[tor-bugs] #33607 [Core Tor/Tor]: Stop forcing IPv4 and IPv6 traffic on non-SOCKSPorts

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#33607: Stop forcing IPv4 and IPv6 traffic on non-SOCKSPorts
------------------------------+--------------------------------
     Reporter:  teor          |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.4.4.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  044-should
Actual Points:                |  Parent ID:
       Points:  0.1           |   Reviewer:
      Sponsor:                |
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 After #32994, the defaults in `port_cfg_new()` will apply to all parsed
 ports. (Not just default ports.)

 I am not sure what we should do with the extra settings in
 `connection_listener_new()`:
 {{{
   if (type != CONN_TYPE_AP_LISTENER) {
     lis_conn->entry_cfg.ipv4_traffic = 1;
     lis_conn->entry_cfg.ipv6_traffic = 1;
     lis_conn->entry_cfg.prefer_ipv6 = 1;
   }
 }}}

 Here are our options:
 * leave them there: non-SOCKSPorts will always have IPv4, IPv6, and prefer
 IPv6 traffic
 * copy the defaults from port_cfg_new(): non-SOCKSPorts will always have
 DNS, Onion, and prefer IPv6 virtual addresses. Forcing these options on
 might make some configs break.
 * delete them: non-SOCKSPorts can now disable IPv4, IPv6, and prefer IPv4
 traffic. Some rare configs might break, because they relied on the options
 being forced on.

 Here's what I think we should do long-term:
 * set reasonable defaults (in #32994)
 * stop forcing options on (this ticket)
 * warn users that some rare configs might break, and they should remove
 NoIPv4Traffic or NoIPv6Traffic as needed (this changes file)

 Note that "prefer IPv6 traffic" was added in #32637 in 0.4.3.1-alpha.
 Maybe we don't want to force that option on in this release? I'll open a
 child ticket.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33607>
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