Add support for Windows to allow selecting between multiple tap0901 adapters on the same system

CONTRIBUTORS

@@ -10,3 +10,5 @@ ajee cai <ajee.cai@gmail.com>
 yinheli <hi@yinheli.com>
 Paul Querna <pquerna@apache.org>
 Cuong Manh Le <cuong.manhle.vn@gmail.com>
+Neil Alexander <neilalexander@users.noreply.github.com>
+Dmitry Shihovtsev <soffokulus@gmail.com>

README.md

@@ -220,6 +220,21 @@ ping 10.1.0.255
 
 You'll see output containing the IPv4 ICMP frame same as the Linux version.
 
+#### Specifying interface name
+
+If you are going to use multiple TAP devices on the Windows, there is a way to specify an interface name to select the exact device that you need:
+
+```go
+ ifce, err := water.New(water.Config{
+ DeviceType: water.TAP,
+ PlatformSpecificParams: water.PlatformSpecificParams{
+ ComponentID: "tap0901",
+ InterfaceName: "Ethernet 3",
+ Network: "192.168.1.10/24",
+ },
+ })
+```
+
 ## TODO
 * tuntaposx for TAP on Darwin
 

params_windows.go

@@ -9,6 +9,10 @@ type PlatformSpecificParams struct {
  // use the default ComponentId. The default ComponentId is set to tap0901,
  // the one used by OpenVPN.
  ComponentID string
+ // InterfaceName is a friendly name of the network adapter as set in Control Panel.
+ // Of course, you may have multiple tap0901 adapters on the system, in which
+ // case we need a friendlier way to identify them.
+ InterfaceName string
  // Network is required when creating a TUN interface. The library will call
  // net.ParseCIDR() to parse this string into LocalIP, RemoteNetaddr,
  // RemoteNetmask. The underlying driver will need those to generate ARP

syscalls_windows.go

@@ -17,6 +17,11 @@ import (
 // or just install OpenVPN
 // https://github.com/OpenVPN/openvpn
 
+const (
+ // tapDriverKey is a location of the TAP driver key.
+ tapDriverKey = `SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}`
+)
+
 var (
  errIfceNameNotFound = errors.New("Failed to find the name of interface")
  // Device Control Codes
@@ -139,10 +144,8 @@ func tap_control_code(request, method uint32) uint32 {
 }
 
 // getdeviceid finds out a TAP device from registry, it *may* requires privileged right to prevent some weird issue.
-func getdeviceid(componentID string) (deviceid string, err error) {
- // TAP driver key location
- regkey := `SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}`
- k, err := registry.OpenKey(registry.LOCAL_MACHINE, regkey, registry.READ)
+func getdeviceid(componentID string, interfaceName string) (deviceid string, err error) {
+ k, err := registry.OpenKey(registry.LOCAL_MACHINE, tapDriverKey, registry.READ)
  if err != nil {
  return "", fmt.Errorf("Failed to open the adapter registry, TAP driver may be not installed, %v", err)
  }
@@ -154,7 +157,7 @@ func getdeviceid(componentID string) (deviceid string, err error) {
  }
  // find the one matched ComponentId
  for _, v := range keys {
- key, err := registry.OpenKey(registry.LOCAL_MACHINE, regkey+"\\"+v, registry.READ)
+ key, err := registry.OpenKey(registry.LOCAL_MACHINE, tapDriverKey+"\\"+v, registry.READ)
  if err != nil {
  continue
  }
@@ -169,12 +172,28 @@ func getdeviceid(componentID string) (deviceid string, err error) {
  key.Close()
  continue
  }
+ if len(interfaceName) > 0 {
+ key2 := fmt.Sprintf("%s\\%s\\Connection", tapDriverKey, val)
+ k2, err := registry.OpenKey(registry.LOCAL_MACHINE, key2, registry.READ)
+ if err != nil {
+ continue
+ }
+ defer k2.Close()
+ val, _, err := k2.GetStringValue("Name")
+ if err != nil || val != interfaceName {
+ continue
+ }
+ }
  key.Close()
  return val, nil
  }
  key.Close()
  }
- return "", fmt.Errorf("Failed to find the tap device in registry with specified ComponentId(%s), TAP driver may be not installed", componentID)
+ if len(interfaceName) > 0 {
+ return "", fmt.Errorf("Failed to find the tap device in registry with specified ComponentId '%s' and InterfaceName '%s', TAP driver may be not installed or you may have specified an interface name that doesn't exist", componentID, interfaceName)
+ }
+
+ return "", fmt.Errorf("Failed to find the tap device in registry with specified ComponentId '%s', TAP driver may be not installed", componentID)
 }
 
 // setStatus is used to bring up or bring down the interface
@@ -216,7 +235,7 @@ func setTUN(fd syscall.Handle, network string) error {
 // openDev find and open an interface.
 func openDev(config Config) (ifce *Interface, err error) {
  // find the device in registry.
- deviceid, err := getdeviceid(config.PlatformSpecificParams.ComponentID)
+ deviceid, err := getdeviceid(config.PlatformSpecificParams.ComponentID, config.PlatformSpecificParams.InterfaceName)
  if err != nil {
  return nil, err
  }