254 lines
9.2 KiB
C
254 lines
9.2 KiB
C
/****************************************************************************
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* net/arp/arp_out.c
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*
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* Copyright (C) 2007-2011, 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Based on uIP which also has a BSD style license:
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*
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* Author: Adam Dunkels <adam@dunkels.com>
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* Copyright (c) 2001-2003, Adam Dunkels.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <string.h>
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#include <debug.h>
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#include <nuttx/net/netdev.h>
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#include <nuttx/net/arp.h>
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#include "arp/arp.h"
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#ifdef CONFIG_NET_ARP
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define ETHBUF ((struct eth_hdr_s *)&dev->d_buf[0])
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#define ARPBUF ((struct arp_hdr_s *)&dev->d_buf[NET_LL_HDRLEN])
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#define IPBUF ((struct arp_iphdr_s *)&dev->d_buf[NET_LL_HDRLEN])
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/* Support for broadcast address */
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static const struct ether_addr g_broadcast_ethaddr =
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{{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}};
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static const uint16_t g_broadcast_ipaddr[2] = {0xffff, 0xffff};
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/* Support for IGMP multicast addresses.
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*
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* Well-known ethernet multicast address:
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*
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* ADDRESS TYPE USAGE
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* 01-00-0c-cc-cc-cc 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual Trunking Protocol)
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* 01-00-0c-cc-cc-cd 0x0802 Cisco Shared Spanning Tree Protocol Address
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* 01-80-c2-00-00-00 0x0802 Spanning Tree Protocol (for bridges) IEEE 802.1D
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* 01-80-c2-00-00-02 0x0809 Ethernet OAM Protocol IEEE 802.3ah
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* 01-00-5e-xx-xx-xx 0x0800 IPv4 IGMP Multicast Address
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* 33-33-00-00-00-00 0x86DD IPv6 Neighbor Discovery
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* 33-33-xx-xx-xx-xx 0x86DD IPv6 Multicast Address (RFC3307)
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*
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* The following is the first three octects of the IGMP address:
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*/
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#if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6)
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static const uint8_t g_multicast_ethaddr[3] = {0x01, 0x00, 0x5e};
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#endif
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: arp_out
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*
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* Description:
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* This function should be called before sending out an IP packet. The
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* function checks the destination IP address of the IP packet to see
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* what Ethernet MAC address that should be used as a destination MAC
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* address on the Ethernet.
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*
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* If the destination IP address is in the local network (determined
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* by logical ANDing of netmask and our IP address), the function
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* checks the ARP cache to see if an entry for the destination IP
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* address is found. If so, an Ethernet header is pre-pended at the
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* beginning of the packet and the function returns.
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*
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* If no ARP cache entry is found for the destination IP address, the
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* packet in the d_buf[] is replaced by an ARP request packet for the
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* IP address. The IP packet is dropped and it is assumed that the
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* higher level protocols (e.g., TCP) eventually will retransmit the
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* dropped packet.
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*
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* Upon return in either the case, a packet to be sent is present in the
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* d_buf[] buffer and the d_len field holds the length of the Ethernet
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* frame that should be transmitted.
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*
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****************************************************************************/
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void arp_out(FAR struct net_driver_s *dev)
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{
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FAR const struct arp_entry *tabptr = NULL;
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FAR struct eth_hdr_s *peth = ETHBUF;
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FAR struct arp_iphdr_s *pip = IPBUF;
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in_addr_t ipaddr;
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in_addr_t destipaddr;
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#if defined(CONFIG_NET_PKT) || defined(CONFIG_NET_ARP_SEND)
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/* Skip sending ARP requests when the frame to be transmitted was
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* written into a packet socket.
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*/
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if ((dev->d_flags & IFF_NOARP) != 0)
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{
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/* Clear the indication and let the packet continue on its way. */
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dev->d_flags &= ~IFF_NOARP;
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return;
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}
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#endif
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/* Find the destination IP address in the ARP table and construct
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* the Ethernet header. If the destination IP address isn't on the
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* local network, we use the default router's IP address instead.
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*
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* If not ARP table entry is found, we overwrite the original IP
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* packet with an ARP request for the IP address.
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*/
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/* First check if destination is a local broadcast. */
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if (net_ipaddr_hdrcmp(pip->eh_destipaddr, g_broadcast_ipaddr))
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{
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memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
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}
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#if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6)
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/* Check if the destination address is a multicast address
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*
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* - IPv4: multicast addresses lie in the class D group -- The address range
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* 224.0.0.0 to 239.255.255.255 (224.0.0.0/4)
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*
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* - IPv6 multicast addresses are have the high-order octet of the
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* addresses=0xff (ff00::/8.)
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*/
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else if (NTOHS(pip->eh_destipaddr[0]) >= 0xe000 &&
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NTOHS(pip->eh_destipaddr[0]) <= 0xefff)
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{
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/* Build the well-known IPv4 IGMP Ethernet address. The first
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* three bytes are fixed; the final three variable come from the
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* last three bytes of the IP address.
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*/
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FAR const uint8_t *ip = ((uint8_t*)pip->eh_destipaddr) + 1;
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memcpy(peth->dest, g_multicast_ethaddr, 3);
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memcpy(&peth->dest[3], ip, 3);
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}
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#endif
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else
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{
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/* Check if the destination address is on the local network. */
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destipaddr = net_ip4addr_conv32(pip->eh_destipaddr);
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if (!net_ipaddr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask))
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{
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/* Destination address is not on the local network */
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#ifdef CONFIG_NET_ROUTE
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/* We have a routing table.. find the correct router to use in
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* this case (or, as a fall-back, use the device's default router
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* address). We will use the router IP address instead of the
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* destination address when determining the MAC address.
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*/
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netdev_router(dev, destipaddr, &ipaddr);
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#else
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/* Use the device's default router IP address instead of the
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* destination address when determining the MAC address.
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*/
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net_ipaddr_copy(ipaddr, dev->d_draddr);
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#endif
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}
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else
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{
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/* Else, we use the destination IP address. */
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net_ipaddr_copy(ipaddr, destipaddr);
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}
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/* Check if we already have this destination address in the ARP table */
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tabptr = arp_find(ipaddr);
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if (!tabptr)
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{
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nllvdbg("ARP request for IP %08lx\n", (unsigned long)ipaddr);
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/* The destination address was not in our ARP table, so we
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* overwrite the IP packet with an ARP request.
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*/
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arp_format(dev, ipaddr);
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arp_dump(ARPBUF);
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return;
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}
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/* Build an Ethernet header. */
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memcpy(peth->dest, tabptr->at_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
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}
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/* Finish populating the Ethernet header */
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memcpy(peth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
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peth->type = HTONS(ETHTYPE_IP);
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dev->d_len += NET_LL_HDRLEN;
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}
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#endif /* CONFIG_NET_ARP */
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