octet is *unset*) will be preferred over + locally administered MAC addresses, but with no other ordering guarantees. + + .. versionchanged:: 3.7 + Universally administered MAC addresses are preferred over locally + administered MAC addresses, since the former are guaranteed to be + globally unique, while the latter are not. .. index:: single: getnode |