make_clickable should not add http:// to ftp. hostnames by default (ftp:// is a better default)

[DavidAnderson]

make_clickable in wp-includes/formatting.php is a default filter.

One of its activities is to detect this regex, and to call _make_web_ftp_clickable_cb on it:

([\s>])((www|ftp)\.[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]+)

_make_web_ftp_clickable_cb then adds an <a href> tag, and pre-pends '
'​http://'.

That seems quite wrong, as a default, for hostnames beginning with "ftp.". It bit me; I sent out an email with something like "FTP server: ftp.example.com" in it. This went through WP Better Emails, and ended up via this filter as 'Host: <a href="​http://ftp.example.com">​http://ftp.example.com</a>' - i.e. ended up confusingly wrong.

I'm not sure that making links clickable by default is a good idea. But regardless of that, it's certainly wrong to *by default* change ftp. hostnames into ​http:// links, instead of into ​ftp:// links.

Therefore the third line of the function _make_web_ftp_clickable_cb in wp-includes/formatting.php should be changed from:

$dest = 'http://' . $dest;

to:

$dest = ('ftp.' == substr($dest,0,4)) ? "ftp://" . $dest : "http://" . $dest;

[SergeyBiryukov]

Duplicate of #22946.

[DavidAnderson]

Hi,

Really sorry for reporting the same bug twice - I completely forgot I'd already done it! I still had it on a 'to-do' list and my memory failed me...