Jabber is broken for certain servers (e.g. jabber.de)

[git-developer]

Bug description

• When this Docker image is used for a FHEM instance containing a Jabber client connecting to jabber.de, Jabber fails to authenticate and remains Disconnected.

Steps to reproduce

1. Prepare an account at jabber.de
2. Start a container from this Dockerfile.
3. Create a Jabber module instance, e.g.
   define jabber Jabber jabber.de 5222 <username> <password> 1 0
4. Look at the modules internal CONNINFO:
   it contains the server response message error invalid-mechanism

Expected behavior

• The device state should be Connected
• The internal CONNINFO should contains the message Connected to jabber.de with username <username>

Environment

• Raspberry Pi 3B+
• Raspbian Buster
• Docker 18.09.1

Additional context

• The Dockerfile bundles package libauthen-sasl-cyrus-perl which enables support for the SASL authentication mechanism SCRAM-SHA-1. This triggers the problem.
• Root cause for the problem is issue SASL authentication fails when multiple mechanisms are available dap/XML-Stream#27.
• Summary: when both server and client support more than 1 SASL authentication mechanism, the XML-Stream library that is used within 70_Jabber.pm creates an invalid authentication request.

Workaround

• The problem does not occur when package libauthen-sasl-cyrus-perl is removed from this Dockerfile. This may be done by a tiny pre-init.sh script containing the line

  apt-get remove -y libauthen-sasl-cyrus-perl

Suggestion

• Depending on whether libauthen-sasl-cyrus-perl is required for other purposes, it may be reasonable to remove this package from the Dockerfile and so avoid the problem without the need for an pre-init script.

[sidey79]

I haven't found any hints for what we use this package.

Can you tell us which Image exactly you used?

[git-developer]

I'm using current latest from Docker Hub on a Raspberry Pi (armv7l):

$ docker images
REPOSITORY                   TAG                  IMAGE ID            CREATED             SIZE
fhem/fhem                    latest               85af1223416b        11 months ago       1.4GB

[sidey79]

Can you please confirm, that this Problem also exists with the updated Image which can be found here:

https://github.com/fhem/fhem-docker/pkgs/container/fhem-experimental/9137917?tag=dev

[git-developer]

I can confirm that the problem still exists in the newer image, and that removal of libauthen-sasl-cyrus-perl fixes it.

Side note
The linked development image is not appropriate for use on a current Raspbian host because of moby/moby#40734. Summary:

• Current Raspbian is based on Buster and bundles Docker 18.09.1 and libseccomp 2.3.3-4
• Images based on Bullseye require at least Docker 19.03.9 and libseccomp version 2.4.2

[sidey79]

I've created a image based on buster:
https://github.com/fhem/fhem-docker/pkgs/container/fhem-experimental/9603541?tag=dev-buster

Would be nice to get some feedback from you.