[tor-bugs] #13593 [Tor]: Is "Link 1 2" in the descriptors obsolete?

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#13593: Is "Link 1 2" in the descriptors obsolete?
--------------------+----------------------------------
 Reporter:  arma    |          Owner:
     Type:  defect  |         Status:  new
 Priority:  normal  |      Milestone:  Tor: unspecified
Component:  Tor     |        Version:
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
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 It looks like we're up to link protocol 4 in practice, but the descriptors
 still write this static string:
 {{{
                     "protocols Link 1 2 Circuit 1\n"
 }}}

 dir-spec.txt tells us
 {{{
        Both lists are space-separated sequences of numbers, to indicate
 which
        protocols the server supports.  As of 30 Mar 2008, specified
        protocols are "Link 1 2 Circuit 1".  See section 4.1 of tor-
 spec.txt
        for more information about link protocol versions.
 }}}

 but Section 4.1 of tor-spec.txt indeed admits to link protocols 3 and 4.

 It looks like nothing in routerparse.c or anywhere else looks at the
 'protocols' line of the descriptor. Heck, normal clients don't even get
 the descriptor anymore.

 I assume the last Tor version to not understand link protocol 2 is way
 obsolete (Tor 0.2.0.x era I think).

 And if clients never see the descriptors, it's hard to imagine how we'll
 be able to tell them a different Circuit protocol anyway.

 Should we dump this line? Have we accidentally lost anything here?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13593>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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