Local discovery problem on Android 11

Support Android
#1

Hello all,

I am using the syncthing-fork for android and local discovery is not working (see also here: 735#) I have these logs when I activated beacon logs:

2020-12-29 11:44:31 Enabled debug data for "beacon"
2020-12-29 11:44:33 route ip+net: netlinkrib: permission denied
2020-12-29 11:44:33 Stopped broadcastBeacon writer: route ip+net: netlinkrib: permission denied
2020-12-29 11:44:33 broadcastBeacon: Failed service 'Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer' (1.999843 failures of 2.000000), restarting: true, error: "{Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer} returned unexpectedly", stacktrace: [unknown stack trace]
2020-12-29 11:44:33 Starting broadcastBeacon writer
2020-12-29 11:45:03 route ip+net: netlinkrib: permission denied
2020-12-29 11:45:03 Stopped broadcastBeacon writer: route ip+net: netlinkrib: permission denied
2020-12-29 11:45:03 broadcastBeacon: Failed service 'Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer' (1.999810 failures of 2.000000), restarting: true, error: "{Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer Service@0x40000d66c0 created by broadcastBeacon@0x4000138230/writer} returned unexpectedly", stacktrace: [unknown stack trace]
2020-12-29 11:45:03 Starting broadcastBeacon writer
2020-12-29 11:45:31 Exiting backoff state.
2020-12-29 11:45:31 Starting multicastBeacon writer
2020-12-29 11:45:31 Starting multicastBeacon reader
2020-12-29 11:45:31 route ip+net: netlinkrib: permission denied
2020-12-29 11:45:31 Stopped multicastBeacon writer: route ip+net: netlinkrib: permission denied
2020-12-29 11:45:31 multicastBeacon: Failed service 'Service@0x40000d6d80 created by multicastBeacon@0x40001382d0/writer' (1.000000 failures of 2.000000), restarting: true, error: "{Service@0x40000d6d80 created by

When you need more information, please let me know.

#2

Hi, does any “Android freak” know if there have been changes to broadcast restrictions in Android 11? I’m still on 10 using a Xiaomi phone and local discovery works as expected. I can’t test this with 11 on the emulator as it does NAT the virtual phone “to” my physical computers running Syncthing. Could this also be a bug in Synching or does the error point to the OS as cause?

I know of generic restrictions in Android, but they were never a dealbreaker for Syncthing Android in the past, e.g. https://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock . Btw we do not aquire special multicast permissions in the app despite other big players like for example BubbleUPNP doing so to be able to use broadcasts.

#3

It seems to be working for me on Android 11.

2020-12-29 20:54:42 sent 515 bytes to 192.168.0.255:21027 2020-12-29 20:54:42 write udp [::]:43262->[ff12::8384]:21027: sendmsg: network is unreachable on write to [ff12::8384]:21027 bond0 2020-12-29 20:54:42 sent 515 bytes to [ff12::8384]:21027 on wlan0 2020-12-29 20:54:42 write udp [::]:43262->[ff12::8384]:21027: sendmsg: network is unreachable on write to [ff12::8384]:21027 wlan1 2020-12-29 20:54:42 write udp [::]:43262->[ff12::8384]:21027: sendmsg: network is unreachable on write to [ff12::8384]:21027 p2p0 2020-12-29 20:54:42 recv 515 bytes from [fe80::b479:c9ff:fe98:1b28%wlan0]:43262 2020-12-29 20:54:58 recv 452 bytes from 192.168.0.102:35263 2020-12-29 20:54:58 recv 452 bytes from [fe80::c069:fd7f:5856:50e9%wlan0]:44536

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