[tor-bugs] #29570 [Core Tor/Tor]: Enforce mutually exclusive logic for IPv6 ORPort flags

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#29570: Enforce mutually exclusive logic for IPv6 ORPort flags
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 Reporter:  s7r                                  |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  unspecified
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-relay, ipv6, reachability,       |  Actual Points:
  needs-proposal-or-tor-dev-email                |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by AVee):

 Replying to [comment:19 s7r]:
 > You are suggesting behavior that does not have any logic,
 I'm suggesting **not** to change the existing behavior. You are suggesting
 a change which makes a specific configuration illegal. Even though there
 is at least one working relay using that config.
 Can you answer this: Do you think it's a good idea to add restrictions
 which break currently running nodes?

 > is confusing for operators
 You'd need to prove that first. It isn't confusing for me. It also wasn't
 for the Charly Ghislain who, despite the complicated setup, got his config
 correct without issues (what was confusing for him was the fact that it
 took days before he got the IPv6Reachable flag). It seems to be confusing
 for you, but that cannot be a reason to disallow other to do this.
 Could you also answer this: Do you have any prove this is a common source
 of configuration errors?

 > Don't you see the logical fracture with advertising a v6 socket but not
 listening on one?
 Yes, I do. Which is why I know I need to do something somewhere in my
 network to make sure the advertised address actually works.

 > Why not just listen to v4, since that's your only open socket?
 Because I want my node to be reachable over IPv6 as well, as teor stated
 (goal 2) we want to "encourage more IPv6 relays".

 > In this case I would like to have only a v6 socket open, and have only
 one `NoListen` IPv4 ORPort entry to be advertised. And I will use HaProxy
 to listen on that IPv4 addr:port and redirect to my IPv6 address. So I
 will be having in my descriptor both IPv4 (which is mandatory) and IPv6,
 and only listen on one IPv6 socket. You suggest this should be possible,
 right?
 Yes that should absolutely be possible as well. Why not?

 > Otherwise why would we have different behavior for same thing, but only
 different versions?
 If that currently isn't allowed that would indeed be inconsistent. But
 then the rule should be: If the node does not have at least one listening
 ORPort it is not allowed to advertise any ORPorts, because the node cannot
 possibly be reachable. (I also expect IPv6 only nodes to become possible
 at some point.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29570#comment:20>
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