net/netdev: add devif_loopback_out() to check the loopback case where a packet is being sent to itself. Modify the net driver to call this function in this case. This function will simply re-inject the packet back into the network and the network driver will not put anything on the wire.

arch/arm/src/c5471/c5471_ethernet.c

@@ -1046,6 +1046,8 @@ static int c5471_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->c_dev))
+        {
           /* Send the packet */
 
           c5471_transmit(priv);
@@ -1061,6 +1063,7 @@ static int c5471_txpoll(struct net_driver_s *dev)
               return 1;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/imxrt/imxrt_enet.c

@@ -600,6 +600,8 @@ static int imxrt_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           imxrt_transmit(priv);
@@ -615,6 +617,7 @@ static int imxrt_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
        }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/kinetis/kinetis_enet.c

@@ -571,6 +571,8 @@ static int kinetis_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           kinetis_transmit(priv);
@@ -586,6 +588,7 @@ static int kinetis_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/lpc17xx/lpc17_ethernet.c

@@ -716,6 +716,8 @@ static int lpc17_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->lp_dev))
+        {
           /* Send this packet.  In this context, we know that there is space for
            * at least one more packet in the descriptor list.
            */
@@ -728,6 +730,7 @@ static int lpc17_txpoll(struct net_driver_s *dev)
 
           ret = lpc17_txdesc(priv);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/lpc43xx/lpc43_ethernet.c

@@ -1165,6 +1165,8 @@ static int lpc43_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           lpc43_transmit(priv);
@@ -1205,6 +1207,7 @@ static int lpc43_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/lpc54xx/lpc54_ethernet.c

@@ -790,6 +790,8 @@ static int lpc54_eth_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->eth_dev))
+        {
           /* Send the packet */
 
           chan   = lpc54_eth_getring(priv);
@@ -835,6 +837,7 @@ static int lpc54_eth_txpoll(struct net_driver_s *dev)
               return 1;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections
    * have been examined.  If there is nothing to be sent, we will return to

arch/arm/src/sam34/sam_emac.c

@@ -889,6 +889,8 @@ static int sam_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           sam_transmit(priv);
@@ -906,6 +908,7 @@ static int sam_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/sama5/sam_emaca.c

@@ -898,6 +898,8 @@ static int sam_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           sam_transmit(priv);
@@ -915,6 +917,7 @@ static int sam_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/sama5/sam_emacb.c

@@ -1233,6 +1233,8 @@ static int sam_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           sam_transmit(priv);
@@ -1250,6 +1252,7 @@ static int sam_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/sama5/sam_gmac.c

@@ -830,6 +830,8 @@ static int sam_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           sam_transmit(priv);
@@ -847,6 +849,7 @@ static int sam_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/samv7/sam_emac.c

@@ -1547,6 +1547,8 @@ static int sam_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           sam_transmit(priv, EMAC_QUEUE_0);
@@ -1564,6 +1566,7 @@ static int sam_txpoll(struct net_driver_s *dev)
               return -EBUSY;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/stm32/stm32_eth.c

@@ -1271,6 +1271,8 @@ static int stm32_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           stm32_transmit(priv);
@@ -1311,6 +1313,7 @@ static int stm32_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/stm32f7/stm32_ethernet.c

@@ -1305,6 +1305,8 @@ static int stm32_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           stm32_transmit(priv);
@@ -1345,6 +1347,7 @@ static int stm32_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/tiva/lm3s_ethernet.c

@@ -644,12 +644,15 @@ static int tiva_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->ld_dev))
+        {
           /* Send the packet.  tiva_transmit() will return zero if the
            * packet was successfully handled.
            */
 
           ret = tiva_transmit(priv);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/arm/src/tiva/tm4c_ethernet.c

@@ -1273,6 +1273,8 @@ static int tiva_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           tiva_transmit(priv);
@@ -1313,6 +1315,7 @@ static int tiva_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/hc/src/m9s12/m9s12_ethernet.c

@@ -244,6 +244,8 @@ static int emac_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->d_dev))
+        {
           /* Send the packet */
 
           emac_transmit(priv);
@@ -252,6 +254,7 @@ static int emac_txpoll(struct net_driver_s *dev)
            * return a non-zero value to terminate the poll.
            */
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/mips/src/pic32mx/pic32mx-ethernet.c

@@ -1149,6 +1149,8 @@ static int pic32mx_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->pd_dev))
+        {
           /* Send this packet.  In this context, we know that there is space for
            * at least one more packet in the descriptor list.
            */
@@ -1176,6 +1178,7 @@ static int pic32mx_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/mips/src/pic32mz/pic32mz-ethernet.c

@@ -1176,6 +1176,8 @@ static int pic32mz_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->pd_dev))
+        {
           /* Send this packet.  In this context, we know that there is space for
            * at least one more packet in the descriptor list.
            */
@@ -1203,6 +1205,7 @@ static int pic32mz_txpoll(struct net_driver_s *dev)
               return -ENOMEM;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/misoc/src/common/misoc_net.c

@@ -334,6 +334,8 @@ static int misoc_net_txpoll(FAR struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->misoc_net_dev))
+        {
           /* Send the packet */
 
           misoc_net_transmit(priv);
@@ -342,6 +344,7 @@ static int misoc_net_txpoll(FAR struct net_driver_s *dev)
            * return a non-zero value to terminate the poll.
            */
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/sim/src/up_netdriver.c

@@ -151,10 +151,13 @@ static int sim_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&g_sim_dev))
+        {
           /* Send the packet */
 
           netdev_send(g_sim_dev.d_buf, g_sim_dev.d_len);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

arch/z80/src/ez80/ez80_emac.c

@@ -1147,12 +1147,15 @@ static int ez80emac_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet.  ez80emac_transmit() will return zero if the
            * packet was successfully handled.
            */
 
           ret = ez80emac_transmit(priv);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/dm90x0.c

@@ -819,6 +819,8 @@ static int dm9x_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dm_dev))
+        {
           /* Send the packet */
 
           dm9x_transmit(priv);
@@ -834,6 +836,7 @@ static int dm9x_txpoll(struct net_driver_s *dev)
               return 1;
             }
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/enc28j60.c

@@ -1213,6 +1213,8 @@ static int enc_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           enc_transmit(priv);
@@ -1221,6 +1223,7 @@ static int enc_txpoll(struct net_driver_s *dev)
 
           return -EBUSY;
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/encx24j600.c

@@ -1194,10 +1194,13 @@ static int enc_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           ret = enc_txenqueue(priv);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/ftmac100.c

@@ -388,6 +388,8 @@ static int ftmac100_txpoll(struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->ft_dev))
+        {
           /* Send the packet */
 
           ftmac100_transmit(priv);
@@ -396,6 +398,7 @@ static int ftmac100_txpoll(struct net_driver_s *dev)
            * return a non-zero value to terminate the poll.
            */
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/skeleton.c

@@ -299,6 +299,13 @@ static int skel_txpoll(FAR struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      /* Check if the network is sending this packet to the IP address of
+       * this device.  If so, just loop the packet back into the network but
+       * don't attmpt to put it on the wire.
+       */
+
+      if (!devif_loopback_out(&priv->sk_dev))
+        {
           /* Send the packet */
 
           skel_transmit(priv);
@@ -307,6 +314,7 @@ static int skel_txpoll(FAR struct net_driver_s *dev)
            * return a non-zero value to terminate the poll.
            */
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/net/slip.c

@@ -404,9 +404,12 @@ static int slip_txpoll(FAR struct net_driver_s *dev)
    */
 
   if (priv->dev.d_len > 0)
+    {
+      if (!devif_loopback_out(&priv->dev))
         {
           slip_transmit(priv);
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

drivers/usbdev/cdcecm.c

@@ -400,6 +400,8 @@ static int cdcecm_txpoll(FAR struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->dev))
+        {
           /* Send the packet */
 
           cdcecm_transmit(priv);
@@ -410,6 +412,7 @@ static int cdcecm_txpoll(FAR struct net_driver_s *dev)
 
           return 1;
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections
    * have been examined.

drivers/usbdev/rndis.c

@@ -994,8 +994,10 @@ static int rndis_txpoll(FAR struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->netdev))
+        {
           ret = rndis_transmit(priv);
-
+        }
     }
 
   /* If zero is returned, the polling will continue until all connections have

drivers/wireless/ieee80211/bcmf_netdev.c

@@ -473,6 +473,8 @@ static int bcmf_txpoll(FAR struct net_driver_s *dev)
         }
 #endif /* CONFIG_NET_IPv6 */
 
+      if (!devif_loopback_out(&priv->bc_dev))
+        {
           /* Send the packet */
 
           bcmf_transmit(priv, priv->cur_tx_frame);
@@ -484,6 +486,7 @@ static int bcmf_txpoll(FAR struct net_driver_s *dev)
           priv->cur_tx_frame = NULL;
           return 1;
         }
+    }
 
   /* If zero is returned, the polling will continue until all connections have
    * been examined.

include/nuttx/net/netdev.h

@@ -568,6 +568,23 @@ int devif_timer(FAR struct net_driver_s *dev, devif_poll_callback_t callback);
 void neighbor_out(FAR struct net_driver_s *dev);
 #endif /* CONFIG_NET_IPv6 */
 
+/****************************************************************************
+ * Name: devif_loopback_out
+ *
+ * Description:
+ *   This function should be called before sending out a packet. The function
+ *   checks the destination address of the packet to see whether the target of
+ *   packet is ourself and then consume the packet directly by calling input
+ *   process functions.
+ *
+ * Returned Value:
+ *   Zero is returned if the packet don't loop back to ourself, otherwise
+ *   a no zero value is returned.
+ *
+ ****************************************************************************/
+
+int devif_loopback_out(FAR struct net_driver_s *dev);
+
 /****************************************************************************
  * Carrier detection
  *

net/devif/Make.defs

@@ -36,6 +36,7 @@
 # Network device interface source files
 
 NET_CSRCS += devif_initialize.c devif_send.c devif_poll.c devif_callback.c
+NET_CSRCS += devif_loopbackout.c
 
 # Device driver IP packet receipt interfaces
 

net/devif/devif_loopbackout.c

@@ -0,0 +1,161 @@
+/****************************************************************************
+ * net/devif/devif_loopbackout.c
+ *
+ *   Copyright (C) 2018 Pinecone Inc. All rights reserved.
+ *   Author: Xiang Xiao <xiaoxiang@pinecone.net>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <debug.h>
+
+#include <nuttx/net/ip.h>
+#include <nuttx/net/pkt.h>
+#include <nuttx/net/netdev.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* This is a helper pointer for accessing the contents of the ip header */
+
+#define IPv4BUF ((FAR struct ipv4_hdr_s *)(dev->d_buf + dev->d_llhdrlen))
+#define IPv6BUF ((FAR struct ipv6_hdr_s *)(dev->d_buf + dev->d_llhdrlen))
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static bool is_loopback(FAR struct net_driver_s *dev)
+{
+  if (dev->d_len > 0)
+    {
+#ifdef CONFIG_NET_IPv4
+      if ((IPv4BUF->vhl & IP_VERSION_MASK) == IPv4_VERSION &&
+           net_ipv4addr_hdrcmp(IPv4BUF->destipaddr, &dev->d_ipaddr))
+        {
+          return true;
+        }
+#endif
+
+#ifdef CONFIG_NET_IPv6
+      if ((IPv6BUF->vtc & IP_VERSION_MASK) == IPv6_VERSION &&
+          net_ipv6addr_hdrcmp(IPv6BUF->destipaddr, dev->d_ipv6addr))
+        {
+          return true;
+        }
+#endif
+    }
+
+  return false;
+}
+
+/****************************************************************************
+ * Name: devif_loopback_out
+ *
+ * Description:
+ *   This function should be called before sending out a packet. The function
+ *   checks the destination address of the packet to see whether the target of
+ *   packet is ourself and then consume the packet directly by calling input
+ *   process functions.
+ *
+ * Returned Value:
+ *   Zero is returned if the packet don't loop back to ourself, otherwise
+ *   a no zero value is returned.
+ *
+ ****************************************************************************/
+
+int devif_loopback_out(FAR struct net_driver_s *dev)
+{
+  if (!is_loopback(dev))
+    {
+      return 0;
+    }
+
+  /* Loop while if there is data "sent" to ourself.
+   * Sending, of course, just means relaying back through the network.
+   */
+
+  do
+    {
+       NETDEV_TXPACKETS(dev);
+       NETDEV_RXPACKETS(dev);
+
+#ifdef CONFIG_NET_PKT
+      /* When packet sockets are enabled, feed the frame into the packet tap */
+
+       pkt_input(dev);
+#endif
+
+      /* We only accept IP packets of the configured type */
+
+#ifdef CONFIG_NET_IPv4
+      if ((IPv4BUF->vhl & IP_VERSION_MASK) == IPv4_VERSION)
+        {
+          ninfo("IPv4 frame\n");
+
+          NETDEV_RXIPV4(dev);
+          ipv4_input(dev);
+        }
+      else
+#endif
+#ifdef CONFIG_NET_IPv6
+      if ((IPv6BUF->vtc & IP_VERSION_MASK) == IPv6_VERSION)
+        {
+          ninfo("Iv6 frame\n");
+
+          NETDEV_RXIPV6(dev);
+          ipv6_input(dev);
+        }
+      else
+#endif
+        {
+          NETDEV_RXDROPPED(dev);
+        }
+
+      NETDEV_TXDONE(dev);
+
+      /* Add the data link header length for the next loop */
+
+      if (dev->d_len != 0)
+        {
+          dev->d_len += dev->d_llhdrlen;
+        }
+    }
+  while (dev->d_len > 0);
+
+  return 1;
+}
+