[FAB-8877] Validate Reserved Fields Name in CouchDB

Ledger removed the "data" wrapper when using CouchDB as the
state database.  This change means that documents in the state
database must meet CouchDB's restrictions for top level field
names.

The validation for simulation and commit needs to be updated
for the following invalid field names:

- Any field beginning with an underscore, "_"
- ~version
- ~metadata

Change-Id: I9203691553de8c15888ce93ade99337bad5222a9
Signed-off-by: Chris Elder <chris.elder@us.ibm.com>

Author: Chris Elder

core/ledger/kvledger/txmgmt/statedb/statecouchdb/couchdoc_conv.go

@@ -23,10 +23,9 @@ const (
 	revField      = "_rev"
 	versionField  = "~version"
 	deletedField  = "_deleted"
+	metadataField = "~metadata"
 )
 
-var reservedFields = [4]string{idField, revField, versionField, deletedField}
-
 type keyValue struct {
 	key string
 	*statedb.VersionedValue
@@ -47,9 +46,9 @@ func castToJSON(b []byte) (jsonValue, error) {
 }
 
 func (v jsonValue) checkReservedFieldsNotPresent() error {
-	for _, fieldName := range reservedFields {
-		if _, fieldFound := v[fieldName]; fieldFound {
-			return fmt.Errorf("The field %s is present", fieldName)
+	for fieldName := range v {
+		if fieldName == versionField || fieldName == metadataField || strings.HasPrefix(fieldName, "_") {
+			return fmt.Errorf("The field [%s] is not valid for the CouchDB state database", fieldName)
 		}
 	}
 	return nil

core/ledger/kvledger/txmgmt/statedb/statecouchdb/statecouchdb_test.go

@@ -198,13 +198,26 @@ func TestUtilityFunctions(t *testing.T) {
 	err = db.ValidateKeyValue(string([]byte{0xff, 0xfe, 0xfd}), []byte("Some random bytes"))
 	testutil.AssertError(t, err, "ValidateKey should have thrown an error for an invalid utf-8 string")
 
+	reservedFields := []string{"~version", "~metadata", "_id", "_test"}
+
 	// ValidateKey should return an error for a json value that already contains one of the reserved fields
+	// at the top level
 	for _, reservedField := range reservedFields {
 		testVal := fmt.Sprintf(`{"%s":"dummyVal"}`, reservedField)
 		err = db.ValidateKeyValue("testKey", []byte(testVal))
 		testutil.AssertError(t, err, fmt.Sprintf(
 			"ValidateKey should have thrown an error for a json value %s, as contains one of the rserved fields", testVal))
 	}
+
+	// ValidateKey should not return an error for a json value that already contains one of the reserved fields
+	// if not at the top level
+	for _, reservedField := range reservedFields {
+		testVal := fmt.Sprintf(`{"data.%s":"dummyVal"}`, reservedField)
+		err = db.ValidateKeyValue("testKey", []byte(testVal))
+		testutil.AssertNoError(t, err, fmt.Sprintf(
+			"ValidateKey should not have thrown an error the json value %s since the reserved field was not at the top level", testVal))
+	}
+
 }
 
 // TestInvalidJSONFields tests for invalid JSON fields