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<?php function normalise_ip($address) { if (preg_match('/(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/', $address, $matches)) { // IPv4 address $num = 0; for ($i = 1; $i <= 4; $i++) { $octet = (int) $matches[$i]; if ($octet > 255) { return false; } $num |= $octet << ((4 - $i) * 8); } return sprintf('00000000000000000000ffff%04x', $num); } else if (preg_match('/\[?((?:[0-9a-f]{1,4}:|::)+[0-9a-f]{1,4})]?/i', strtolower($address), $matches)) { // IPv6 address $parts = explode(':', $matches[1]); $numParts = count($parts); if ($parts[0] === '') { array_splice($parts, 0, 2, array_fill(0, 8 - ($numParts - 2), '0000')); } else if ($parts[$numParts - 1] === '') { echo "end\n"; array_splice($parts, $numParts - 2, 2, array_fill(0, 8 - ($numParts - 2), '0000')); } else { foreach ($parts as $i => $part) { if ($part === '') { array_splice($parts, $i, 1, array_fill(0, 8 - ($numParts - 1), '0000')); } } } foreach ($parts as &$part) { $part = sprintf('%04s', $part); } return implode('', $parts); } else { // invalid return false; } } echo normalise_ip('192.168.0.1') . "\n"; echo normalise_ip('::ffff:C0A8:0001') . "\n"; echo normalise_ip('::ffff:C0A8:1') . "\n"; echo normalise_ip('[::ffff:C0A8:0001]') . "\n"; echo normalise_ip('[C0A8:0001::]') . "\n";