Support nopi mode

diff --git a/tun_linux.go b/tun_linux.go
index 97973a73f8087ae8f7a5101639ef610b2cd4469f..da53907b043f045615ed129c08da8a524f93392c 100644 (file)
--- a/tun_linux.go
+++ b/tun_linux.go
@@ -27,6 +27,7 @@ type NativeTun struct {
        name   string        // name of interface
        errors chan error    // async error handling
        events chan TUNEvent // device related events
+       nopi   bool          // the device was pased IFF_NO_PI
 }
 
 func toRTMGRP(sc uint) uint {
@@ -242,21 +243,25 @@ func (tun *NativeTun) MTU() (int, error) {
 
 func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
 
-       // reserve space for header
+       if tun.nopi {
+               buff = buff[offset:]
+       } else {
+               // reserve space for header
 
-       buff = buff[offset-4:]
+               buff = buff[offset-4:]
 
-       // add packet information header
+               // add packet information header
 
-       buff[0] = 0x00
-       buff[1] = 0x00
+               buff[0] = 0x00
+               buff[1] = 0x00
 
-       if buff[4] == ipv6.Version<<4 {
-               buff[2] = 0x86
-               buff[3] = 0xdd
-       } else {
-               buff[2] = 0x08
-               buff[3] = 0x00
+               if buff[4] == ipv6.Version<<4 {
+                       buff[2] = 0x86
+                       buff[3] = 0xdd
+               } else {
+                       buff[2] = 0x08
+                       buff[3] = 0x00
+               }
        }
 
        // write
@@ -269,12 +274,16 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
        case err := <-tun.errors:
                return 0, err
        default:
-               buff := buff[offset-4:]
-               n, err := tun.fd.Read(buff[:])
-               if n < 4 {
-                       return 0, err
+               if tun.nopi {
+                       return tun.fd.Read(buff[offset:])
+               } else {
+                       buff := buff[offset-4:]
+                       n, err := tun.fd.Read(buff[:])
+                       if n < 4 {
+                               return 0, err
+                       }
+                       return n - 4, err
                }
-               return n - 4, err
        }
 }
 
@@ -292,6 +301,7 @@ func CreateTUNFromFile(name string, fd *os.File) (TUNDevice, error) {
                name:   name,
                events: make(chan TUNEvent, 5),
                errors: make(chan error, 5),
+               nopi:   false,
        }
 
        // start event listener
@@ -349,6 +359,7 @@ func CreateTUN(name string) (TUNDevice, error) {
                name:   newName,
                events: make(chan TUNEvent, 5),
                errors: make(chan error, 5),
+               nopi:   false,
        }
 
        // start event listener