Date: Tue, 30 May 2017 03:28:00 +0000 (UTC) From: Cy Schubert <cy@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r319177 - in stable: 10/usr.sbin/nscd 11/usr.sbin/nscd Message-ID: <201705300328.v4U3S0eS061502@repo.freebsd.org>
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Author: cy Date: Tue May 30 03:27:59 2017 New Revision: 319177 URL: https://svnweb.freebsd.org/changeset/base/319177 Log: MFC r318578: Fix non-recoverable name resolution failures due to negative cache entries never expiring. This patch honours the negative cache timeout. To test/experience the failure do the following: 1. Edit /etc/ncd.conf to adjust the cache timeouts as follows: positive-time-to-live hosts 30 negative-time-to-live hosts 1 2. Ensure that nsswitch.conf hosts line contains something like: hosts: files cache dns Note that cache must be specified before dns. 3. Start nscd. 4. Run the following command: while true; do nc -z -w 3 www.google.com 80; sleep 5; done 5. While running the command, remove or comment out all nameserver statements in /etc/resolv.conf. After a short while you will notice non-recoverable name rsolution failures. 6. Uncomment or replace all nameserver statements back into /etc/resolv.conf. Take note that name resolution never recovers. To recover nscd must be restarted. This patch fixes this. PR: 207804 Submitted by: Jov <amutu@amutu.com> Modified: stable/10/usr.sbin/nscd/query.c Directory Properties: stable/10/ (props changed) Changes in other areas also in this revision: Modified: stable/11/usr.sbin/nscd/query.c Directory Properties: stable/11/ (props changed) Modified: stable/10/usr.sbin/nscd/query.c ============================================================================== --- stable/10/usr.sbin/nscd/query.c Tue May 30 03:25:05 2017 (r319176) +++ stable/10/usr.sbin/nscd/query.c Tue May 30 03:27:59 2017 (r319177) @@ -743,9 +743,14 @@ on_read_request_process(struct query_state *qstate) &read_response->data_size); if (read_response->error_code == -2) { - read_response->error_code = 0; - read_response->data = NULL; - read_response->data_size = 0; + read_response->data = malloc( + read_response->data_size); + assert(read_response != NULL); + read_response->error_code = cache_read(neg_c_entry, + read_request->cache_key, + read_request->cache_key_size, + read_response->data, + &read_response->data_size); } } configuration_unlock_entry(qstate->config_entry, CELT_NEGATIVE);
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