Check what happens on Linux in terms of connectivity on wakeup

[mrekucci]

• what signal is received after wakening up from sleep
• isNetworkError returns true when the network interface is being disabled: https://github.com/ethersphere/bee/blob/master/pkg/topology/kademlia/kademlia.go#L1626
• do we get notifications about disconnections from libp2p: https://github.com/ethersphere/bee/blob/master/pkg/topology/kademlia/kademlia.go#L1132
• is there a way to somehow safely assume whether the computer is connected to the network

[notanatol]

confirmed that on Linux the resume signal is syscall.SIGCONT (12)

[notanatol]

@mrekucci I've been looking into the last point, trying to asses if we are connected to a network. So basically there are two layer:

• We can asses whether there is a network interface with an 192.168.0.16/24 ip.
• We can asses whether the network interface is enabled by checking if it has an IPv6 address assigned.
• We can asses if we have access to the wider network by trying to resolve (or Dial) to an external host.

Not sure which one is the right way to go.

[notanatol]

not sure if the second point was a question, but I double checked.

if the network interface is down then the error returned is being successfully detected by topology.isNetworkError