Support Zeroconf based Authentication

[jonkerj]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
I'd like spotifyd to have a mode in which is does not require credentials in the config file, but plays "on behalf" of the initiating spotify connect client (eg my iPhone). I know this is possible, as the Spotify Android app on my mibox/chromecast behaves this way. When the device is turned on, any spotify client can play "through" this device over (I assume) spotify connect. I know fairly sure I am not "casting", as it shows "Spotify Connect" next to the device.

When I dump traffic between iPhone and mibox, I see a lot of spotify-related mDNS going on.

This "mode" probably has a proper name, if anyone know this, I'll update the issue title.

Describe alternatives you've considered
It could very well be that this is already possible, I tried to launch spotifyd without credentials and with Avahi running, but could not get it running. If it's possible, I'd like to see how, of course :-)

[JojiiOfficial]

Correct me if I'm wrong but it should work by removing all credential providing config options. Although when I tried this, I couldn't select my PC as playback device in the App (it was grayed out but available). The logs confirmed my phone trying to use it as device but for some reason it failed.

[jonkerj]

It was not very clear to me (at least from the docs) if this should work or not. When running in verbose mode, it does show mdns interaction indeed, but it does not work.

So, is it a bug or a missing feature?

[klarkc]

Same here, I just tried without password or username:

set 17 10:39:13 ssdinarch systemd[424]: Started A spotify playing daemon.
set 17 10:39:13 ssdinarch spotifyd[39915]: Loading config from "/home/klarkc/.config/spotifyd"
set 17 10:39:13 ssdinarch spotifyd[39915]: No username specified. Checking username_cmd
set 17 10:39:13 ssdinarch spotifyd[39915]: No username_cmd specified
set 17 10:39:13 ssdinarch spotifyd[39915]: No password specified. Checking password_cmd
set 17 10:39:13 ssdinarch spotifyd[39915]: No password_cmd specified
set 17 10:39:13 ssdinarch spotifyd[39915]: No proxy specified
set 17 10:39:13 ssdinarch spotifyd[39915]: Using software volume controller.

Nothing shows up on devices list on web client, native client, android client.

It seems there is a missing part in documentation regarding zeroconf option. I've also tried without luck to set some port (4070, 4444) with --zeroconf-port option.

What is avahi? It's a service to broadcast something in the network?

[knuton]

I had the same or a similar issue and it turned out to be firewall related. Try setting a fixed zeroconf port in spotifyd and unblock it in your firewall.

Doing so made my spotifyd instance appear in a same-network iOS Spotify client, no need for credentials.

[jonkerj]

You are right, it simply works if you remove authentication options from the config. The machine I was testing on probably needs some tuning in the firewall. @klarkc: avahi is an open source "bonjour" implementation.

Lots of applications doing mdns-based auto-discovery typically leverage avahi. Spotifyd/librespot seem to work perfectly without avahi, so this was a wild goose.

[jonkerj]

The plot thickens even more: the box on which I did not get spotifyd/zeroconf working has multiple interfaces, one of them being my ISP. The way librespot/libmdns works means that multicast replies follow kernel routing, so they were sent to my ISP (because the default route points there).

I'll work around this by adding a static route (yuck) for 224.0.0.251

[einarpersson]

I had the same or a similar issue and it turned out to be firewall related. Try setting a fixed zeroconf port in spotifyd and unblock it in your firewall.

Doing so made my spotifyd instance appear in a same-network iOS Spotify client, no need for credentials.

But what zeroconf port should be used? Whatever, as long as it is opened in the firewall?

For me it is working if I disable ufw completely but not when using 5353 in config and ufw

[eladyn]

Okay, maybe some explanation on how the process works:
Spotifyd sets up a mdns responder (on 5353 UDP, so that needs to be open) and an HTTP server on a high random port (or zeroconf_port, if set - that is TCP). Through the MDNS responder, it advertises the HTTP server together with its port, so that it's irrelevant which port you enter as long as that one's free. (And connecting devices make a query to the HTTP server and supply an auth blob, but that is not that relevant.)

So to conclude, you need to open two ports:

• 5353 UDP
• zeroconf_port TCP. And any value above 1024 should be fine here, as long as it's not already taken.

Hope this helps.

[einarpersson]

Okay, maybe some explanation on how the process works: Spotifyd sets up a mdns responder (on 5353 UDP, so that needs to be open) and an HTTP server on a high random port (or zeroconf_port, if set - that is TCP). Through the MDNS responder, it advertises the HTTP server together with its port, so that it's irrelevant which port you enter as long as that one's free. (And connecting devices make a query to the HTTP server and supply an auth blob, but that is not that relevant.)

So to conclude, you need to open two ports:

• 5353 UDP
• zeroconf_port TCP. And any value above 1024 should be fine here, as long as it's not already taken.

Hope this helps.

This was exactly what I needed to understand. I would highly recommend adding this information that you just wrote to the documentation. Great explanation!

[eladyn]

Thanks and good point, will do, when I get around to updating the documentation. (Currently it's lacking in some ways...)

[knuton]

Thanks and good point, will do, when I get around to updating the documentation. (Currently it's lacking in some ways...)

Maybe a minimal addition like this will do for the meantime?

#1236

[einarpersson]

Thanks and good point, will do, when I get around to updating the documentation. (Currently it's lacking in some ways...)

Maybe a minimal addition like this will do for the meantime?

#1236

Perfect! Glad I could help, and excited to get spotifyd working :)