bug6038: interims commit, starting to work on reverse hostname lookup

java/com.sap.sse.landscape.aws/src/com/sap/sse/landscape/aws/AwsLandscape.java

@@ -757,6 +757,17 @@ public interface AwsLandscape<ShardingKey> extends Landscape<ShardingKey> {
 
     CompletableFuture<Iterable<ResourceRecordSet>> getResourceRecordSetsAsync(String hostname);
 
+    /**
+     * For an IP address looks for Route53 resource records that hold an A- or AAAA-record pointing
+     * to that {@code ipAddress} and returns the record set name as the hostname. This searches
+     * the whole of all resource record sets in the AWS account.<p>
+     * 
+     * Example: asking for "172.31.13.233" may return something like "mongo0.internal.sapsailing.com"
+     * 
+     * @return the fully-qualified resource record set name if found, otherwise {@code null}
+     */
+    String findHostnamesForIP(String ipAddress);
+    
     Iterable<ResourceRecordSet> getResourceRecordSets(String hostname);
     
     DNSCache getNewDNSCache();

java/com.sap.sse.landscape.aws/src/com/sap/sse/landscape/aws/impl/AwsLandscapeImpl.java

@@ -181,6 +181,7 @@ import software.amazon.awssdk.services.route53.model.ChangeInfo;
 import software.amazon.awssdk.services.route53.model.ChangeResourceRecordSetsRequest;
 import software.amazon.awssdk.services.route53.model.ChangeResourceRecordSetsResponse;
 import software.amazon.awssdk.services.route53.model.GetChangeRequest;
+import software.amazon.awssdk.services.route53.model.HostedZone;
 import software.amazon.awssdk.services.route53.model.ListResourceRecordSetsResponse;
 import software.amazon.awssdk.services.route53.model.RRType;
 import software.amazon.awssdk.services.route53.model.ResourceRecord;
@@ -1753,6 +1754,21 @@ public class AwsLandscapeImpl<ShardingKey> implements AwsLandscape<ShardingKey>
             Util.filter(response.resourceRecordSets(), resourceRecordSet->AwsLandscape.removeTrailingDotFromHostname(resourceRecordSet.name()).equals(hostname)));
     }
     
+    @Override
+    public String findHostnamesForIP(String ipAddress) {
+        final Route53Client route53Client = getRoute53Client();
+        for (final HostedZone hostedZone : route53Client.listHostedZones().hostedZones()) {
+            for (final ResourceRecordSet resourceRecordSet : route53Client.listResourceRecordSets(b->b.hostedZoneId(hostedZone.id())).resourceRecordSets()) {
+                for (final ResourceRecord resourceRecord : resourceRecordSet.resourceRecords()) {
+                    if (Util.equalsWithNull(resourceRecord.value(), ipAddress)) {
+                        return resourceRecordSet.name();
+                    }
+                }
+            }
+        }
+        return null;
+    }
+    
     @Override
     public Iterable<ResourceRecordSet> getResourceRecordSets(String hostname) {
         final Route53Client route53Client = getRoute53Client();