percolator: Fix NPE in percolator's 'now' range check for percolator queries with range queries.

Closes #22355

modules/percolator/src/main/java/org/elasticsearch/percolator/PercolatorFieldMapper.java

@@ -377,12 +377,18 @@ public class PercolatorFieldMapper extends FieldMapper {
             RangeQueryBuilder rangeQueryBuilder = (RangeQueryBuilder) queryBuilder;
             if (rangeQueryBuilder.from() instanceof String) {
                 String from = (String) rangeQueryBuilder.from();
-                String to = (String) rangeQueryBuilder.to();
-                if (from.contains("now") || to.contains("now")) {
+                if (from.contains("now")) {
                     throw new IllegalArgumentException("percolator queries containing time range queries based on the " +
                             "current time is unsupported");
                 }
             }
+            if (rangeQueryBuilder.to() instanceof String) {
+                String to = (String) rangeQueryBuilder.to();
+                if (to.contains("now")) {
+                    throw new IllegalArgumentException("percolator queries containing time range queries based on the " +
+                        "current time is unsupported");
+                }
+            }
         } else if (queryBuilder instanceof HasChildQueryBuilder) {
             throw new IllegalArgumentException("the [has_child] query is unsupported inside a percolator query");
         } else if (queryBuilder instanceof HasParentQueryBuilder) {

modules/percolator/src/test/java/org/elasticsearch/percolator/PercolatorFieldMapperTests.java

@@ -442,6 +442,53 @@ public class PercolatorFieldMapperTests extends ESSingleNodeTestCase {
                 }
         );
         assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
+        e = expectThrows(MapperParsingException.class, () -> {
+                mapperService.documentMapper(typeName).parse("test", typeName, "1",
+                    jsonBuilder().startObject()
+                        .field(fieldName, rangeQuery("date_field").from("now"))
+                        .endObject().bytes());
+            }
+        );
+        assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
+        e = expectThrows(MapperParsingException.class, () -> {
+                mapperService.documentMapper(typeName).parse("test", typeName, "1",
+                    jsonBuilder().startObject()
+                        .field(fieldName, rangeQuery("date_field").to("now"))
+                        .endObject().bytes());
+            }
+        );
+        assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
+    }
+
+    // https://github.com/elastic/elasticsearch/issues/22355
+    public void testVerifyRangeQueryWithNullBounds() throws Exception {
+        addQueryMapping();
+        MapperParsingException e = expectThrows(MapperParsingException.class, () -> {
+                mapperService.documentMapper(typeName).parse("test", typeName, "1",
+                    jsonBuilder().startObject()
+                        .field(fieldName, rangeQuery("date_field").from("now").to(null))
+                        .endObject().bytes());
+            }
+        );
+        assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
+        e = expectThrows(MapperParsingException.class, () -> {
+                mapperService.documentMapper(typeName).parse("test", typeName, "1",
+                    jsonBuilder().startObject()
+                        .field(fieldName, rangeQuery("date_field").from(null).to("now"))
+                        .endObject().bytes());
+            }
+        );
+        assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
+
+        // No validation failures:
+        mapperService.documentMapper(typeName).parse("test", typeName, "1",
+            jsonBuilder().startObject()
+                .field(fieldName, rangeQuery("date_field").from("2016-01-01").to(null))
+                .endObject().bytes());
+        mapperService.documentMapper(typeName).parse("test", typeName, "1",
+            jsonBuilder().startObject()
+                .field(fieldName, rangeQuery("date_field").from(null).to("2016-01-01"))
+                .endObject().bytes());
     }
 
     public void testUnsupportedQueries() {