PHP，CURL和你的安全！
简介
如果最近你在美国看电视，你会经常看到一个广告——一个和蔼友善的家伙说“我希望我的电脑被病毒感染”，“我希望所有我家的照片都被人删除，找不回来。”或“我希望我的笔记本运转的声音听起来像打雷。”
当然，没有一个正常人希望遇到这样的痛苦，但如果你不对自己的电脑采取保护措施，结果就是让黑客得逞。你需要理解，这就像在你家里，车或钱袋子，你不能让它们都敞着口放在外面，你不能认为陌生路人都是可信的。大部分的陌生人并不像你想象的那样友好。
如果没有人告诉你应该怎么做，你很容会犯错误。置之不理是愚蠢的，幸好你读了这篇文章。我要首先假设你不是那么愚蠢的人。
立即学习“PHP免费学习笔记（深入）”；
不应该做的事情
下面是一个列表，解释了什么不该做，以及为什么。
-
<?php include('http://www.webhek.com'); ?>这是外表美味可口巧克力，里面却藏着恶魔。它的意思是“去http://www.webhek.com网站，取回页面内容，运行这些内容，不论是什么内容。”如果是像下面的这些内容到无所谓：<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>b</span><span class="token punctuation">></span></span>Hello World<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>b</span><span class="token punctuation">></span></span>
但是，如果你不那么幸运，这个网站被人动过手脚，它的内容被替换成：
Evil ruuLzzzzorz<span class="token operator">!</span><span class="token operator">!</span><span class="token operator">!</span> <span class="token operator"><</span><span class="token operator">?</span>php <span class="token function">system<span class="token punctuation">(</span></span><span class="token string">"rm -rf /*"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token delimiter">?></span>
这句代码会删除你的电脑上的所有东西。
-
<?php print readfile('http://www.webhek.com'); ?>这样会稍微安全一些，因为这句代码的做法是读取远程页面的内容，然后打印它们。即使有人在内容里插入了恶意的PHP代码，这些代码也没有机会被执行。但是，黑客仍然可以在内容里注入恶意的JavaScript，你会发现你的页面上突然间被植入了无数的弹出式广告窗口页面。这会让你的网站的浏览者非常恼怒。
这里面有很多的学问，但上面这些是最大的问题。
立即学习“PHP免费学习笔记（深入）”；
应该如何做
PHP里面有一个非常强大的函数库，它们的目的就是让你安全的从远程网站上取回内容。这些函数被称作CURL。现在，你不要被CURL官方页面上大量的东西吓阻，它实际上非常的简单。
下面是一个简单的替换上面read_file()命令的做法：
<span class="token operator"><</span><span class="token operator">?</span>php<span class="token variable">$curl_handle</span><span class="token operator">=</span><span class="token function">curl_init<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_URL</span><span class="token punctuation">,</span><span class="token string">'http://www.webhek.com'</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_exec<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_close<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token delimiter">?></span>
就是这样，这才是你应该做的，最后一句curl_close()不是必要的。
小心，你仍然有被远程网站上的恶意JavaScript和cookie盗取者袭击的风险。防范这些攻击需要牵涉到更多的内容。如果你想做这些，我建议你使用PHP正则表达式函数里的preg_replace()。
假设我们确实要用CURL来做一些事情。假设www.webhek.com这个网站不是那么稳定。它有时候会没有响应，一个页面需要30秒才能拉取成功。对于这种情况，我们的办法是：
<span class="token operator"><</span><span class="token operator">?</span>php<span class="token variable">$curl_handle</span><span class="token operator">=</span><span class="token function">curl_init<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_URL</span><span class="token punctuation">,</span><span class="token string">'http://www.webhek.com'</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_CONNECTTIMEOUT</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_exec<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_close<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token delimiter">?></span>
这种写法是说，2秒钟内如果不能抓取完数据就做超时处理。是的，也许你更愿意设定为1秒就算超时，因为它妨碍你的页面的速度。(注意，不要设置为0，这是告诉curl没有超时限制。)
但是，如果是什么东西都没有取回了，你想显示一个提示信息，这该怎么办？哈哈，简单！
<span class="token operator"><</span><span class="token operator">?</span>php<span class="token variable">$curl_handle</span><span class="token operator">=</span><span class="token function">curl_init<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_URL</span><span class="token punctuation">,</span><span class="token string">'http://www.webhek.com'</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_CONNECTTIMEOUT</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_setopt<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">,</span><span class="token constant">CURLOPT_RETURNTRANSFER</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token variable">$buffer</span> <span class="token operator">=</span> <span class="token function">curl_exec<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">curl_close<span class="token punctuation">(</span></span><span class="token variable">$curl_handle</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function">empty<span class="token punctuation">(</span></span><span class="token variable">$buffer</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token keyword">print</span> <span class="token string">"抱歉，webhek.com 这个网站又无响应了。<p>"</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span> <span class="token keyword">print</span> <span class="token variable">$buffer</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token delimiter">?></span>你有没有开始感觉到CURL的强大之处？
