#29 Export cdemu-daemon devices over iSCSI (no vhba-module necessary)

[Damjan Jovanovic]

Some time I ago I emailed cdemu-devel with a proposal to get cdemu-daemon to run as an iSCSI network server, instead of using the vhba kernel module (https://sourceforge.net/p/cdemu/mailman/message/58803615/).

I've managed to implement a first draft of this idea, just to see whether it works and how well it works. And it is already showing spectacular results:

• VLC plays CDDA from cdemu's virtual CDs.
• ISO9660 filesystems can be mounted from cdemu's virtual CDs.
• Games work.
• Wireshark can capture the iSCSI network traffic from the loopback network interface and view the iSCSI protocol details nicely.
• It even works on FreeBSD, where the Linux-only vhba-module can't be ported and would need to be rewritten. And porting cdemu to other operating systems, including Windows and macOS, should be much easier with iSCSI in place of vbha-module.

There is still a lot to do. Only the minimum amount of the iSCSI protocol has been implemented so far: only a single client is supported, login options are hardcoded, only a single cdemu device will work, and it has to be killed with "kill -9" to exit it. Glib integration needs to be improved, and maybe it should use Glib's sockets instead of BSD sockets directly. And maybe iSCSI shouldn't fully replace vbha-module, but devices could be exported over both where possible, or maybe you want to use iSCSI only and nuke the problematic vbha-module (which needs constant babysitting and updates to keep up with the unstable kernel API)?

But the open-source way is "release early, release often", so I thought I'd post what I've done so far and get some feedback.

Also, longer term, maybe cdemu needs to be redesigned to support networking better. If we allow cdemu-daemon to run on a different machine (as iSCSI allows), then DBus isn't really appropriate for communication with cdemu-client.

Usage, on FreeBSD:

# Start the patched cdemu-daemon, which will start listening on
# the iSCSI TCP/IP endpoint 127.0.0.1:3260:
./cdemu-daemon

# Start FreeBSD's iSCSI client daemon ("onestart" = this time only,
# not across reboots):
sudo service iscsid onestart

# Connect to cdemu-daemon over iSCSI. The "target0" is irrelevant,
# you can use any name for now
# (although maybe cdemu-daemon should care):
sudo iscsictl -A -p 127.0.0.1 -t iqn.target0

# That will create 1 device, eg. /dev/cd0.
# For now, only 1 device is supported properly.
# Set permissions on /dev/cd0 to allow non-root users to access it:
sudo chmod 644 /dev/cd0

# Instruct cdemu-daemon to load a .toc image into that device:
python3.11 cdemu load 0 /path/to/file.toc

And now /dev/cd0 can be used like any CDROM device. If the .toc/.bin
files are from a music CD, VLC will play music like it was a real
music CD.

Anyway, thank you for cdemu, and let me know what you think?