PHP表单一天只能提交一次验证

表单：

<form action="" method="post" class="form"> 
    <div><input type="text" name="user" value="" class="name" placeholder="您的称呼"/></div> 
    <div><input type="number" name="area" value="" class="mianji" placeholder="房屋面积" maxlength="5"/><span>m²</span></div> 
    <div><input type="tel" name="tel" value="" class="phone" placeholder="留下您的手机，获得预算价格" maxlength="11"/></div> 
    <p  id="tijiaos"><img src="__PUBLIC__/Home/images/ysimg/hqbj.gif"  class="imgs"/></p> 
    <input type="button" value="提交" onclick="save()" /> 
</form>

ajax提交：

var URL={ 
    'url':"{:U(hd/ysbj)}" 
    }; 
function save(){ 
    var name=$('.name').val(), mianji=$('.mianji').val(), phone=$('.phone').val(); 
    var myreg = /^[1][3,4,5,7,8][0-9]{9}$/; 
    if(!name){  
        layer.msg("请输入您的姓名");  
        return 
    } 
    if(!mianji){  
        layer.msg("请输入您的房屋面积");  
        return 
    } 
    if(!phone){  
        layer.msg("请输入您的手机号码");  
        return 
    }else if(!myreg.test(phone)){  
        layer.msg('请输入有效的手机号码');  
        return 
    }  
    var data = $('.form').serialize();  
    $.ajax({ 
        type:'POST', 
        url:URL.url, 
        data:data, 
        dataType: 'json', 
        contentType: 'application/x-www-form-urlencoded; 
        charset=utf-8',
        success:function(data,status){ 
            console.log(status); 
            console.log(data); 
            if(data){ 
                layer.msg(data); 
            } 
         },error:function(msg){ 
             layer.msg(msg); 
         }  
    })}

方法：

public function  ysbj(){     
    $obj = M('Ysbj'); 
    if(IS_POST){     
        $addtime = date('Y-m-d H:i:s', time());     
        $data['user'] = I('post.user','','htmlspecialchars');             
        $data['area']=I('post.area');             
        $data['tel'] = I('post.tel');             
        $data['ip']=get_client_ip(); 
        $data['addr']=getOs(); 
        $data['url'] = $_SERVER["HTTP_REFERER"]; 
        $data['addtime'] = $addtime;  
        $res = $obj->where("tel=".$data['tel'])->field('addtime')->select(); 
        for ($i=0; $i <count($res) ; $i++) {  
                $time =$res[$i]['addtime']; 
                $b = substr($time,0,10);                 
                $t = date('Y-m-d');                 
                if($b==$t){                 
                    $this->ajaxReturn("您今日已经提交过了");                 
                } 
        } 
        $mail=new \Org\Util\Ysbj; 
            if($mail->sendmail($_POST['user'],$_POST['area'],$_POST['tel'],$data['ip'],$data['addr'],$data['url'],$data['addtime'])){ 
                if ($obj->add($data)) { 
                    $this->ajaxReturn("报价成功,我们将稍后与您联系"); } 
                else { 
                    $this->ajaxReturn("系统异常,联系在线客服"); 
                }  
             }     
         }     
         $this->display();     
         }