nihilist/tor
1
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/core/tor.git synced 2024-11-28 06:13:31 +01:00
Code Issues Packages Projects Releases Wiki Activity

Merge branch 'bug21394_029_redux' into maint-0.2.9

Browse Source
This commit is contained in:
Nick Mathewson 2019-01-04 15:04:54 -05:00
commit 73de7b4bcb
2 changed files with 18 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
changes/bug21394.2 Normal file
View File

@ -0,0 +1,7 @@
o Minor bugfix (Exit node DNS retries):
- Re-attempt timed-out DNS queries 3 times before failure, since our
timeout is 5 seconds for them, but clients wait 10-15. Also allow
slightly more timeouts per resolver before giving up on it in the
case where an exit has multiple resolvers configured. Fixes bug 21394;
bugfix on 0.3.1.9.

19
src/or/dns.c
View File

@ -1428,27 +1428,30 @@ configure_nameservers(int force)
// If we only have one nameserver, it does not make sense to back off
// from it for a timeout. Unfortunately, the value for max-timeouts is
// currently clamped by libevent to 255, but it does not hurt to set
// it higher in case libevent gets a patch for this.
// Reducing attempts in the case of just one name server too, because
// it is very likely to be a local one where a network connectivity
// issue should not cause an attempt to fail.
// it higher in case libevent gets a patch for this. Higher-than-
// default maximum of 3 with multiple nameservers to avoid spuriously
// marking one down on bursts of timeouts resulting from scans/attacks
// against non-responding authoritative DNS servers.
if (evdns_base_count_nameservers(the_evdns_base) == 1) {
SET("max-timeouts:", "1000000");
SET("attempts:", "1");
} else {
SET("max-timeouts:", "3");
SET("max-timeouts:", "10");
}
// Elongate the queue of maximum inflight dns requests, so if a bunch
// time out at the resolver (happens commonly with unbound) we won't
// remain pending at the resolver (happens commonly with Unbound) we won't
// stall every other DNS request. This potentially means some wasted
// CPU as there's a walk over a linear queue involved, but this is a
// much better tradeoff compared to just failing DNS requests because
// of a full queue.
SET("max-inflight:", "8192");
// Time out after 5 seconds if no reply.
// Two retries at 5 and 10 seconds for bind9/named which relies on
// clients to handle retries. Second retry for retried circuits with
// extended 15 second timeout. Superfluous with local-system Unbound
// instance--has its own elaborate retry scheme.
SET("timeout:", "5");
SET("attempts:","3");
if (options->ServerDNSRandomizeCase)
SET("randomize-case:", "1");