[tor-bugs] #24546 [Core Tor/Tor]: Use tor_addr_is_v4() rather than family, or reject all v6-mapped IPv4 addresses

[Tor Bug Tracker & Wiki]

#24546: Use tor_addr_is_v4() rather than family, or reject all v6-mapped IPv4
addresses
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     Reporter:  teor          |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.3.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  tor-dirauth, ipv6
Actual Points:                |  Parent ID:
       Points:  1             |   Reviewer:
      Sponsor:  SponsorV-can  |
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 In Tor, we try to support v6-mapped IPv4 addresses.
 We should either:
 * reject them unconditionally, or
 * audit all uses of tor_addr_t.family to see if we should be calling
 tor_addr_is_v4() instead, and add a comment to the struct that says we
 should consider using tor_addr_is_v4() rather than comparing family.

 If no relay in the consensus is currently using these addresses, then
 maybe we should just call them internal on authorities, relays, and
 clients, and remove all the code that tries to deal with them.

 Discovered as part of #15518.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24546>
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