Networking: Add logic to search the Neighbor Table and update the destination address in the output Ethernet header OR to send an ICMPv6 Neighbor Solicitation if there is no entry in the Neighbor table for the IPv6 address

3 files changed, 249 insertions, 3 deletions

diff --git a/nuttx/net/neighbor/Make.defs b/nuttx/net/neighbor/Make.defs
index 19cbb13e1..cf13cbb73 100644
--- a/nuttx/net/neighbor/Make.defs
+++ b/nuttx/net/neighbor/Make.defs
@@ -39,6 +39,7 @@ ifeq ($(CONFIG_NET_IPv6),y)
 
 NET_CSRCS += neighbor_initialize.c neighbor_add.c neighbor_lookup.c
 NET_CSRCS += neighbor_update.c neighbor_periodic.c neighbor_findentry.c
+NET_CSRCS += neighbor_out.c
 
 # Include utility build support
 
diff --git a/nuttx/net/neighbor/neighbor_lookup.c b/nuttx/net/neighbor/neighbor_lookup.c
index 4c7d9b04a..dc42e54e1 100644
--- a/nuttx/net/neighbor/neighbor_lookup.c
+++ b/nuttx/net/neighbor/neighbor_lookup.c
@@ -61,11 +61,11 @@
  *
  * Input Parameters:
  *   ipaddr - The IPv6 address to use in the lookup;
+ *   lladdr - The location to return the link layer address
  *
  * Returned Value:
- *   A read-only reference to the link layer address in the Neighbor Table is
- *   returned on success.  NULL is returned if there is no matching entry in
- *   the Neighbor Table.
+ *   Returns OK if the address was successfully obtain; a negated errno
+ *   value is returned on failure.
  *
  ****************************************************************************/
 
diff --git a/nuttx/net/neighbor/neighbor_out.c b/nuttx/net/neighbor/neighbor_out.c
new file mode 100644
index 000000000..94cad10d2
--- /dev/null
+++ b/nuttx/net/neighbor/neighbor_out.c
@@ -0,0 +1,245 @@
+/****************************************************************************
+ * net/neighbor/neighbor_out.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <string.h>
+#include <debug.h>
+
+#include <nuttx/net/arp.h>
+#include <nuttx/net/netdev.h>
+
+#include "route/route.h"
+#include "icmpv6/icmpv6.h"
+#include "neighbor/neighbor.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define ETHBUF  ((struct eth_hdr_s *)dev->d_buf)
+#define IPv6BUF ((struct ipv6_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev)])
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* Support for broadcast address */
+
+static const struct ether_addr g_broadcast_ethaddr =
+  {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}};
+
+/* Support for IGMP multicast addresses.
+ *
+ * Well-known ethernet multicast address:
+ *
+ * ADDRESS           TYPE   USAGE
+ * 01-00-0c-cc-cc-cc 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual Trunking Protocol)
+ * 01-00-0c-cc-cc-cd 0x0802 Cisco Shared Spanning Tree Protocol Address
+ * 01-80-c2-00-00-00 0x0802 Spanning Tree Protocol (for bridges) IEEE 802.1D
+ * 01-80-c2-00-00-02 0x0809 Ethernet OAM Protocol IEEE 802.3ah
+ * 01-00-5e-xx-xx-xx 0x0800 IPv4 IGMP Multicast Address
+ * 33-33-00-00-00-00 0x86DD IPv6 Neighbor Discovery
+ * 33-33-xx-xx-xx-xx 0x86DD IPv6 Multicast Address (RFC3307)
+ *
+ * The following is the first three octects of the IGMP address:
+ */
+
+#ifdef CONFIG_NET_IGMP
+static const uint8_t g_multicast_ethaddr[3] = {0x01, 0x00, 0x5e};
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: neighbor_out
+ *
+ * Description:
+ *   This function should be called before sending out an IPv6 packet. The
+ *   function checks the destination IPv6 address of the IPv6 packet to see
+ *   what Ethernet MAC address that should be used as a destination MAC
+ *   address on the Ethernet.
+ *
+ *   If the destination IPv6 address is in the local network (determined
+ *   by logical ANDing of netmask and our IPv6 address), the function
+ *   checks the Neighbor Table to see if an entry for the destination IPv6
+ *   address is found.  If so, an Ethernet header is pre-pended at the
+ *   beginning of the packet and the function returns.
+ *
+ *   If no Neighbor Table entry is found for the destination IPv6 address,
+ *   the packet in the d_buf[] is replaced by an ICMPv6 Neighbor Solict
+ *   request packet for the IPv6 address. The IPv6 packet is dropped and 
+ *   it is assumed that the higher level protocols (e.g., TCP) eventually
+ *   will retransmit the dropped packet.
+ *
+ *   Upon return in either the case, a packet to be sent is present in the
+ *   d_buf[] buffer and the d_len field holds the length of the Ethernet
+ *   frame that should be transmitted.
+ *
+ ****************************************************************************/
+
+void neighbor_out(FAR struct net_driver_s *dev)
+{
+  FAR const struct neighbor_addr_s *naddr;
+  FAR struct eth_hdr_s *eth = ETHBUF;
+  FAR struct ipv6_hdr_s *ip = IPv6BUF;
+  net_ipv6addr_t ipaddr;
+
+#if defined(CONFIG_NET_PKT) || defined(CONFIG_NET_NEIGHBOR_SEND)
+  /* Skip sending ARP requests when the frame to be transmitted was
+   * written into a packet socket.
+   */
+
+  if ((dev->d_flags & IFF_NOARP) != 0)
+    {
+      /* Clear the indication and let the packet continue on its way. */
+
+      dev->d_flags &= ~IFF_NOARP;
+      return;
+    }
+#endif
+
+  /* Find the destination IPv6 address in the ARP table and construct
+   * the Ethernet header. If the destination IPv6 address isn't on the
+   * local network, we use the default router's IPv6 address instead.
+   *
+   * If not ARP table entry is found, we overwrite the original IPv6
+   * packet with an ARP request for the IPv6 address.
+   */
+
+  /* First check if destination is a IPv6 multicast address.  IPv6
+   * multicast addresses in IPv6 have the prefix ff00::/8
+   * 
+   *   Bits 120-127: Prefix
+   *   Bits 116-119: Flags (1, 2, or 3 defined)
+   *   Bits 112-115: Scope
+   *
+   * REVISIT: Need to revisit IPv6 broadcast support.  Broadcast
+   * IP addresses are not used with IPv6; multicast is used instead.
+   * Does this mean that all multicast address should go to the
+   * broadcast Ethernet address?
+   */
+
+  if ((ip->destipaddr[0] & 0xff00) == 0xff00)
+    {
+      memcpy(eth->dest, g_broadcast_ethaddr.ether_addr_octet,
+             ETHER_ADDR_LEN);
+    }
+
+#ifdef CONFIG_NET_IGMP
+  /* Check if the destination address is a multicast address
+   *
+   *   IPv6 multicast addresses are have the high-order octet of the
+   *   addresses=0xff (ff00::/8.)
+   *
+   * REVISIT:  See comments above.  How do we distinguish broadcast
+   * from IGMP multicast?
+   */
+#warning Missing logic
+#endif
+
+  else
+    {
+      /* Check if the destination address is on the local network. */
+
+      if (!net_ipv6addr_maskcmp(ip->destipaddr, dev->d_ipv6addr,
+                                dev->d_ipv6netmask))
+        {
+          /* Destination address is not on the local network */
+
+#ifdef CONFIG_NET_ROUTE
+          /* We have a routing table.. find the correct router to use in
+           * this case (or, as a fall-back, use the device's default router
+           * address).  We will use the router IPv6 address instead of the
+           * destination address when determining the MAC address.
+           */
+
+          netdev_ipv6_router(dev, ip->destipaddr, ipaddr);
+#else
+          /* Use the device's default router IPv6 address instead of the
+           * destination address when determining the MAC address.
+           */
+
+          net_ipv6addr_copy(ipaddr, dev->d_ipv6draddr);
+#endif
+        }
+      else
+        {
+          /* Else, we use the destination IPv6 address. */
+
+          net_ipv6addr_copy(ipaddr, ip->destipaddr);
+        }
+
+      /* Check if we already have this destination address in the Neighbor Table */
+
+      naddr = neighbor_lookup(ipaddr);
+      if (!naddr)
+        {
+           nllvdbg("IPv6 Neighbor solicitation for IPv6\n");
+
+          /* The destination address was not in our Neighbor Table, so we
+           * overwrite the IPv6 packet with an ICMDv6 Neighbor Solicitation
+           * message.
+           */
+
+          icmpv6_solicit(dev, ipaddr);
+          return;
+        }
+
+      /* Build an Ethernet header. */
+
+      memcpy(eth->dest, naddr->na_addr.ether_addr_octet, ETHER_ADDR_LEN);
+    }
+
+  /* Finish populating the Ethernet header */
+
+  memcpy(eth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
+  eth->type  = HTONS(ETHTYPE_IP6);
+  dev->d_len += ETH_HDRLEN;
+}