| msg303360 - (view) |
Author: Ivan Pozdeev (Ivan.Pozdeev) * |
Date: 2017-09-29 21:37 |
| Ethernet emulation for some devices like Android phones' tethering use all-zero MAC addresses (which is okay since they don't actually pass Ethernet frames to other NICs). This results in a node ID of 0 if I'm currently connected to the Net via such a device. Which fails range checks in the corresponding tests. RFC 4122 doesn't actually have any prohibitions of using a node ID of 0. Neither does IEEE 802.3 (or rather, whatever info I gathered on it since the standard's text is not freely available) assign any special meaning to an all-zero MAC address. The patch also corrects the check call in test_windll_getnode since the tested function always generates UUID from a MAC address. |
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| msg303373 - (view) |
Author: Ivan Pozdeev (Ivan.Pozdeev) * |
Date: 2017-09-29 23:30 |
| Example failure: ====================================================================== FAIL: test_windll_getnode (test.test_uuid.TestInternals) ---------------------------------------------------------------------- Traceback (most recent call last): File "C:\Ivan\cpython\lib\test\test_uuid.py", line 501, in test_windll_getnode self.check_node(node) File "C:\Ivan\cpython\lib\test\test_uuid.py", line 449, in check_node "%s is not an RFC 4122 node ID" % hex) AssertionError: False is not true : 000000000000 is not an RFC 4122 node ID ====================================================================== FAIL: test_getnode (test.test_uuid.TestUUID) ---------------------------------------------------------------------- Traceback (most recent call last): File "C:\Ivan\cpython\lib\test\test_uuid.py", line 296, in test_getnode self.assertTrue(0 < node1 < (1 << 48), '%012x' % node1) AssertionError: False is not true : 000000000000 |
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| msg308097 - (view) |
Author: Xavier de Gaye (xdegaye) *  |
Date: 2017-12-12 09:01 |
| On a Samsung device with Android 5.1 and tethering enabled, only one network device has a MAC address and it is not an all-zero MAC address. Ivan can you please provide more information about this problem: which device, what Android version, what is the output of 'ip link' ? |
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| msg308100 - (view) |
Author: Serhiy Storchaka (serhiy.storchaka) *  |
Date: 2017-12-12 09:39 |
| I'm not sure that 000000000000 is better than a random address. Even if an all-zero MAC address is not explicitly prohibited it is used in a multiple independent devices. A random address looks more appropriate fore the purpose of generating a UUID. |
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| msg308104 - (view) |
Author: Xavier de Gaye (xdegaye) * |
Date: 2017-12-12 10:21 |
| > I'm not sure that 000000000000 is better than a random address. I agree, getnode() when obtained from a MAC address should not return 0. RFC 4122 states (emphasis on 'uniqueness' is mine): This document specifies three algorithms to generate UUIDs: the first leverages the unique values of 802 MAC addresses to guarantee *uniqueness*, ... |
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| msg308152 - (view) |
Author: Ivan Pozdeev (__Vano) |
Date: 2017-12-12 21:28 |
| > Xavier de Gaye <xdegaye@gmail.com> added the comment: > > On a Samsung device with Android 5.1 and tethering enabled, only one network device has a MAC address and it is not an all-zero MAC address. > > Ivan can you please provide more information about this problem: which device, what Android version, what is the output of 'ip link' ? C:\> ipconfig -all <...> Samsung Galaxy S7 - Ethernet адаптер: DNS-суффикс этого подключения . . : Описание . . . . . . . . . . . . : Android USB Ethernet/RNDIS Физический адрес. . . . . . . . . : 00-00-00-00-00-00 Dhcp включен. . . . . . . . . . . : да Автонастройка включена . . . . . : да IP-адрес . . . . . . . . . . . . : 192.168.42.2 Маска подсети . . . . . . . . . . : 255.255.255.0 Основной шлюз . . . . . . . . . . : 192.168.42.129 DHCP-сервер . . . . . . . . . . . : 192.168.42.129 DNS-серверы . . . . . . . . . . . : 192.168.42.129 Device name: Samsung Galaxy S7 Model number: SM-G930F Android version: 6.0.1 Firmware version: G930FXXU1APGJ Baseband version: G930VVRS4APH1 Build number: MMB29M.G930VVRU2APG5 > Serhiy Storchaka<storchaka+cpython@gmail.com> added the comment: > > I'm not sure that 000000000000 is better than a random address. Even if an all-zero MAC address is not explicitly prohibited it is used in a multiple independent devices. A random address looks more appropriate fore the purpose of generating a UUID. The question is not whether it's good UUID source material. The question, for the purpose of the test, is whether it's valid getnode() output -- which it is for the current logic. |
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| msg308194 - (view) |
Author: Xavier de Gaye (xdegaye) * |
Date: 2017-12-13 09:33 |
| > C:\> ipconfig -all So the all-zero MAC address occurs on a Windows box and that explains the test_windll_getnode failure (this test is skipped on Android). I missed that point in your initial post and knowing what Android device you are using is irrelevant. |
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