Convert "little endian" hex string to IP address in Python

Network address manipulation is provided by the socket module.

socket.inet_ntoa(packed_ip)

Convert a 32-bit packed IPv4 address (a string four characters in length) to its standard dotted-quad string representation (for example, ‘123.45.67.89’). This is useful when conversing with a program that uses the standard C library and needs objects of type struct in_addr, which is the C type for the 32-bit packed binary data this function takes as an argument.

You can translate your hex string to packed ip using struct.pack() and the little endian, unsigned long format.

s = "0200A8C0"

import socket
import struct
addr_long = int(s, 16)
print(hex(addr_long))  # '0x200a8c0'
print(struct.pack("<L", addr_long))  # '\xc0\xa8\x00\x02'
print(socket.inet_ntoa(struct.pack("<L", addr_long)))  # '192.168.0.2'

>>> s = "0200A8C0"
>>> bytes = ["".join(x) for x in zip(*[iter(s)]*2)]
>>> bytes
['02', '00', 'A8', 'C0']
>>> bytes = [int(x, 16) for x in bytes]
>>> bytes
[2, 0, 168, 192]
>>> print ".".join(str(x) for x in reversed(bytes))
192.168.0.2

It is short and clear; wrap it up in a function with error checking to suit your needs.

---

Handy grouping functions:

def group(iterable, n=2, missing=None, longest=True):
  """Group from a single iterable into groups of n.

  Derived from http://bugs.python.org/issue1643
  """
  if n < 1:
    raise ValueError("invalid n")
  args = (iter(iterable),) * n
  if longest:
    return itertools.izip_longest(*args, fillvalue=missing)
  else:
    return itertools.izip(*args)

def group_some(iterable, n=2):
  """Group from a single iterable into groups of at most n."""
  if n < 1:
    raise ValueError("invalid n")
  iterable = iter(iterable)
  while True:
    L = list(itertools.islice(iterable, n))
    if L:
      yield L
    else:
      break

You could do something like this:

>>> s = '0200A8C0'
>>> octets = [s[i:i+2] for i in range(0, len(s), 2)]
>>> ip = [int(i, 16) for i in reversed(octets)]
>>> ip_formatted = '.'.join(str(i) for i in ip)
>>> print ip_formatted
192.168.0.2

The octet splitting could probably be done more elegantly, but I can't think of a simpler way off the top of my head.

EDIT: Or on one line:

>>> s = '0200A8C0'
>>> print '.'.join(str(int(i, 16)) for i in reversed([s[i:i+2] for i in range(0, len(s), 2)]))
192.168.0.2