Networking: If sending out of the subnet, device lookup by IP will fail. Fall back to ETH0 for now. From Max Holtzberg

ChangeLog

@@ -5642,4 +5642,9 @@
 	  definitions (2013-9-26).
 	* arch/arm/src/sama5/sam_gmac.c and include/nuttx/net/gmii.h:
 	  Beginning of support for GMII/RGMII PHY support (2013-9-26)
+	* net/netdev_txnotify.c:  Look up of device using subnet will fail
+	  if the packet is being sent out of our subnet (via a router).
+	  The fallback here is just to use "eth0" if the subnet lookup
+	  fails.  This will, of course, will have to be revisited if/when
+	  multiple NICs are supported (2013-9-27).
 

net/netdev_txnotify.c

@@ -95,6 +95,20 @@ void netdev_txnotify(const uip_ipaddr_t *raddr)
   /* Find the device driver that serves the subnet of the remote address */
 
   struct uip_driver_s *dev = netdev_findbyaddr(raddr);
+
+  /* The above lookup will fail if the packet is being sent out of our
+   * out subnet to a router.  REVISIT:  For now, we fall back and try "eth0".
+   */ 
+
+  if (dev == NULL)
+    {
+      /* If the destination address is not in our subnet, assume eth0 as the
+       * default device.
+       */
+
+      dev = netdev_findbyname("eth0");
+    }
+
   if (dev && dev->d_txavail)
     {
       /* Notify the device driver that new TX data is available. */