将准备好的语句包装在函数中 [英] Wrapping a prepared statement in a function

问题描述

我一直在阅读有关SQL注入的文章，并决定修改我的代码以防止SQL注入.

I've been reading articles about SQL Injection, and decided to modify my code to prevent SQL injection.

例如，我有一个输入，将该值插入到数据库中.最初，我的预防注射措施是:

For example, I have an input which I insert the value to my database. Initially, my guard against injection was this:

function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    // $data = addslashes($data);
    $data = mysql_real_escape_string($data);
    return $data;
}

$artist = $_POST["artist"];     // can be anything
$artist = test_input($artist);  // escaped chars are &, quotes, <, >, \n, \r, etc.

if ($mysqli->query("SELECT * FROM `my_table` WHERE `artist` = '$artist'")->num_rows == 0) {
    $mysqli->query("INSERT INTO my_table (artist) VALUES ('$artist')");
    echo "New artist is added.";
} else {
    echo "Artist already exists.";
}

在我读过的文章中，有人建议应该使用准备好的语句.我已经更改了代码并使用了它:

In the articles I've read, it was suggested that one should use prepared statements. I've changed my code and used that:

$artist = $_POST["artist"]; // can be anything

$query = $mysqli->prepare("SELECT * FROM my_table WHERE artist = ?");
$query->bind_param("s", $artist);
$query->execute();
$result = $query->get_result();
$query->close();

if ($result->num_rows == 0) {
    echo "Artist doesn't exist in the DB." . PHP_EOL;
    $query = $mysqli->prepare("INSERT INTO my_table (artist) VALUES (?)");
    $query->bind_param("s", $artist);
    $query->execute();
    if ($query->affected_rows > 0) {
        echo "Artist is added to the DB." . PHP_EOL;
    }
    $query->close();
} else {
    echo "Artist already exists in the DB." . PHP_EOL;
}

虽然这可以防止SQL注入，但是它对XSS并没有任何作用.因此，我决定修改test_input(已删除$data = mysql_real_escape_string($data);)并使用它来防止脚本注入.

While this prevents SQL injection, it doesn't do anything about XSS. So I decided to modify test_input (removed $data = mysql_real_escape_string($data);) and use it to prevent script injection.

function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}

$artist = $_POST["artist"]; // can be anything
$artist = test_input($artist);

现在，我的问题是关于使用准备好的语句.我将插入三个项目；艺术家，专辑和歌曲.一遍又一遍地重复相同的过程(准备，绑定，执行，关闭)对我来说似乎是多余的.我想创建一个函数，并用它包装准备好的语句过程.像这样:

Now, my problem is about using prepared statements. I'll be inserting three items; artist, album, and song. Repeating the same process (prepare, bind, execute, close) over and over again seems redundent to me. I want to create a function and wrap the prepared statement process with it. Something like this:

function p_statement($mysqli, $query_string = "", $type = "", $vars = []) {
    $query = $mysqli->prepare($query_string);
    $query->bind_param($type, $vars);
    $query->execute();
    $result = null;
    preg_match("/^[A-Z]+/", $query_string, $command);
    switch ($command[0]) {
        case "SELECT":
            $result = $query->get_result();
            break;
        case "INSERT":
            $result = $query->affected_rows;
            break;
    }
    $query->close();
    return $result;
}

但是，这带来了一个问题:$vars数组.由于将传递给mysqli_stmt::bind_param()的变量数量是可变的/动态的，因此我在主函数p_statement中使用了一个数组.我不知道如何将数组中的项目传递给mysqli_stmt::bind_param(). bind_param期望(type, var1, var2, varn,)，并且我有一个数组.

Though, this presents a problem: $vars array. Since the number of variables that'll be passed to mysqli_stmt::bind_param() will be variable/dynamic, I've used an array in the main function p_statement. I don't know how I should the pass the items in the array to the mysqli_stmt::bind_param(). bind_param expects (type, var1, var2, varn,), and I've got an array.

我该如何进行这项工作?

How can I make this work?

推荐答案

您正在寻找 implode()

查看联机帮助页，它显示了有关使用call_user_func_array的信息.然后，我编辑了您的一些代码段.

Looking at to manpage and it shows a light about using call_user_func_array. And I edit some of your snippet.

function p_statement($mysqli, $query_string = "", $type = "", $vars = []) {

    $query = $mysqli->prepare($query_string);

    //assign $type to first index of $vars
    array_unshift($vars, $type);

    //Turn all values into reference since call_user_func_array
    //expects arguments of bind_param to be references
    //@see mysqli::bind_param() manpage
    foreach ($vars as $key => $value) {
        $vars[$key] =& $vars[$key];
    }

    call_user_func_array(array($query, 'bind_param'), $vars);
    $query->execute();

    //INSERT, SELECT, UPDATE and DELETE have each 6 chars, you can
    //validate it using substr() below for better and faster performance
    if (strtolower(substr($query_string, 0, 6)) == "select") {
        $result = $query->get_result();
    } else {
        $result = $query->affected_rows;
    }

    $query->close();
    return $result;
}

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