r"""UUID objects (universally unique identifiers) according to RFC 4122.
This module provides immutable UUID objects (class UUID) and the functions
uuid1(), uuid3(), uuid4(), uuid5() for generating version 1, 3, 4, and 5
UUIDs as specified in RFC 4122.
If all you want is a unique ID, you should probably call uuid1() or uuid4().
Note that uuid1() may compromise privacy since it creates a UUID containing
the computer's network address. uuid4() creates a random UUID.
# make a UUID based on the host ID and current time
>>> uuid.uuid1() # doctest: +SKIP
UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')
# make a UUID using an MD5 hash of a namespace UUID and a name
>>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')
>>> uuid.uuid4() # doctest: +SKIP
UUID('16fd2706-8baf-433b-82eb-8c7fada847da')
# make a UUID using a SHA-1 hash of a namespace UUID and a name
>>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')
# make a UUID from a string of hex digits (braces and hyphens ignored)
>>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')
# convert a UUID to a string of hex digits in standard form
'00010203-0405-0607-0809-0a0b0c0d0e0f'
# get the raw 16 bytes of the UUID
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
# make a UUID from a 16-byte string
>>> uuid.UUID(bytes=x.bytes)
UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')
__author__ = 'Ka-Ping Yee <ping@zesty.ca>'
RESERVED_NCS, RFC_4122, RESERVED_MICROSOFT, RESERVED_FUTURE = [
'reserved for NCS compatibility', 'specified in RFC 4122',
'reserved for Microsoft compatibility', 'reserved for future definition']
int_ = int # The built-in int type
bytes_ = bytes # The built-in bytes type
"""Instances of the UUID class represent UUIDs as specified in RFC 4122.
UUID objects are immutable, hashable, and usable as dictionary keys.
Converting a UUID to a string with str() yields something in the form
'12345678-1234-1234-1234-123456789abc'. The UUID constructor accepts
five possible forms: a similar string of hexadecimal digits, or a tuple
of six integer fields (with 32-bit, 16-bit, 16-bit, 8-bit, 8-bit, and
48-bit values respectively) as an argument named 'fields', or a string
of 16 bytes (with all the integer fields in big-endian order) as an
argument named 'bytes', or a string of 16 bytes (with the first three
fields in little-endian order) as an argument named 'bytes_le', or a
single 128-bit integer as an argument named 'int'.
UUIDs have these read-only attributes:
bytes the UUID as a 16-byte string (containing the six
integer fields in big-endian byte order)
bytes_le the UUID as a 16-byte string (with time_low, time_mid,
and time_hi_version in little-endian byte order)
fields a tuple of the six integer fields of the UUID,
which are also available as six individual attributes
and two derived attributes:
time_low the first 32 bits of the UUID
time_mid the next 16 bits of the UUID
time_hi_version the next 16 bits of the UUID
clock_seq_hi_variant the next 8 bits of the UUID
clock_seq_low the next 8 bits of the UUID
node the last 48 bits of the UUID
time the 60-bit timestamp
clock_seq the 14-bit sequence number
hex the UUID as a 32-character hexadecimal string
int the UUID as a 128-bit integer
urn the UUID as a URN as specified in RFC 4122
variant the UUID variant (one of the constants RESERVED_NCS,
RFC_4122, RESERVED_MICROSOFT, or RESERVED_FUTURE)
version the UUID version number (1 through 5, meaningful only
when the variant is RFC_4122)
def __init__(self, hex=None, bytes=None, bytes_le=None, fields=None,
r"""Create a UUID from either a string of 32 hexadecimal digits,
a string of 16 bytes as the 'bytes' argument, a string of 16 bytes
in little-endian order as the 'bytes_le' argument, a tuple of six
integers (32-bit time_low, 16-bit time_mid, 16-bit time_hi_version,
8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as
the 'fields' argument, or a single 128-bit integer as the 'int'
argument. When a string of hex digits is given, curly braces,
hyphens, and a URN prefix are all optional. For example, these
expressions all yield the same UUID:
UUID('{12345678-1234-5678-1234-567812345678}')
UUID('12345678123456781234567812345678')
UUID('urn:uuid:12345678-1234-5678-1234-567812345678')
UUID(bytes='\x12\x34\x56\x78'*4)
UUID(bytes_le='\x78\x56\x34\x12\x34\x12\x78\x56' +
'\x12\x34\x56\x78\x12\x34\x56\x78')
UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678))
UUID(int=0x12345678123456781234567812345678)
Exactly one of 'hex', 'bytes', 'bytes_le', 'fields', or 'int' must
be given. The 'version' argument is optional; if given, the resulting
UUID will have its variant and version set according to RFC 4122,
overriding the given 'hex', 'bytes', 'bytes_le', 'fields', or 'int'.
if [hex, bytes, bytes_le, fields, int].count(None) != 4:
raise TypeError('one of the hex, bytes, bytes_le, fields, '
'or int arguments must be given')
hex = hex.replace('urn:', '').replace('uuid:', '')
hex = hex.strip('{}').replace('-', '')
raise ValueError('badly formed hexadecimal UUID string')
raise ValueError('bytes_le is not a 16-char string')
bytes = (bytes_le[4-1::-1] + bytes_le[6-1:4-1:-1] +
bytes_le[8-1:6-1:-1] + bytes_le[8:])
raise ValueError('bytes is not a 16-char string')
assert isinstance(bytes, bytes_), repr(bytes)
int = int_.from_bytes(bytes, byteorder='big')
raise ValueError('fields is not a 6-tuple')
(time_low, time_mid, time_hi_version,
clock_seq_hi_variant, clock_seq_low, node) = fields
if not 0 <= time_low < 1<<32:
raise ValueError('field 1 out of range (need a 32-bit value)')
if not 0 <= time_mid < 1<<16:
raise ValueError('field 2 out of range (need a 16-bit value)')
if not 0 <= time_hi_version < 1<<16:
raise ValueError('field 3 out of range (need a 16-bit value)')
if not 0 <= clock_seq_hi_variant < 1<<8:
raise ValueError('field 4 out of range (need an 8-bit value)')
if not 0 <= clock_seq_low < 1<<8:
raise ValueError('field 5 out of range (need an 8-bit value)')
if not 0 <= node < 1<<48:
raise ValueError('field 6 out of range (need a 48-bit value)')
clock_seq = (clock_seq_hi_variant << 8) | clock_seq_low
int = ((time_low << 96) | (time_mid << 80) |
(time_hi_version << 64) | (clock_seq << 48) | node)
if not 0 <= int < 1<<128:
raise ValueError('int is out of range (need a 128-bit value)')
if not 1 <= version <= 5:
raise ValueError('illegal version number')
# Set the variant to RFC 4122.
# Set the version number.
self.__dict__['int'] = int
if isinstance(other, UUID):
return self.int == other.int
# Q. What's the value of being able to sort UUIDs?
# A. Use them as keys in a B-Tree or similar mapping.
if isinstance(other, UUID):
return self.int < other.int
if isinstance(other, UUID):
return self.int > other.int
if isinstance(other, UUID):
return self.int <= other.int
if isinstance(other, UUID):
return self.int >= other.int
return '%s(%r)' % (self.__class__.__name__, str(self))
def __setattr__(self, name, value):
raise TypeError('UUID objects are immutable')
return '%s-%s-%s-%s-%s' % (
hex[:8], hex[8:12], hex[12:16], hex[16:20], hex[20:])
return self.int.to_bytes(16, 'big')
return (bytes[4-1::-1] + bytes[6-1:4-1:-1] + bytes[8-1:6-1:-1] +
return (self.time_low, self.time_mid, self.time_hi_version,
self.clock_seq_hi_variant, self.clock_seq_low, self.node)
return (self.int >> 80) & 0xffff
def time_hi_version(self):
return (self.int >> 64) & 0xffff
def clock_seq_hi_variant(self):
return (self.int >> 56) & 0xff
return (self.int >> 48) & 0xff
return (((self.time_hi_version & 0x0fff) << 48) |
(self.time_mid << 32) | self.time_low)
return (((self.clock_seq_hi_variant & 0x3f) << 8) |
return self.int & 0xffffffffffff
return '%032x' % self.int
return 'urn:uuid:' + str(self)
if not self.int & (0x8000 << 48):
elif not self.int & (0x4000 << 48):
elif not self.int & (0x2000 << 48):
return RESERVED_MICROSOFT
# The version bits are only meaningful for RFC 4122 UUIDs.
if self.variant == RFC_4122:
return int((self.int >> 76) & 0xf)
def _popen(command, *args):
import os, shutil, subprocess
executable = shutil.which(command)
path = os.pathsep.join(('/sbin', '/usr/sbin'))
executable = shutil.which(command, path=path)
# LC_ALL=C to ensure English output, stderr=DEVNULL to prevent output
# on stderr (Note: we don't have an example where the words we search
# for are actually localized, but in theory some system could do so.)
proc = subprocess.Popen((executable,) + args,
stderr=subprocess.DEVNULL,
def _find_mac(command, args, hw_identifiers, get_index):
proc = _popen(command, *args.split())
words = line.lower().rstrip().split()
for i in range(len(words)):
if words[i] in hw_identifiers:
word = words[get_index(i)]
mac = int(word.replace(b':', b''), 16)
except (ValueError, IndexError):
# Virtual interfaces, such as those provided by
# VPNs, do not have a colon-delimited MAC address
# as expected, but a 16-byte HWAddr separated by
# dashes. These should be ignored in favor of a
"""Get the hardware address on Unix by running ifconfig."""
# This works on Linux ('' or '-a'), Tru64 ('-av'), but not all Unixes.
keywords = (b'hwaddr', b'ether', b'address:', b'lladdr')
for args in ('', '-a', '-av'):
mac = _find_mac('ifconfig', args, keywords, lambda i: i+1)
"""Get the hardware address on Unix by running ip."""
# This works on Linux with iproute2.
mac = _find_mac('ip', 'link', [b'link/ether'], lambda i: i+1)
"""Get the hardware address on Unix by running arp."""
ip_addr = socket.gethostbyname(socket.gethostname())
# Try getting the MAC addr from arp based on our IP address (Solaris).
mac = _find_mac('arp', '-an', [os.fsencode(ip_addr)], lambda i: -1)
mac = _find_mac('arp', '-an', [os.fsencode(ip_addr)], lambda i: i+1)
# This works on Linux, FreeBSD and NetBSD
mac = _find_mac('arp', '-an', [os.fsencode('(%s)' % ip_addr)],
"""Get the hardware address on Unix by running lanscan."""
# This might work on HP-UX.
return _find_mac('lanscan', '-ai', [b'lan0'], lambda i: 0)
"""Get the hardware address on Unix by running netstat."""
# This might work on AIX, Tru64 UNIX and presumably on IRIX.
proc = _popen('netstat', '-ia')
words = proc.stdout.readline().rstrip().split()
i = words.index(b'Address')
words = line.rstrip().split()
if len(word) == 17 and word.count(b':') == 5:
mac = int(word.replace(b':', b''), 16)
except (ValueError, IndexError):
"""Get the hardware address on Windows by running ipconfig.exe."""
import os, re, subprocess
dirs = ['', r'c:\windows\system32', r'c:\winnt\system32']
buffer = ctypes.create_string_buffer(300)
ctypes.windll.kernel32.GetSystemDirectoryA(buffer, 300)
dirs.insert(0, buffer.value.decode('mbcs'))
proc = subprocess.Popen([os.path.join(dir, 'ipconfig'), '/all'],
value = line.split(':')[-1].strip().lower()
if re.fullmatch('(?:[0-9a-f][0-9a-f]-){5}[0-9a-f][0-9a-f]', value):
return int(value.replace('-', ''), 16)
"""Get the hardware address on Windows using NetBIOS calls.
See http://support.microsoft.com/kb/118623 for details."""
import win32wnet, netbios
ncb.Command = netbios.NCBENUM
ncb.Buffer = adapters = netbios.LANA_ENUM()
if win32wnet.Netbios(ncb) != 0:
for i in range(adapters.length):
ncb.Command = netbios.NCBRESET
ncb.Lana_num = ord(adapters.lana[i])
if win32wnet.Netbios(ncb) != 0:
ncb.Command = netbios.NCBASTAT
ncb.Lana_num = ord(adapters.lana[i])
ncb.Callname = '*'.ljust(16)
ncb.Buffer = status = netbios.ADAPTER_STATUS()
if win32wnet.Netbios(ncb) != 0:
bytes = status.adapter_address[:6]
return int.from_bytes(bytes, 'big')
# Thanks to Thomas Heller for ctypes and for his help with its use here.
# If ctypes is available, use it to find system routines for UUID generation.
# XXX This makes the module non-thread-safe!
_uuid_generate_time = _UuidCreate = None
import ctypes, ctypes.util
# The uuid_generate_* routines are provided by libuuid on at least
# Linux and FreeBSD, and provided by libc on Mac OS X.
if not sys.platform.startswith('win'):
for libname in _libnames:
lib = ctypes.CDLL(ctypes.util.find_library(libname))
if hasattr(lib, 'uuid_generate_time'):
_uuid_generate_time = lib.uuid_generate_time
# The uuid_generate_* functions are broken on MacOS X 10.5, as noted
# in issue #8621 the function generates the same sequence of values
# in the parent process and all children created using fork (unless
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
