短信防刷办法

短信接口在业务中是必然会有的，那么怎么保证接口被刷呢？
我简单总结一下我的想法

/**
     * 手机登录验证码
     * @author marain
     * @time  2017-06-27
     * 
     */
    public function get_code(){
        $phone  =   $_REQUEST['tel'];
        $token_key =   $_REQUEST['token_key'];
        $key='marain';
        $now=date('Y-m-d');
        $signkey=md5($key.$now.$phone.'marain'); //根据手机号和时间产生 token

        if ($token_key !== $signkey){
            $result = array();
            $result['code']     =400;
            $result['msg']      ='4001:令牌错误';
            $result['info']     = '';
            echo json_encode($result);
            exit();
        }
        if ($phone==''){
            $result = array();
            $result['code']     =400;
            $result['msg']      ='4002:电话不能为空';
            $result['info']     = '';
            echo json_encode($result);
            exit();
        }
        if (!preg_match("/^1[34578]\d{9}$/", $phone)){
            $result = array();
            $result['code']     =400;
            $result['msg']      ='4003:电话格式不正确';
            $result['info']     = '';
            echo json_encode($result);
            exit();
        }
        $ip=get_client_ip();
        $where_ip['create_ip']=$ip;//ip控制

        $sms_data = M('App_sms')->where($where_ip)->select();
        $today_date = date('Y-m-d');
        $total_onoip_count=0;
        foreach ($sms_data as $k1=>$v1){
            if(substr($v1['create_time'],0,10) == $today_date){
                $total_onoip_count++;
            }
        }
        if (count($sms_data) > 500){
           //ip 大于500报警
        }
        if ($total_onoip_count> 100){
            //单日ip 大于100报警
        }

        $where_who['tel_number']=$phone;
        $sms_data = M('App_sms')->where($where_who)->order("id desc")->select();

        //这个手机号没有注册
        if(empty($sms_data)){
            $code = $this->_create_code();
            $this->send_sms($phone, $code, $ip);
            $result = array();
            $result['code']    =200;
            $result['msg']    ='获取成功';
            $result['info']     = $code;
            echo json_encode($result);
            exit();
        }

        $total_send_count = 0;
        foreach($sms_data as $key1=>$row1){
            if(empty($key1)){
                $last_send_time = $row1['create_time'];
            }
            if(substr($row1['create_time'],0,10) == $today_date){
                $total_send_count++;
                $code = $row1['code'];
            }
        }
        if(empty($code)) $code = $this->_create_code();

        if((strtotime($last_send_time) + 60) > time()){
            $result['code']    =400;
            $result['msg']    ='4004:获取失败，请不要频繁获取';
            $result['info']     = '';
        }else{
            if($total_send_count < 30){
                $this->send_sms($phone, $code, $ip);
                $result['code']     =200;
                $result['msg']      ='获取成功';
                $result['info']     = $code;
            }else{
                $result['code']    =400;
                $result['msg']    ='4005:获取失败,每人每天只能获取三十次验证码';
                $result['info']     = '';
            }
        }
        echo json_encode($result);
        exit();
    }

    /**
     * 产生验证码
     */
    public function _create_code($length=4,$type="number"){
        $array = array(
            'number' => '01234567',
            'string' => 'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
            'mixed' => '01234567ABCDEFGHIJKLMNOPQRSTUVWXYZ',
        );
        $string = $array[$type];
        $count = strlen($string)-1;
        $rand = '';
        for ($i = 0; $i < $length; $i++) {
            $rand .= $string[mt_rand(0, $count)];
        }
        return $rand;
    }
private function send_sms($mobile, $code, $ip){
        if(empty($mobile) || empty($code) || empty($ip)) return false;
        $content = '您的注册验证码是'.$code;
          $url='发送短信接口'
        //$send_result = file_get_contents($url);
        $data = array();
        $data['tel_number'] = $mobile;
        $data['content'] = $content;
        $data['code'] = $code;
        $data['create_time'] = date('Y-m-d H:i:s');
        $data['create_ip'] = get_client_ip();
        $data['send_result'] = $send_result;
        $insertid = M('App_sms')->add($data);
        if($insertid) return true;
        return false;
    }