Simplifies Platform Specific Interface Creation

The interface `Config` object is now passed directly into each creation
function in order to more easily use additional options.

In addition, the linux and darwin parameters were split to better
capture different options for each platform.

if.go

@@ -2,6 +2,7 @@ package water
 
 import (
 	"io"
+	"errors"
 )
 
 // Interface is a TUN/TAP interface.
@@ -48,7 +49,14 @@ func New(config Config) (ifce *Interface, err error) {
 	if zeroConfig == config {
 		config = defaultConfig()
 	}
-	return newDev(config)
+	switch config.DeviceType {
+	case TUN:
+		return newTUN(config)
+	case TAP:
+		return newTAP(config)
+	default:
+		return nil, errors.New("unknown device type")
+	}
 }
 
 // IsTUN returns true if ifce is a TUN interface.
@@ -65,3 +73,5 @@ func (ifce *Interface) IsTAP() bool {
 func (ifce *Interface) Name() string {
 	return ifce.name
 }
+
+

if_unix.go

@@ -1,16 +0,0 @@
-// +build linux darwin
-
-package water
-
-import "errors"
-
-func newDev(config Config) (ifce *Interface, err error) {
-	switch config.DeviceType {
-	case TUN:
-		return newTUN(config.Name)
-	case TAP:
-		return newTAP(config.Name)
-	default:
-		return nil, errors.New("unknown device type")
-	}
-}

if_windows.go

@@ -1,12 +0,0 @@
-// +build windows
-
-package water
-
-import "errors"
-
-func newDev(config Config) (ifce *Interface, err error) {
-	if config.DeviceType != TAP && config.DeviceType != TUN {
-		return nil, errors.New("unknown device type")
-	}
-	return openDev(config)
-}

params_darwin.go

@@ -0,0 +1,13 @@
+
+package water
+
+// PlatformSpecificParams defines parameters in Config that are specific to
+// macOS. A zero-value of such type is valid, yielding an interface
+// with OS defined name.
+// Currently it is not possible to set the interface name in macOS.
+type PlatformSpecificParams struct {
+}
+
+func defaultPlatformSpecificParams() PlatformSpecificParams {
+	return PlatformSpecificParams{}
+}

params_linux.go

@@ -1,9 +1,8 @@
-// +build linux darwin
 
 package water
 
 // PlatformSpecificParams defines parameters in Config that are specific to
-// Linux and macOS. A zero-value of such type is valid, yielding an interface
+// Linux. A zero-value of such type is valid, yielding an interface
 // with OS defined name.
 type PlatformSpecificParams struct {
 	// Name is the name to be set for the interface to be created. This overrides

syscalls_darwin.go

@@ -61,7 +61,7 @@ type sockaddrCtl struct {
 
 var sockaddrCtlSize uintptr = 32
 
-func newTUN(string) (ifce *Interface, err error) {
+func newTUN(config Config) (ifce *Interface, err error) {
 	var fd int
 	// Supposed to be socket(PF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL), but ...
 	//
@@ -122,6 +122,10 @@ func newTUN(string) (ifce *Interface, err error) {
 	}, nil
 }
 
+func newTAP(config Config) (ifce *Interface, err error) {
+	return nil, errors.New("tap interface not implemented on this platform")
+}
+
 // tunReadCloser is a hack to work around the first 4 bytes "packet
 // information" because there doesn't seem to be an IFF_NO_PI for darwin.
 type tunReadCloser struct {
@@ -189,7 +193,3 @@ func (t *tunReadCloser) Close() error {
 
 	return t.f.Close()
 }
-
-func newTAP(ifName string) (ifce *Interface, err error) {
-	return nil, errors.New("tap interface not implemented on this platform")
-}

syscalls_linux.go

@@ -21,12 +21,12 @@ type ifReq struct {
 	pad   [0x28 - 0x10 - 2]byte
 }
 
-func newTAP(ifName string) (ifce *Interface, err error) {
+func newTAP(config Config) (ifce *Interface, err error) {
 	file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
-	name, err := createInterface(file.Fd(), ifName, cIFF_TAP|cIFF_NO_PI)
+	name, err := createInterface(file.Fd(), config.Name, cIFF_TAP|cIFF_NO_PI)
 	if err != nil {
 		return nil, err
 	}
@@ -34,12 +34,12 @@ func newTAP(ifName string) (ifce *Interface, err error) {
 	return
 }
 
-func newTUN(ifName string) (ifce *Interface, err error) {
+func newTUN(config Config) (ifce *Interface, err error) {
 	file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
-	name, err := createInterface(file.Fd(), ifName, cIFF_TUN|cIFF_NO_PI)
+	name, err := createInterface(file.Fd(), config.Name, cIFF_TUN|cIFF_NO_PI)
 	if err != nil {
 		return nil, err
 	}

syscalls_other.go

@@ -4,10 +4,10 @@ package water
 
 import "errors"
 
-func newTAP(ifName string) (ifce *Interface, err error) {
+func newTAP(config Config) (ifce *Interface, err error) {
 	return nil, errors.New("tap interface not implemented on this platform")
 }
 
-func newTUN(ifName string) (ifce *Interface, err error) {
+func newTUN(config Config) (ifce *Interface, err error) {
 	return nil, errors.New("tap interface not implemented on this platform")
 }

syscalls_windows.go

@@ -289,14 +289,10 @@ func openDev(config Config) (ifce *Interface, err error) {
 	return nil, errIfceNameNotFound
 }
 
-func newTAP(ifName string) (ifce *Interface, err error) {
+func newTAP(config Config) (ifce *Interface, err error) {
-	config := defaultConfig()
-	config.DeviceType = TAP
 	return openDev(config)
 }
 
-func newTUN(ifName string) (ifce *Interface, err error) {
+func newTUN(config Config) (ifce *Interface, err error) {
-	config := defaultConfig()
-	config.DeviceType = TUN
 	return openDev(config)
 }