Add validation against schema for JSON

Author: mcfvs

nodeutil/json_rdr.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"strings"
 
+	"github.com/freeconf/yang/fc"
 	"github.com/freeconf/yang/node"
 	"github.com/freeconf/yang/val"
 
@@ -44,6 +45,105 @@ func (self *JSONRdr) Node() (node.Node, error) {
 	return JsonContainerReader(self.values), nil
 }
 
+// This function inspects the JSON payload against YANG schema,
+// looking for missing or unexpected keys.
+func (self *JSONRdr) Validate(selection *node.Selection) error {
+	n, err := self.Node()
+	if err != nil {
+		return err
+	}
+
+	err = validate(self.values, selection.Split(n))
+	if err != nil {
+		return fmt.Errorf("%w: %s", fc.BadRequestError, err)
+	}
+
+	return nil
+}
+
+func validate(value interface{}, selection *node.Selection) error {
+	m := selection.Meta()
+	if meta.IsContainer(m) {
+		containerValue, ok := value.(map[string]interface{})
+		if !ok {
+			return fmt.Errorf("expected a container, got: %+v", value)
+		}
+		return validateContainer(containerValue, selection)
+	} else if meta.IsList(m) {
+		listValue, ok := value.([]interface{})
+		if !ok {
+			return fmt.Errorf("expected a list, got: %+v", value)
+		}
+		return validateList(listValue, selection)
+	} else {
+		// TODO: no validation for leaves, choices, and the rest
+	}
+
+	return nil
+}
+
+func validateList(elements []interface{}, selection *node.Selection) error {
+	elementSelection, err := selection.First()
+
+	for i := range elements {
+		for err != nil {
+			return fmt.Errorf("error selecting list element %d: %s", i, err)
+		}
+		path := elementSelection.Selection.Path.String()
+
+		element, ok := elements[i].(map[string]interface{})
+		if !ok {
+			return fmt.Errorf("expected a map for path %s, got %+v", path, elements[i])
+		}
+		if err := validateChildNodes(element, elementSelection.Selection); err != nil {
+			return err
+		}
+		elementSelection, err = elementSelection.Next()
+	}
+
+	return nil
+}
+
+func validateChildNodes(values map[string]interface{}, selection *node.Selection) error {
+	m := selection.Meta()
+	path := selection.Path.String()
+	metaChildren := map[string]struct{}{}
+	hd := m.(meta.HasDataDefinitions)
+
+	for _, child := range hd.DataDefinitions() {
+		id := child.Ident()
+		metaChildren[id] = struct{}{}
+		details := child.(meta.HasDetails)
+
+		value, ok := values[id]
+		if !ok {
+			if details.Mandatory() {
+				return fmt.Errorf("missing mandatory node: %s/%s", path, id)
+			}
+		} else {
+			newSelection, err := selection.Find(id)
+			if err != nil {
+				return fmt.Errorf("error finding: %s/%s: %s", path, id, err)
+			}
+			if err := validate(value, newSelection); err != nil {
+				return err
+			}
+		}
+	}
+
+	for k := range values {
+		if _, ok := metaChildren[k]; !ok {
+			return fmt.Errorf("unexpected node: %s/%s", path, k)
+		}
+	}
+
+	return nil
+}
+
+func validateContainer(values map[string]interface{}, selection *node.Selection) error {
+	return validateChildNodes(values, selection)
+}
+
 func (self *JSONRdr) decode() (map[string]interface{}, error) {
 	if self.values == nil {
 		d := json.NewDecoder(self.In)

nodeutil/json_rdr_test.go

@@ -1,6 +1,7 @@
 package nodeutil
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/freeconf/yang/fc"
@@ -277,3 +278,140 @@ func TestReadQualifiedJsonIdentRef(t *testing.T) {
 	fc.AssertEqual(t, "derived-type", actual["type"].(val.IdentRef).Label)
 	fc.AssertEqual(t, "local-type", actual["type2"].(val.IdentRef).Label)
 }
+
+func TestValidateHappyCase(t *testing.T) {
+	mstring := `
+	module x {
+		revision 0;
+		container c {
+			leaf l1 {
+				type int32;
+				mandatory true;
+			}
+			leaf l2 {
+				type int32;
+			}
+		}
+		list l {
+			leaf l1 {
+				type int32;
+				mandatory true;
+			}
+			leaf l2 {
+				type int32;
+			}
+		}
+	}`
+	payload := `
+	{
+		"c": {
+			"l1": 1
+		},
+		"l": [
+			{"l1": 1, "l2": 2},
+			{"l1": 1}
+		]
+	}`
+	module, err := parser.LoadModuleFromString(nil, mstring)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Log(payload)
+
+	n, err := ReadJSON(payload)
+	fc.AssertEqual(t, nil, err)
+	selection := node.NewBrowser(module, n).Root()
+
+	reader := JSONRdr{In: strings.NewReader(payload)}
+	if err := reader.Validate(selection); err != nil {
+		t.Errorf("validation should pass, but got error: %s", err)
+	}
+}
+
+func TestValidateForInvalidPayloads(t *testing.T) {
+	tests := []struct{
+		mstring     string
+		payload     string
+		msg         string
+		expectedErr string
+	}{
+		{
+			mstring: `
+			module x {
+				revision 0;
+				leaf l {
+					type int32;
+					mandatory true;
+				}
+			}`,
+			payload: `{}`,
+			msg: "should fail when mandatory container child is missing",
+			expectedErr: "missing mandatory node: x/l",
+		},
+		{
+			mstring: `
+			module x {
+				revision 0;
+				container c {
+					leaf l1 {
+						type string;
+					}
+				}
+			}`,
+			payload: `{"c": {"l1": 1, "extra": 3}}`,
+			msg: "should fail on unexpected container child",
+			expectedErr: "unexpected node: x/c/extra",
+		},
+		{
+			mstring: `
+			module x {
+				revision 0;
+				list l {
+					leaf l1 {
+						type string;
+						mandatory true;
+					}
+				}
+			}`,
+			payload: `{"l": [{}]}`,
+			msg: "should fail when mandatory list child is missing",
+			expectedErr: "missing mandatory node: x/l/l1",
+		},
+		{
+			mstring: `
+			module x {
+				revision 0;
+				list l {
+					leaf l1 {
+						type string;
+						mandatory true;
+					}
+				}
+			}`,
+			payload: `{"l": [{"l1": "foo", "extra": 1}]}`,
+			msg: "should fail on unexpected list child",
+			expectedErr: "unexpected node: x/l/extra",
+		},
+	}
+
+	for _, test := range tests {
+		module, err := parser.LoadModuleFromString(nil, test.mstring)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		t.Log(test.payload)
+
+		n, err := ReadJSON(test.payload)
+		fc.AssertEqual(t, nil, err)
+		selection := node.NewBrowser(module, n).Root()
+
+		reader := JSONRdr{In: strings.NewReader(test.payload)}
+		if err := reader.Validate(selection); err != nil {
+			fc.AssertEqual(t, strings.Contains(err.Error(), test.expectedErr), true, "unexpected error")
+		} else {
+			t.Errorf(test.msg)
+		}
+	}
+}