[tor-bugs] #21310 [Core Tor/Tor]: Exits should tell clients when they are connecting to an IPv6-only hostname

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#21310: Exits should tell clients when they are connecting to an IPv6-only hostname
--------------------------+------------------------------------
 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  needs_revision
 Priority:  Medium        |      Milestone:  Tor: 0.3.1.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.2.4.7-alpha
 Severity:  Normal        |     Resolution:
 Keywords:  ipv6          |  Actual Points:  0.1
Parent ID:  #21311        |         Points:  1
 Reviewer:                |        Sponsor:
--------------------------+------------------------------------
Changes (by teor):

 * status:  needs_review => needs_revision


Comment:

 Replying to [comment:5 arma]:
 > {{{
 > -  if (! options->IPv6Exit) {
 > -    /* I don't care if you prefer IPv6; I can't give you any. */
 > -    bcell.flags &= ~BEGIN_FLAG_IPV6_PREFERRED;
 > -    /* If you don't want IPv4, I can't help. */
 > -    if (bcell.flags & BEGIN_FLAG_IPV4_NOT_OK) {
 > -      tor_free(address);
 > -      relay_send_end_cell_from_edge(rh.stream_id, circ,
 > -                                    END_STREAM_REASON_EXITPOLICY,
 NULL);
 > -      return 0;
 > -    }
 > -  }
 > }}}
 >
 > Shouldn't we leave the "if you won't be ok with v4, and I won't exit to
 v6, then return an end cell immediately" clause in there?
 >
 > I think if clients are going to say they're not ok with v4, then it's
 their responsibility to pick an exit that says it can do v6.

 I think we could keep this in, but we can't adjust the flags on the cell.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21310#comment:8>
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