1 files changed, 29 insertions, 0 deletions
diff --git a/src/main/java/com/btr/proxy/selector/whitelist/IPv4WithSubnetChecker.java b/src/main/java/com/btr/proxy/selector/whitelist/IPv4WithSubnetChecker.java
new file mode 100644
index 0000000..b8e713e
--- /dev/null
+++ b/src/main/java/com/btr/proxy/selector/whitelist/IPv4WithSubnetChecker.java
@@ -0,0 +1,29 @@
+package com.btr.proxy.selector.whitelist;
+
+import java.util.regex.Pattern;
+
+/*****************************************************************************
+ * Checks if the given string is a IP4 range subnet definition
+ * of the format 192.168.0/24
+ * Based on a contribution by Jan Engler  
+ * @author Bernd Rosstauscher (proxyvole@rosstauscher.de) Copyright 2009
+ ****************************************************************************/
+
+public class IPv4WithSubnetChecker {
+
+	private static Pattern IP_SUB_PATTERN = Pattern.compile(
+			"^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
+			+ "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
+			+ "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
+			+ "([01]?\\d\\d?|2[0-4]\\d|25[0-5])/(\\d|([12]\\d|3[0-2]))$");
+
+	/*************************************************************************
+	 * Tests if a given string is of in the correct format for an IP4 subnet mask.
+	 * @param possibleIPAddress to test for valid format.
+	 * @return true if valid else false.
+	 ************************************************************************/
+	
+	public static boolean isValid(String possibleIPAddress) {
+		return IP_SUB_PATTERN.matcher(possibleIPAddress).matches();
+	}
+}