From 3985e59019700bfa215a9de026b3cb6bd544bda3 Mon Sep 17 00:00:00 2001 From: cy Date: Tue, 30 May 2017 03:27:59 +0000 Subject: [PATCH] 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 git-svn-id: svn://svn.freebsd.org/base/stable/10@319177 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- usr.sbin/nscd/query.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/usr.sbin/nscd/query.c b/usr.sbin/nscd/query.c index 270992ebd..a2b93d607 100644 --- a/usr.sbin/nscd/query.c +++ b/usr.sbin/nscd/query.c @@ -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); -- 2.45.0