When you would like to deal with low-level network functions, sometimes, the usual string notation of IP addresses are not very useful. They need to be converted to the packed 32-bit binary formats.
The Python socket library has utilities to deal with the various IP address formats. Here, we will use two of them: inet_aton() and inet_ntoa().
Let us create the convert_ip4_address() function, where inet_aton() and inet_ntoa() will be used for the IP address conversion. We will use two sample IP addresses, 127.0.0.1 and 192.168.0.1.
Listing 1.3 shows ip4_address_conversion as follows:
#!/usr/bin/env python
# Python Network Programming Cookbook -- Chapter – 1
# This program is optimized for Python 2.7.
# It may run on any other version with/without modifications.
import socket
from binascii import hexlify
def convert_ip4_address():
for ip_addr in ['127.0.0.1', '192.168.0.1']:
packed_ip_addr = socket.inet_aton(ip_addr)
unpacked_ip_addr = socket.inet_ntoa(packed_ip_addr)
print "IP Address: %s => Packed: %s, Unpacked: %s"
%(ip_addr, hexlify(packed_ip_addr), unpacked_ip_addr)
if __name__ == '__main__':
convert_ip4_address()Now, if you run this recipe, you will see the following output:
$ python 1_3_ip4_address_conversion.py IP Address: 127.0.0.1 => Packed: 7f000001, Unpacked: 127.0.0.1 IP Address: 192.168.0.1 => Packed: c0a80001, Unpacked: 192.168.0.1
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