Panic on stopping vpn client

[ersonp]

Describe the bug
The visor panics when VPN client is stopped via UI.

Environment information:

• OS: Linux
• Platform: Linux 5.11.0-34-generic x86_64

Steps to Reproduce
Steps to reproduce the behavior:

1. Start visor A on with a vpn-server
2. Start visor B and connect to visor A via vpn-client
3. Stop vpn-client on visor B
4. See error

Note: This does not happen often. So might have to try multiple times.

Actual behavior
Deployment: myownsky (env removed), varuns deployment (more info in the PR)
Branch: 1faca3
Transport used : dmsg

[2021-09-15T15:38:27+05:30] ERROR [RouteGroup rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44]: Error during close route group: close route group timed out: context deadline exceeded
[2021-09-15T15:38:27+05:30] INFO [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Request processed. _elapsed="2.000828229s" _method="CloseConn" _received="3:38PM" input=0xc000125be8
[2021-09-15T15:38:27+05:30] INFO [RouteGroup rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44]: Remote got closed, stopping network probe loop
[2021-09-15T15:38:27+05:30] INFO [RouteGroup rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44]: Remote got closed, stopping keep-alive loop
[2021-09-15T15:38:27+05:30] WARN [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Received unexpected error when reading from server. error="io: read/write on closed pipe"
[2021-09-15T15:38:27+05:30] INFO [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Request processed. _elapsed="51.979µs" _method="SetDetailedStatus" _received="3:38PM" input=0xc0017af620
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Error resending traffic from TUN tun0 to VPN server: io: read/write on closed pipe
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Error resending traffic from VPN server to TUN tun0: read tun: file already closed
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Closed TUN
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Removing direct route to 104.21.72.123
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Removing direct route to 172.67.184.157
[2021-09-15T15:38:27+05:30] INFO (STDOUT) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: Removing direct route to 165.232.178.201
[2021-09-15T15:38:27+05:30] INFO (STDERR) [proc:vpn-client:97fb6652b50143b49de8096c9d7ecfc7]: 2021/09/15 15:38:27 rpc.Serve: accept:accept tcp 127.0.0.1:34099: use of closed network connection
2021/09/15 15:38:27 [erson-69/q8yuFPHfxL-000013] "PUT http://localhost:8000/api/visors/03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66/apps/vpn-client HTTP/1.1" from [::1]:49458 - 200 175B in 2.128615344s
[2021-09-15T15:38:28+05:30] DEBUG [transport_manager]: Locked in cleanup
[2021-09-15T15:38:28+05:30] DEBUG [transport_manager]: Unlocked in cleanup
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet header. header_len=7 header_raw=[4 0 0 0 2 0 16]
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet payload. payload_len=16
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Received packet. rt_id=2 size=16 type="NetworkProbe"
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Awaiting packet...
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet of type NetworkProbe with route ID 2
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet with descriptor rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44
[2021-09-15T15:38:28+05:30] DEBUG [router]: Got new remote packet with size 16 and route ID 2. Using rule: REV(keyRtID:2, rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44)
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet header. header_len=7 header_raw=[0 0 0 0 2 5 246]
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet payload. payload_len=1526
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Received packet. rt_id=2 size=1526 type="DataPacket"
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Awaiting packet...
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet of type DataPacket with route ID 2
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet with descriptor rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44
[2021-09-15T15:38:28+05:30] DEBUG [router]: Got new remote packet with size 1526 and route ID 2. Using rule: REV(keyRtID:2, rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44)
[2021-09-15T15:38:28+05:30] WARN [router]: Failed to handle transport frame: io: read/write on closed pipe
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet header. header_len=7 header_raw=[0 0 0 0 2 5 246]
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet payload. payload_len=1526
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Received packet. rt_id=2 size=1526 type="DataPacket"
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Awaiting packet...
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet of type DataPacket with route ID 2
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet with descriptor rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44
[2021-09-15T15:38:28+05:30] DEBUG [router]: Got new remote packet with size 1526 and route ID 2. Using rule: REV(keyRtID:2, rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44)
[2021-09-15T15:38:28+05:30] WARN [router]: Failed to handle transport frame: io: read/write on closed pipe
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet header. header_len=7 header_raw=[0 0 0 0 2 5 246]
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Read packet payload. payload_len=1526
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Received packet. rt_id=2 size=1526 type="DataPacket"
[2021-09-15T15:38:28+05:30] DEBUG readPacket [tp:03f228]: Awaiting packet...
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet of type DataPacket with route ID 2
[2021-09-15T15:38:28+05:30] DEBUG [router]: Handling packet with descriptor rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44
[2021-09-15T15:38:28+05:30] DEBUG [router]: Got new remote packet with size 1526 and route ID 2. Using rule: REV(keyRtID:2, rAddr:03c1d911914f4306bf88f3345edc856c29f9b674fba2e6009a2fe4e4a2ce22fb66:49153, lAddr:03f228c861436cb8e108739df3b74c9e444de4433b2732892d472a000aa2ac6256:44)
panic: send on closed channel

goroutine 115 [running]:
github.com/skycoin/skywire/pkg/router.(*RouteGroup).handleDataPacket(0xc0002001c0, 0xc0017e8000, 0x5fd, 0x600, 0xec, 0xc0019ddc00)
        /home/erson/Workspace/Go/skywire/pkg/router/route_group.go:624 +0x2e5
github.com/skycoin/skywire/pkg/router.(*RouteGroup).handlePacket(0xc0002001c0, 0xc0017e8000, 0x5fd, 0x600, 0x0, 0x0)
        /home/erson/Workspace/Go/skywire/pkg/router/route_group.go:588 +0x23f
github.com/skycoin/skywire/pkg/router.(*NoiseRouteGroup).handlePacket(...)
        /home/erson/Workspace/Go/skywire/pkg/router/noise_route_group.go:62
github.com/skycoin/skywire/pkg/router.(*router).handleDataHandshakePacket(0xc000396f80, 0x17aee58, 0xc00007a4c0, 0xc0017e8000, 0x5fd, 0x600, 0x43948b, 0xc00028fb00)
        /home/erson/Workspace/Go/skywire/pkg/router/router.go:524 +0xda7
github.com/skycoin/skywire/pkg/router.(*router).handleTransportPacket(0xc000396f80, 0x17aee58, 0xc00007a4c0, 0xc0017e8000, 0x5fd, 0x600, 0x179d9c0, 0xc00011a090)
        /home/erson/Workspace/Go/skywire/pkg/router/router.go:484 +0xb3
github.com/skycoin/skywire/pkg/router.(*router).serveTransportManager(0xc000396f80, 0x17aee58, 0xc00007a4c0)
        /home/erson/Workspace/Go/skywire/pkg/router/router.go:336 +0x125
created by github.com/skycoin/skywire/pkg/router.(*router).Serve
        /home/erson/Workspace/Go/skywire/pkg/router/router.go:316 +0x10e

Expected behavior
Stop app without panic.

[ersonp]

One thing that I have noticed is that vpn on stcpr runs smoothly but it runs in some (presumably) bandwidth issues on dmsg which causes the panic on app close.