test_uuid.test_netstat_getnode() fails on FreeBSD VM: uuid._netstat_getnode() uses IPv6 address as MAC address

[vstinner]

BPO	39991
Nosy	@warsaw, @vstinner
PRs	bpo-39991: uuid._netstat_getnode() ignores IPv6 addresses #19043 bpo-39991: Enhance uuid parser for MAC address #19045

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-03-17.17:37:36.319>
created_at = <Date 2020-03-17.11:27:33.918>
labels = ['tests', '3.9']
title = 'test_uuid.test_netstat_getnode() fails on FreeBSD VM: uuid._netstat_getnode() uses IPv6 address as MAC address'
updated_at = <Date 2020-03-17.17:37:36.318>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2020-03-17.17:37:36.318>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-03-17.17:37:36.319>
closer = 'vstinner'
components = ['Tests']
creation = <Date 2020-03-17.11:27:33.918>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 39991
keywords = ['patch']
message_count = 6.0
messages = ['364412', '364432', '364435', '364439', '364459', '364460']
nosy_count = 2.0
nosy_names = ['barry', 'vstinner']
pr_nums = ['19043', '19045']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue39991'
versions = ['Python 3.9']

[vstinner]

My FreeBSD VM has a NIC with the IPv6 address fe80::5054:ff:fe9: local-link IPv6 address. It's used by uuid._netstat_getnode() as a MAC address, but it seems like this IPv6 address doesn't respect RFC 4122 and so should be skipped.

_find_mac_under_heading() should reject IPv6 address: only use MAC address.

vstinner@freebsd$ uname -a
FreeBSD freebsd 12.1-RELEASE-p2 FreeBSD 12.1-RELEASE-p2 GENERIC amd64

======================================================================
FAIL: test_netstat_getnode (test.test_uuid.TestInternalsWithExtModule)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/usr/home/vstinner/python/master/Lib/test/test_uuid.py", line 767, in test_netstat_getnode
    self.check_node(node, 'netstat')
  File "/usr/home/vstinner/python/master/Lib/test/test_uuid.py", line 736, in check_node
    self.assertTrue(0 < node < (1 << 48),
AssertionError: False is not true : fe805054fffe9 is not an RFC 4122 node ID

======================================================================
FAIL: test_netstat_getnode (test.test_uuid.TestInternalsWithoutExtModule)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/usr/home/vstinner/python/master/Lib/test/test_uuid.py", line 767, in test_netstat_getnode
    self.check_node(node, 'netstat')
  File "/usr/home/vstinner/python/master/Lib/test/test_uuid.py", line 736, in check_node
    self.assertTrue(0 < node < (1 << 48),
AssertionError: False is not true : fe805054fffe9 is not an RFC 4122 node ID

It's using a qemu VM run by virt-manager.

fe805054fffe9 seems to be the MAC address of my vtnet network interface:

vstinner@freebsd$ netstat -ian
Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll
vtnet 1500 <Link#1> 52:54:00:9d:0e:67 10017 0 0 8174 0 0
vtnet - fe80::%vtnet0 fe80::5054:ff:fe9 0 - - 4 - -
vtnet - 192.168.122.0 192.168.122.45 8844 - - 8171 - -
lo0 16384 <Link#2> lo0 260148 0 0 260148 0 0
lo0 - ::1/128 ::1 193 - - 193 - -
ff01::1%lo0
ff02::2:2eb7:74fa
ff02::2:ff2e:b774
ff02::1%lo0
ff02::1:ff00:1%lo
lo0 - fe80::%lo0/64 fe80::1%lo0 0 - - 0 - -
ff01::1%lo0
ff02::2:2eb7:74fa
ff02::2:ff2e:b774
ff02::1%lo0
ff02::1:ff00:1%lo
lo0 - 127.0.0.0/8 127.0.0.1 259955 - - 259955 - -
224.0.0.1

[vstinner]

New changeset eb886db by Victor Stinner in branch 'master':
bpo-39991: uuid._netstat_getnode() ignores IPv6 addresses (GH-19043)
eb886db

[vstinner]

It seems like this issue is a regression caused by the following change of bpo-28009:

commit 0bcbfa4
Author: Michael Felt <aixtools@users.noreply.github.com>
Date: Thu Sep 26 20:43:15 2019 +0100

bpo-28009: Fix uuid.uuid1() and uuid.get_node() on AIX (GH-8672)

which replaced:
if len(word) == 17 and word.count(b':') == 5:
with:
if len(word) == 17:

[vstinner]

My fix is incomplete: the IPv6 address "123:2:3:4:5:6:7:8" is a valid IPv6 address and uuid.py accepts it as a valid MAC address, whereas it's not a MAC address.

[vstinner]

New changeset ebf6bb9 by Victor Stinner in branch 'master':
bpo-39991: Enhance uuid parser for MAC address (GH-19045)
ebf6bb9

[vstinner]

Ok, the new stricter parser should now cover all cases. If not, it should be easier to fix it ;-) I close the issue.