Re: Bidirectional text and URLs

[Ted Zlatanov]

On Fri, 28 Nov 2014 03:51:14 +0100 Lars Magne Ingebrigtsen <address@hidden> 
wrote: 

LMI> Using right-to-left markers to do phishing and obscure URLs has gotten
LMI> some attention on the webs today.  For instance, can you easily tell
LMI> where the link below takes you if you click on it in Gnus and
LMI> (presumably) rmail?

LMI>      Works on URLs too.                                               
                                                                      
LMI>      ‮http://myspace.com/#/segami/moc.koobecaf//:sptth                 
                                                                      
LMI> Unless I messed something up while cut'n'pasting that, you should see
LMI> the problem.

LMI> Now, should we do something about that?  And if so -- what?

My uni-confusables package in the GNU ELPA would help detect things like
б (CYRILLIC SMALL LETTER BE) confused with the number 6.  The relevant
line from confusables.txt is:

0431 ;  0036 ;  SL      # ( б → 6 ) CYRILLIC SMALL LETTER BE → DIGIT SIX        
#

which maps to (1073 "6") in `uni-confusables-char-table-single'. EWW and
SHR could opportunistically use that table to highlight such characters.

I could also add RTL markers and other useful things to uni-confusables
if you think it's the right place, and maybe provide the function for
EWW and SHR and others to use when looking for suspicious characters. Or
I could keep the package to a single purpose. I'm not sure of the right
thing because this feels a little bit like core functionality.

Ted