Moved linux specific code to the syscalls_linux.go file. Also removed unneeded constants from the syscalls_other.go file.

if.go

@@ -15,32 +15,14 @@ type Interface struct {
 // If ifName is empty, a default name (tap0, tap1, ... ) will be assigned.
 // ifName should not exceed 16 bytes.
 func NewTAP(ifName string) (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)
-	if err != nil {
-		return nil, err
-	}
-	ifce = &Interface{isTAP: true, file: file, name: name}
-	return
+	return newTAP(ifName)
 }
 
 // Create a new TUN interface whose name is ifName.
 // If ifName is empty, a default name (tap0, tap1, ... ) will be assigned.
 // ifName should not exceed 16 bytes.
 func NewTUN(ifName string) (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)
-	if err != nil {
-		return nil, err
-	}
-	ifce = &Interface{isTAP: false, file: file, name: name}
-	return
+	return newTUN(ifName)
 }
 
 // Returns true if ifce is a TUN interface, otherwise returns false;

syscalls_linux.go

@@ -3,6 +3,7 @@
 package water
 
 import (
+	"os"
 	"strings"
 	"syscall"
 	"unsafe"
@@ -20,6 +21,32 @@ type ifReq struct {
 	pad   [0x28 - 0x10 - 2]byte
 }
 
+func newTAP(ifName string) (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)
+	if err != nil {
+		return nil, err
+	}
+	ifce = &Interface{isTAP: true, file: file, name: name}
+	return
+}
+
+func newTUN(ifName string) (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)
+	if err != nil {
+		return nil, err
+	}
+	ifce = &Interface{isTAP: false, file: file, name: name}
+	return
+}
+
 func createInterface(fd uintptr, ifName string, flags uint16) (createdIFName string, err error) {
 	var req ifReq
 	req.Flags = flags

syscalls_other.go

@@ -2,18 +2,10 @@
 
 package water
 
-const (
-	cIFF_TUN   = 0
-	cIFF_TAP   = 0
-	cIFF_NO_PI = 0
-)
-
-type ifReq struct {
-	Name  [0]byte
-	Flags uint16
-	pad   [0]byte
+func newTAP(ifName string) (ifce *Interface, err error) {
+	panic("water: tap interface not implemented on this platform")
 }
 
-func createInterface(fd uintptr, ifName string, flags uint16) (createdIFName string, err error) {
-	panic("water: createInterface not implemented on this platform")
-}
+func newTUN(ifName string) (ifce *Interface, err error) {
+	panic("water: tap interface not implemented on this platform")
+}

waterutil/doc.go

@@ -8,10 +8,10 @@ TAP - MAC Frame:
   +-----------------------------------------------------------------------------
   | Octet |00|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|...
   +-----------------------------------------------------------------------------
-  | Field | MAC Destination |   MAC  Source   |EType| Payload        
+  | Field | MAC Destination |   MAC  Source   |EType| Payload
   +-----------------------------------------------------------------------------
 
-   Single-Tagged -- Octets [12,13] == {0x81, 0x00} 
+   Single-Tagged -- Octets [12,13] == {0x81, 0x00}
   +-----------------------------------------------------------------------------
   | Octet |00|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|...
   +-----------------------------------------------------------------------------
@@ -22,7 +22,7 @@ TAP - MAC Frame:
   +-----------------------------------------------------------------------------
   | Octet |00|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|...
   +-----------------------------------------------------------------------------
-  | Field | MAC Destination |   MAC  Source   | Outer Tag | Inner Tag | Payload        
+  | Field | MAC Destination |   MAC  Source   | Outer Tag | Inner Tag | Payload
   +-----------------------------------------------------------------------------
 
 TUN - IPv4 Packet: