/****************************************************************************
* net/uip/uip_arp.c
* Implementation of the ARP Address Resolution Protocol.
*
* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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.
*
****************************************************************************/
/* The Address Resolution Protocol ARP is used for mapping between IP
* addresses and link level addresses such as the Ethernet MAC
* addresses. ARP uses broadcast queries to ask for the link level
* address of a known IP address and the host which is configured with
* the IP address for which the query was meant, will respond with its
* link level address.
*
* Note: This ARP implementation only supports Ethernet.
*/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifdef CONFIG_NET
#include <sys/ioctl.h>
#include <stdint.h>
#include <string.h>
#include <debug.h>
#include <netinet/in.h>
#include <net/ethernet.h>
#include <net/uip/uip-arch.h>
#include <net/uip/uip-arp.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define ARP_REQUEST 1
#define ARP_REPLY 2
#define ARP_HWTYPE_ETH 1
#define ETHBUF ((struct uip_eth_hdr *)&dev->d_buf[0])
#define ARPBUF ((struct arp_hdr *)&dev->d_buf[UIP_LLH_LEN])
#define IPBUF ((struct ethip_hdr *)&dev->d_buf[UIP_LLH_LEN])
/****************************************************************************
* Private Types
****************************************************************************/
/* ARP header -- Size 28 bytes */
struct arp_hdr
{
uint16_t ah_hwtype; /* 16-bit Hardware type (Ethernet=0x001) */
uint16_t ah_protocol; /* 16-bit Protocol type (IP=0x0800) */
uint8_t ah_hwlen; /* 8-bit Hardware address size (6) */
uint8_t ah_protolen; /* 8-bit Procotol address size (4) */
uint16_t ah_opcode; /* 16-bit Operation */
uint8_t ah_shwaddr[6]; /* 48-bit Sender hardware address */
uint16_t ah_sipaddr[2]; /* 32-bit Sender IP adress */
uint8_t ah_dhwaddr[6]; /* 48-bit Target hardware address */
uint16_t ah_dipaddr[2]; /* 32-bit Target IP address */
};
/* IP header -- Size 20 or 24 bytes */
struct ethip_hdr
{
uint8_t eh_vhl; /* 8-bit Version (4) and header length (5 or 6) */
uint8_t eh_tos; /* 8-bit Type of service (e.g., 6=TCP) */
uint8_t eh_len[2]; /* 16-bit Total length */
uint8_t eh_ipid[2]; /* 16-bit Identification */
uint8_t eh_ipoffset[2]; /* 16-bit IP flags + fragment offset */
uint8_t eh_ttl; /* 8-bit Time to Live */
uint8_t eh_proto; /* 8-bit Protocol */
uint16_t eh_ipchksum; /* 16-bit Header checksum */
uint16_t eh_srcipaddr[2]; /* 32-bit Source IP address */
uint16_t eh_destipaddr[2]; /* 32-bit Destination IP address */
uint16_t eh_ipoption[2]; /* (optional) */
};
/****************************************************************************
* 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_MULTICAST) && !defined(CONFIG_NET_IPv6)
static const uint8_t g_multicast_ethaddr[3] = {0x01, 0x00, 0x5e};
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
#if defined(CONFIG_NET_DUMPARP) && defined(CONFIG_DEBUG)
static void uip_arp_dump(struct arp_hdr *arp)
{
nlldbg(" HW type: %04x Protocol: %04x\n",
arp->ah_hwtype, arp->ah_protocol);\
nlldbg(" HW len: %02x Proto len: %02x Operation: %04x\n",
arp->ah_hwlen, arp->ah_protolen, arp->ah_opcode);
nlldbg(" Sender MAC: %02x:%02x:%02x:%02x:%02x:%02x IP: %d.%d.%d.%d\n",
arp->ah_shwaddr[0], arp->ah_shwaddr[1], arp->ah_shwaddr[2],
arp->ah_shwaddr[3], arp->ah_shwaddr[4], arp->ah_shwaddr[5],
arp->ah_sipaddr[0] & 0xff, arp->ah_sipaddr[0] >> 8,
arp->ah_sipaddr[1] & 0xff, arp->ah_sipaddr[1] >> 8);
nlldbg(" Dest MAC: %02x:%02x:%02x:%02x:%02x:%02x IP: %d.%d.%d.%d\n",
arp->ah_dhwaddr[0], arp->ah_dhwaddr[1], arp->ah_dhwaddr[2],
arp->ah_dhwaddr[3], arp->ah_dhwaddr[4], arp->ah_dhwaddr[5],
arp->ah_dipaddr[0] & 0xff, arp->ah_dipaddr[0] >> 8,
arp->ah_dipaddr[1] & 0xff, arp->ah_dipaddr[1] >> 8);
}
#else
# define uip_arp_dump(arp)
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/* ARP processing for incoming ARP packets.
*
* This function should be called by the device driver when an ARP
* packet has been received. The function will act differently
* depending on the ARP packet type: if it is a reply for a request
* that we previously sent out, the ARP cache will be filled in with
* the values from the ARP reply. If the incoming ARP packet is an ARP
* request for our IP address, an ARP reply packet is created and put
* into the d_buf[] buffer.
*
* When the function returns, the value of the field d_len
* indicates whether the device driver should send out a packet or
* not. If d_len is zero, no packet should be sent. If d_len is
* non-zero, it contains the length of the outbound packet that is
* present in the d_buf[] buffer.
*
* This function expects an ARP packet with a prepended Ethernet
* header in the d_buf[] buffer, and the length of the packet in the
* global variable d_len.
*/
void uip_arp_arpin(struct uip_driver_s *dev)
{
struct arp_hdr *parp = ARPBUF;
in_addr_t ipaddr;
if (dev->d_len < (sizeof(struct arp_hdr) + UIP_LLH_LEN))
{
nlldbg("Too small\n");
dev->d_len = 0;
return;
}
dev->d_len = 0;
ipaddr = uip_ip4addr_conv(parp->ah_dipaddr);
switch(parp->ah_opcode)
{
case HTONS(ARP_REQUEST):
nllvdbg("ARP request for IP %04lx\n", (long)ipaddr);
/* ARP request. If it asked for our address, we send out a reply. */
if (uip_ipaddr_cmp(ipaddr, dev->d_ipaddr))
{
struct uip_eth_hdr *peth = ETHBUF;
/* First, we register the one who made the request in our ARP
* table, since it is likely that we will do more communication
* with this host in the future.
*/
uip_arp_update(parp->ah_sipaddr, parp->ah_shwaddr);
parp->ah_opcode = HTONS(ARP_REPLY);
memcpy(parp->ah_dhwaddr, parp->ah_shwaddr, ETHER_ADDR_LEN);
memcpy(parp->ah_shwaddr, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(peth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(peth->dest, parp->ah_dhwaddr, ETHER_ADDR_LEN);
parp->ah_dipaddr[0] = parp->ah_sipaddr[0];
parp->ah_dipaddr[1] = parp->ah_sipaddr[1];
uiphdr_ipaddr_copy(parp->ah_sipaddr, &dev->d_ipaddr);
uip_arp_dump(parp);
peth->type = HTONS(UIP_ETHTYPE_ARP);
dev->d_len = sizeof(struct arp_hdr) + UIP_LLH_LEN;
}
break;
case HTONS(ARP_REPLY):
nllvdbg("ARP reply for IP %04lx\n", (long)ipaddr);
/* ARP reply. We insert or update the ARP table if it was meant
* for us.
*/
if (uip_ipaddr_cmp(ipaddr, dev->d_ipaddr))
{
uip_arp_update(parp->ah_sipaddr, parp->ah_shwaddr);
}
break;
}
}
/* Prepend Ethernet header to an outbound IP packet and see if we need
* to send out an ARP request.
*
* 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 prepended 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 they higher level protocols (e.g., TCP)
* eventually will retransmit the dropped packet.
*
* If the destination IP address is not on the local network, the IP
* address of the default router is used instead.
*
* When the function returns, a packet is present in the d_buf[]
* buffer, and the length of the packet is in the field d_len.
*/
void uip_arp_out(struct uip_driver_s *dev)
{
const struct arp_entry *tabptr = NULL;
struct arp_hdr *parp = ARPBUF;
struct uip_eth_hdr *peth = ETHBUF;
struct ethip_hdr *pip = IPBUF;
in_addr_t ipaddr;
in_addr_t destipaddr;
/* Find the destination IP address in the ARP table and construct
* the Ethernet header. If the destination IP addres 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 (uiphdr_ipaddr_cmp(pip->eh_destipaddr, g_broadcast_ipaddr))
{
memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
}
#if defined(CONFIG_NET_MULTICAST) && !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 (pip->eh_destipaddr[0] >= HTONS(0xe000) &&
pip->eh_destipaddr[0] <= HTONS(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.
*/
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 = uip_ip4addr_conv(pip->eh_destipaddr);
if (!uip_ipaddr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask))
{
/* Destination address was not on the local network, so we need to
* use the default router's IP address instead of the destination
* address when determining the MAC address.
*/
uip_ipaddr_copy(ipaddr, dev->d_draddr);
}
else
{
/* Else, we use the destination IP address. */
uip_ipaddr_copy(ipaddr, destipaddr);
}
/* Check if we already have this destination address in the ARP table */
tabptr = uip_arp_find(ipaddr);
if (!tabptr)
{
nllvdbg("ARP request for IP %04lx\n", (long)ipaddr);
/* The destination address was not in our ARP table, so we
* overwrite the IP packet with an ARP request.
*/
memset(peth->dest, 0xff, ETHER_ADDR_LEN);
memset(parp->ah_dhwaddr, 0x00, ETHER_ADDR_LEN);
memcpy(peth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(parp->ah_shwaddr, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
uiphdr_ipaddr_copy(parp->ah_dipaddr, &ipaddr);
uiphdr_ipaddr_copy(parp->ah_sipaddr, &dev->d_ipaddr);
parp->ah_opcode = HTONS(ARP_REQUEST);
parp->ah_hwtype = HTONS(ARP_HWTYPE_ETH);
parp->ah_protocol = HTONS(UIP_ETHTYPE_IP);
parp->ah_hwlen = ETHER_ADDR_LEN;
parp->ah_protolen = 4;
uip_arp_dump(parp);
peth->type = HTONS(UIP_ETHTYPE_ARP);
dev->d_len = sizeof(struct arp_hdr) + UIP_LLH_LEN;
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(UIP_ETHTYPE_IP);
dev->d_len += UIP_LLH_LEN;
}
#endif /* CONFIG_NET */
