ARP: Add support for the case where there are multiple networks: One being Etherenet and the other not (say slip or perhaps someday PPP). In that case, we need to suppress ARP-related operations on the SLIP/PPP interface only

3 files changed, 21 insertions, 3 deletions

diff --git a/nuttx/net/Kconfig b/nuttx/net/Kconfig
index c303146ba..85b71c576 100644
--- a/nuttx/net/Kconfig
+++ b/nuttx/net/Kconfig
@@ -120,6 +120,7 @@ config NET_ETHERNET
 	bool
 	default y if !NET_SLIP
 	default n if NET_SLIP
+	select NETDEV_MULTINIC if NET_SLIP
 	---help---
 		If NET_SLIP is not selected, then Ethernet will be used (there is
 		no need to define anything special in the configuration file to use
@@ -128,6 +129,7 @@ config NET_ETHERNET
 config NET_SLIP
 	bool "SLIP support"
 	default n
+	select NETDEV_MULTINIC if NET_ETHERNET
 	---help---
 		Enables building of the SLIP driver. SLIP requires
 		at least one IP protocol selected and the following additional
diff --git a/nuttx/net/arp/Make.defs b/nuttx/net/arp/Make.defs
index 8132e7ecc..28772a87b 100644
--- a/nuttx/net/arp/Make.defs
+++ b/nuttx/net/arp/Make.defs
@@ -33,9 +33,9 @@
 #
 ############################################################################
 
-# ARP supported is not provided for SLIP (Ethernet only)
+# ARP support is available for Ethernet only
 
-ifneq ($(CONFIG_NET_SLIP),y)
+ifeq ($(CONFIG_NET_ETHERNET),y)
 NET_CSRCS +=arp_arpin.c arp_out.c arp_format.c arp_table.c arp_timer.c
 
 ifeq ($(CONFIG_NET_ARP_IPIN),y)
@@ -55,4 +55,4 @@ endif
 DEPPATH += --dep-path arp
 VPATH += :arp
 
-endif
+endif # CONFIG_NET_ETHERNET
diff --git a/nuttx/net/arp/arp_send.c b/nuttx/net/arp/arp_send.c
index e97156823..c7bbb92c8 100644
--- a/nuttx/net/arp/arp_send.c
+++ b/nuttx/net/arp/arp_send.c
@@ -229,6 +229,22 @@ int arp_send(in_addr_t ipaddr)
       goto errout;
     }
 
+  /* If this device does not require ARP bail out.  ARP is only built of
+   * CONFIG_NET_ETHERNET is enabled which always requires ARP support.  The
+   * following can happening only there multiple network interfaces enabled
+   * (CONFIG_NET_MULTINIC) and one of the interfaces is not Ethernet.  At
+   * present, this is possible only if one of the interfaces is SLIP.
+   *
+   * REVISIT:  This will need to be extended if PPP is ever incorporated.
+   */
+
+#ifdef CONFIG_NET_SLIP
+  if (dev->d_flags & IFF_NOARP)
+    {
+      return OK;
+    }
+#endif
+
   /* Check if the destination address is on the local network. */
 
   if (!net_ipaddr_maskcmp(ipaddr, dev->d_ipaddr, dev->d_netmask))