fix: reject an empty start-after and continuation-token in ListObjects (V1)

tests/integration/ListObjects.go

@@ -195,9 +195,9 @@ func ListObjects_invalid_max_keys(s *S3Conf) error {
 	})
 }
 
-// start-after belongs to ListObjectsV2, so S3 rejects it on a V1 listing
-// instead of ignoring it. The SDK ListObjects input has no StartAfter field,
-// so the request is signed and sent by hand.
+// start-after and continuation-token belong to ListObjectsV2, so S3 rejects
+// either one on a V1 listing, with or without a value. The SDK ListObjects
+// input has neither field, so the requests are signed and sent by hand.
 func ListObjects_start_after(s *S3Conf) error {
 	testName := "ListObjects_start_after"
 	return actionHandler(s, testName, func(s3client *s3.Client, bucket string) error {
@@ -206,19 +206,36 @@ func ListObjects_start_after(s *S3Conf) error {
 			return err
 		}
 
-		req, err := createSignedReq(http.MethodGet, s.endpoint,
-			fmt.Sprintf("%v?start-after=bar", bucket),
-			s.awsID, s.awsSecret, "s3", s.awsRegion, "", nil, time.Now(), nil)
-		if err != nil {
-			return err
+		startAfterErr := s3err.GetInvalidArgumentErr(s3err.InvalidArgStartAfter, "")
+		contTokenErr := s3err.GetInvalidArgumentErr(s3err.InvalidArgContinuationToken, "")
+		for _, test := range []struct {
+			query    string
+			expected s3err.S3Error
+		}{
+			{"start-after=bar", startAfterErr},
+			{"start-after=", startAfterErr},
+			{"start-after", startAfterErr},
+			{"continuation-token=bar", contTokenErr},
+			{"continuation-token=", contTokenErr},
+		} {
+			req, err := createSignedReq(http.MethodGet, s.endpoint,
+				fmt.Sprintf("%v?%v", bucket, test.query),
+				s.awsID, s.awsSecret, "s3", s.awsRegion, "", nil, time.Now(), nil)
+			if err != nil {
+				return err
+			}
+
+			resp, err := s.httpClient.Do(req)
+			if err != nil {
+				return err
+			}
+
+			if err := checkHTTPResponseApiErr(resp, test.expected); err != nil {
+				return fmt.Errorf("%v: %w", test.query, err)
+			}
 		}
 
-		resp, err := s.httpClient.Do(req)
-		if err != nil {
-			return err
-		}
-
-		return checkHTTPResponseApiErr(resp, s3err.GetInvalidArgumentErr(s3err.InvalidArgStartAfter, ""))
+		return nil
 	})
 }