lua: Bind after_message_stored and before_mail_accepted (#322)

Signed-off-by: James Hillyerd <james@hillyerd.com>

Signed-off-by: James Hillyerd <james@hillyerd.com>

pkg/extension/luahost/bind_policy.go

@@ -0,0 +1,17 @@
+package luahost
+
+import (
+	lua "github.com/yuin/gopher-lua"
+)
+
+const policyName = "policy"
+
+func registerPolicyType(ls *lua.LState) {
+	mt := ls.NewTypeMetatable(policyName)
+	ls.SetGlobal(policyName, mt)
+
+	// Static attributes.
+	ls.SetField(mt, "allow", lua.LTrue)
+	ls.SetField(mt, "deny", lua.LFalse)
+	ls.SetField(mt, "defer", lua.LNil)
+}