[tbb-bugs] #23545 [Applications/Tor Browser]: UX improvement: Tor Browser should handle bogus HSv3 addresses

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#23545: UX improvement: Tor Browser should handle bogus HSv3 addresses
-------------------------------------+-------------------------------------
     Reporter:  asn                  |      Owner:  tbb-team
         Type:  defect               |     Status:  new
     Priority:  Medium               |  Milestone:  Tor: 0.3.3.x-final
    Component:  Applications/Tor     |    Version:
  Browser                            |   Keywords:  prop224, ux, tor-
     Severity:  Normal               |  browser
Actual Points:                       |  Parent ID:
       Points:                       |   Reviewer:
      Sponsor:                       |
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 HS v3 addresses are big but also contain a checksum. This means that Tor
 Browser could catch mistyped addresses and warn the user.

 With current master and current Tor browser, if you mistype an hsv3
 address you go to the ''Unable to connect'' page:
 {{{
 Unable to connect

 Firefox can’t establish a connection to the server at
 4acth47i6kxnvkewtm6q7ib2s3ufpo5sqbsnzjpbi7utijcltosqeflock.onion.

     The site could be temporarily unavailable or too busy. Try again in a
 few moments.
     If you are unable to load any pages, check your computer’s network
 connection.
     If your computer or network is protected by a firewall or proxy, make
 sure that Tor Browser is permitted to access the Web.
 }}}

 In the logs you can see a parsing error:
 {{{
 [warn] Invalid onion hostname [scrubbed]; rejecting
 }}}
 which is a bit generic.

 I wonder what's the best way to offer better UX here. How should the user
 be warned?

 Also how should we implement this? Should the Browser do the checksum
 check itself? Or should Tor do the checksum check and inform Tor Browser
 somehow?

 How to do this best?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23545>
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