04dbdd613fe5c0a742de915e07553614cd4cbf46 [net] SocketHandler: log peer id for close and disconnect (Sjors Provoost)
Pull request description:
When combined with `-logips` this makes it easier to diagnose disconnects.
To test on macOS, find a connection you want to disrupt:
```
lsof -nP -iTCP:8333 -sTCP:ESTABLISHED
```
To shut it down gracefully you can use tcpkill or this Python script: https://github.com/google/tcp_killer
The log should say:
```
2019-10-25T13:26:55Z socket closed for peer=1
2019-10-25T13:26:55Z disconnecting peer=1
2019-10-25T13:26:55Z Cleared nodestate for peer=1
```
To shut it down ungracefully I made a patch to the above script, adding a `-force` argument. _Careful, this may result in data corruption_. Then the log should say:
```
2019-10-25T13:39:57Z socket select error Bad file descriptor (9)
2019-10-25T13:39:57Z socket recv error for peer=0: Bad file descriptor (9)
2019-10-25T13:39:57Z disconnecting peer=0
2019-10-25T13:39:57Z Socket close failed: 35. Error: Bad file descriptor (9)
2019-10-25T13:39:57Z Cleared nodestate for peer=0
```
Backport of Core PR17251