diff options
Diffstat (limited to 'Lib/uuid.py')
| -rw-r--r-- | Lib/uuid.py | 71 |
1 files changed, 60 insertions, 11 deletions
diff --git a/Lib/uuid.py b/Lib/uuid.py index 020c6e73c8..cb2bc092bd 100644 --- a/Lib/uuid.py +++ b/Lib/uuid.py @@ -342,11 +342,30 @@ def _popen(command, *args): env=env) return proc +# For MAC (a.k.a. IEEE 802, or EUI-48) addresses, the second least significant +# bit of the first octet signifies whether the MAC address is universally (0) +# or locally (1) administered. Network cards from hardware manufacturers will +# always be universally administered to guarantee global uniqueness of the MAC +# address, but any particular machine may have other interfaces which are +# locally administered. An example of the latter is the bridge interface to +# the Touch Bar on MacBook Pros. +# +# This bit works out to be the 42nd bit counting from 1 being the least +# significant, or 1<<41. We'll prefer universally administered MAC addresses +# over locally administered ones since the former are globally unique, but +# we'll return the first of the latter found if that's all the machine has. +# +# See https://en.wikipedia.org/wiki/MAC_address#Universal_vs._local + +def _is_universal(mac): + return not (mac & (1 << 41)) + def _find_mac(command, args, hw_identifiers, get_index): + first_local_mac = None try: proc = _popen(command, *args.split()) if not proc: - return + return None with proc: for line in proc.stdout: words = line.lower().rstrip().split() @@ -355,8 +374,9 @@ def _find_mac(command, args, hw_identifiers, get_index): try: word = words[get_index(i)] mac = int(word.replace(b':', b''), 16) - if mac: + if _is_universal(mac): return mac + first_local_mac = first_local_mac or mac except (ValueError, IndexError): # Virtual interfaces, such as those provided by # VPNs, do not have a colon-delimited MAC address @@ -366,6 +386,7 @@ def _find_mac(command, args, hw_identifiers, get_index): pass except OSError: pass + return first_local_mac or None def _ifconfig_getnode(): """Get the hardware address on Unix by running ifconfig.""" @@ -375,6 +396,7 @@ def _ifconfig_getnode(): mac = _find_mac('ifconfig', args, keywords, lambda i: i+1) if mac: return mac + return None def _ip_getnode(): """Get the hardware address on Unix by running ip.""" @@ -382,6 +404,7 @@ def _ip_getnode(): mac = _find_mac('ip', 'link list', [b'link/ether'], lambda i: i+1) if mac: return mac + return None def _arp_getnode(): """Get the hardware address on Unix by running arp.""" @@ -404,8 +427,10 @@ def _arp_getnode(): # This works on Linux, FreeBSD and NetBSD mac = _find_mac('arp', '-an', [os.fsencode('(%s)' % ip_addr)], lambda i: i+2) + # Return None instead of 0. if mac: return mac + return None def _lanscan_getnode(): """Get the hardware address on Unix by running lanscan.""" @@ -415,32 +440,36 @@ def _lanscan_getnode(): def _netstat_getnode(): """Get the hardware address on Unix by running netstat.""" # This might work on AIX, Tru64 UNIX. + first_local_mac = None try: proc = _popen('netstat', '-ia') if not proc: - return + return None with proc: words = proc.stdout.readline().rstrip().split() try: i = words.index(b'Address') except ValueError: - return + return None for line in proc.stdout: try: words = line.rstrip().split() word = words[i] if len(word) == 17 and word.count(b':') == 5: mac = int(word.replace(b':', b''), 16) - if mac: + if _is_universal(mac): return mac + first_local_mac = first_local_mac or mac except (ValueError, IndexError): pass except OSError: pass + return first_local_mac or None def _ipconfig_getnode(): """Get the hardware address on Windows by running ipconfig.exe.""" import os, re + first_local_mac = None dirs = ['', r'c:\windows\system32', r'c:\winnt\system32'] try: import ctypes @@ -458,18 +487,23 @@ def _ipconfig_getnode(): for line in pipe: value = line.split(':')[-1].strip().lower() if re.match('([0-9a-f][0-9a-f]-){5}[0-9a-f][0-9a-f]', value): - return int(value.replace('-', ''), 16) + mac = int(value.replace('-', ''), 16) + if _is_universal(mac): + return mac + first_local_mac = first_local_mac or mac + return first_local_mac or None def _netbios_getnode(): """Get the hardware address on Windows using NetBIOS calls. See http://support.microsoft.com/kb/118623 for details.""" import win32wnet, netbios + first_local_mac = None ncb = netbios.NCB() ncb.Command = netbios.NCBENUM ncb.Buffer = adapters = netbios.LANA_ENUM() adapters._pack() if win32wnet.Netbios(ncb) != 0: - return + return None adapters._unpack() for i in range(adapters.length): ncb.Reset() @@ -488,7 +522,11 @@ def _netbios_getnode(): bytes = status.adapter_address[:6] if len(bytes) != 6: continue - return int.from_bytes(bytes, 'big') + mac = int.from_bytes(bytes, 'big') + if _is_universal(mac): + return mac + first_local_mac = first_local_mac or mac + return first_local_mac or None _generate_time_safe = _UuidCreate = None @@ -601,9 +639,19 @@ def _windll_getnode(): return UUID(bytes=bytes_(_buffer.raw)).node def _random_getnode(): - """Get a random node ID, with eighth bit set as suggested by RFC 4122.""" + """Get a random node ID.""" + # RFC 4122, $4.1.6 says "For systems with no IEEE address, a randomly or + # pseudo-randomly generated value may be used; see Section 4.5. The + # multicast bit must be set in such addresses, in order that they will + # never conflict with addresses obtained from network cards." + # + # The "multicast bit" of a MAC address is defined to be "the least + # significant bit of the first octet". This works out to be the 41st bit + # counting from 1 being the least significant bit, or 1<<40. + # + # See https://en.wikipedia.org/wiki/MAC_address#Unicast_vs._multicast import random - return random.getrandbits(48) | 0x010000000000 + return random.getrandbits(48) | (1 << 40) _node = None @@ -626,13 +674,14 @@ def getnode(): getters = [_unix_getnode, _ifconfig_getnode, _ip_getnode, _arp_getnode, _lanscan_getnode, _netstat_getnode] - for getter in getters + [_random_getnode]: + for getter in getters: try: _node = getter() except: continue if _node is not None: return _node + return _random_getnode() _last_timestamp = None |