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Date:      Tue, 08 Mar 2016 12:00:55 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-bugs@FreeBSD.org
Subject:   [Bug 207804] nscd negtive cache do not timeout for getaddrinfo:Non -recoverable failure in name resolution
Message-ID:  <bug-207804-8@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207804

            Bug ID: 207804
           Summary: nscd negtive cache do not timeout for getaddrinfo:Non
                    -recoverable failure in name resolution
           Product: Base System
           Version: 10.1-RELEASE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: bin
          Assignee: freebsd-bugs@FreeBSD.org
          Reporter: amutu@amutu.com

I met this bug several times for the last years=EF=BC=8Ctoday I can reprodu=
ce it on a
machine.I can always restart nscd or use nscd -i hosts to clear the nscd
cache=EF=BC=8Cbut I think it is better to fix this bug.

config:

cat /etc/nsswitch.conf=20
group: compat
group_compat: nis
hosts: cache files dns
networks: files
passwd: compat
passwd_compat: nis
shells: files
services: compat
services_compat: nis
protocols: files
rpc: files

cat /etc/nscd.conf
threads 1
enable-cache passwd yes
enable-cache group yes
enable-cache hosts yes
enable-cache services yes
enable-cache protocols yes
enable-cache rpc yes
enable-cache networks yes

positive-time-to-live hosts 30
negative-time-to-live hosts 1

on the first console :
>pkg install bash postgresql95-client
>bash
>while true; do psql -p 80 -h www.google.com; sleep 50; done

you will see
psql: received invalid response to SSL...

on the second console:
edit the /etc/resolv.conf,comment all the nameserver using "#'

now on the first console,you will see:
psql: could not translate host name "www.google.com" to address: hostname n=
or
servname provided,or not known
psql: could not translate host name "www.google.com" to address: Non
-recoverable failure in name resolution
...............repeate the last message.........
you can ping www.google.com,but psql can not resolve the error.I read the p=
sql
code,and find it use getaddrinfo to resolve the addr.

now even if you un-comment the servername in /etc/resolv.conf ,the  "Non
-recoverable failure in name resolution" still there,unless you restart nsc=
d,or
nscd -i hosts for that user.

uname -a
FreeBSD xx 10.1-RELEASE-p26 FreeBSD 10.1-RELEASE-p26 #0: Wed Jan 13 20:59:29
UTC 2016     root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERI=
C=20
amd64

--=20
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