Couldn't parse packet type 47 is invalid

[sebirdman]

Creating bug at request of: librespot-org/librespot#545

running librespot separately like:

/usr/bin/librespot --name Snapcast --bitrate 320 --backend pipe --initial-volume 100 --verbose

Yields:

[2020-12-03T21:05:57Z INFO  librespot] librespot 89cafd7 (2020-11-27). Built on 2020-12-03. Build ID: tnGD7Qeu
[2020-12-03T21:05:57Z DEBUG librespot_connect::discovery] Zeroconf server listening on 0.0.0.0:44899
[2020-12-03T21:06:02Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:02Z WARN  libmdns::fsm] couldn't parse packet from [fe80::dcde:59ff:fe7e:71e5]:5353: type 47 is invalid
[2020-12-03T21:06:03Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:06Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:06Z WARN  libmdns::fsm] couldn't parse packet from [fe80::dcde:59ff:fe7e:71e5]:5353: type 47 is invalid
[2020-12-03T21:06:11Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:14Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:15Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid
[2020-12-03T21:06:15Z WARN  libmdns::fsm] couldn't parse packet from [fe80::dcde:59ff:fe7e:71e5]:5353: type 47 is invalid
[2020-12-03T21:06:16Z WARN  libmdns::fsm] couldn't parse packet from 10.10.1.1:5353: type 47 is invalid

this currently breaks librespot and should be addressed. From @ashthespy:

Type 47 should map to Next Secure record from rfc4034
Would you open up an issue in libmdns for this?

Either way @willstott101 something to consider?

[willstott101]

Hm, atm we're vendoring an old version dns-parser, probably about time we switched, to something maintained.

Candidates are probably: https://crates.io/crates/trust-dns-proto and https://crates.io/crates/dns-message-parser

I might also investigate using a higher-level library like https://crates.io/crates/trust-dns-client making libmdns be a completely minimal wrapper to simplify usage.

[ashthespy]

Ah, I was under the impression it was a written by @plietar back in the day, but now see it's actually a fork of tailhook/dns-parser.

Wouldn't it be less work to just add this record into

libmdns/src/dns_parser/enums.rs

Lines 7 to 10 in e63275f

	pub enum Type {
	/// a host addresss
	A = 1,
	/// an authoritative name server

And since we (librespot) don't actively parse this packet, it would just fall into the Unknown RData? But then again, my knowledge here is next to nil :-D

[willstott101]

I'll have to check but I'd assumed we already ignoring this packet, so all that would do is stop the logging (which is probably helpful anyway). The original issue is about a failure in the discovery of the librespot service, which implies this 47 might be something to respond to.

[sebirdman]

@willstott101 i may have misdiagnosed the issue, as i thought this message was breaking things for me.

[2opremio]

I am still getting these error messages.

couldn't parse packet from 10.10.20.61:5353: type 47 is invalid
couldn't parse packet from 10.10.20.63:5353: type 47 is invalid
couldn't parse packet from 10.10.20.64:5353: type 47 is invalid
couldn't parse packet from 10.10.20.57:5353: type 47 is invalid

[rindlerblabla]

So do I. Those messages started when I moved my snapserver, which uses librespot, to another VLAN/subnet.

[2opremio]

I got rid of the problem by switching to avahi in librespot.

[eljojo]

@2opremio could you explain how?

[2opremio]

Enable the "with-dns-sd" feature form librespot

[jonathanicq]

@2opremio
Can you explain how to do that?

Thank you in advance

[2opremio]

It’s a Cargo feature. There are lots of tutorials about how to build Rust projects on the web.

[willstott101]

I've not confirmed this is fixed - didn't intend github to auto close it.

[willstott101]

I would appreciate it if someone affected by this could test that the current main branch and see if the solution is as easy as ca9b289.

If that doesn't work, a copy of one of these packets would also be very helpful.

[Gnarflord]

Hi there,
I can confirm, that this completely fixes the issue for me, thank you so much!

I'm using librespot, a Spotify API player, that communicates to other devices via mdns. If I compile the package with libmdns version=0.6 I'm getting spammed with warnings, as other devices (smart IOT power plugs in my case) use this packet type 47.

If I compile it with version=0.7 I get no warnings at all, while previously about >1000 daily warning messages ended in my journal :))

[willstott101]

That's great. Thanks for confirming, and for the librespot PR.