From 310a9f93bfdf769b5cf6be48fd3e76b167c59e2d Mon Sep 17 00:00:00 2001
From: Dmitriy Tverdiakov <dmitriy.tverdiakov@neo4j.com>
Date: Thu, 4 Feb 2021 11:45:56 +0200
Subject: [PATCH] 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.
---
 .../driver/internal/BoltServerAddress.java    |  6 ++++-
 .../internal/cluster/RediscoveryImpl.java     |  6 ++---
 .../internal/cluster/RediscoveryTest.java     | 22 ++++++++++++++++---
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/driver/src/main/java/org/neo4j/driver/internal/BoltServerAddress.java b/driver/src/main/java/org/neo4j/driver/internal/BoltServerAddress.java
index c4620d753f..159ced30d4 100644
--- a/driver/src/main/java/org/neo4j/driver/internal/BoltServerAddress.java
+++ b/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();
diff --git a/driver/src/main/java/org/neo4j/driver/internal/cluster/RediscoveryImpl.java b/driver/src/main/java/org/neo4j/driver/internal/cluster/RediscoveryImpl.java
index 99bcef1bc3..fe15f2db6b 100644
--- a/driver/src/main/java/org/neo4j/driver/internal/cluster/RediscoveryImpl.java
+++ b/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 )
diff --git a/driver/src/test/java/org/neo4j/driver/internal/cluster/RediscoveryTest.java b/driver/src/test/java/org/neo4j/driver/internal/cluster/RediscoveryTest.java
index 21b7b98b93..01df9b3550 100644
--- a/driver/src/test/java/org/neo4j/driver/internal/cluster/RediscoveryTest.java
+++ b/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;
@@ -400,7 +402,8 @@ 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
@@ -408,14 +411,27 @@ void shouldNotLogWhenSingleRetryAttemptFails()
         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 );