[tor-bugs] #21394 [Core Tor/Tor]: connection timeouts are affecting Tor Browser usability

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#21394: connection timeouts are affecting Tor Browser usability
--------------------------------------------+------------------------------
 Reporter:  arthuredelstein                 |          Owner:
     Type:  defect                          |         Status:  new
 Priority:  Medium                          |      Milestone:  Tor:
                                            |  unspecified
Component:  Core Tor/Tor                    |        Version:
 Severity:  Normal                          |     Resolution:
 Keywords:  tbb-performance, tbb-usability  |  Actual Points:
Parent ID:                                  |         Points:
 Reviewer:                                  |        Sponsor:
--------------------------------------------+------------------------------

Comment (by cypherpunks):

 > 16:51 < armadev> or maybe it gets the begin cell and starts its dns
 resolve and that takes a while

 This.
 Some exits can't return answer for resolve requests. Tested with
 BC630CBBB518BE7E9F4E09712AB0269E9DC7D626, but triggered for many (IPv6
 enabled?) exit relays too.


 {{{
     log_info(LD_EXIT, "Launching eventdns request for %s",
              escaped_safe_str(resolve->address));
     resolve->res_status_ipv4 = RES_STATUS_INFLIGHT;
     if (get_options()->IPv6Exit)
       resolve->res_status_ipv6 = RES_STATUS_INFLIGHT;

     if (launch_one_resolve(resolve->address, DNS_IPv4_A, NULL) < 0) {
       resolve->res_status_ipv4 = 0;
       r = -1;
     }

     if (r==0 && get_options()->IPv6Exit) {
       /* We ask for an IPv6 address for *everything*. */
       if (launch_one_resolve(resolve->address, DNS_IPv6_AAAA, NULL) < 0) {
         resolve->res_status_ipv6 = 0;
         r = -1;
       }
     }
 }}}
 It launches two DNS requests for the same address on behalf of any client
 (begin cell's flags ignored) if IPv6 enabled. It need to get answers for
 both DNS requests to send resolved stuff down the circuit.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21394#comment:11>
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