authz: support empty principals and fix rbac authenticated matcher (#4883)

* authz: support empty principals in SDK and fixes to rbac authenticated
matcher.

* Minor formatting

* Remove pointer from principals fields

* resolving comments

Author: ashithasantosh

authz/rbac_translator.go

@@ -155,14 +155,20 @@ func parsePrincipalNames(principalNames []string) []*v3rbacpb.Principal {
 }
 
 func parsePeer(source peer) (*v3rbacpb.Principal, error) {
-	if len(source.Principals) > 0 {
-		return principalOr(parsePrincipalNames(source.Principals)), nil
+	if source.Principals == nil {
+		return &v3rbacpb.Principal{
+			Identifier: &v3rbacpb.Principal_Any{
+				Any: true,
+			},
+		}, nil
 	}
-	return &v3rbacpb.Principal{
-		Identifier: &v3rbacpb.Principal_Any{
-			Any: true,
-		},
-	}, nil
+	if len(source.Principals) == 0 {
+		return &v3rbacpb.Principal{
+			Identifier: &v3rbacpb.Principal_Authenticated_{
+				Authenticated: &v3rbacpb.Principal_Authenticated{},
+			}}, nil
+	}
+	return principalOr(parsePrincipalNames(source.Principals)), nil
 }
 
 func parsePaths(paths []string) []*v3rbacpb.Permission {

authz/rbac_translator_test.go

@@ -205,6 +205,32 @@ func TestTranslatePolicy(t *testing.T) {
 				},
 			},
 		},
+		"empty principal field": {
+			authzPolicy: `{
+				"name": "authz",
+				"allow_rules": [{
+					"name": "allow_authenticated",
+					"source": {"principals":[]}
+				}]
+			}`,
+			wantPolicies: []*v3rbacpb.RBAC{
+				{
+					Action: v3rbacpb.RBAC_ALLOW,
+					Policies: map[string]*v3rbacpb.Policy{
+						"authz_allow_authenticated": {
+							Principals: []*v3rbacpb.Principal{
+								{Identifier: &v3rbacpb.Principal_Authenticated_{
+									Authenticated: &v3rbacpb.Principal_Authenticated{},
+								}},
+							},
+							Permissions: []*v3rbacpb.Permission{
+								{Rule: &v3rbacpb.Permission_Any{Any: true}},
+							},
+						},
+					},
+				},
+			},
+		},
 		"unknown field": {
 			authzPolicy: `{"random": 123}`,
 			wantErr:     "failed to unmarshal policy",