Add util method to get root domain

components/identity-core/org.wso2.carbon.identity.core/src/main/java/org/wso2/carbon/identity/core/util/IdentityUtil.java

@@ -561,6 +561,29 @@ public static boolean isSubdomain(String domainName, String subdomainName) {
  return subdomainName.endsWith("." + domainName);
  }
 
+ /**
+ * Get the root domain of the given domain.
+ * Note: this assumes that the root domain only consists of two parts (eg: wso2.io). The method will not work for
+ * TLDs with more than two parts (eg: wso2.co.uk).
+ *
+ * @param domain Domain.
+ * @return Root domain.
+ */
+ public static String getRootDomain(String domain) {
+
+ if (StringUtils.isBlank(domain)) {
+ return domain;
+ }
+ String[] domainParts = domain.split("\\.");
+ int length = domainParts.length;
+
+ if (length > 2) {
+ return domainParts[length - 2] + "." + domainParts[length - 1];
+ } else {
+ return domain;
+ }
+ }
+
  private static StringBuilder getServerUrlWithPort(String hostName) {
 
  String mgtTransport = CarbonUtils.getManagementTransport();

components/identity-core/org.wso2.carbon.identity.core/src/test/java/org/wso2/carbon/identity/core/util/IdentityUtilTest.java

@@ -838,6 +838,18 @@ public Object[][] getSubdomainData() {
  };
  }
 
+ @DataProvider(name = "rootDomainDataProvider")
+ public Object[][] getRootDomainData() {
+ return new Object[][] {
+ {"dev.api.wso2.io", "wso2.io"}, // Deeper subdomain
+ {"api.test.com", "test.com"}, // Typical subdomain
+ {"abc.com", "abc.com"}, // Root domain itself
+ {"localhost", "localhost"}, // Localhost
+ {null, null}, // Null case
+ {"", ""} // Empty string
+ };
+ }
+
  @Test(dataProvider = "getClockSkewData")
  public void testGetClockSkewInSeconds(String value, int expected) throws Exception {
  Map<String, Object> mockConfiguration = new HashMap<>();
@@ -859,10 +871,18 @@ public void testIsSupportedByUserStore() throws Exception {
 
  @Test(dataProvider = "getSubdomainData")
  public void testCheckSubdomain(String domainName, String subdomainName, boolean expectedResult) throws Exception {
+
  boolean result = IdentityUtil.isSubdomain(domainName, subdomainName);
  assertEquals(result, expectedResult, "Subdomain check failed for: " + domainName + " and " + subdomainName);
  }
 
+ @Test(dataProvider = "rootDomainDataProvider")
+ public void testGetRootDomain(String domain, String expectedRootDomain) {
+
+ String actualRootDomain = IdentityUtil.getRootDomain(domain);
+ assertEquals(actualRootDomain, expectedRootDomain, "Root domain extraction failed for: " + domain);
+ }
+
  private void setPrivateStaticField(Class<?> clazz, String fieldName, Object newValue)
  throws NoSuchFieldException, IllegalAccessException {