Simple input checking for event generation (#14)

TODO

@@ -1,6 +1,7 @@
-* Write tests
 * Use interfaces
 * Improve overall code construct
 * Work with default values or force mandatory fields
 * Implement extension fields
+* Implement interface for struct and write use reflect to verify
+  mandatory fields being set
 * ..

cefevent/cefevent.go

@@ -1,6 +1,7 @@
 package cefevent
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 )
@@ -16,6 +17,15 @@ type CefEvent struct {
 	Extensions         map[string]string
 }
 
+func isSet(field ...string) bool {
+	for _, f := range field {
+		if f == "" {
+			return false
+		}
+	}
+	return true
+}
+
 // todo: don't dupe the function but handle
 // with methods part of an Extension struct
 func cefEscapeField(field string) string {
@@ -41,16 +51,30 @@ func cefEscapeExtension(field string) string {
 	return replacer.Replace(field)
 }
 
-func (event *CefEvent) Generate() string {
+func (event *CefEvent) Generate() (string, error) {
+
+	if (isSet)(
+		event.Version,
+		event.DeviceVendor,
+		event.DeviceProduct,
+		event.DeviceVersion,
+		event.DeviceEventClassId,
+		event.Name,
+		event.Severity) {
+
+		event.Version = cefEscapeField(event.Version)
+		event.DeviceVendor = cefEscapeField(event.DeviceVendor)
+		event.DeviceProduct = cefEscapeField(event.DeviceProduct)
+		event.DeviceVersion = cefEscapeField(event.DeviceVersion)
+		event.DeviceEventClassId = cefEscapeField(event.DeviceEventClassId)
+		event.Name = cefEscapeField(event.Name)
+		event.Severity = cefEscapeField(event.Severity)
 
-	// todo: do this nicely with methods
-	event.Version = cefEscapeField(event.Version)
-	event.DeviceVendor = cefEscapeField(event.DeviceVendor)
-	event.DeviceProduct = cefEscapeField(event.DeviceProduct)
-	event.DeviceVersion = cefEscapeField(event.DeviceVersion)
-	event.DeviceEventClassId = cefEscapeField(event.DeviceEventClassId)
-	event.Name = cefEscapeField(event.Name)
-	event.Severity = cefEscapeField(event.Severity)
+	} else {
+
+		return "", errors.New("Not all mandatory CEF fields are set.")
+
+	}
 
 	var p strings.Builder
 
@@ -67,10 +91,13 @@ func (event *CefEvent) Generate() string {
 	// fields according to the CEF standard.
 	extensionString := strings.TrimSpace(p.String())
 
-	return fmt.Sprintf(
+	eventCef := fmt.Sprintf(
 		"CEF:%v|%v|%v|%v|%v|%v|%v|%v",
 		event.Version, event.DeviceVendor,
 		event.DeviceProduct, event.DeviceVersion,
 		event.DeviceEventClassId, event.Name,
-		event.Severity, extensionString)
+		event.Severity, extensionString,
+	)
+
+	return eventCef, nil
 }

cefevent_test.go

@@ -22,7 +22,7 @@ func TestCefEventExpected(t *testing.T) {
 	}
 
 	want := "CEF:0|Cool Vendor|Cool Product|1.0|COOL_THING|Something cool happened.|Unknown|sourceAddress=127.0.0.1"
-	got := event.Generate()
+	got, _ := event.Generate()
 
 	if want != got {
 		t.Errorf("event.Generate() = %q, want %q", got, want)
@@ -47,10 +47,31 @@ func TestCefEventEscape(t *testing.T) {
 	}
 
 	want := "CEF:0|\\\\Cool\\nVendor\\||Cool Product|1.0|COOL_THING|Something cool happened.|Unknown|sourceAddress\\\\=\\n127.0.0.1\\="
-	got := event.Generate()
+	got, _ := event.Generate()
 
 	if want != got {
 		t.Errorf("event.Generate() = %q, want %q", got, want)
 	}
 
 }
+
+func TestCefEventMandatoryFields(t *testing.T) {
+
+	event := cefevent.CefEvent{
+		Version:            "0",
+		DeviceVendor:       "Cool Vendor",
+		DeviceProduct:      "Cool Product",
+		DeviceVersion:      "1.0",
+		DeviceEventClassId: "COOL_THING",
+		Name:               "Something cool happened.",
+		Severity:           "Unknown",
+	}
+
+	noVersion := event
+	noVersion.Version = ""
+	_, err := noVersion.Generate()
+
+	if err == nil {
+		t.Errorf("%v", err)
+	}
+}

go.mod

@@ -1,3 +1,5 @@
 module cefevent
 
 go 1.12
+
+require github.com/pkg/errors v0.9.1