我们写程序,难免会有问题(是经常会遇到问题 ),而PHP遇到错误时,就会给出出错脚本的位置、行数和原因。有很多人说,这并没有什么大不了。确实,在调试程序阶段,这确实是没啥的,而且我认为给出错误路径是必要的。
但泄露了实际路径的后果是不堪设想的,对于某些入侵者,这个信息可是非常重要,而事实上现在有很多的服务器都存在这个问题。有些网管干脆把PHP配置文件中的display_errors设置为Off来解决(貌似我们就是这样做的),但本人认为这个方法过于消极。
有些时候,我们的确需要PHP返回错误的信息以便调试。而且在出错时也可能需要给用户一个交待,甚至导航到另一页面。
那么,有啥解决办法呢?
set_error_handler()
PHP从4.1.0开始提供了自定义错误处理句柄的功能函数set_error_handler(),但很少数脚本编写者知道。set_error_handler这个函数可以很好地防止错误路径泄露,当然还有其它更多的作用。
set_error_handler的使用方法如下:
<span>string</span> set_error_handler ( callback error_handler [, <span>int</span> error_types])
现在我们就用自定义的错误处理把实际路径过滤掉。假设有一个变量$admin,我们是用来判断访问者是否是管理员的(可以通过IP或者登录的用户id来做这个判断)
<span>//</span><span>admin为管理员的身份判定,true为管理员。 </span><span>//</span><span>自定义的错误处理函数一定要有这4个输入变量$errno,$errstr,$errfile,$errline,否则无效。</span> <span> function my_error_handler($errno,$errstr,$errfile,$errline) { </span><span>//</span><span>如果不是管理员就过滤实际路径 </span> <span>if</span>(!<span>admin) { $errfile</span>=str_replace(getcwd(),<span>""</span><span>,$errfile); $errstr</span>=str_replace(getcwd(),<span>""</span><span>,$errstr); } </span><span>switch</span><span>($errno) { </span><span>case</span><span> E_ERROR: echo </span><span>"</span><span>ERROR: [ID $errno] $errstr (Line: $errline of $errfile) \n</span><span>"</span><span>; echo </span><span>"</span><span>程序已经停止运行,请联系管理员。</span><span>"</span><span>; </span><span>//</span><span>遇到Error级错误时退出脚本 </span> <span>break</span><span>; </span><span>case</span><span> E_WARNING: echo </span><span>"</span><span>WARNING: [ID $errno] $errstr (Line: $errline of $errfile) \n</span><span>"</span><span>; </span><span>break</span><span>; </span><span>default</span><span>: </span><span>//</span><span>不显示Notice级的错误 </span> <span>break</span><span>; } } </span>
这样就自定义了一个错误处理函数,那么怎么把错误的处理交给这个自定义函数呢?
<span>//</span><span> 应用到类 </span> set_error_handler(array(&$<span>this</span>,<span>"</span><span>appError</span><span>"</span><span>)); </span><span>//</span><span>示例的做法 </span> set_error_handler(<span>"</span><span>my_error_handler</span><span>"</span>);
so easy,这样,就可以很好地解决安全和调试方便的矛盾了。而且你还可以花点心思,使错误提示更加美观以配合网站的风格。
原作者给出了两点需要注意的地方,我也放出来吧,希望引起广大同胞们的注意:
<span>//</span><span>先定义一个函数,也可以定义在其他的文件中,再用require()调用 </span> <span>function myErrorHandler($errno, $errstr, $errfile, $errline) { </span><span>//</span><span>为了安全起见,不暴露出真实物理路径,下面两行过滤实际路径 </span> $errfile=str_replace(getcwd(),<span>""</span><span>,$errfile); $errstr</span>=str_replace(getcwd(),<span>""</span><span>,$errstr); </span><span>switch</span><span> ($errno) { </span><span>case</span><span> E_USER_ERROR: echo </span><span>"</span><span><b>My ERROR</b> [$errno] $errstr<br />\n</span><span>"</span><span>; echo </span><span>"</span><span> Fatal error on line $errline in file $errfile</span><span>"</span><span>; echo </span><span>"</span><span>, PHP </span><span>"</span> . PHP_VERSION . <span>"</span><span> (</span><span>"</span> . PHP_OS . <span>"</span><span>)<br />\n</span><span>"</span><span>; echo </span><span>"</span><span>Aborting...<br />\n</span><span>"</span><span>; exit(</span><span>1</span><span>); </span><span>break</span><span>; </span><span>case</span><span> E_USER_WARNING: echo </span><span>"</span><span><b>My WARNING</b> [$errno] $errstr<br />\n</span><span>"</span><span>; </span><span>break</span><span>; </span><span>case</span><span> E_USER_NOTICE: echo </span><span>"</span><span><b>My NOTICE</b> [$errno] $errstr<br />\n</span><span>"</span><span>; </span><span>break</span><span>; </span><span>default</span><span>: echo </span><span>"</span><span>Unknown error type: [$errno] $errstr<br />\n</span><span>"</span><span>; </span><span>break</span><span>; } </span><span>/*</span><span> Don't execute PHP internal error handler </span><span>*/</span> <span>return</span> <span>true</span><span>; } </span><span>//</span><span>下面开始连接MYSQL服务器,我们故意指定MYSQL端口为3333,实际为3306。 </span> $link_id=@mysql_pconnect(<span>"</span><span>localhost:3333</span><span>"</span>,<span>"</span><span>root</span><span>"</span>,<span>"</span><span>password</span><span>"</span><span>); set_error_handler(myErrorHandler); </span><span>if</span> (!<span>$link_id) { trigger_error(</span><span>"</span><span>出错了</span><span>"</span><span>, E_USER_ERROR); } </span>
好了,总结一下,下面是 set_error_handler 三种用法:
<span>class</span><span> CallbackClass { function CallbackFunction() { </span><span>//</span><span> refers to $this </span> <span> } function StaticFunction() { </span><span>//</span><span> doesn't refer to $this </span> <span> } } function NonClassFunction($errno, $errstr, $errfile, $errline) { } </span><span>//</span><span> 三种方法如下: </span> <span>1</span>: set_error_handler(<span>'</span><span>NonClassFunction</span><span>'</span>); <span>//</span><span> 直接转到一个普通的函数 NonClassFunction </span> <span>2</span>: set_error_handler(array(<span>'</span><span>CallbackClass</span><span>'</span>, <span>'</span><span>StaticFunction</span><span>'</span>)); <span>//</span><span> 转到 CallbackClass 类下的静方法 StaticFunction </span> <span>3</span>: $o =& <span>new</span><span> CallbackClass(); set_error_handler(array($o, </span><span>'</span><span>CallbackFunction</span><span>'</span>)); <span>//</span><span> 转到类的构造函数,其实本质上跟下面的第四条一样。 </span> <span>4</span>. $o = <span>new</span><span> CallbackClass(); </span><span>//</span><span> The following may also prove useful: </span> <span>class</span><span> CallbackClass { function CallbackClass() { set_error_handler(array(</span>&$<span>this</span>, <span>'</span><span>CallbackFunction</span><span>'</span>)); <span>//</span><span> the & is important </span> <span> } function CallbackFunction() { </span><span>//</span><span> refers to $this </span> <span> } } </span>