core: retry session connection

[kingosticks]

When session connection fails, retry the access point. If still fails for a non-auth-login reason, repeat for the other access points. Also some logging tweaks.

When blocking ap-gew1.spotify.com, now I see each a retry for each AP on that host, until it finds an AP on a different host and succeeds.

[2024-09-20T22:41:44Z DEBUG librespot_core::http_client] Requesting https://apresolve.spotify.com/?type=accesspoint&type=dealer&type=spclient
[2024-09-20T22:41:44Z INFO  librespot_core::session] Connecting to AP "ap-gew1.spotify.com:4070"
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Retry access point...
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z WARN  librespot_core::session] Try another access point...
[2024-09-20T22:41:44Z INFO  librespot_core::session] Connecting to AP "ap-gew1.spotify.com:443"
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Retry access point...
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z WARN  librespot_core::session] Try another access point...
[2024-09-20T22:41:44Z INFO  librespot_core::session] Connecting to AP "ap-gew1.spotify.com:80"
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Retry access point...
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Connection failed: Connection refused (os error 111)
[2024-09-20T22:41:44Z WARN  librespot_core::session] Try another access point...
[2024-09-20T22:41:44Z INFO  librespot_core::session] Connecting to AP "ap-guc3.spotify.com:4070"
[2024-09-20T22:41:44Z DEBUG librespot_core::connection] Authenticating with AP using AUTHENTICATION_STORED_SPOTIFY_CREDENTIALS
[2024-09-20T22:41:45Z INFO  librespot_core::session] Authenticated as 'XXX' !

When using bad credentials, it does not retry:

[2024-09-20T23:12:15Z DEBUG librespot_core::http_client] Requesting https://apresolve.spotify.com/?type=accesspoint&type=dealer&type=spclient
[2024-09-20T23:12:15Z INFO  librespot_core::session] Connecting to AP "ap-gew1.spotify.com:4070"
[2024-09-20T23:12:15Z DEBUG librespot_core::connection] Authenticating with AP using AUTHENTICATION_SPOTIFY_TOKEN
[2024-09-20T23:12:15Z ERROR librespot] could not initialize spirc: Permission denied { Login failed with reason: Bad credentials }

[kingosticks]

@michaelherger I re-implemented this after realising it was retrying even when the auth failed due to a bad login, and it was also looping around the access points forever.

[michaelherger]

I'm away for the weekend... with limited internet access. I'll look into this ASAP. Thanks a ton!

[michaelherger]

My Rust is very limited... I probably learned more from that PR than I knew before 🤦🏻.

But given my limited understanding I believe the change makes sense. See inline comments for some validation of my assumptions. Thanks!

[michaelherger]

...and testing the code I'm already seeing a first "Connection refused" event fixed by this patch. 👍🏻

[roderickvd]

So, good to merge?

Depending on the discussion with login5, this could be a good last one to get in before v0.5. I feel like Spotify's infra error was good fortune, so people switched to dev and gave it a good shakedown.

[michaelherger]

So, good to merge?

If @kingosticks can confirm my assumptions, then I'd be happy to have this merged! It clearly improves behaviour for my use case.

Depending on the discussion with login5, this could be a good last one to get in before v0.5. I feel like Spotify's infra error was good fortune, so people switched to dev and gave it a good shakedown.

I feel caught out 😁.

[michaelherger]

FWIW: I've now played about 70 tracks without hiccup, for which librespot needed to re-try three times. Great job!

[michaelherger]

Thanks for the clarifications!

IMHO good to merge.