Kata

Introduction

Both the IPv4 address and subnet mask is made up of 32 bits. The bits are divided into four sections called octets (groups of eight). Each octet can have a number in the range 0 to 255 (unsigned 8-bit integers).

When learning IPv4 addressing it is essential to know how the Binary Number System works as well as having the right tools for the task you are facing. But, you are lacking a good peace of code to visualize the IPv4 addresses and subnet masks in binary form...

The Assignment

Your task is to implement a function void ipv4_to_binary(const char *ipv4_addr, char ipv4_binary[36]) which takes in an IPv4 address ipv4_addr and writes the result converted into Dotted Binary Notation in the output parameter ipv4_binary, a pre-allocated character buffer large enough to hold the result. The function has no return value.

Here are a few examples of input (left) and output (right):

192.168.0.33    = 11000000.10101000.00000000.00100001
255.255.255.0   = 11111111.11111111.11111111.00000000

10.55.0.13      = 00001010.00110111.00000000.00001101
255.255.255.252 = 11111111.11111111.11111111.11111100

192.168.0.33 in the example above is the Dotted Decimal Notation and 11000000.10101000.00000000.00100001 is the corresponding Dotted Binary Notation.

Having a function that prints an address this way might make it easier when making various bitwise calculations later on (in subsequent katas).

Testing

The tests will challenge your function with addresses in the full 32-bit range (0.0.0.0 - 255.255.255.255) and nothing else.

Links

Check out these links for more information:

• https://en.wikipedia.org/wiki/IPv4#Addressing
• https://en.wikipedia.org/wiki/Binary_number