Throw exception on read failure (one of them atleast when status < 0)

Added close method to close tun interface

source/libtun/adapter.d

@@ -55,6 +55,7 @@ public class TUNAdapter
     {
         sanityCheck();
 
+        /* TODO: Get device MTU and add functions for setting it */
         ushort mtu = cast(ushort)-1;
 
         /* Temporary scratchpad buffer */
@@ -75,7 +76,7 @@ public class TUNAdapter
       
         if(status < 0)
         {
-
+            throw new TUNException("Read failed");
         }
         else if(status == 0)
         {
@@ -103,6 +104,16 @@ public class TUNAdapter
 
         tunWrite(tunFD, cast(char*)buffer.ptr, cast(int)buffer.length);
     }
+
+    public void close()
+    {
+        int status = destroyTun(tunFD);
+
+        if(status)
+        {
+            throw new TUNException("Closing tun interface failed");
+        }
+    }
 }
 
 public final class TUNException : Exception

source/libtun/tunctl.c

@@ -50,7 +50,7 @@ int createTun(char* interfaceName, int iffFlags)
 
 int destroyTun(int fd)
 {
-    return 68;
+    return close(fd);
 }
 
 int tunWrite(int fd, char* data, int length)