编码

MySQL内部编码安全性

参考

• https://www.anquanke.com/post/id/84967

使用MySQL命令行执行以下命令（MySQL5.7.32）

mysql> select 'a'='À';
+----------+
| 'a'='À'  |
+----------+
|        1 |
+----------+

可以看出MySQL认为字符À于a等价。类似的我们有以下字符：

编写脚本获取所有字母的等价字符：

<?php

function search_chars($key){
    // $key = 'U+'.$key;
    $regex_rul = '/<p class="uid">U\+([0-9A-F]{4})<\/p>/';
    // $search_url = 'https://www.compart.com/en/unicode/'.$key;
    $search_url = 'https://www.compart.com/en/unicode/search?q='.$key;
    $contents = file_get_contents($search_url);
    preg_match_all($regex_rul, $contents, $results);
    $regx_res = $results[1];
    return $regx_res;
}

function deunicode($unicode_string){
    return json_decode('"\u'.$unicode_string.'"');
}

function exec_query($sql){
    global $mysqli_con;
    $result = $mysqli_con->query($sql);
    $rows = $result->fetch_all(MYSQLI_ASSOC);
    return $rows[0]['res'];
}

function verify_key($key, $respect_array){
    foreach($respect_array as $_key => $value){
        $compare_string = deunicode($value);
        $sql = "select '$key'='$compare_string' as res";
        if(exec_query($sql)){
            echo "$key = $compare_string\n";
        };
    }
}

$mysqli_con = new Mysqli('127.0.0.1', 'root', 'xxxxx&');

$keys = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
for($i=0; $i<strlen($keys); $i++){
    $key = $keys[$i];
    $respect_array = search_chars($key);
    verify_key($key, $respect_array);
    // break;
}

$mysqli_con->close();

字母Q及q和0-9、()*&^等都不存在等价字符。

mb_strtolower()与mb_strtoupper()

详情见函数滥用