Work on UAPI

Cross-platform API (get operation)
Handshake initiation creation process
Outbound packet flow
Fixes from code-review

src/helper_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"bytes"
+	"testing"
+)
+
+/* Helpers for writing unit tests
+ */
+
+type DummyTUN struct {
+	name    string
+	mtu     uint
+	packets chan []byte
+}
+
+func (tun *DummyTUN) Name() string {
+	return tun.name
+}
+
+func (tun *DummyTUN) MTU() uint {
+	return tun.mtu
+}
+
+func (tun *DummyTUN) Write(d []byte) (int, error) {
+	tun.packets <- d
+	return len(d), nil
+}
+
+func (tun *DummyTUN) Read(d []byte) (int, error) {
+	t := <-tun.packets
+	copy(d, t)
+	return len(t), nil
+}
+
+func CreateDummyTUN(name string) (TUNDevice, error) {
+	var dummy DummyTUN
+	dummy.mtu = 1024
+	dummy.packets = make(chan []byte, 100)
+	return &dummy, nil
+}
+
+func assertNil(t *testing.T, err error) {
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func assertEqual(t *testing.T, a []byte, b []byte) {
+	if bytes.Compare(a, b) != 0 {
+		t.Fatal(a, "!=", b)
+	}
+}
+
+func randDevice(t *testing.T) *Device {
+	sk, err := newPrivateKey()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tun, _ := CreateDummyTUN("dummy")
+	device := NewDevice(tun)
+	device.SetPrivateKey(sk)
+	return device
+}