/****************************************************************************
* net/arp/arp_out.c
*
* Copyright (C) 2007-2011, 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Based on uIP which also has a BSD style license:
*
* Author: Adam Dunkels <adam@dunkels.com>
* Copyright (c) 2001-2003, Adam Dunkels.
* All rights reserved.
*
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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/netdev.h>
#include <nuttx/net/arp.h>
#include "arp/arp.h"
#ifdef CONFIG_NET_ARP
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define ETHBUF ((struct eth_hdr_s *)&dev->d_buf[0])
#define ARPBUF ((struct arp_hdr_s *)&dev->d_buf[ETH_HDRLEN])
#define IPBUF ((struct arp_iphdr_s *)&dev->d_buf[ETH_HDRLEN])
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/* Support for broadcast address */
static const struct ether_addr g_broadcast_ethaddr =
{{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}};
static const uint16_t g_broadcast_ipaddr[2] = {0xffff, 0xffff};
/* 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:
*/
#if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6)
static const uint8_t g_multicast_ethaddr[3] = {0x01, 0x00, 0x5e};
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: arp_out
*
* Description:
* This function should be called before sending out an IP packet. The
* function checks the destination IP address of the IP packet to see
* what Ethernet MAC address that should be used as a destination MAC
* address on the Ethernet.
*
* If the destination IP address is in the local network (determined
* by logical ANDing of netmask and our IP address), the function
* checks the ARP cache to see if an entry for the destination IP
* address is found. If so, an Ethernet header is pre-pended at the
* beginning of the packet and the function returns.
*
* If no ARP cache entry is found for the destination IP address, the
* packet in the d_buf[] is replaced by an ARP request packet for the
* IP address. The IP 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 arp_out(FAR struct net_driver_s *dev)
{
FAR const struct arp_entry *tabptr = NULL;
FAR struct eth_hdr_s *peth = ETHBUF;
FAR struct arp_iphdr_s *pip = IPBUF;
in_addr_t ipaddr;
in_addr_t destipaddr;
#if defined(CONFIG_NET_PKT) || defined(CONFIG_NET_ARP_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 IP address in the ARP table and construct
* the Ethernet header. If the destination IP address isn't on the
* local network, we use the default router's IP address instead.
*
* If not ARP table entry is found, we overwrite the original IP
* packet with an ARP request for the IP address.
*/
/* First check if destination is a local broadcast. */
if (net_ipaddr_hdrcmp(pip->eh_destipaddr, g_broadcast_ipaddr))
{
memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
}
#if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6)
/* Check if the destination address is a multicast address
*
* - IPv4: multicast addresses lie in the class D group -- The address range
* 224.0.0.0 to 239.255.255.255 (224.0.0.0/4)
*
* - IPv6 multicast addresses are have the high-order octet of the
* addresses=0xff (ff00::/8.)
*/
else if (NTOHS(pip->eh_destipaddr[0]) >= 0xe000 &&
NTOHS(pip->eh_destipaddr[0]) <= 0xefff)
{
/* Build the well-known IPv4 IGMP Ethernet address. The first
* three bytes are fixed; the final three variable come from the
* last three bytes of the IP address.
*/
FAR const uint8_t *ip = ((uint8_t*)pip->eh_destipaddr) + 1;
memcpy(peth->dest, g_multicast_ethaddr, 3);
memcpy(&peth->dest[3], ip, 3);
}
#endif
else
{
/* Check if the destination address is on the local network. */
destipaddr = net_ip4addr_conv32(pip->eh_destipaddr);
if (!net_ipaddr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask))
{
/* 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 IP address instead of the
* destination address when determining the MAC address.
*/
netdev_router(dev, destipaddr, &ipaddr);
#else
/* Use the device's default router IP address instead of the
* destination address when determining the MAC address.
*/
net_ipaddr_copy(ipaddr, dev->d_draddr);
#endif
}
else
{
/* Else, we use the destination IP address. */
net_ipaddr_copy(ipaddr, destipaddr);
}
/* Check if we already have this destination address in the ARP table */
tabptr = arp_find(ipaddr);
if (!tabptr)
{
nllvdbg("ARP request for IP %08lx\n", (unsigned long)ipaddr);
/* The destination address was not in our ARP table, so we
* overwrite the IP packet with an ARP request.
*/
arp_format(dev, ipaddr);
arp_dump(ARPBUF);
return;
}
/* Build an Ethernet header. */
memcpy(peth->dest, tabptr->at_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
}
/* Finish populating the Ethernet header */
memcpy(peth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
peth->type = HTONS(ETHTYPE_IP);
dev->d_len += ETH_HDRLEN;
}
#endif /* CONFIG_NET_ARP */
