Proof of concept URIUtil.isHostName

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/URIUtil.java

@@ -29,6 +29,7 @@ import java.util.List;
 import java.util.Objects;
 import java.util.StringTokenizer;
 import java.util.function.Supplier;
+import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 import org.eclipse.jetty.util.resource.ResourceFactory;
@@ -1315,6 +1316,21 @@ public final class URIUtil
         return false;
     }
 
+    /**
+     * Test if the token is a valid hostname and not an IP-Literal.
+     *
+     * @param token the token to check
+     * @return true if token is a Host name, not an IP-Literal
+     */
+    public static boolean isHostName(String token)
+    {
+        Pattern patIPv4 = Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}");
+        if (patIPv4.matcher(token).matches())
+            return false;
+        else
+            return isValidHostRegisteredName(token);
+    }
+
     /**
      * True if token is a <a href="https://www.rfc-editor.org/rfc/rfc3986">RFC3986</a> {@code reg-name} (Registered Name)
      *

jetty-core/jetty-util/src/test/java/org/eclipse/jetty/util/URIUtilTest.java

@@ -34,6 +34,7 @@ import org.junit.jupiter.api.condition.OS;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
@@ -893,6 +894,20 @@ public class URIUtilTest
         assertEquals(path, decoded);
     }
 
+    @ParameterizedTest
+    @CsvSource(textBlock = """
+        127.0.0.1       , false
+        ::1             , false
+        [::1]           , false
+        localhost       , true
+        localhost.local , true
+        sub.example.com , true
+        """)
+    public void testIsHostName(String token, boolean expected)
+    {
+        assertEquals(expected, URIUtil.isHostName(token));
+    }
+
     @ParameterizedTest
     @ValueSource(strings = {
         "a",