[tor-bugs] #32315 [Core Tor/Tor]: Can't perform reverse DNS lookup for a (binary) IPv6 address

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#32315: Can't perform reverse DNS lookup for a (binary) IPv6 address
--------------------------+------------------------------------
 Reporter:  liberat       |          Owner:  (none)
     Type:  defect        |         Status:  needs_review
 Priority:  Medium        |      Milestone:  Tor: 0.4.3.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.4.1.6
 Severity:  Normal        |     Resolution:
 Keywords:  ipv6, dns     |  Actual Points:
Parent ID:                |         Points:
 Reviewer:  teor          |        Sponsor:
--------------------------+------------------------------------

Comment (by liberat):

 Looking at the latest maint-0.2.9 / maint-0.3.5 branches:

 **0.2.9** doesn't allow ASCII addresses for RESOLVE_PTR.  It only allows
 binary v4 or v6 addresses, and both seem to work correctly.  If you try to
 use an ASCII address with RESOLVE_PTR, it shows the error message:
 {{{
 socks5 received RESOLVE_PTR command with hostname type. Rejecting.
 }}}

 **0.3.5** shows the same symptoms as described above for 0.4.1.6: it
 accepts either a binary address or an ASCII address. But in the case of
 IPv6, binary addresses are rejected with the same error message:
 {{{
 socks5 received RESOLVE_PTR command with hostname type. Rejecting.
 }}}
 which is now somewhat misleading.

 Here's a unit test to check for correct handling of IPv6 binary addresses:
 {{{
 --- a/src/test/test_socks.c
 +++ b/src/test/test_socks.c
 @@ -277,6 +277,23 @@ test_socks_5_supported_commands(void *ptr)
    tt_str_op("2.2.2.5",OP_EQ, socks->address);

    tt_int_op(0,OP_EQ, buf_datalen(buf));
 +  socks_request_clear(socks);
 +
 +  /* SOCKS 5 Send RESOLVE_PTR [F1] for an IPv6 address */
 +  ADD_DATA(buf, "\x05\x01\x00");
 +  ADD_DATA(buf, "\x05\xF1\x00\x04"
 +
 "\x20\x01\x0d\xb8\x85\xa3\x00\x00\x00\x00\x8a\x2e\x03\x70\x73\x34"
 +           "\x12\x34");
 +  tt_int_op(fetch_from_buf_socks(buf, socks, get_options()->TestSocks,
 +                                 get_options()->SafeSocks),
 +            OP_EQ, 1);
 +  tt_int_op(5,OP_EQ, socks->socks_version);
 +  tt_int_op(2,OP_EQ, socks->replylen);
 +  tt_int_op(5,OP_EQ, socks->reply[0]);
 +  tt_int_op(0,OP_EQ, socks->reply[1]);
 +  tt_str_op("[2001:db8:85a3::8a2e:370:7334]",OP_EQ, socks->address);
 +
 +  tt_int_op(0,OP_EQ, buf_datalen(buf));

   done:
    ;
 }}}

 What's the best way to perform a more complete test?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/32315#comment:8>
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