1 files changed, 91 insertions, 0 deletions
diff --git a/inc/iputil.inc.php b/inc/iputil.inc.php
index 9ec78f50..a9b79573 100644
--- a/inc/iputil.inc.php
+++ b/inc/iputil.inc.php
@@ -75,4 +75,95 @@ class IpUtil
 		return ['start' => $ip & ~$bits, 'end' => $ip | $bits];
 	}
 
+	/**
+	 * Normalizes an IP address to the canonical form.
+	 * This supports all numeric IPv4, IPv6 and IPv4-mapped IPv6 addresses.
+	 * As well as odd formats like IPv4 with multiple octets collapsed into a single one.
+	 * Returns null if the address is invalid.
+	 */
+	public static function normalizeIp(string $ip): ?string
+	{
+		$ip = trim($ip);
+		if ($ip === '')
+			return null;
+
+		// Check simple case first
+		$addr = @inet_pton($ip);
+		if ($addr !== false) {
+			$ret = inet_ntop($addr);
+			if (substr($ret, 0, 7) === '::ffff:')
+				return substr($ret, 7);
+			return $ret;
+		}
+		if (strpos($ip, ':') !== false)
+			return null;
+
+		// IPv4 handling
+		// Support octal, hex and shorthand notations
+		$parts = explode('.', $ip);
+		$numParts = count($parts);
+		if ($numParts > 4)
+			return null;
+
+		$values = [];
+		foreach ($parts as $part) {
+			$part = trim($part);
+			if ($part === '')
+				return null;
+			// Check for hex (0x...)
+			if (strncasecmp($part, '0x', 2) === 0) {
+				if (!ctype_xdigit(substr($part, 2)))
+					return null;
+				$values[] = hexdec($part);
+			} elseif ($part[0] === '0' && strlen($part) > 1) {
+				// Octal (starts with 0, but not just 0)
+				if (!preg_match('/^[0-7]+$/', $part))
+					return null;
+				$values[] = octdec($part);
+			} else {
+				// Decimal
+				if (!preg_match('/^[0-9]+$/', $part))
+					return null;
+				$values[] = (int)$part;
+			}
+		}
+
+		if (empty($values))
+			return null;
+
+		// Validate values and handle shorthands
+		// Rules:
+		// 1 part: a (32 bits)
+		// 2 parts: a.b (a: 8 bits, b: 24 bits)
+		// 3 parts: a.b.c (a: 8 bits, b: 8 bits, c: 16 bits)
+		// 4 parts: a.b.c.d (a: 8 bits, b: 8 bits, c: 8 bits, d: 8 bits)
+		$ipv4int = 0;
+		for ($i = 0; $i < $numParts; $i++) {
+			$val = $values[$i];
+			if ($i === $numParts - 1) {
+				// Last part
+				$max = (2 ** (8 * (4 - $i))) - 1;
+				if ($val < 0 || $val > $max)
+					return null;
+				$ipv4int = ($ipv4int << (8 * (4 - $i))) | (int)$val;
+			} else {
+				if ($val < 0 || $val > 255)
+					return null;
+				$ipv4int = ($ipv4int << 8) | (int)$val;
+			}
+		}
+
+		return long2ip($ipv4int);
+	}
+
+	/**
+	 * Check if given string is a valid IP address.
+	 * Supports all kinds of IP address formats that PHP supports,
+	 * including IPv6, IPv4-mapped IPv6, IPv4-in-IPv6, etc.
+	 */
+	public static function isValidIp(string $ip): bool
+	{
+		return self::normalizeIp($ip) !== null;
+	}
+
 }