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diff --git a/lib/htmlpurifier/docs/enduser-id.html b/lib/htmlpurifier/docs/enduser-id.html deleted file mode 100644 index 53d2da248..000000000 --- a/lib/htmlpurifier/docs/enduser-id.html +++ /dev/null @@ -1,148 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head> -<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> -<meta name="description" content="Explains various methods for allowing IDs in documents safely in HTML Purifier." /> -<link rel="stylesheet" type="text/css" href="./style.css" /> - -<title>IDs - HTML Purifier</title> - -</head><body> - -<h1 class="subtitled">IDs</h1> -<div class="subtitle">What they are, why you should(n't) wear them, and how to deal with it</div> - -<div id="filing">Filed under End-User</div> -<div id="index">Return to the <a href="index.html">index</a>.</div> -<div id="home"><a href="http://htmlpurifier.org/">HTML Purifier</a> End-User Documentation</div> - -<p>Prior to HTML Purifier 1.2.0, this library blithely accepted user input that -looked like this:</p> - -<pre><a id="fragment">Anchor</a></pre> - -<p>...presenting an attractive vector for those that would destroy standards -compliance: simply set the ID to one that is already used elsewhere in the -document and voila: validation breaks. There was a half-hearted attempt to -prevent this by allowing users to blacklist IDs, but I suspect that no one -really bothered, and thus, with the release of 1.2.0, IDs are now <em>removed</em> -by default.</p> - -<p>IDs, however, are quite useful functionality to have, so if users start -complaining about broken anchors you'll probably want to turn them back on -with %Attr.EnableID. But before you go mucking around with the config -object, it's probably worth to take some precautions to keep your page -validating. Why?</p> - -<ol> - <li>Standards-compliant pages are good</li> - <li>Duplicated IDs interfere with anchors. If there are two id="foobar"s in a - document, which spot does a browser presented with the fragment #foobar go - to? Most browsers opt for the first appearing ID, making it impossible - to references the second section. Similarly, duplicated IDs can hijack - client-side scripting that relies on the IDs of elements.</li> -</ol> - -<p>You have (currently) four ways of dealing with the problem.</p> - - - -<h2 class="subtitled">Blacklisting IDs</h2> -<div class="subsubtitle">Good for pages with single content source and stable templates</div> - -<p>Keeping in terms with the -<acronym title="Keep It Simple, Stupid">KISS</acronym> principle, let us -deal with the most obvious solution: preventing users from using any IDs that -appear elsewhere on the document. The method is simple:</p> - -<pre>$config->set('Attr.EnableID', true); -$config->set('Attr.IDBlacklist' array( - 'list', 'of', 'attribute', 'values', 'that', 'are', 'forbidden' -));</pre> - -<p>That being said, there are some notable drawbacks. First of all, you have to -know precisely which IDs are being used by the HTML surrounding the user code. -This is easier said than done: quite often the page designer and the system -coder work separately, so the designer has to constantly be talking with the -coder whenever he decides to add a new anchor. Miss one and you open yourself -to possible standards-compliance issues.</p> - -<p>Furthermore, this position becomes untenable when a single web page must hold -multiple portions of user-submitted content. Since there's obviously no way -to find out before-hand what IDs users will use, the blacklist is helpless. -And since HTML Purifier validates each segment separately, perhaps doing -so at different times, it would be extremely difficult to dynamically update -the blacklist in between runs.</p> - -<p>Finally, simply destroying the ID is extremely un-userfriendly behavior: after -all, they might have simply specified a duplicate ID by accident.</p> - -<p>Thus, we get to our second method.</p> - - - -<h2 class="subtitled">Namespacing IDs</h2> -<div class="subsubtitle">Lazy developer's way, but needs user education</div> - -<p>This method, too, is quite simple: add a prefix to all user IDs. With this -code:</p> - -<pre>$config->set('Attr.EnableID', true); -$config->set('Attr.IDPrefix', 'user_');</pre> - -<p>...this:</p> - -<pre><a id="foobar">Anchor!</a></pre> - -<p>...turns into:</p> - -<pre><a id="user_foobar">Anchor!</a></pre> - -<p>As long as you don't have any IDs that start with user_, collisions are -guaranteed not to happen. The drawback is obvious: if a user submits -id="foobar", they probably expect to be able to reference their page with -#foobar. You'll have to tell them, "No, that doesn't work, you have to add -user_ to the beginning."</p> - -<p>And yes, things get hairier. Even with a nice prefix, we still have done -nothing about multiple HTML Purifier outputs on one page. Thus, we have -a second configuration value to piggy-back off of: %Attr.IDPrefixLocal:</p> - -<pre>$config->set('Attr.IDPrefixLocal', 'comment' . $id . '_');</pre> - -<p>This new attributes does nothing but append on to regular IDPrefix, but is -special in that it is volatile: it's value is determined at run-time and -cannot possibly be cordoned into, say, a .ini config file. As for what to -put into the directive, is up to you, but I would recommend the ID number -the text has been assigned in the database. Whatever you pick, however, it -has to be unique and stable for the text you are validating. Note, however, -that we require that %Attr.IDPrefix be set before you use this directive.</p> - -<p>And also remember: the user has to know what this prefix is too!</p> - - - -<h2>Abstinence</h2> - -<p>You may not want to bother. That's okay too, just don't enable IDs.</p> - -<p>Personally, I would take this road whenever user-submitted content would be -possibly be shown together on one page. Why a blog comment would need to use -anchors is beyond me.</p> - - - -<h2>Denial</h2> - -<p>To revert back to pre-1.2.0 behavior, simply:</p> - -<pre>$config->set('Attr.EnableID', true);</pre> - -<p>Don't come crying to me when your page mysteriously stops validating, though.</p> - -</body> -</html> - -<!-- vim: et sw=4 sts=4 ---> |