Check null values in Host Address (#3526)

Add a null check for host addresses to avoid
NPE in getVersionFormattedHostAddress().

common/src/main/java/org/corfudb/common/util/URLUtils.java

@@ -63,9 +63,16 @@ public static String getVersionFormattedEndpointURL(String address) {
      *
      * @param host host address that needs formatting
      * @return version-formatted address
+     * @throws IllegalArgumentException if the parameter host is null or empty
      */
     public static String getVersionFormattedHostAddress(String host) {
 
+        // In LR-SaaS, host could be null.
+        if (host == null || host.isEmpty()) {
+            throw new IllegalArgumentException("getVersionFormattedHostAddress: " +
+                    "host is either null or empty.");
+        }
+
         // getByName(host) fails when host has scope/interface in it like ([....%eth0])
         // remove the trailing names %eth0 or %en0 if present
         String formattedHost = host.trim().split("%")[0];

common/src/test/java/org/corfudb/common/util/URLUtilsTest.java

@@ -8,6 +8,7 @@
 import java.net.InetSocketAddress;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.Mockito.when;
 
 /**
@@ -37,6 +38,7 @@ public class URLUtilsTest {
     private static final String IPV6_ENDPOINT_URL_3_SHORT_MALFORMED = "::1:9000";
     private static final String IPV6_ENDPOINT_URL_MALFORMED_1 = "0:0:0:0:0:0:0:1:9000";
     private static final String IPV6_ENDPOINT_URL_MALFORMED_2 = "0:0:0:0:0:0:0:2:9001";
+    private static final String EMPTY_STRING = "";
 
     /**
      * Utility method to get a mock ChannelHandlerContext object.
@@ -107,6 +109,14 @@ void testGetVersionFormattedHostAddress() {
         // Should return version-formatted IPv6 Address with '[' and ']'
         assertThat(URLUtils.getVersionFormattedHostAddress(IPV6_ADDRESS_2_MALFORMED))
                 .isEqualTo(IPV6_ADDRESS_2_SHORT);
+
+        // Empty Host Address should throw IllegalArgumentException
+        assertThatThrownBy(() -> URLUtils.getVersionFormattedHostAddress(EMPTY_STRING)).
+                isInstanceOf(IllegalArgumentException.class);
+
+        // null Host Address should throw IllegalArgumentException
+        assertThatThrownBy(() -> URLUtils.getVersionFormattedHostAddress(null)).
+                isInstanceOf(IllegalArgumentException.class);
     }
 
     /**