Add controls over DBus capacity regarding call parameters

Author: Léonard Dallot

internal/apis/call.go

@@ -27,6 +27,10 @@ func CallOnObject(path dbus.ObjectPath, callName string, args ...any) error {
 		return err
 	}
 
+	if err = checkDbusCompatibilityWitArgs(conn, args); err != nil {
+		return err
+	}
+
 	obj := conn.Object(ObjectName, path)
 	call := obj.Call(callName, 0, args...)
 	return call.Err
@@ -38,7 +42,13 @@ func call(callName string, args ...any) (*dbus.Call, error) {
 		return nil, err
 	}
 
+	if err = checkDbusCompatibilityWitArgs(conn, args); err != nil {
+		return nil, err
+	}
+
 	obj := conn.Object(ObjectName, ObjectPath)
+
 	call := obj.Call(callName, 0, args...)
+
 	return call, call.Err
 }

internal/apis/checks.go

@@ -0,0 +1,30 @@
+package apis
+
+import (
+	"errors"
+
+	"github.com/godbus/dbus/v5"
+)
+
+func checkDbusCompatibilityWitArgs(conn *dbus.Conn, args ...any) error {
+	// Sending file through DBus must be tested before proceeding
+	// See https://pkg.go.dev/github.com/godbus/dbus?utm_source=godoc#hdr-Unix_FD_passing
+	if anyOf[any](args, isFileDescriptor) && !conn.SupportsUnixFDs() {
+		return errors.New("DBus connection does not support passing unix file descriptors")
+	}
+	return nil
+}
+
+func isFileDescriptor(v any) bool {
+	_, ok := v.(dbus.UnixFD)
+	return ok
+}
+
+func anyOf[T any](values []T, assertion func(T) bool) bool {
+	for _, v := range values {
+		if assertion(v) {
+			return true
+		}
+	}
+	return false
+}

internal/apis/checks_test.go

@@ -0,0 +1,109 @@
+package apis
+
+import (
+	"testing"
+
+	"github.com/godbus/dbus/v5"
+)
+
+func isNegative(v int) bool {
+	return v < 0
+}
+
+func TestAnyOfIsNegativeTrue(t *testing.T) {
+	testValues := []int{5, 7, -4, 6, 8}
+	expected := true
+	result := anyOf[int](testValues, isNegative)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsNegativeFalse(t *testing.T) {
+	testValues := []int{5, 7, 4, 6, 8}
+	expected := false
+	result := anyOf[int](testValues, isNegative)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsNegativeEmpty(t *testing.T) {
+	testValues := []int{}
+	expected := false
+	result := anyOf[int](testValues, isNegative)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsNegativeFirst(t *testing.T) {
+	testValues := []int{-5, 7, 4, 6, 8}
+	expected := true
+	result := anyOf[int](testValues, isNegative)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsNegativeLast(t *testing.T) {
+	testValues := []int{5, 7, 4, 6, -8}
+	expected := true
+	result := anyOf[int](testValues, isNegative)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestIsFDTrue(t *testing.T) {
+	var tested dbus.UnixFD
+	expected := true
+	result := isFileDescriptor(tested)
+
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestIsFDInt(t *testing.T) {
+	var tested int
+	expected := false
+	result := isFileDescriptor(tested)
+
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestIsFDInterface(t *testing.T) {
+	var tested interface{}
+	expected := false
+	result := isFileDescriptor(tested)
+
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsFDTrue(t *testing.T) {
+	var fd dbus.UnixFD
+	var i interface{}
+
+	testValues := []any{5, fd, i}
+	expected := true
+	result := anyOf[any](testValues, isFileDescriptor)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}
+
+func TestAnyOfIsFDFalse(t *testing.T) {
+	var i interface{}
+
+	testValues := []any{5, -7, i}
+	expected := false
+	result := anyOf[any](testValues, isFileDescriptor)
+	if expected != result {
+		t.Errorf("Expecting %v, got %v", expected, result)
+	}
+}