getIPBanRange.php

<?php

function getIPBanRange(array $start, array $end)
{
	$parts_count = count($start);

	if ($parts_count !== count($end))
	{
		throw new \InvalidArgumentException('$start and $end must be the same length');
	}

	// Find the first element that isn't the same
	for ($i = 0; $i < $parts_count; $i++)
	{
		if ($start[$i] !== $end[$i])
		{
			// @todo check if $end > $start
			$size = $end[$i] - $start[$i];
			$starting_part = $i;
			break;
		}
	}

	$parts = array_fill(0, $parts_count, array('low' => 0, 'high' => 255));

	$range = array_fill(0, $size, $parts);

	for ($i = 0; $i < $parts_count; $i++)
	{
		$range[0][$i]['low'] = $start[$i];
	}

	if ($starting_part !== 0)
	{
		for ($i = 1; $i < $size; $i++)
		{
			for($p = 0; $p < $starting_part; $p++)
			{
				$range[$i] = array(
					'low' => $start[$p],
					'high' => $start[$p]
				);
			}
		}
	}

	// Set the maximums
	for ($i = 0; $i < $parts_count; $i++)
	{
		$range[$size][$i]['high'] = $end[$i];
	}

	return $range;
}

$start = explode('152.9.13.4', '.');
$end = explode('187.22.1.122', '.');

var_dump(getIPBanRange($start, $end));