Implemented MAC1/2 calculation

src/constants.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"time"
+)
+
+const (
+	RekeyAfterMessage  = (1 << 64) - (1 << 16) - 1
+	RekeyAfterTime     = time.Second * 120
+	RekeyAttemptTime   = time.Second * 90
+	RekeyTimeout       = time.Second * 5
+	RejectAfterTime    = time.Second * 180
+	RejectAfterMessage = (1 << 64) - (1 << 4) - 1
+	KeepaliveTimeout   = time.Second * 10
+	CookieRefreshTime  = time.Second * 2
+)