Strip '\r' in notification messages to avoid 'Content-Type: application/octet-stream'

[robert-scheck]

Without this patch, an accidential \r in e.g. $NOTIFICATIONCOMMENT leads to a Content-Type: application/octet-stream header in e-mails. The accidential \r might slip in usually using Icinga/Nagios apps...

#!/bin/bash

NOTIFICATION_MESSAGE=`cat << EOF
***** Service Monitoring on icinga2.example.net *****

CPU Load on tux.example.net is CRITICAL!

Info:    CRITICAL - load average: 812.35, 553.01, 269.48

When:    2019-05-16 07:39:05 +0200
Service: CPU Load
Host:    tux.example.net
IPv4:    192.0.2.42

Comment by Beastie:
  ACK
EOF
`

# Append accidential '\r' manually
NOTIFICATION_MESSAGE=${NOTIFICATION_MESSAGE}$'\r'

# Bashism to remove '\r'
#NOTIFICATION_MESSAGE=${NOTIFICATION_MESSAGE//[$'\r']}

# Issue reproducer (RHEL/SUSE/etc.)
/usr/bin/printf "%b" "$NOTIFICATION_MESSAGE" \
| mailx -r "monitoring@example.net" -s "[ACKNOWLEDGEMENT] CPU Load on tux.example.net is CRITICAL!" root@localhost

# Bashishm-free '\r' removal (RHEL/SUSE/etc.)
/usr/bin/printf "%b" "$NOTIFICATION_MESSAGE" | tr -d '\015' \
| mailx -r "monitoring@example.net" -s "[ACKNOWLEDGEMENT] CPU Load on tux.example.net is CRITICAL!" root@localhost

[robert-scheck]

@dnsmichi or @mxhash, who could review this?

[dnsmichi]

@bsdlme Does this work on FreeBSD?

[bsdlme]

Should work on FreeBSD with

#!/usr/bin/env bash

as shebang.

[robert-scheck]

@bsdlme, I'm a bit confused now: My pull request is bashism free, only my bug reproducer uses bash.

[bsdlme]

@robert-scheck Oops, yes. Sorry.

The tr -d '\015' line should also work on FreeBSD.

[dnsmichi]

Ok, thanks both 👍

[dnsmichi]

Ah, Fedora. Hello :-)

[sircubbi]

Is there a reason why this bugfix was reverted (c783448)?

With most recent icinga-version mails once again get corrupted (on Rocky 8) is acknowledgements/notifications contain newlines.

[julianbrost]

Seems like due to compatibility issues on Debian: #7648 #7706

[sircubbi]

Thanks for the pointer. However that issues seems more like related to shell-syntax. Just the removal of carriage-returns via the additional "tr"-command in the pipe shouldn't break Debian/Dash-shell.

The main culprit is, that using newlines on comments will be passed as "\r\n" in "$NOTIFICATION_MESSAGE", which aren't proper newlines on Unix. So either that should already filtered/converted by icingaweb or the icingadaemon, or just stripped out while piping to mail/mailx just like before.

Maybe a light fix might be to just put the "tr -d '\015'" in (and leave the base64-encoding for the subject out, as that part of the fix seems to break on dash and isn't really needed at least for mailx I guess).