至于在这个线程的主要问题,其他职位讲明为什么准备语句时,我们不能绑定值的列名,所以这里是一个解决方案:
class myPdo{
private $user = 'dbuser';
private $pass = 'dbpass';
private $host = 'dbhost';
private $db = 'dbname';
private $pdo;
private $dbInfo;
public function __construct($type){
$this->pdo = new PDO('mysql:host='.$this->host.';dbname='.$this->db.';charset=utf8',$this->user,$this->pass);
if(isset($type)){
//when class is called upon, it stores column names and column types from the table of you choice in $this->dbInfo;
$stmt = "select distinct column_name,column_type from information_schema.columns where table_name='sometable';";
$stmt = $this->pdo->prepare($stmt);//not really necessary since this stmt doesn't contain any dynamic values;
$stmt->execute();
$this->dbInfo = $stmt->fetchAll(PDO::FETCH_ASSOC);
}
}
public function pdo_param($col){
$param_type = PDO::PARAM_STR;
foreach($this->dbInfo as $k => $arr){
if($arr['column_name'] == $col){
if(strstr($arr['column_type'],'int')){
$param_type = PDO::PARAM_INT;
break;
}
}
}//for testing purposes i only used INT and VARCHAR column types. Adjust to your needs...
return $param_type;
}
public function columnIsAllowed($col){
$colisAllowed = false;
foreach($this->dbInfo as $k => $arr){
if($arr['column_name'] === $col){
$colisAllowed = true;
break;
}
}
return $colisAllowed;
}
public function q($data){
//$data is received by post as a JSON object and looks like this
//{"data":{"column_a":"value","column_b":"value","column_c":"value"},"get":"column_x"}
$data = json_decode($data,TRUE);
$continue = true;
foreach($data['data'] as $column_name => $value){
if(!$this->columnIsAllowed($column_name)){
$continue = false;
//means that someone possibly messed with the post and tried to get data from a column that does not exist in the current table, or the column name is a sql injection string and so on...
break;
}
}
//since $data['get'] is also a column, check if its allowed as well
if(isset($data['get']) && !$this->columnIsAllowed($data['get'])){
$continue = false;
}
if(!$continue){
exit('possible injection attempt');
}
//continue with the rest of the func, as you normally would
$stmt = "SELECT DISTINCT ".$data['get']." from sometable WHERE ";
foreach($data['data'] as $k => $v){
$stmt .= $k.' LIKE :'.$k.'_val AND ';
}
$stmt = substr($stmt,0,-5)." order by ".$data['get'];
//$stmt should look like this
//SELECT DISTINCT column_x from sometable WHERE column_a LIKE :column_a_val AND column_b LIKE :column_b_val AND column_c LIKE :column_c_val order by column_x
$stmt = $this->pdo->prepare($stmt);
//obviously now i have to bindValue()
foreach($data['data'] as $k => $v){
$stmt->bindValue(':'.$k.'_val','%'.$v.'%',$this->pdo_param($k));
//setting PDO::PARAM... type based on column_type from $this->dbInfo
}
$stmt->execute();
return $stmt->fetchAll(PDO::FETCH_ASSOC);//or whatever
}
}
$pdo = new myPdo('anything');//anything so that isset() evaluates to TRUE.
var_dump($pdo->q($some_json_object_as_described_above));
以上仅仅是一个例子,不用说,复制 - >粘贴不起作用。根据您的需求调整。 现在这可能不会提供100%的安全性,但它允许对列名称进行一些控制,当它们作为动态字符串“进入”时可以在用户端更改。此外,由于它们是从information_schema中提取的,因此不需要使用表列名称和类型构建一些数组。
来源
2014-09-09 15:36:05
man
+1用于白名单选项而不是使用任何种类的动态方法。另一种替代方法可能是将可接受的表名映射到一个数组,其中键对应于潜在的用户输入(例如`array('u'=>'users','t'=>'table','n'=>'nonsensitive_data ')`等等) – Kzqai 2011-12-22 18:05:20
读过这个,对我来说,这里的例子为坏的输入生成无效的SQL,因为它没有`default`。如果使用这种模式,你应该将你的`case`s标记为`default`,或者添加一个明确的错误情况,比如`default:throw new InvalidArgumentException;` – IMSoP 2015-10-22 09:34:59
我在想一个简单的`if(in_array($ tbl ,''users','products',...]){$ sql =“SELECT * FROM $ tbl”;}`。Thanks for the idea。 – philtune 2016-03-02 17:20:06