-Here is a patch [[tag patch]] to add a *forward*ing functionality
+Here is a patch [[!tag patch]] to add a *forward*ing functionality
to the [[`meta`_plugin|plugins/meta]].
+> [[done]], with some changes --[[Joey]]
+
Find the most recent version at
<http://www.schwinge.homeip.net/~thomas/tmp/meta_forward.patch>.
I can also submit a Git patch, if desired.
-*Syntax:*
+# Syntax
**URL** = http://some.nice/place/ (*etc.*)
-**WHITHER** = \[\[**[[wikilink]]**]] | **URL**
+**WHITHER** = \[\[**[[ikiwiki/wikilink]]**]] | **URL**
**D** = natural number (*meaning seconds*)
**OPT_DELAY** = delay=**D** | empty (*immediatelly*)
-\[[meta forward="*WHITHER*" *OPT_DELAY*]]
+\[[!meta forward="**WHITHER**" **OPT_DELAY**]]
+
+# Extensions and Ideas
+
+It might be doable to add references to pages that refer to the page containg
+the forwarding statement also to the referred-to page.
--[[tschwinge]]
+
+# Discussion
+
> The html scrubber cannot scrub meta headers. So if you emit one
> containing user-supplied data, it's up to you to scrub it to avoid all
> possible XSS attacks. Two attacks I'd worry about are cyclic meta refresh
> something in the delay value that closes the tag can probably insert
> javascript ATM; and are there ways to embed javascript in the url?)
> --[[Joey]]
+
+>> OK. I can add code to make sure that `$delay` **D** indeed is a natural number
+>> and that the passed target address **WHITHER** is nothing but a valid target address.
+>> (How to qualify a valid target address?)
+>> What is a *cyclic meta refresh loop*? Two pages in turn forwarding to each other?
+>> I think it would be possible to implement such a guard when only in-wiki links
+>> ([[ikiwiki/wikilink]]s) are being used, but how to do so for external links? --[[tschwinge]]
+
+>>> This seems a lot more securely to do for in-wiki links, since we know
+>>> that a link generated by a wikilink is safe, and can avoid cycles.
+>>> Obviously there's no way to avoid cycles when using external links.
+>>>
+>>> An example of code that doesn't detect such cycles is LWP::UserAgent,
+>>> which will happily follow cycles forever. There's a LWPx::ParanoidAgent
+>>> that can deal with cycles. I suppose this could be considered a client
+>>> side issue, except that if I were going to turn this redirect feature
+>>> on in my wikis, I'd really prefer to not have to worry about my wiki
+>>> causing such problems for clients. I feel it makes sense to make
+>>> external redirects or other potentially unsafe things an option,
+>>> and have the default behavior be only things that are known to be
+>>> secure.
+>>>
+>>> I haven't checked if there's a way to embed javascript in meta refresh
+>>> links or not. Given all the other places I've seen it be embedded, I'll
+>>> assume it is possible until it's shown not to be though.. --[[Joey]]