为 HTML 输入自定义验证

Question

I want to allow same HTML tags like <img> <strong> <p> to be usable by site users, but how to check misusing these tags, such as unclosed <p> that can match by a closing </p> in site theme and make page corrupted? also, I make shorten long posts for showing on index page that can make broken tags too.

Laravel has a csrf-token tag for preventing cross-site scripts, but doesn't seem to check things i said.

Answer 1

I don't know the laravelish way for this issue, but you could write your own validation function using regular expressions. Here's a demo for p tags:

// Html code here
$html = 'here'; 

// Strip newlines so we won't need multilines modifiers
$html = str_replace("\r\n", "", $html);

// Strip correct <p>...</p> tags and their content from html data
$html = preg_replace("@<p>.*?</p>@", "", $html);

// Check if any <p> tag remains in data. If so, it means a tag has been unenclosed/enclosed incorrectly
$s[0] = strpos($html, '<p>');
$s[1] = strpos($html, '</p>');

if($s[0] !== false || $s[1] !== false)
    echo "Syntax error in HTML code";