message: improve docs

message.go

@@ -65,6 +65,18 @@ func Decode(data []byte, m *Message) error {
 //
 // 	Message, its fields, results of m.Get or any attribute a.GetFrom
 //	are valid only until Message.Raw is not modified.
+//
+// Usage:
+// 	var m Message
+// 	if err := m.Build(TransactionID, BindingRequest, Fingerprint); err != nil {
+// 		panic(err)
+// 	}
+// You can call Build on zero value, and m.Raw will contain on-the-wire
+// representation of Message. To decode message from byte slice, use Decode:
+// 	var m Message
+// 	if err := Decode(buf, &m); err != nil {
+// 		panic(err)
+// 	}
 type Message struct {
 	Type          MessageType
 	Length        uint32 // len(Raw) not including header
@@ -92,7 +104,7 @@ func (m *Message) NewTransactionID() error {
 	return err
 }
 
-func (m *Message) String() string {
+func (m Message) String() string {
 	tID := base64.StdEncoding.EncodeToString(m.TransactionID[:])
 	return fmt.Sprintf("%s l=%d attrs=%d id=%s", m.Type, m.Length, len(m.Attributes), tID)
 }

message_test.go

@@ -671,6 +671,20 @@ func TestMessage_Contains(t *testing.T) {
 	}
 }
 
+func TestMessage_Build(t *testing.T) {
+	var m Message
+	if err := m.Build(TransactionID, BindingRequest, Fingerprint); err != nil {
+		panic(err)
+	}
+	var p Message
+	if err := Decode(m.Raw, &p); err != nil {
+		panic(err)
+	}
+	if !m.Equal(&p) {
+		t.Fatal("Not equal")
+	}
+}
+
 func ExampleMessage() {
 	buf := new(bytes.Buffer)
 	m := new(Message)

stun.go

@@ -47,5 +47,5 @@ func (transactionIDSetter) AddTo(m *Message) error {
 	return m.NewTransactionID()
 }
 
-// TransactionID is Setter for m.TransactionID.
+// TransactionID sets message transaction id to random value.
 var TransactionID Setter = transactionIDSetter{}