Check field data type before casting when applying geo distance sort (elastic#130924) (elastic#131020)

If a user tries to apply geo distance sorting to a field of the wrong type, they'll get
a 500 error that causes shard failures, because the field data impl gets casted to the
expected type without first checking that the field type is the one expected.
This commit addresses that by returning a 400 error instead.

Closes elastic#129500

Author: javanna

docs/changelog/130924.yaml

@@ -0,0 +1,6 @@
+pr: 130924
+summary: Check field data type before casting when applying geo distance sort
+area: Search
+type: bug
+issues:
+ - 129500

server/src/main/java/org/elasticsearch/search/sort/GeoDistanceSortBuilder.java

@@ -624,7 +624,13 @@ private IndexGeoPointFieldData fieldData(SearchExecutionContext context) {
                 throw new IllegalArgumentException("failed to find mapper for [" + fieldName + "] for geo distance based sort");
             }
         }
-        return context.getForField(fieldType, MappedFieldType.FielddataOperation.SEARCH);
+        IndexFieldData<?> indexFieldData = context.getForField(fieldType, MappedFieldType.FielddataOperation.SEARCH);
+        if (indexFieldData instanceof IndexGeoPointFieldData) {
+            return (IndexGeoPointFieldData) indexFieldData;
+        }
+        throw new IllegalArgumentException(
+            "unable to apply geo distance sort to field [" + fieldName + "] of type [" + fieldType.typeName() + "]"
+        );
     }
 
     private Nested nested(SearchExecutionContext context) throws IOException {

server/src/test/java/org/elasticsearch/search/sort/GeoDistanceSortBuilderTests.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.index.mapper.GeoPointFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.NestedPathFieldMapper;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
 import org.elasticsearch.index.query.GeoValidationMethod;
 import org.elasticsearch.index.query.MatchAllQueryBuilder;
 import org.elasticsearch.index.query.MatchNoneQueryBuilder;
@@ -99,6 +100,9 @@ public static GeoDistanceSortBuilder randomGeoDistanceSortBuilder() {
 
     @Override
     protected MappedFieldType provideMappedFieldType(String name) {
+        if (name.equals("double")) {
+            return new NumberFieldMapper.NumberFieldType(name, NumberFieldMapper.NumberType.DOUBLE);
+        }
         return new GeoPointFieldMapper.GeoPointFieldType(name);
     }
 
@@ -531,6 +535,12 @@ public void testBuildInvalidPoints() throws IOException {
             );
             assertEquals("illegal longitude value [-360.0] for [GeoDistanceSort] for field [fieldName].", ex.getMessage());
         }
+        {
+            GeoDistanceSortBuilder sortBuilder = new GeoDistanceSortBuilder("double", 0.0, 180.0);
+            sortBuilder.validation(GeoValidationMethod.STRICT);
+            IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> sortBuilder.build(searchExecutionContext));
+            assertEquals("unable to apply geo distance sort to field [double] of type [double]", ex.getMessage());
+        }
     }
 
     /**