net/arp: Improve arp_find() commit 9774d35010 to reduce the amount and frequency of data copies.

include/nuttx/net/arp.h

@@ -2,7 +2,8 @@
  * include/nuttx/net/arp.h
  * Macros and definitions for the ARP module.
  *
- *   Copyright (C) 2007, 2009-2012, 2015-2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009-2012, 2015-2016, 2018 Gregory Nutt. All rights
+ *     reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Derived from uIP with has a similar BSD-style license:
@@ -78,7 +79,7 @@
 
 /* One entry in the ARP table (volatile!) */
 
-struct arp_entry
+struct arp_entry_s
 {
   in_addr_t         at_ipaddr;   /* IP address */
   struct ether_addr at_ethaddr;  /* Hardware address */

net/arp/arp.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/arp/arp.h
  *
- *   Copyright (C) 2014-2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014-2016, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -384,7 +384,7 @@ void arp_notify(in_addr_t ipaddr);
  *
  ****************************************************************************/
 
-FAR struct arp_entry *arp_lookup(in_addr_t ipaddr);
+FAR struct arp_entry_s *arp_lookup(in_addr_t ipaddr);
 
 /****************************************************************************
  * Name: arp_find
@@ -394,15 +394,19 @@ FAR struct arp_entry *arp_lookup(in_addr_t ipaddr);
  *   not be in the ARP table (it may, instead, be a local network device).
  *
  * Input Parameters:
- *   ipaddr - Refers to an IP address in network order
+ *   ipaddr -  Refers to an IP address in network order
- *   entry  - location to return a copy of the ARP table entry.
+ *   ethaddr - Location to return the corresponding Ethernet MAN address.
+ *             This address may be NULL.  In that case, this function may be
+ *             used simply to determine if the Ethernet MAC address is
+ *             available.
  *
  * Assumptions
  *   The network is locked to assure exclusive access to the ARP table.
  *
  ****************************************************************************/
 
-int arp_find(in_addr_t ipaddr, FAR struct arp_entry *entry);
+struct ether_addr;  /* Forward reference */
+int arp_find(in_addr_t ipaddr, FAR struct ether_addr *ethaddr);
 
 /****************************************************************************
  * Name: arp_delete

net/arp/arp_out.c

@@ -1,7 +1,8 @@
 /****************************************************************************
  * net/arp/arp_out.c
  *
- *   Copyright (C) 2007-2011, 2014-2015, 2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2011, 2014-2015, 2017-2018 Gregory Nutt. All rights
+ *     reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Based on uIP which also has a BSD style license:
@@ -136,7 +137,7 @@ static const uint8_t g_multicast_ethaddr[3] =
 
 void arp_out(FAR struct net_driver_s *dev)
 {
-  struct arp_entry entry;
+  struct ether_addr ethaddr;
   FAR struct eth_hdr_s *peth = ETHBUF;
   FAR struct arp_iphdr_s *pip = IPBUF;
   in_addr_t ipaddr;
@@ -250,7 +251,7 @@ void arp_out(FAR struct net_driver_s *dev)
 
   /* Check if we already have this destination address in the ARP table */
 
-  ret = arp_find(ipaddr, &entry);
+  ret = arp_find(ipaddr, &ethaddr);
   if (ret >= 0)
     {
       ninfo("ARP request for IP %08lx\n", (unsigned long)ipaddr);
@@ -266,7 +267,7 @@ void arp_out(FAR struct net_driver_s *dev)
 
   /* Build an Ethernet header. */
 
-  memcpy(peth->dest, entry.at_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
+  memcpy(peth->dest, ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
 
   /* Finish populating the Ethernet header */
 

net/arp/arp_send.c

@@ -315,8 +315,6 @@ int arp_send(in_addr_t ipaddr)
 
   while (state.snd_retries < CONFIG_ARP_SEND_MAXTRIES)
     {
-      struct arp_entry entry;
-
       /* Check if the address mapping is present in the ARP table.  This
        * is only really meaningful on the first time through the loop.
        *
@@ -324,7 +322,7 @@ int arp_send(in_addr_t ipaddr)
        * issue.
        */
 
-      if (arp_find(ipaddr, &entry) >= 0)
+      if (arp_find(ipaddr, NULL) >= 0)
         {
           /* We have it!  Break out with success */
 

net/arp/arp_table.c

@@ -49,7 +49,6 @@
 #include <sys/ioctl.h>
 #include <stdint.h>
 #include <string.h>
-#include <assert.h>
 #include <debug.h>
 
 #include <netinet/in.h>
@@ -66,13 +65,23 @@
 
 #ifdef CONFIG_NET_ARP
 
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct arp_table_info_s
+{
+  in_addr_t              ai_ipaddr;   /* IP address for lookup */
+  FAR struct ether_addr *ai_ethaddr;  /* Location to return the MAC address */
+};
+
 /****************************************************************************
  * Private Data
  ****************************************************************************/
 
 /* The table of known address mappings */
 
-static struct arp_entry g_arptable[CONFIG_NET_ARPTAB_SIZE];
+static struct arp_entry_s g_arptable[CONFIG_NET_ARPTAB_SIZE];
 static uint8_t g_arptime;
 
 /****************************************************************************
@@ -90,19 +99,38 @@ static uint8_t g_arptime;
 
 static int arp_match(FAR struct net_driver_s *dev, FAR void *arg)
 {
-  FAR struct arp_entry *entry = arg;
+  FAR struct arp_table_info_s *info = arg;
 
-  if (dev->d_lltype != NET_LL_ETHERNET)
+  /* Make sure that this is an Ethernet device (or an IEEE 802.11 device
+   * which is also Ethernet)
+   */
+
+  if (dev->d_lltype != NET_LL_ETHERNET &&
+      dev->d_lltype != NET_LL_IEEE80211)
     {
       return 0;
     }
 
-  if (!net_ipv4addr_cmp(dev->d_ipaddr, entry->at_ipaddr))
+  /* Check if the network device has been assigned the IP address of the
+   * lookup.
+   */
+
+  if (!net_ipv4addr_cmp(dev->d_ipaddr, info->ai_ipaddr))
     {
       return 0;
     }
 
-  memcpy(&entry->at_ethaddr, &dev->d_mac.ether, ETHER_ADDR_LEN);
+  /* Yes.. Return the matching Ethernet MAC address if the caller of
+   * arp_find() provided a non-NULL location.
+   */
+
+  if (info->ai_ethaddr != NULL)
+    {
+      memcpy(info->ai_ethaddr, &dev->d_mac.ether, ETHER_ADDR_LEN);
+    }
+
+  /* Return success in any event */
+
   return 1;
 }
 
@@ -141,7 +169,7 @@ void arp_reset(void)
 
 void arp_timer(void)
 {
-  FAR struct arp_entry *tabptr;
+  FAR struct arp_entry_s *tabptr;
   int i;
 
   ++g_arptime;
@@ -179,7 +207,7 @@ void arp_timer(void)
 
 int arp_update(in_addr_t ipaddr, FAR uint8_t *ethaddr)
 {
-  struct arp_entry *tabptr = NULL;
+  struct arp_entry_s *tabptr = NULL;
   int               i;
 
   /* Walk through the ARP mapping table and try to find an entry to
@@ -299,9 +327,9 @@ void arp_hdr_update(FAR uint16_t *pipaddr, FAR uint8_t *ethaddr)
  *
  ****************************************************************************/
 
-FAR struct arp_entry *arp_lookup(in_addr_t ipaddr)
+FAR struct arp_entry_s *arp_lookup(in_addr_t ipaddr)
 {
-  FAR struct arp_entry *tabptr;
+  FAR struct arp_entry_s *tabptr;
   int i;
 
   /* Check if the IPv4 address is already in the ARP table. */
@@ -328,25 +356,40 @@ FAR struct arp_entry *arp_lookup(in_addr_t ipaddr)
  *   not be in the ARP table (it may, instead, be a local network device).
  *
  * Input Parameters:
- *   ipaddr - Refers to an IP address in network order
+ *   ipaddr -  Refers to an IP address in network order
+ *   ethaddr - Location to return the corresponding Ethernet MAN address.
+ *             This address may be NULL.  In that case, this function may be
+ *             used simply to determine if the Ethernet MAC address is
+ *             available.
  *
- * Assumptions:
+ * Assumptions
  *   The network is locked to assure exclusive access to the ARP table.
  *
  ****************************************************************************/
 
-int arp_find(in_addr_t ipaddr, FAR struct arp_entry *entry)
+int arp_find(in_addr_t ipaddr, FAR struct ether_addr *ethaddr)
 {
-  FAR struct arp_entry *tabptr;
+  FAR struct arp_entry_s *tabptr;
-
+  struct arp_table_info_s info;
-  DEBUGASSERT(entry);
 
   /* Check if the IPv4 address is already in the ARP table. */
 
   tabptr = arp_lookup(ipaddr);
   if (tabptr != NULL)
     {
-      memcpy(entry, tabptr, sizeof(struct arp_entry));
+      /* Yes.. return the Ethernet MAC address if the caller has provided a
+       * non-NULL address in 'ethaddr'.
+       */
+
+      if (ethaddr != NULL)
+        {
+          memcpy(ethaddr, &tabptr->at_ethaddr, ETHER_ADDR_LEN);
+        }
+
+      /* Return success in any case meaning that a valid Ethernet MAC
+       * address mapping is available for the IP address.
+       */
+
       return OK;
     }
 
@@ -355,8 +398,10 @@ int arp_find(in_addr_t ipaddr, FAR struct arp_entry *entry)
    * to the Ethernet MAC address assigned to the network device.
    */
 
-  entry->at_ipaddr = ipaddr;
+  info.ai_ipaddr  = ipaddr;
-  if (netdev_foreach(arp_match, entry) != 0)
+  info.ai_ethaddr = ethaddr;
+
+  if (netdev_foreach(arp_match, &info) != 0)
     {
       return OK;
     }
@@ -382,7 +427,7 @@ int arp_find(in_addr_t ipaddr, FAR struct arp_entry *entry)
 
 void arp_delete(in_addr_t ipaddr)
 {
-  FAR struct arp_entry *tabptr;
+  FAR struct arp_entry_s *tabptr;
 
   /* Check if the IPv4 address is in the ARP table. */
 

net/ipforward/ipfwd_forward.c

@@ -159,10 +159,9 @@ static inline bool ipfwd_addrchk(FAR struct forward_s *fwd)
     {
 #if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
       FAR struct ipv4_hdr_s *ipv4 = (FAR struct ipv4_hdr_s *)fwd->f_iob->io_data;
-      struct arp_entry entry;
       int ret;
 
-      ret = arp_find(*(in_addr_t *)ipv4->destipaddr, &entry);
+      ret = arp_find(*(in_addr_t *)ipv4->destipaddr, NULL);
       return (ret >= 0);
 #else
       return true;

net/netdev/netdev_ioctl.c

@@ -1259,7 +1259,7 @@ static int netdev_arp_ioctl(FAR struct socket *psock, int cmd,
 
               /* Find the existing ARP table entry for this protocol address. */
 
-              FAR struct arp_entry *entry = arp_lookup(addr->sin_addr.s_addr);
+              FAR struct arp_entry_s *entry = arp_lookup(addr->sin_addr.s_addr);
               if (entry != NULL)
                 {
                   /* The ARP table is fixed size; an entry is deleted
@@ -1287,19 +1287,18 @@ static int netdev_arp_ioctl(FAR struct socket *psock, int cmd,
             {
               FAR struct sockaddr_in *addr =
                 (FAR struct sockaddr_in *)&req->arp_pa;
-              struct arp_entry entry;
 
-              /* Find the existing ARP table entry for this protocol address. */
+              /* Get the hardware address from an existing ARP table entry
+               * matching this protocol address.
+               */
 
-              ret = arp_find(addr->sin_addr.s_addr, &entry);
+              ret = arp_find(addr->sin_addr.s_addr,
+                            (FAR struct ether_addr *)req->arp_ha.sa_data);
               if (ret >= 0)
                 {
                   /* Return the mapped hardware address. */
 
                   req->arp_ha.sa_family = ARPHRD_ETHER;
-                  memcpy(req->arp_ha.sa_data,
-                         entry.at_ethaddr.ether_addr_octet,
-                         ETHER_ADDR_LEN);
                   ret = OK;
                 }
             }

net/tcp/tcp_send_buffered.c

@@ -309,9 +309,7 @@ static inline bool psock_send_addrchck(FAR struct tcp_conn_s *conn)
 #endif
 
 #if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
-      struct arp_entry entry;
+      if (arp_find(conn->u.ipv4.raddr, NULL) >= 0)
-
-      if (arp_find(conn->u.ipv4.raddr, &entry) >= 0)
         {
           /* Return true if the address was found in the ARP table */
 

net/tcp/tcp_send_unbuffered.c

@@ -258,9 +258,7 @@ static inline bool psock_send_addrchck(FAR struct tcp_conn_s *conn)
       in_addr_t router;
 #endif
 #if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
-      struct arp_entry entry;
+      if (arp_find(conn->u.ipv4.raddr, NULL) >= 0)
-
-      if (arp_find(conn->u.ipv4.raddr, &entry) >= 0)
         {
           /* Return true if the address was found in the ARP table */
 

net/tcp/tcp_sendfile.c

@@ -296,9 +296,7 @@ static inline bool sendfile_addrcheck(FAR struct tcp_conn_s *conn)
 #endif
     {
 #if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
-      struct arp_entry entry;
+      return (arp_find(conn->u.ipv4.raddr, NULL) >= 0);
-
-      return (arp_find(conn->u.ipv4.raddr, &entry) >= 0);
 #else
       return true;
 #endif

net/udp/udp_psock_sendto_buffered.c

@@ -281,9 +281,7 @@ static inline bool sendto_addrcheck(FAR struct udp_conn_s *conn,
 #endif
     {
 #if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
-      struct arp_entry entry;
+      return (arp_find(conn->u.ipv4.raddr, NULL) >= 0);
-
-      return (arp_find(conn->u.ipv4.raddr, entry) >= 0);
 #else
       return true;
 #endif