connection refused when updating index

[Sw3d15h-F1s4]

Describe the problem

When running arduino-cli core update-index

Downloading index: library_index.tar.bz2 Get "https://downloads.arduino.cc/libraries/library_index.tar.bz2": dial tcp: lookup downloads.arduino.cc on [::1]:53: read udp [::1]:54136->[::1]:53: read: connection refused Error updating indexes: Error downloading index 'https://downloads.arduino.cc/libraries/library_index.tar.bz2': Get "https://downloads.arduino.cc/libraries/library_index.tar.bz2": dial tcp: lookup downloads.arduino.cc on [::1]:53: read udp [::1]:54136->[::1]:53: read: connection refused

To reproduce

installed linux arm64 binary from arduino.github.io's installation instructions, moved it to /bin and executed. seems to work fine otherwise. ran arduino-cli config init as well.

Expected behavior

i expect it to update the board index

Arduino CLI version

arduino-cli Version: 0.32.2 Commit: 2661f5d Date: 2023-04-12T09:41:53Z

Operating system

Linux

Operating system version

linux aarch64 5.4.147-qgki-25884040-abT733XXU2CWC5

Additional context

No response

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the nightly build
• My report contains all necessary details

[cmaglie]

This looks like a network configuration problem:

dial tcp: lookup downloads.arduino.cc on [::1]:53: read udp [::1]:54136->[::1]:53: read: connection refused

Arduino CLI cannot resolve the name downloads.arduino.cc.
Does ping downloads.arduino.cc works?

[codeandfire]

Hi, I'm having the same issue; tried the Nightly version, v0.32.2, and v0.31.0.

ping downloads.arduino.cc works, though it seems to be a bit slow:

PING downloads.arduino.cc.cdn.cloudflare.net (104.18.12.241) 56(84) bytes of data.
64 bytes from 104.18.12.241 (104.18.12.241): icmp_seq=1 ttl=53 time=38.7 ms
64 bytes from 104.18.12.241 (104.18.12.241): icmp_seq=2 ttl=53 time=41.3 ms
64 bytes from 104.18.12.241 (104.18.12.241): icmp_seq=3 ttl=53 time=39.7 ms
^C64 bytes from 104.18.12.241: icmp_seq=4 ttl=53 time=37.8 ms

--- downloads.arduino.cc.cdn.cloudflare.net ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 23270ms
rtt min/avg/max/mdev = 37.827/39.388/41.293/1.288 ms

I'm also able to manually download that file (https://downloads.arduino.cc/libraries/library_index.tar.bz2), if that helps.

[cmaglie]

Do you have an error similar to the following?

dial tcp: lookup downloads.arduino.cc on [::1]:53: read udp [::1]:54136->[::1]:53: read: connection refused

if yes, could you paste the output of:

sudo netstat -puntl

and

dig downloads.arduino.cc

[codeandfire]

@cmaglie thanks for responding.

Do you have an error similar to the following?

dial tcp: lookup downloads.arduino.cc on [::1]:53: read udp [::1]:54136->[::1]:53: read: connection refused

Yes, precisely.

if yes, could you paste the output of:

sudo netstat -puntl

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.54:53           0.0.0.0:*               LISTEN      428/systemd-resolve 
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      428/systemd-resolve 
tcp        0      0 0.0.0.0:5355            0.0.0.0:*               LISTEN      428/systemd-resolve 
tcp6       0      0 :::5355                 :::*                    LISTEN      428/systemd-resolve 
udp        0      0 127.0.0.54:53           0.0.0.0:*                           428/systemd-resolve 
udp        0      0 127.0.0.53:53           0.0.0.0:*                           428/systemd-resolve 
udp        0      0 192.168.1.7:68          0.0.0.0:*                           488/iwd             
udp        0      0 0.0.0.0:5353            0.0.0.0:*                           428/systemd-resolve 
udp        0      0 0.0.0.0:5355            0.0.0.0:*                           428/systemd-resolve 
udp6       0      0 :::5353                 :::*                                428/systemd-resolve 
udp6       0      0 :::5355                 :::*                                428/systemd-resolve 

and

dig downloads.arduino.cc

;; communications error to ::1#53: connection refused
;; communications error to ::1#53: connection refused
;; communications error to ::1#53: connection refused
;; communications error to 127.0.0.1#53: connection refused

; <<>> DiG 9.18.14 <<>> downloads.arduino.cc
;; global options: +cmd
;; no servers could be reached

[cmaglie]

The fact that dig cannot resolve the name smells like a system configuration problem:

;; communications error to ::1#53: connection refused

this is basically the same error happening in the Arduino CLI.
The CLI is trying to resolve the name using the DNS server on 127.0.0.1:53 (AKA [::1]:53), while systemd-resolved is listening to 127.0.0.53:53 and 127.0.0.54:53 (?), this is causing the connection refused error.

At this point, I think that /etc/resolv.conf file is not updated for some reason. To verify it could you paste the output of:

cat /etc/resolv.conf

?

[cmaglie]

Also knowing the Linux distribution may help to find if there are open bugs.

[codeandfire]

Thank you for the explanation! I have a fresh Arch Linux installation so /etc/resolv.conf is basically empty:

$ cat /etc/resolv.conf 
# Resolver configuration file.
# See resolv.conf(5) for details.

Is that the problem? I am not facing network issues anywhere else - am able to browse normally, etc. - so I wasn't suspecting network configuration issues on my end.

[cmaglie]

Actually, I don't know if this is a configuration problem or an issue in the CLI.

In the CLI we are using the golang standard net.Dial function to connect to the download server, it should use the configured DNS resolver, but at this point, I don't know how it is determined. I'm an old-style UNIX admin, so I thought it was written in /etc/resolv.conf but based on your feedback, I see that there are other ways to get the configured DNS nowadays :-).

I found this doc: https://wiki.archlinux.org/title/NetworkManager#/etc/resolv.conf
So, maybe, an additional config should be made based on your setup?

Also on my Ubuntu resolv.conf is symlinked to systemd-resolved stub:

$ ls -l /etc/resolv.conf 
lrwxrwxrwx 1 root root 39 dic 14 00:04 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

Maybe doing the same would fix your issue. I don't know, just trying to figure out the best workaround...

[Sw3d15h-F1s4]

Ok, so after some searching, reading, and learning, I think I know what my issue is. I'm trying to run the arduino cli on Android through Termux, which has many differences from regular Linux (such as no etc/resolv.conf and using different c libraries instead of gcc). Now I don't need to compile, I was just trying to use arduino-cli to set up arduino-language-server for neovim (surprisingly neovim is quite nice to use on Android, other than lsp installation and setup being harder than usual) since I wanted to be able to contribute to my team's arduino sketches while on the move at college. Yeah, ik, dumb to run this on android, whatever. For anyone in the same boat, platformio works a little better for Android since it uses regular .cpp files, and you can set up clangd or whatever else like normal (only get a mild issue of no thread api but again you shouldn't need to compile from an android device, like how are you going to push code to the board your USB ports are a challenge to access through termux). Anyway, sorry for the trouble. I'm a noob to Linux, and figured throwing myself in the deep end on Termux might learn me something. Hope yall have a nice day.

[codeandfire]

@cmaglie symlinking /etc/resolv.conf to /run/systemd/resolve/stub-resolv.conf worked for me ... Thank you very much for your help!

[cmaglie]

Thanks for the feedback!
Since it seems resolved in one way or another, I'm closing the issue.