ghx88

使用安全json parser防止json注入


有些程序员如果没有很好的在javascript中解析json数据,往往会直接eval把json转成js对象,这时候如果json的数据中包含了被注入的恶意数据,则可能导致代码注入的问题。

正确的做法是分割出json里包含的特殊字符,然后再解析为对象

http://json.org/json2.js 中是通过正则来完成的。

// We split the second stage into 4 regexp operations in order to work around
// crippling inefficiencies in IE's and Safari's regexp engines. First we
// replace the JSON backslash pairs with '@' (a non-JSON character). Second, we
// replace all simple value tokens with ']' characters. Third, we delete all
// open brackets that follow a colon or comma or that begin the text. Finally,
// we look to see that the remaining characters are only whitespace or ']' or
// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.


if (/^[\],:{}\s]*$/.
test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {

// In the third stage we use the eval function to compile the text into a
// JavaScript structure. The '{' operator is subject to a syntactic ambiguity
// in JavaScript: it can begin a block or an object literal. We wrap the text
// in parens to eliminate the ambiguity.

j = eval('(' + text + ')');
目前不少写的好的框架和js解析函数都取用了这种做法。

所以,以后千万别直接eval了。

posted on 2009-05-19 14:17  ghx88  阅读(632)  评论(1编辑  收藏  举报

导航