DNS change fix

This update fixes an issue when the driver fails to update the routing table if the router DNS entry returns a different IP address.

Author: injectives

driver/src/main/java/org/neo4j/driver/internal/BoltServerAddress.java

@@ -25,7 +25,6 @@
 import java.net.UnknownHostException;
 import java.util.List;
 import java.util.Objects;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import org.neo4j.driver.net.ServerAddress;
@@ -154,6 +153,11 @@ public int port()
         return port;
     }
 
+    public boolean isResolved()
+    {
+        return resolved != null;
+    }
+
     private static String hostFrom( URI uri )
     {
         String host = uri.getHost();

driver/src/main/java/org/neo4j/driver/internal/cluster/RediscoveryImpl.java

@@ -268,9 +268,9 @@ private ClusterComposition handleRoutingProcedureError( Throwable error, Routing
     public List<BoltServerAddress> resolve()
     {
         return resolver.resolve( initialRouter )
-                .stream()
-                .flatMap( resolved -> resolveAll( BoltServerAddress.from( resolved ) ) )
-                .collect( toList() ); // collect to list to preserve the order
+                       .stream()
+                       .map( BoltServerAddress::from )
+                       .collect( toList() ); // collect to list to preserve the order
     }
 
     private Stream<BoltServerAddress> resolveAll( BoltServerAddress address )

driver/src/test/java/org/neo4j/driver/internal/cluster/RediscoveryTest.java

@@ -24,6 +24,7 @@
 
 import java.io.IOException;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.neo4j.driver.Logger;
@@ -49,6 +50,7 @@
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
@@ -400,22 +402,36 @@ void shouldNotLogWhenSingleRetryAttemptFails()
         Rediscovery rediscovery = new RediscoveryImpl( A, settings, compositionProvider, eventExecutor, resolver, logger );
         RoutingTable table = routingTableMock( A );
 
-        ServiceUnavailableException e = assertThrows( ServiceUnavailableException.class, () -> await( rediscovery.lookupClusterComposition( table, pool, empty() ) ) );
+        ServiceUnavailableException e =
+                assertThrows( ServiceUnavailableException.class, () -> await( rediscovery.lookupClusterComposition( table, pool, empty() ) ) );
         assertThat( e.getMessage(), containsString( "Could not perform discovery" ) );
 
         // rediscovery should not log about retries and should not schedule any retries
         verify( logger, never() ).info( startsWith( "Unable to fetch new routing table, will try again in " ) );
         assertEquals( 0, eventExecutor.scheduleDelays().size() );
     }
 
+    @Test
+    void shouldNotResolveToIPs()
+    {
+        ServerAddressResolver resolver = resolverMock( A, A );
+        Rediscovery rediscovery = new RediscoveryImpl( A, null, null, null, resolver, null );
+
+        List<BoltServerAddress> addresses = rediscovery.resolve();
+
+        verify( resolver, times( 1 ) ).resolve( A );
+        assertEquals( 1, addresses.size() );
+        assertFalse( addresses.get( 0 ).isResolved() );
+    }
+
     private Rediscovery newRediscovery( BoltServerAddress initialRouter, ClusterCompositionProvider compositionProvider,
-            ServerAddressResolver resolver )
+                                        ServerAddressResolver resolver )
     {
         return newRediscovery( initialRouter, compositionProvider, resolver, DEV_NULL_LOGGER );
     }
 
     private Rediscovery newRediscovery( BoltServerAddress initialRouter, ClusterCompositionProvider compositionProvider,
-            ServerAddressResolver resolver, Logger logger )
+                                        ServerAddressResolver resolver, Logger logger )
     {
         RoutingSettings settings = new RoutingSettings( 1, 0, 0 );
         return new RediscoveryImpl( initialRouter, settings, compositionProvider, GlobalEventExecutor.INSTANCE, resolver, logger );