yii框架 微信開發多域名中轉服務

/**
 * openid中轉服務，爲了使公衆帳號支持多個多個二級域名
 * 中轉服務只負責和微信服務器通信，獲取用戶基本信息和openid，並將openid保存到session中
 * 調用過程:
 * 1.A.com 跳轉到 openid.B.com
 * 2.openid.B.com將referer存儲到session，跳轉到微信服務器獲取授權碼
 * 3.微信服務器帶授權碼返回到openid.B.com 
 * 4.openid.B.com拿到openid, access_token寫入到session，並從session中獲取referrer，跳轉回 A.com
 */
class IndexController extends Controller{

    public function actionIndex(){
        $fromUrl = Yii::$app->request->get('from_url');
        $wx = WxapiModel::getWx();
        $res = $wx->getOpenIdUserInfo();
        $res = json_decode($res, true);
        Yii::$app->session->set('openid', $res['openid']);
        Yii::$app->session->set('access_token_userinfo', $res['access_token']);
        if(!$fromUrl){
            return 'no referer';
        }
        return $this->redirect($fromUrl);
    }
    public function actionGetWxInfo(){
        $fromUrl = Yii::$app->request->get('from_url');
        $wx = WxapiModel::getWx();
        $res = $wx->getOpenIdUserInfo();
        $res = json_decode($res, true);
        Yii::$app->session->set('openid', $res['openid']);
        Yii::$app->session->set('access_token_userinfo', $res['access_token']);
        return json_encode([
            'oid' => $res['openid'],
            'access_token' => $res['access_token']
        ]);
        if(!$fromUrl){
            return 'no referer';
        }
        return $this->redirect($fromUrl);
    }
}