[tor-bugs] #22251 [Core Tor/Tor]: Time to retire old link versions?

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#22251: Time to retire old link versions?
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     Reporter:  arma          |      Owner:
         Type:  enhancement   |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.2.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
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 In our spec, we have
 {{{
    All new relay implementations of the Tor protocol MUST support
    backwards-compatible renegotiation
 }}}

 But the v3 link handshake came out in Tor 0.2.3.6-alpha. That's certainly
 older than any relays. Is it older than any clients that we expect to
 work?

 Step 0 in phasing out old link versions would be to admit in tor-spec that
 supporting them is not a MUST. I'd say we're ready to do this one any
 time. We could put v3 as the minimum you MUST implement, or we might pick
 v4, since it came out in 0.2.4.11-alpha, and that's pretty old now too.

 Step 1 in phasing out old link versions would be to actually remove the
 code from mainline Tor. In preparation, we should try to figure out which
 Tor client versions are still in use today, and which ones still happen to
 work with the current network, and figure out in what time frame we'll be
 ok breaking those old Tor clients.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22251>
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