feat: Add flags to enable multi-conn support

Author: pojntfx

README.md

@@ -190,7 +190,7 @@ $ rm -f disk.img && truncate -s 10G disk.img && go run ./cmd/go-nbd-example-serv
 $ go run ./cmd/go-nbd-example-server-memory .
 
 # With the C NBD client
-$ sudo umount ~/Downloads/mnt; sudo nbd-client -d /dev/nbd1 && echo 'NBD starting' | sudo tee /dev/kmsg && sudo nbd-client -N default localhost 10809
+$ sudo umount ~/Downloads/mnt; sudo nbd-client -d /dev/nbd1 && echo 'NBD starting' | sudo tee /dev/kmsg && sudo nbd-client -N default localhost 10809 /dev/nbd1
 
 # With the Go NBD client
 $ sudo umount ~/Downloads/mnt; go build -o /tmp/go-nbd-example-client ./cmd/go-nbd-example-client/ && sudo /tmp/go-nbd-example-client --file /dev/nbd1

cmd/go-nbd-example-server-file/main.go

@@ -21,6 +21,7 @@ func main() {
 	minimumBlockSize := flag.Uint("minimum-block-size", 1, "Minimum block size")
 	preferredBlockSize := flag.Uint("preferred-block-size", client.MaximumBlockSize, "Preferred block size")
 	maximumBlockSize := flag.Uint("maximum-block-size", 0xffffffff, "Maximum block size")
+	multiConn := flag.Bool("multi-conn", true, "Whether to advertise support for multiple simultaneous connections")
 
 	flag.Parse()
 
@@ -88,6 +89,7 @@ func main() {
 					MinimumBlockSize:   uint32(*minimumBlockSize),
 					PreferredBlockSize: uint32(*preferredBlockSize),
 					MaximumBlockSize:   uint32(*maximumBlockSize),
+					SupportsMultiConn:  *multiConn,
 				}); err != nil {
 				panic(err)
 			}

cmd/go-nbd-example-server-memory/main.go

@@ -20,6 +20,7 @@ func main() {
 	minimumBlockSize := flag.Uint("minimum-block-size", 1, "Minimum block size")
 	preferredBlockSize := flag.Uint("preferred-block-size", client.MaximumBlockSize, "Preferred block size")
 	maximumBlockSize := flag.Uint("maximum-block-size", 0xffffffff, "Maximum block size")
+	multiConn := flag.Bool("multi-conn", true, "Whether to advertise support for multiple simultaneous connections")
 
 	flag.Parse()
 
@@ -73,6 +74,7 @@ func main() {
 					MinimumBlockSize:   uint32(*minimumBlockSize),
 					PreferredBlockSize: uint32(*preferredBlockSize),
 					MaximumBlockSize:   uint32(*maximumBlockSize),
+					SupportsMultiConn:  *multiConn,
 				}); err != nil {
 				panic(err)
 			}