2 files changed, 35 insertions, 2 deletions
diff --git a/api/vppapi_errors.go b/api/vppapi_errors.go
index c921e14..18ab87f 100644
--- a/api/vppapi_errors.go
+++ b/api/vppapi_errors.go
@@ -5,16 +5,26 @@ import (
 	"strconv"
 )
 
+// RetvalToVPPApiError returns error for retval value.
+// Retval 0 returns nil error.
+func RetvalToVPPApiError(retval int32) error {
+	if retval == 0 {
+		return nil
+	}
+	return VPPApiError(retval)
+}
+
 // VPPApiError represents VPP's vnet API error that is usually
 // returned as Retval field in replies from VPP binary API.
 type VPPApiError int32
 
 func (e VPPApiError) Error() string {
+	errid := int64(e)
 	var errstr string
 	if s, ok := vppApiErrors[e]; ok {
-		errstr = s
+		errstr = fmt.Sprintf("%s (%d)", s, errid)
 	} else {
-		errstr = strconv.Itoa(int(e))
+		errstr = strconv.FormatInt(errid, 10)
 	}
 	return fmt.Sprintf("VPPApiError: %s", errstr)
 }
diff --git a/api/vppapi_errors_test.go b/api/vppapi_errors_test.go
new file mode 100644
index 0000000..78e1fbf
--- /dev/null
+++ b/api/vppapi_errors_test.go
@@ -0,0 +1,23 @@
+package api
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+func TestUnspecified(t *testing.T) {
+	RegisterTestingT(t)
+
+	var err error = VPPApiError(-1)
+	errstr := err.Error()
+	Expect(errstr).Should(BeEquivalentTo("VPPApiError: Unspecified Error (-1)"))
+}
+
+func TestUnknown(t *testing.T) {
+	RegisterTestingT(t)
+
+	var err error = VPPApiError(-999)
+	errstr := err.Error()
+	Expect(errstr).Should(BeEquivalentTo("VPPApiError: -999"))
+}