[wp-trac] [WordPress Trac] #15774: Don't Double URL Query Args in Canonical Redirect

[WordPress Trac]

#15774: Don't Double URL Query Args in Canonical Redirect
--------------------------+-------------------------------------------------
 Reporter:  filosofo      |       Owner:           
     Type:  defect (bug)  |      Status:  new      
 Priority:  normal        |   Milestone:  3.1      
Component:  Canonical     |     Version:  3.1      
 Severity:  normal        |    Keywords:  has-patch
--------------------------+-------------------------------------------------
 Currently, when using "default" permalinks and requesting something that
 triggers canonical redirect, the query portion of the request URL can
 double up the same request arguments, which leads to
 `redirect_canonical()`'s returning falsely different URLs.

 In other words, suppose you have a custom post type of `custom_post_thing`
 with an object that has a slug `a-custom-post-thingy-title` and an ID of
 123.

 If you request `/?p=123` `redirect_canonical()` figures out that its
 correct, canonical URL is actually

 {{{
 /?custom_post_thing=a-custom-post-thingy-title
 }}}

 However, when `redirect_canonical()` is called again at line 362, it
 appends the same query value to the fetched URL, like so:

 {{{
 /?custom_post_thing=a-custom-post-thingy-title&custom_post_thing=a-custom-
 post-thingy-title
 }}}

 The result is that

 {{{
 /?custom_post_thing=a-custom-post-thingy-title&custom_post_thing=a-custom-
 post-thingy-title
 }}}

 and

 {{{
 /?custom_post_thing=a-custom-post-thingy-title
 }}}

 differ as strings even though they're the same in actual meaning, and the
 redirect fails and a 404 results.

 (I have seen this happen in other redirect situations--it's not limited to
 custom post types.)

 The patch parses the redirect URL's query value and uses `add_query_arg()`
 to add it, rather than the current naive string concatenation.  The result
 is that arguments do not get doubled, and the redirect succeeds.

-- 
Ticket URL: <http://core.trac.wordpress.org/ticket/15774>
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