gh-132710: only use stable _uuid.generate_time_safe() to deduce MAC address

[picnixz]

• Issue: uuid.getnode() is not tied to MAC address when using libuuid #132710

[picnixz]

cc @zanieb

[picnixz]

@zanieb Does it actually solve your issue? because my system also appears to be unable to get the MAC address... but I was offline (I work offline during the week in general) and I didn't check when I'm online.

[zanieb]

It's kind of hard to test because I haven't added support for the latest 3.14 in python-build-standalone and the patch doesn't apply cleanly to 3.13.

[zanieb]

Okay, the patch does apply cleanly to the previous 3.14 alpha so I can test this. On macOS, it does resolve the problem. I did not test Linux.

[zanieb]

I tested a Linux build at astral-sh/python-build-standalone#595 (comment) and it didn't seem to work.

[picnixz]

Hum. It's very strange. Did I mess the configure script? what's the value of HAVE_UUID_GENERATE_TIME_SAFE_STABLE_MAC?

[zanieb]

Looking at the logs... "HAVE_UUID_GENERATE_TIME_SAFE_STABLE_MAC": "0",

[picnixz]

... so it's not _unix_node() that is being called?

[zanieb]

The builds are attached there if you want to hop into a debugger.

Briefly... yeah it looks like it's called and we try each getter until we reach the random one:

(Pdb) getter
<function _unix_getnode at 0xffffb77b74d0>
(Pdb) s
--Call--
> /python/install/lib/python3.14/uuid.py(634)_unix_getnode()
-> def _unix_getnode():
(Pdb) n
> /python/install/lib/python3.14/uuid.py(636)_unix_getnode()
-> if _generate_time_safe and _has_stable_extractable_node:
(Pdb) n
--Return--
> /python/install/lib/python3.14/uuid.py(636)_unix_getnode()->None
-> if _generate_time_safe and _has_stable_extractable_node:
(Pdb) n
> /python/install/lib/python3.14/uuid.py(706)getnode()
-> if (_node is not None) and (0 <= _node < (1 << 48)):
(Pdb) l
701  	   for getter in _GETTERS + [_random_getnode]:
702  	       try:
703  	           _node = getter()
704  	       except:
705  	           continue
706  ->	       if (_node is not None) and (0 <= _node < (1 << 48)):
707  	           return _node
708  	   assert False, '_random_getnode() returned invalid value: {}'.format(_node)
709  	
710  	
711  	_last_timestamp = None
(Pdb) n
> /python/install/lib/python3.14/uuid.py(701)getnode()
-> for getter in _GETTERS + [_random_getnode]:
(Pdb) n
> /python/install/lib/python3.14/uuid.py(702)getnode()
-> try:
(Pdb) getter
<function _ip_getnode at 0xffffb77b71d0>
(Pdb) n
> /python/install/lib/python3.14/uuid.py(703)getnode()
-> _node = getter()
(Pdb) n
> /python/install/lib/python3.14/uuid.py(706)getnode()
-> if (_node is not None) and (0 <= _node < (1 << 48)):
(Pdb) _node
(Pdb) n
> /python/install/lib/python3.14/uuid.py(701)getnode()
-> for getter in _GETTERS + [_random_getnode]:
(Pdb) n
> /python/install/lib/python3.14/uuid.py(702)getnode()
-> try:
(Pdb) getter
<function _ifconfig_getnode at 0xffffb77b7110>
(Pdb) n
> /python/install/lib/python3.14/uuid.py(703)getnode()
-> _node = getter()
(Pdb) n
> /python/install/lib/python3.14/uuid.py(706)getnode()
-> if (_node is not None) and (0 <= _node < (1 << 48)):
(Pdb) _node
(Pdb) n
> /python/install/lib/python3.14/uuid.py(701)getnode()
-> for getter in _GETTERS + [_random_getnode]:
(Pdb) n
> /python/install/lib/python3.14/uuid.py(702)getnode()
-> try:
(Pdb) getter
<function _random_getnode at 0xffffb77b7650>
(Pdb) n
> /python/install/lib/python3.14/uuid.py(703)getnode()
-> _node = getter()
(Pdb) n
> /python/install/lib/python3.14/uuid.py(706)getnode()
-> if (_node is not None) and (0 <= _node < (1 << 48)):
(Pdb) _node
23292345252342

[zanieb]

So, the patch worked but it turns out generate_time_safe is necessary for MAC address retrieval on (at least) ubuntu:latest?

[picnixz]

Maybe we should add all possible getnode fallbacks based on ifconfig, ip, arp, netstat, lanscan?

[zanieb]

We did try _ip_getnode and _ifconfig_getnode as expected there. I didn't look into why those might fail. It does feel like a bit of a separate concern than this patch.

[picnixz]

I suggest adding a print in the except: continue as well just in case and also print the output of the invoked command to see whether we need to upgrade how the output is being parsed.

[zanieb]

Those commands are just not installed by default in the ubuntu image. If you apt-get install net-tools, the getnode result is static.

[picnixz]

Ha! so that's why. Let's also fix this by adding them as a dependency then

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @picnixz for commit 16200ae 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F132901%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @picnixz for commit fd84b3c 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F132901%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[picnixz]

Note: the buildbot failures are unrelated so I'll ignore them.

[picnixz]

Hum, is our backport bot sick? it didn't make an automatic backport, so I'll do it for 3.14

[miss-islington-app]

Thanks @picnixz for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @picnixz, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 3bffada46728e51f84c41ecbb0d3722595693e63 3.13

[picnixz]

huh... ok I'll make the manual bp, add a DO-NOT-MERGE and so that we don't forget it

[bedevere-app]

GH-134704 is a backport of this pull request to the 3.13 branch.