如何绕过PHP eval代码中的管道符号（按位OR运算符）

Question

Is there an equivalent in PHP for the bitwise OR operator (pipe symbol | )? I am using wordpress insert php plugin to allow php code in my content entries on posts and pages, and the way the plugin works is to take the code and run an eval statement on it, but eval function hiccups on certain symbols like bitwise OR or double-pipe OR or dollar sign $. I came across the problem while trying to call json_encode with some flags connected by bitwise OR and of course the eval'ed code barfed when run. My solution is to put the code into a function (like json_encode_eval() ) and define the function in functions.php with the call to json_encode ie return json_encode($str, FLAG | ANOTHER_FLAG); , but is there a better solution? Thanks in advance.

Answer 1

Check if wordpress is encoding the | to an html escaped code. (Look for any of

| | | | |

)

If so, you'll have to unescape it before evalling.

[I'm pretty sure there's always a better way than evalling user submitted text - you may have a huge security hole there.]

I tried this and it gives the expected answer:

<?php
eval("\$a = 2|1;");
$b = 2|1;

var_dump($a);
var_dump($b);

Outputs:

int(3)
int(3)