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Re: [tor-bugs] #21310 [Core Tor/Tor]: Exits should tell clients when they are connecting to an IPv6-only hostname
#21310: Exits should tell clients when they are connecting to an IPv6-only hostname
-------------------------------------------------+-------------------------
Reporter: teor | Owner: teor
Type: defect | Status:
| needs_revision
Priority: Medium | Milestone: Tor:
| unspecified
Component: Core Tor/Tor | Version: Tor:
| 0.2.4.7-alpha
Severity: Normal | Resolution:
Keywords: ipv6, 034-triage-20180328, | Actual Points: 0.1
034-removed-20180328 |
Parent ID: #17811 | Points: 1
Reviewer: | Sponsor:
-------------------------------------------------+-------------------------
Description changed by teor:
Old description:
> Edit: Turns out that these IPv6Exit option checks prevent clients ever
> seeing that they're trying to connect to an IPv6-only hostname
>
> This code is wrong for at least two reasons:
> * it should also unset BEGIN_FLAG_IPV6_OK, and
> * ~~it's way too early in the function: we might end up resolving an
> IPv6-only hostname, learn that it doesn't match our exit policy, and send
> the address back in the REASON_EXITPOLICY RELAY_END cell~~
> ~~(See https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n1436
> )~~
> (Apparently this works anyway.)
>
> {{{
> 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;
> }
> }
> }}}
New description:
When #21311 is finished, we need to make exits tell clients that the
hostname they asked for is IPv6-only
--
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21310#comment:21>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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