Optimize `terms` queries on `ip` addresses to use a `PointInSetQuery` whenever possible. (#25669)

We can't do it in the general case because of prefix queries, but I believe this
is mostly used in query strings and not in explicit `terms` queries.

Closes #25667

core/src/main/java/org/elasticsearch/index/mapper/IpFieldMapper.java

@@ -177,6 +177,30 @@ public class IpFieldMapper extends FieldMapper {
             }
         }
 
+        @Override
+        public Query termsQuery(List<?> values, QueryShardContext context) {
+            InetAddress[] addresses = new InetAddress[values.size()];
+            int i = 0;
+            for (Object value : values) {
+                InetAddress address;
+                if (value instanceof InetAddress) {
+                    address = (InetAddress) value;
+                } else {
+                    if (value instanceof BytesRef) {
+                        value = ((BytesRef) value).utf8ToString();
+                    }
+                    if (value.toString().contains("/")) {
+                        // the `terms` query contains some prefix queries, so we cannot create a set query
+                        // and need to fall back to a disjunction of `term` queries
+                        return super.termsQuery(values, context);
+                    }
+                    address = InetAddresses.forString(value.toString());
+                }
+                addresses[i++] = address;
+            }
+            return InetAddressPoint.newSetQuery(name(), addresses);
+        }
+
         @Override
         public Query rangeQuery(Object lowerTerm, Object upperTerm, boolean includeLower, boolean includeUpper, QueryShardContext context) {
             failIfNotIndexed();

core/src/test/java/org/elasticsearch/index/mapper/IpFieldTypeTests.java

@@ -19,10 +19,14 @@
 package org.elasticsearch.index.mapper;
 
 import java.net.InetAddress;
+import java.util.Arrays;
 
 import org.apache.lucene.document.InetAddressPoint;
 import org.apache.lucene.index.IndexOptions;
+import org.apache.lucene.search.BooleanQuery;
+import org.apache.lucene.search.ConstantScoreQuery;
 import org.apache.lucene.search.MatchNoDocsQuery;
+import org.apache.lucene.search.BooleanClause.Occur;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.network.InetAddresses;
 
@@ -78,6 +82,22 @@ public class IpFieldTypeTests extends FieldTypeTestCase {
         assertEquals("Cannot search on field [field] since it is not indexed.", e.getMessage());
     }
 
+    public void testTermsQuery() {
+        MappedFieldType ft = createDefaultFieldType();
+        ft.setName("field");
+
+        assertEquals(InetAddressPoint.newSetQuery("field", InetAddresses.forString("::2"), InetAddresses.forString("::5")),
+                ft.termsQuery(Arrays.asList(InetAddresses.forString("::2"), InetAddresses.forString("::5")), null));
+        assertEquals(InetAddressPoint.newSetQuery("field", InetAddresses.forString("::2"), InetAddresses.forString("::5")),
+                ft.termsQuery(Arrays.asList("::2", "::5"), null));
+
+        // if the list includes a prefix query we fallback to a bool query
+        assertEquals(new ConstantScoreQuery(new BooleanQuery.Builder()
+                .add(ft.termQuery("::42", null), Occur.SHOULD)
+                .add(ft.termQuery("::2/16", null), Occur.SHOULD).build()),
+                ft.termsQuery(Arrays.asList("::42", "::2/16"), null));
+    }
+
     public void testRangeQuery() {
         MappedFieldType ft = createDefaultFieldType();
         ft.setName("field");