[tor-bugs] #33035 [Applications/Tor Browser]: create strings for onion service error pages

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#33035: create strings for onion service error pages
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 Reporter:  brade                     |          Owner:  tbb-team
     Type:  defect                    |         Status:  new
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:                            |  Actual Points:
Parent ID:  #19251                    |         Points:
 Reviewer:                            |        Sponsor:  Sponsor27-must
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Comment (by dgoulet):

 Those codes are linked to different failure event when trying to connect
 to an onion service. But most of them can be summarized into a non
 technical term that is "what and why it is happening". Here is my attempt:

 * `XF0`: A descriptor that is not found means the service is not
 publishing it which summarize to: "Service A.onion is not running".

 * `XF1`: This will be extremely rare but can happen due to a bug service
 or client side. Or if someone is deliberately doing it. Or if the service
 is a custom tor implementation that is mis-behaving. It can be summarized
 to: "Service is unreachable due to an internal error".

 * `XF2`: Introduction circuit failed that means the service we are trying
 to reach does not have circuit established to the introduction point. In
 other words, it can be considerered: "Service A.onion is not running".

 * `XF3`: Unable to finalize the connection to the service through the
 rendezvous circuit. This means two things: Either the rendezvous point is
 overwhelmed or malicious that is dropping voluntarily the packets. Or,
 more likely scenario, the service is overwhelmed and is unable to
 rendezvous in time. The latter is probably what we want to tell the user
 ;). Like, come back later type of message, NOT pressing new circuit :P.

 * `XF4`: This one is easy :)

 * `XF5`: This one is easy :)

 * `XF6`: This one is easy :)

 * `XF7`: This should be quite rare but still, maybe not on bad networks.
 This means that for whatever circuit we tried, it timed out which means we
 are not even sure we reached the rendezvous or introduction. This most of
 the time results in a message that could be around "Bad network" or
 "Unstable connection"... something like that.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33035#comment:7>
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