[ML-DataFrame] validate group name to not contain invalid characters (elastic#42292)

disallows of creating groupBy field with '[', ']', '>' in the name to be consistent with aggregations

Author: Hendrik Muhs

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/dataframe/transforms/pivot/GroupConfig.java

@@ -20,6 +20,7 @@
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
+import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.elasticsearch.xpack.core.dataframe.DataFrameField;
 import org.elasticsearch.xpack.core.dataframe.DataFrameMessages;
 import org.elasticsearch.xpack.core.dataframe.utils.ExceptionsHelper;
@@ -29,6 +30,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
+import java.util.regex.Matcher;
 
 import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpectedToken;
 
@@ -135,6 +137,7 @@ public static GroupConfig fromXContent(final XContentParser parser, boolean leni
 
     private static Map<String, SingleGroupSource> parseGroupConfig(final XContentParser parser,
             boolean lenient) throws IOException {
+        Matcher validAggMatcher = AggregatorFactories.VALID_AGG_NAME.matcher("");
         LinkedHashMap<String, SingleGroupSource> groups = new LinkedHashMap<>();
 
         // be parsing friendly, whether the token needs to be advanced or not (similar to what ObjectParser does)
@@ -150,6 +153,11 @@ private static Map<String, SingleGroupSource> parseGroupConfig(final XContentPar
 
             ensureExpectedToken(XContentParser.Token.FIELD_NAME, token, parser::getTokenLocation);
             String destinationFieldName = parser.currentName();
+            if (validAggMatcher.reset(destinationFieldName).matches() == false) {
+                throw new ParsingException(parser.getTokenLocation(), "Invalid group name [" + destinationFieldName
+                        + "]. Group names can contain any character except '[', ']', and '>'");
+            }
+
             token = parser.nextToken();
             ensureExpectedToken(XContentParser.Token.START_OBJECT, token, parser::getTokenLocation);
             token = parser.nextToken();

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/dataframe/transforms/pivot/GroupConfigTests.java

@@ -6,6 +6,7 @@
 
 package org.elasticsearch.xpack.core.dataframe.transforms.pivot;
 
+import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.Writeable.Reader;
 import org.elasticsearch.common.xcontent.ToXContent;
@@ -27,6 +28,9 @@
 
 public class GroupConfigTests extends AbstractSerializingTestCase<GroupConfig> {
 
+    // array of illegal characters, see {@link AggregatorFactories#VALID_AGG_NAME}
+    private static final char[] ILLEGAL_FIELD_NAME_CHARACTERS = {'[', ']', '>'};
+
     public static GroupConfig randomGroupConfig() {
         Map<String, Object> source = new LinkedHashMap<>();
         Map<String, SingleGroupSource> groups = new LinkedHashMap<>();
@@ -88,6 +92,34 @@ public void testEmptyGroupBy() throws IOException {
         }
     }
 
+    public void testInvalidGroupByNames() throws IOException {
+
+        String invalidName = randomAlphaOfLengthBetween(0, 5)
+                + ILLEGAL_FIELD_NAME_CHARACTERS[randomIntBetween(0, ILLEGAL_FIELD_NAME_CHARACTERS.length - 1)]
+                + randomAlphaOfLengthBetween(0, 5);
+
+        XContentBuilder source = JsonXContent.contentBuilder()
+                .startObject()
+                    .startObject(invalidName)
+                        .startObject("terms")
+                            .field("field", "user")
+                        .endObject()
+                    .endObject()
+                .endObject();
+
+        // lenient, passes but reports invalid
+        try (XContentParser parser = createParser(source)) {
+            GroupConfig groupConfig = GroupConfig.fromXContent(parser, true);
+            assertFalse(groupConfig.isValid());
+        }
+
+        // strict throws
+        try (XContentParser parser = createParser(source)) {
+            Exception e = expectThrows(ParsingException.class, () -> GroupConfig.fromXContent(parser, false));
+            assertTrue(e.getMessage().startsWith("Invalid group name"));
+        }
+    }
+
     private static Map<String, Object> getSource(SingleGroupSource groupSource) {
         try (XContentBuilder xContentBuilder = XContentFactory.jsonBuilder()) {
             XContentBuilder content = groupSource.toXContent(xContentBuilder, ToXContent.EMPTY_PARAMS);