public class IpUtil {
private static final String N255 = "(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)";
private static final Pattern PATTERN = Pattern.compile("^(?:" + N255 + "\\.){3}" + N255 + "$");
private IpUtil() {
}
private static String longToIpV4(long longIp) {
int octet3 = (int) ((longIp >> 24) % 256);
int octet2 = (int) ((longIp >> 16) % 256);
int octet1 = (int) ((longIp >> 8) % 256);
int octet0 = (int) ((longIp) % 256);
return octet3 + "." + octet2 + "." + octet1 + "." + octet0;
}
private static long ipV4ToLong(String ip) {
String[] octets = ip.split("\\.");
return (Long.parseLong(octets[0]) << 24) + (Integer.parseInt(octets[1]) << 16)
+ (Integer.parseInt(octets[2]) << 8) + Integer.parseInt(octets[3]);
}
private static boolean isIPv4Private(String ip) {
long longIp = ipV4ToLong(ip);
return (longIp >= ipV4ToLong("10.0.0.0") && longIp <= ipV4ToLong("10.255.255.255"))
|| (longIp >= ipV4ToLong("172.16.0.0") && longIp <= ipV4ToLong("172.31.255.255"))
|| longIp >= ipV4ToLong("192.168.0.0") && longIp <= ipV4ToLong("192.168.255.255");
}
private static boolean isIPv4Valid(String ip) {
return PATTERN.matcher(ip).matches();
}
public static String getIpFromRequest(HttpServletRequest request) {
String ip;
boolean found = false;
if ((ip = request.getHeader("x-forwarded-for")) != null) {
StrTokenizer tokenizer = new StrTokenizer(ip, ",");
while (tokenizer.hasNext()) {
ip = tokenizer.nextToken().trim();
if (isIPv4Valid(ip) && !isIPv4Private(ip)) {
found = true;
break;
}
}
}
if (!found) {
ip = request.getRemoteAddr();
}
return ip;
}