PHP 中巧用数组降低程序的时间复杂度
OpenX adserver version 2.8.1 and lower is vulnerable to remote code
execution. To be exploited, this vulnerability requires banner / file
upload permissions, such as granted to the 'advertiser' and
'administrator' roles.
This vulnerability is caused by the (insecure) file upload mechanism of
affected OpenX versions. These would check magic bytes of an uploaded
file to determine its MIME type, and erroneously assume this
information to be reliable. Additionally, while the file name of
uploaded files is changed, the file extension is not.
As such, it is possible to upload image files with embedded PHP code and
.php file extension. Unless PHP script execution is explicitly prevented
for the file upload location (which has not been documented in the OpenX
manual so far and it is not the result of a default installation), the
PHP code will execute as soon as HTTP access to the file location will
cause it to be executed by the web server.
To clarify, an attacker exploiting this security issue does require
prior access to OpenX, i.e. exploitation is only possible after
successful authentication. On the other hand, advertiser access is a
rather low permission level and should not allow for system access.
If these bugs were not hidden from OpenX' bug tracker, you could read up
more about issue X-5747 here:
https://developer.openx.org/jira/browse/OX/fixforversion/10910
OpenX 2.8.2 has already been released in October to fix this issue and
can be downloaded from Roll forming machine
http://www.openx.org/ad-server/download
Moritz Naumann
Naumann IT Security Consulting
Berlin, Germany
http://www.moritz-naumann.com/
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--------------------------------------------------------------- ......
cookie默认不能存数组，所以下面的写法是错误的。
<?php
$arr = array(1,2,3);
setcookie('a',$arr);
$arr = array(1,2,3);
setcookie('a',$arr);
?>
报错如下：
Warning: setcookie() expects parameter 2 to be string, array given in
但是PHP可以把同名且后面以[]结尾的cookie解析为数组。在 ......
服务器变量 $_SERVER 详解：
1、$_SESSION['PHP_SELF'] -- 获取当前正在执行脚本的文件名
2、$_SERVER['SERVER_PROTOCOL'] -- 请求页面时通信协议的名称和版本。例如，“HTTP/1.0”。
3、$_SERVER['REQUEST_TIME'] -- 请求开始时的时间戳。从 PHP 5.1.0 起有效。和time函数效果一样。
4、$_SERVER['argv'] - ......
解决的办法有好几个：
第一个是：str_split()，这个方法是PHP5加入的。
<?php
$str = "Hello Friend";
$arr1 = str_split($str);
$arr2 = str_split($str, 3);
print_r($arr1);
print_r($arr2);
?>
输出就是：
Array
(
[0] => H
[1] => e
[2] => l
[3] => l
......
1.如果一个方法可静态化，就对它做静态声明。速率可提升至4倍。
2.echo 比 print 快。
3.使用echo的多重参数（译注：指用逗号而不是句点）代替字符串连接。
4.在执行for循环之前确定最大循环数，不要每循环一次都计算最大值。
5.注销那些不用的变量尤其是大数组，以便释放内存。
6.尽量避免使用__get，__se ......
