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Bug#933231: exim4-base: /etc/cron.daily/exim4-base can't detect hostname via hostname --fqdn

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Christian Garbs

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Jul 27, 2019, 5:00:02 PM7/27/19
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Package: exim4-base
Version: 4.92-8+deb10u1
Severity: normal
Tags: ipv6

After the update from Stretch to Buster, on one of my systems
/etc/cron.daily/exim4-base failed on every run with just

hostname: Name or service not known

as an error message.

I could trace this to the usage of "hostname --fqdn" in the script.
On this (and so far only on this) system this call simply fails:

$ hostname --fqdn
hostname: Name or service not known

The manpage of hostname(1) warns about the --fqdn option:

| If a machine has multiple network interfaces/addresses or
| is used in a mobile environment, then it may either have
| multiple FQDNs/domain names or none at all. Therefore
| avoid using hostname --fqdn, hostname --domain and dnsdomainname.
| hostname --ip-address is subject to the same limitations
| so it should be avoided as well.

I don't yet know why, but I indeed have two hostnames:

$ hostname --all-fqdns
het.cgarbs.de het.cgarbs.de

I guess one is for the IPv4 connection and the other for IPv6.


Because in my case both entries are the same and the cron.daily
script only needs one, I created a shell function that returns
only the first hostname and added it to the top of the cron.daily
script (see attached changed config file below):

# fix multiple hostnames, see warning about THE FQDN in hostname(1)
hostname()
{
/bin/hostname --all-fqdns | tr " " "\n" | grep -F . | sort | uniq | head -n 1
}


The shell function takes precedence over /bin/hostname and everything
works as expected.

Unfortunately, the hostname(1) manpage says "Do not make any assumptions
about the order of the output." regarding the --all-fqdns option.



So while using the shell function might be a partial fix, it is not a
very good one.

Is there another way to get a proper hostname, perhaps from Exim
or the Exim configuration, that can be used in /etc/cron.daily/exim4-base
instead of calling "hostname --fqdn"?


Regards
Christian

-- Package-specific info:
Exim version 4.92 #3 built 20-Jul-2019 11:35:58
Copyright (c) University of Cambridge, 1995 - 2018
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2018
Berkeley DB: Berkeley DB 5.3.28: (September 9, 2013)
Support for: crypteq iconv() IPv6 PAM Perl Expand_dlfunc GnuTLS move_frozen_messages Content_Scanning DANE DKIM DNSSEC Event OCSP PRDR PROXY SOCKS TCP_Fast_Open
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch ldap ldapdn ldapm mysql nis nis0 passwd pgsql sqlite
Authenticators: cram_md5 cyrus_sasl dovecot plaintext spa tls
Routers: accept dnslookup ipliteral iplookup manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore/mbx autoreply lmtp pipe smtp
Malware: f-protd f-prot6d drweb fsecure sophie clamd avast sock cmdline
Fixed never_users: 0
Configure owner: 0:0
Size of off_t: 8
Configuration file search path is /etc/exim4/exim4.conf:/var/lib/exim4/config.autogenerated
Configuration file is /var/lib/exim4/config.autogenerated
# /etc/exim4/update-exim4.conf.conf
#
# Edit this file and /etc/mailname by hand and execute update-exim4.conf
# yourself or use 'dpkg-reconfigure exim4-config'
#
# Please note that this is _not_ a dpkg-conffile and that automatic changes
# to this file might happen. The code handling this will honor your local
# changes, so this is usually fine, but will break local schemes that mess
# around with multiple versions of the file.
#
# update-exim4.conf uses this file to determine variable values to generate
# exim configuration macros for the configuration file.
#
# Most settings found in here do have corresponding questions in the
# Debconf configuration, but not all of them.
#
# This is a Debian specific file

dc_eximconfig_configtype='internet'
dc_other_hostnames='cgarbs.de'
dc_local_interfaces='0.0.0.0.25 ; ::0.25'
dc_readhost=''
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost=''
CFILEMODE='644'
dc_use_split_config='true'
dc_hide_mailname=''
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'

mailname:cgarbs.de
# /etc/default/exim4
EX4DEF_VERSION=''

# 'combined' - one daemon running queue and listening on SMTP port
# 'no' - no daemon running the queue
# 'separate' - two separate daemons
# 'ppp' - only run queue with /etc/ppp/ip-up.d/exim4.
# 'nodaemon' - no daemon is started at all.
# 'queueonly' - only a queue running daemon is started, no SMTP listener.
# setting this to 'no' will also disable queueruns from /etc/ppp/ip-up.d/exim4
QUEUERUNNER='combined'
# how often should we run the queue
QUEUEINTERVAL='30m'
# options common to quez-runner and listening daemon
COMMONOPTIONS=''
# more options for the daemon/process running the queue (applies to the one
# started in /etc/ppp/ip-up.d/exim4, too.
QUEUERUNNEROPTIONS=''
# special flags given to exim directly after the -q. See exim(8)
QFLAGS=''
# Options for the SMTP listener daemon. By default, it is listening on
# port 25 only. To listen on more ports, it is recommended to use
# -oX 25:587:10025 -oP /run/exim4/exim.pid
SMTPLISTENEROPTIONS=''

-- System Information:
Debian Release: 10.0
APT prefers oldstable-updates
APT policy: (500, 'oldstable-updates'), (500, 'stable'), (500, 'oldstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-5-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages exim4-base depends on:
ii adduser 3.118
ii cron [cron-daemon] 3.0pl1-134
ii debconf [debconf-2.0] 1.5.71
ii exim4-config [exim4-config-2] 4.92-8+deb10u1
ii libc6 2.28-10
ii libdb5.3 5.3.28+dfsg1-0.5
ii lsb-base 10.2019051400
ii netbase 5.6

Versions of packages exim4-base recommends:
ii bsd-mailx [mailx] 8.1.2-0.20180807cvs-1
pn psmisc <none>

Versions of packages exim4-base suggests:
ii bsd-mailx [mail-reader] 8.1.2-0.20180807cvs-1
ii emacs-nox [mail-reader] 1:26.1+1-3.2
pn exim4-doc-html | exim4-doc-info <none>
pn eximon4 <none>
ii file 1:5.35-4
ii gnutls-bin 3.6.7-4
ii openssl 1.1.1c-1
pn spf-tools-perl <none>
pn swaks <none>

-- Configuration Files:
/etc/cron.daily/exim4-base changed:
if [ -n "$EX4DEBUG" ]; then
echo "now debugging $0 $@"
set -x
fi
hostname()
{
/bin/hostname --all-fqdns | tr " " "\n" | grep -F . | sort | uniq | head -n 1
}
E4BCD_DAILY_REPORT_TO="postmaster"
E4BCD_DAILY_REPORT_OPTIONS=""
E4BCD_WATCH_PANICLOG="yes"
E4BCD_PANICLOG_LINES="10"
E4BCD_PANICLOG_NOISE=""
if [ ! -x /usr/lib/exim4/exim4 ]; then
exit 0
fi
[ -f /etc/default/exim4 ] && . /etc/default/exim4
SPOOLDIR="$(exim4 -bP spool_directory | sed 's/.*=[[:space:]]\(.*\)/\1/')"
E4BCD_MAINLOG_NOISE="^[[:digit:][:space:]:-]\{20\}\(\(Start\|End\) queue run: pid=[[:digit:]]\+\|exim [[:digit:]\.]\+ daemon started: pid=[[:digit:]]\+, .*\)$"
if [ -n "$E4BCD_DAILY_REPORT_TO" ]; then
if [ -x "$(command -v eximstats)" ] && [ -x "$(command -v mail)" ]; then
if [ "$(< /var/log/exim4/mainlog grep -v "$E4BCD_MAINLOG_NOISE" | wc -l)" -gt "0" ]; then
< /var/log/exim4/mainlog grep -v "$E4BCD_MAINLOG_NOISE" \
| eximstats $E4BCD_DAILY_REPORT_OPTIONS \
| mail -s"$(hostname --fqdn) Daily e-mail activity report" \
$E4BCD_DAILY_REPORT_TO
else
echo "no mail activity in this interval" \
| mail -s"$(hostname --fqdn) Daily e-mail activity report" \
$E4BCD_DAILY_REPORT_TO
fi
else
echo "The exim4 cron job is configured to send a daily report, but eximstats"
echo "and/or mail cannot be found. Please check and make sure that these two"
echo "binaries are available"
fi
fi
log_this() {
TEXT="$@"
if ! logger -t exim4 -p mail.alert $TEXT; then
RET="$?"
echo >&2 "ALERT: could not syslog $TEXT, logger return value $RET"
fi
}
if [ "$E4BCD_WATCH_PANICLOG" != "no" ]; then
if [ -s "/var/log/exim4/paniclog" ]; then
if [ -x "/usr/local/lib/exim4/nonzero_paniclog_hook" ]; then
/usr/local/lib/exim4/nonzero_paniclog_hook
fi
if [ -z "$E4BCD_PANICLOG_NOISE" ] || grep -vq "$E4BCD_PANICLOG_NOISE" /var/log/exim4/paniclog; then
log_this "ALERT: exim paniclog /var/log/exim4/paniclog has non-zero size, mail system possibly broken"
if ! printf "Subject: exim paniclog on %s has non-zero size\nTo: root\n\nexim paniclog /var/log/exim4/paniclog on %s has non-zero size, mail system might be broken. The last ${E4BCD_PANICLOG_LINES} lines are quoted below.\n\n%s\n" \
"$(hostname --fqdn)" "$(hostname --fqdn)" \
"$(tail -n "${E4BCD_PANICLOG_LINES}" /var/log/exim4/paniclog)" \
| exim4 root; then
log_this "PANIC: sending out e-mail warning has failed, exim has non-zero return code"
fi
if [ "$E4BCD_WATCH_PANICLOG" = "once" ]; then
logrotate -f /etc/logrotate.d/exim4-paniclog
fi
fi
fi
fi
if [ -x /usr/sbin/exim_tidydb ]; then
cd $SPOOLDIR/db || exit 1
if ! find $SPOOLDIR/db -maxdepth 1 -name '*.lockfile' -or -name 'log.*' \
-or -type f -printf '%f\0' | \
xargs -0r -n 1 \
start-stop-daemon --start --exec /usr/sbin/exim_tidydb \
--chuid Debian-exim:Debian-exim -- $SPOOLDIR > /dev/null; then
# if we reach this, invoking exim_tidydb from start-stop-daemon has
# failed, most probably because of libpam-tmpdir being in use
# (see #373786 and #376165)
find $SPOOLDIR/db -maxdepth 1 -name '*.lockfile' -or -name 'log.*' \
-or -type f -printf '%f\0' | \
runuser --shell=/bin/bash \
--command="xargs -0r -n 1 /usr/sbin/exim_tidydb $SPOOLDIR > /dev/null" \
Debian-exim
fi
fi


-- debconf information:
* exim4-base/drec:
exim4/purge_spool: false

Andreas Metzler

unread,
Jul 28, 2019, 8:10:03 AM7/28/19
to
On 2019-07-27 Christian Garbs <mi...@cgarbs.de> wrote:
> Package: exim4-base
> Version: 4.92-8+deb10u1
> Severity: normal
> Tags: ipv6

> After the update from Stretch to Buster, on one of my systems
> /etc/cron.daily/exim4-base failed on every run with just

> hostname: Name or service not known

> as an error message.

> I could trace this to the usage of "hostname --fqdn" in the script.
> On this (and so far only on this) system this call simply fails:

> $ hostname --fqdn
> hostname: Name or service not known
[...]
> I don't yet know why, but I indeed have two hostnames:

> $ hostname --all-fqdns
> het.cgarbs.de het.cgarbs.de

> I guess one is for the IPv4 connection and the other for IPv6.
[...]

Hello Christian,

on this system, hostname --fqdn succeeds but hostname --all-fqdns fails:
--
ametzler@argenau:~$ hostname --fqdn ; echo FQDN $? ; hostname --all-fqdns ; echo fqdnS $?
argenau.bebt.de
FQDN 0

fqdnS 0
--

In /etc/hosts I have got 127.0.0.1 as localhost and 127.0.1.1 as my
normal FQDN, which I think is not totally broken.

> Is there another way to get a proper hostname, perhaps from Exim
> or the Exim configuration, that can be used in /etc/cron.daily/exim4-base
> instead of calling "hostname --fqdn"?

There is
/usr/sbin/exim4 -bP primary_hostname
or
/usr/sbin/exim4 -be '${primary_hostname}'

How about the attached patch?

cu Andreas
--
`What a good friend you are to him, Dr. Maturin. His other friends are
so grateful to you.'
`I sew his ears on from time to time, sure'
better.hostname.diff

Christian Garbs

unread,
Jul 31, 2019, 4:50:03 PM7/31/19
to
On Sun, Jul 28, 2019 at 02:08:20PM +0200, Andreas Metzler wrote:
> On 2019-07-27 Christian Garbs <mi...@cgarbs.de> wrote:
> > Package: exim4-base
> > Version: 4.92-8+deb10u1
> > Severity: normal
> > Tags: ipv6
>
> > After the update from Stretch to Buster, on one of my systems
> > /etc/cron.daily/exim4-base failed on every run with just
>
> > hostname: Name or service not known
>
> > as an error message.
>
> > I could trace this to the usage of "hostname --fqdn" in the script.

[...]

> > Is there another way to get a proper hostname, perhaps from Exim
> > or the Exim configuration, that can be used in /etc/cron.daily/exim4-base
> > instead of calling "hostname --fqdn"?
>
> There is
> /usr/sbin/exim4 -bP primary_hostname
> or
> /usr/sbin/exim4 -be '${primary_hostname}'
>
> How about the attached patch?

Hello Andreas,

the patch looks good!

The fallback to hostname without any parameters is a nice touch – if
the admin can keep his systems apart, everything is ok, no need for
any flags ;-)


I have applied the patch against the original /etc/cron.daily/exim4-base
from Buster and deployed it to three systems (the one that showed the
bug plus two unaffected others): Everything works as expected.

Please apply the patch to the next version.

Thanks for the quick reply and patch!
Christian
--
....Christian.Garbs....................................https://www.cgarbs.de

A truly wise man never plays leapfrog with a unicorn.
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