Tunnel client socket stays in ESATBLISHED state on removing/deleting target

[Shikha-Chowdhary]

I am using C++ client (my network element) with gNMIC tunnel server

• Subscription works, but I am unable to close client socket when deleting/removing target at my network element.
• Is there any specific sequence which one need to follow while deleting/removing target from tunnel client?
• GNMIC traces show that client has been closed, but the client socket remains in ESTABLISHED state

} ] } 2023/06/12 10:54:25.790673 /home/runner/go/pkg/mod/google.golang.org/grpc@v1.54.0/grpclog/logger.go:53: [gnmic] [transport] transport: closing: connection error: desc = "error reading from server: EOF" 2023/06/12 10:54:25.790737 /home/runner/go/pkg/mod/google.golang.org/grpc@v1.54.0/grpclog/logger.go:53: [gnmic] [core] [Channel #8 SubChannel #9] Subchannel Connectivity change to IDLE 2023/06/12 10:54:25.790807 /home/runner/go/pkg/mod/google.golang.org/grpc@v1.54.0/grpclog/logger.go:53: [gnmic] [core] pickfirstBalancer: UpdateSubConnState: 0xc000c20300, {IDLE } 2023/06/12 10:54:25.790851 /home/runner/go/pkg/mod/google.golang.org/grpc@v1.54.0/grpclog/logger.go:53: [gnmic] [core] [Channel #8] Channel Connectivity change to IDLE 2023/06/12 10:54:25.790847 /home/runner/work/gnmic/gnmic/app/collector.go:111: [gnmic] target "OME-000102031000": subscription default-1686576182 rcv error: rpc error: code = Unavailable desc = error reading from server: EOF 2023/06/12 10:54:25.790881 /home/runner/work/gnmic/gnmic/app/collector.go:111: [gnmic] target "OME-000102031000": subscription default-1686576182 rcv error: retrying in 10s 2023/06/12 10:54:25.790861 /home/runner/go/pkg/mod/google.golang.org/grpc@v1.54.0/grpclog/logger.go:53: [gnmic] [transport] transport: loopyWriter exiting with error: transport closed by client 2023/06/12 10:54:30.846313 /home/runner/work/gnmic/gnmic/app/tunnel.go:169: [gnmic] tunnel server target {ID:OME-000102031000 Type:GNMI_GNOI} deregister request client 192.168.0.16:53564 is not in subsc1aq1qription list

• Tunnel client netstat, socket remains in ESTABLISHED state only
  TCP 0 0 ::ffff:192.168.0.16.56027 ::ffff:10.179.193.207.50051 ESTABLISHED
  TCP 0 0 ::ffff:192.168.0.16.53564 ::ffff:10.179.193.207.50051 ESTABLISHED

• Whereas on Ctrl-C at GNMIC, the tunnel client socket goes to CLOSE_WAIT state forever.

• Also, is there any minimum gRPC stack and gnmi.proto version which is needed for tunnel.proto to work ? Here are the version details
  1)gRPC stack : 1.0.0
  2)gnmi.proto : 0.7.0
  3)tunnel.proto : 0.1
  4)GNMIC : 0.31.0