Fix value method on ip scripts (#61230)

Fixes `doc['ip'].value` when `ip` is a script field. It didn't work
properly before because it wasn't whitelisted. We can't whitelist it
easilly because it was over in a module rather than core. This fixes
that by sharing more code with core that *is* whitelisted.

Author: nik9000

server/src/main/java/org/elasticsearch/index/fielddata/ScriptDocValues.java

@@ -481,25 +481,30 @@ protected void resize(int newSize) {
         public int size() {
             return count;
         }
-
     }
 
-    public static final class Strings extends BinaryScriptDocValues<String> {
-
+    public static class Strings extends BinaryScriptDocValues<String> {
         public Strings(SortedBinaryDocValues in) {
             super(in);
         }
 
         @Override
-        public String get(int index) {
+        public final String get(int index) {
             if (count == 0) {
                 throw new IllegalStateException("A document doesn't have a value for a field! " +
                     "Use doc[<field>].size()==0 to check if a document is missing a field!");
             }
-            return values[index].get().utf8ToString();
+            return bytesToString(values[index].get());
+        }
+
+        /**
+         * Convert the stored bytes to a String.
+         */
+        protected String bytesToString(BytesRef bytes) {
+            return bytes.utf8ToString();
         }
 
-        public String getValue() {
+        public final String getValue() {
             return get(0);
         }
     }

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/fielddata/ScriptIpFieldData.java

@@ -8,6 +8,7 @@
 
 import org.apache.lucene.document.InetAddressPoint;
 import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.network.InetAddresses;
@@ -22,7 +23,6 @@
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 import org.elasticsearch.xpack.runtimefields.IpScriptFieldScript;
 
-import java.io.IOException;
 import java.net.InetAddress;
 
 public class ScriptIpFieldData extends ScriptBinaryFieldData {
@@ -54,7 +54,7 @@ public ScriptBinaryLeafFieldData loadDirect(LeafReaderContext context) throws Ex
         return new ScriptBinaryLeafFieldData() {
             @Override
             public ScriptDocValues<String> getScriptValues() {
-                return new IpScriptDocValues(script);
+                return new IpScriptDocValues(getBytesValues());
             }
 
             @Override
@@ -70,46 +70,19 @@ public ValuesSourceType getValuesSourceType() {
     }
 
     /**
-     * We can't share {@link IpFieldMapper.IpFieldType.IpScriptDocValues} because it
-     * is based on global ordinals and we don't have those.
+     * Doc values implementation for ips. We can't share
+     * {@link IpFieldMapper.IpFieldType.IpScriptDocValues} because it is based
+     * on global ordinals and we don't have those.
      */
-    public static class IpScriptDocValues extends ScriptDocValues<String> {
-        private final IpScriptFieldScript script;
-
-        public IpScriptDocValues(IpScriptFieldScript script) {
-            this.script = script;
+    public static class IpScriptDocValues extends ScriptDocValues.Strings {
+        public IpScriptDocValues(SortedBinaryDocValues in) {
+            super(in);
         }
 
         @Override
-        public void setNextDocId(int docId) throws IOException {
-            script.runForDoc(docId);
-        }
-
-        public String getValue() {
-            if (size() == 0) {
-                return null;
-            }
-            return get(0);
-        }
-
-        @Override
-        public String get(int index) {
-            if (index >= size()) {
-                if (size() == 0) {
-                    throw new IllegalStateException(
-                        "A document doesn't have a value for a field! "
-                            + "Use doc[<field>].size()==0 to check if a document is missing a field!"
-                    );
-                }
-                throw new ArrayIndexOutOfBoundsException("There are only [" + size() + "] values.");
-            }
-            InetAddress addr = InetAddressPoint.decode(BytesReference.toBytes(new BytesArray(script.values()[index])));
+        protected String bytesToString(BytesRef bytes) {
+            InetAddress addr = InetAddressPoint.decode(BytesReference.toBytes(new BytesArray(bytes)));
             return InetAddresses.toAddrString(addr);
         }
-
-        @Override
-        public int size() {
-            return script.count();
-        }
     }
 }

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/50_ip.yml

@@ -111,6 +111,24 @@ setup:
   - match: {aggregations.ip.buckets.1.key: 26.1.0.0}
   - match: {aggregations.ip.buckets.1.doc_count: 1}
 
+---
+"use in scripts":
+  - do:
+      search:
+        index: http_logs
+        body:
+          aggs:
+            ip:
+              terms:
+                script:
+                  String v = doc['ip'].value;
+                  return v.substring(0, v.indexOf('.'));
+  - match: {hits.total.value: 6}
+  - match: {aggregations.ip.buckets.0.key: '247'}
+  - match: {aggregations.ip.buckets.0.doc_count: 2}
+  - match: {aggregations.ip.buckets.1.key: '232'}
+  - match: {aggregations.ip.buckets.1.doc_count: 1}
+
 ---
 "term query":
   - do: