[ML] Check influencer names are valid (elastic/x-pack-elasticsearch#2073)

Original commit: elastic/x-pack-elasticsearch@75869cacb3

plugin/src/main/java/org/elasticsearch/xpack/ml/job/config/AnalysisConfig.java

@@ -36,7 +36,6 @@ import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
 import java.util.stream.Collectors;
 
-
 /**
  * Autodetect analysis configuration options describes which fields are
  * analysed and the functions to use.
@@ -558,6 +557,7 @@ public class AnalysisConfig implements ToXContentObject, Writeable {
             }
 
             verifyNoInconsistentNestedFieldNames();
+            verifyInfluencerNames();
 
             return new AnalysisConfig(bucketSpan, categorizationFieldName, categorizationFilters,
                     latency, summaryCountFieldName, detectors, influencers, overlappingBuckets,
@@ -675,6 +675,17 @@ public class AnalysisConfig implements ToXContentObject, Writeable {
             }
         }
 
+        private void verifyInfluencerNames() {
+            for (String influencer : influencers) {
+                if (influencer == null || influencer.isEmpty()) {
+                    throw ExceptionsHelper.badRequestException(
+                            Messages.getMessage(Messages.JOB_CONFIG_INFLUENCER_CANNOT_BE_EMPTY));
+                }
+
+                Detector.Builder.verifyFieldName(influencer);
+            }
+        }
+
         private static void checkDetectorsHavePartitionFields(List<Detector> detectors) {
             for (Detector detector : detectors) {
                 if (!Strings.isNullOrEmpty(detector.getPartitionFieldName())) {

plugin/src/main/java/org/elasticsearch/xpack/ml/job/messages/Messages.java

@@ -101,10 +101,11 @@ public final class Messages {
     public static final String JOB_CONFIG_FUNCTION_REQUIRES_OVERFIELD = "over_field_name must be set when the ''{0}'' function is used";
     public static final String JOB_CONFIG_ID_ALREADY_TAKEN = "The job cannot be created with the Id ''{0}''. The Id is already used.";
     public static final String JOB_CONFIG_ID_TOO_LONG = "The job id cannot contain more than {0,number,integer} characters.";
+    public static final String JOB_CONFIG_INFLUENCER_CANNOT_BE_EMPTY = "Influencer names cannot be empty strings";
     public static final String JOB_CONFIG_INVALID_CREATE_SETTINGS =
             "The job is configured with fields [{0}] that are illegal to set at job creation";
     public static final String JOB_CONFIG_INVALID_FIELDNAME_CHARS =
-            "Invalid field name ''{0}''. Field names including over, by and partition fields cannot contain any of these characters: {1}";
+            "Invalid field name ''{0}''. Field names cannot contain any of these characters: {1}";
     public static final String JOB_CONFIG_INVALID_FIELDNAME =
             "Invalid field name ''{0}''. Field names including over, by and partition fields cannot be ''{1}''";
     public static final String JOB_CONFIG_INVALID_TIMEFORMAT = "Invalid Time format string ''{0}''";

plugin/src/test/java/org/elasticsearch/xpack/ml/job/config/AnalysisConfigTests.java

@@ -790,6 +790,20 @@ public class AnalysisConfigTests extends AbstractSerializingTestCase<AnalysisCon
         assertEquals(Messages.getMessage(Messages.JOB_CONFIG_PER_PARTITION_NORMALIZATION_CANNOT_USE_INFLUENCERS), e.getMessage());
     }
 
+    public void testVerifyInfluencerNames() {
+        AnalysisConfig.Builder config = createValidConfig();
+        Detector.Builder builder = new Detector.Builder(config.build().getDetectors().get(0));
+        config.build().getDetectors().set(0, builder.build());
+
+        config.setInfluencers(Arrays.asList("inf1", ""));
+        ElasticsearchException e = ESTestCase.expectThrows(ElasticsearchException.class, config::build);
+        assertEquals("Influencer names cannot be empty strings", e.getMessage());
+
+        config.setInfluencers(Arrays.asList("invalid\\backslash"));
+        e = ESTestCase.expectThrows(ElasticsearchException.class, config::build);
+        assertEquals("Invalid field name 'invalid\\backslash'. Field names cannot contain any of these characters: \",\\", e.getMessage());
+    }
+
     public void testVerify_GivenCategorizationFiltersContainInvalidRegex() {
         AnalysisConfig.Builder config = createValidCategorizationConfig();
         config.setCategorizationFilters(Arrays.asList("foo", "("));