/****************************************************************************
* net/uip/uip-arp.c
* Implementation of the ARP Address Resolution Protocol.
*
* Copyright (C) 2007 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/types.h>
#include <sys/ioctl.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>
/****************************************************************************
* 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 ah_hwtype; /* 16-bit Hardware type (Ethernet=0x001) */
uint16 ah_protocol; /* 16-bit Protocoal type (IP=0x0800 */
uint8 ah_hwlen; /* 8-bit Hardware address size (6) */
uint8 ah_protolen; /* 8-bit Procotol address size (4) */
uint16 ah_opcode; /* 16-bit Operation */
uint8 ah_shwaddr[6]; /* 48-bit Sender hardware address */
uint16 ah_sipaddr[2]; /* 32-bit Sender IP adress */
uint8 ah_dhwaddr[6]; /* 48-bit Target hardware address */
uint16 ah_dipaddr[2]; /* 32-bit Target IP address */
};
/* IP header -- Size 20 or 24 bytes */
struct ethip_hdr
{
uint8 eh_vhl; /* 8-bit Version (4) and header length (5 or 6) */
uint8 eh_tos; /* 8-bit Type of service (e.g., 6=TCP) */
uint8 eh_len[2]; /* 16-bit Total length */
uint8 eh_ipid[2]; /* 16-bit Identification */
uint8 eh_ipoffset[2]; /* 16-bit IP flags + fragment offset */
uint8 eh_ttl; /* 8-bit Time to Live */
uint8 eh_proto; /* 8-bit Protocol */
uint16 eh_ipchksum; /* 16-bit Header checksum */
uint16 eh_srcipaddr[2]; /* 32-bit Source IP address */
uint16 eh_destipaddr[2]; /* 32-bit Destination IP address */
uint16 eh_ipoption[2]; /* (optional) */
};
struct arp_entry
{
in_addr_t at_ipaddr;
struct ether_addr at_ethaddr;
uint8 at_time;
};
/****************************************************************************
* Private Data
****************************************************************************/
static const struct ether_addr broadcast_ethaddr =
{{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}};
static const uint16 broadcast_ipaddr[2] = {0xffff, 0xffff};
static struct arp_entry arp_table[CONFIG_NET_ARPTAB_SIZE];
static uint8 g_arptime;
/****************************************************************************
* Private Functions
****************************************************************************/
#if defined(CONFIG_NET_DUMPARP) && defined(CONFIG_DEBUG)
static void uip_arp_dump(struct arp_hdr *arp)
{
ndbg(" HW type: %04x Protocol: %04x\n",
arp->ah_hwtype, arp->ah_protocol);\
ndbg(" HW len: %02x Proto len: %02x Operation: %04x\n",
arp->ah_hwlen, arp->ah_protolen, arp->ah_opcode);
ndbg(" 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);
ndbg(" 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
static void uip_arp_update(uint16 *pipaddr, uint8 *ethaddr)
{
struct arp_entry *tabptr;
in_addr_t ipaddr = uip_ip4addr_conv(pipaddr);
int i;
/* Walk through the ARP mapping table and try to find an entry to
* update. If none is found, the IP -> MAC address mapping is
* inserted in the ARP table.
*/
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
tabptr = &arp_table[i];
/* Only check those entries that are actually in use. */
if (tabptr->at_ipaddr != 0)
{
/* Check if the source IP address of the incoming packet matches
* the IP address in this ARP table entry.
*/
if (uip_ipaddr_cmp(ipaddr, tabptr->at_ipaddr))
{
/* An old entry found, update this and return. */
memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN);
tabptr->at_time = g_arptime;
return;
}
}
}
/* If we get here, no existing ARP table entry was found, so we
create one. */
/* First, we try to find an unused entry in the ARP table. */
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
tabptr = &arp_table[i];
if (tabptr->at_ipaddr == 0)
{
break;
}
}
/* If no unused entry is found, we try to find the oldest entry and
* throw it away.
*/
if (i == CONFIG_NET_ARPTAB_SIZE)
{
uint8 tmpage = 0;
int j = 0;
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
tabptr = &arp_table[i];
if (g_arptime - tabptr->at_time > tmpage)
{
tmpage = g_arptime - tabptr->at_time;
j = i;
}
}
i = j;
tabptr = &arp_table[i];
}
/* Now, i is the ARP table entry which we will fill with the new
* information.
*/
tabptr->at_ipaddr = ipaddr;
memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN);
tabptr->at_time = g_arptime;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/* Initialize the ARP module. */
void uip_arp_init(void)
{
int i;
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
memset(&arp_table[i].at_ipaddr, 0, sizeof(in_addr_t));
}
}
/* Periodic ARP processing function.
*
* This function performs periodic timer processing in the ARP module
* and should be called at regular intervals. The recommended interval
* is 10 seconds between the calls.
*/
void uip_arp_timer(void)
{
struct arp_entry *tabptr;
int i;
++g_arptime;
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
tabptr = &arp_table[i];
if (tabptr->at_ipaddr != 0 && g_arptime - tabptr->at_time >= UIP_ARP_MAXAGE)
{
tabptr->at_ipaddr = 0;
}
}
}
/* 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)
{
in_addr_t ipaddr;
if (dev->d_len < (sizeof(struct arp_hdr) + UIP_LLH_LEN))
{
dev->d_len = 0;
return;
}
dev->d_len = 0;
ipaddr = uip_ip4addr_conv(ARPBUF->ah_dipaddr);
switch(ARPBUF->ah_opcode)
{
case HTONS(ARP_REQUEST):
/* ARP request. If it asked for our address, we send out a reply. */
if (uip_ipaddr_cmp(ipaddr, dev->d_ipaddr))
{
/* 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(ARPBUF->ah_sipaddr, ARPBUF->ah_shwaddr);
ARPBUF->ah_opcode = HTONS(ARP_REPLY);
memcpy(ARPBUF->ah_dhwaddr, ARPBUF->ah_shwaddr, ETHER_ADDR_LEN);
memcpy(ARPBUF->ah_shwaddr, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(ETHBUF->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(ETHBUF->dest, ARPBUF->ah_dhwaddr, ETHER_ADDR_LEN);
ARPBUF->ah_dipaddr[0] = ARPBUF->ah_sipaddr[0];
ARPBUF->ah_dipaddr[1] = ARPBUF->ah_sipaddr[1];
uiphdr_ipaddr_copy(ARPBUF->ah_sipaddr, &dev->d_ipaddr);
uip_arp_dump(ARPBUF);
ETHBUF->type = HTONS(UIP_ETHTYPE_ARP);
dev->d_len = sizeof(struct arp_hdr) + UIP_LLH_LEN;
}
break;
case HTONS(ARP_REPLY):
/* 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(ARPBUF->ah_sipaddr, ARPBUF->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)
{
struct arp_entry *tabptr;
in_addr_t ipaddr;
in_addr_t destipaddr;
int i;
/* 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(IPBUF->eh_destipaddr, broadcast_ipaddr))
{
memcpy(ETHBUF->dest, broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
}
else
{
/* Check if the destination address is on the local network. */
destipaddr = uip_ip4addr_conv(IPBUF->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 */
for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
{
tabptr = &arp_table[i];
if (uip_ipaddr_cmp(ipaddr, tabptr->at_ipaddr))
{
break;
}
}
if (i == CONFIG_NET_ARPTAB_SIZE)
{
/* The destination address was not in our ARP table, so we
* overwrite the IP packet with an ARP request.
*/
memset(ETHBUF->dest, 0xff, ETHER_ADDR_LEN);
memset(ARPBUF->ah_dhwaddr, 0x00, ETHER_ADDR_LEN);
memcpy(ETHBUF->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
memcpy(ARPBUF->ah_shwaddr, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
uiphdr_ipaddr_copy(ARPBUF->ah_dipaddr, &ipaddr);
uiphdr_ipaddr_copy(ARPBUF->ah_sipaddr, &dev->d_ipaddr);
ARPBUF->ah_opcode = HTONS(ARP_REQUEST);
ARPBUF->ah_hwtype = HTONS(ARP_HWTYPE_ETH);
ARPBUF->ah_protocol = HTONS(UIP_ETHTYPE_IP);
ARPBUF->ah_hwlen = ETHER_ADDR_LEN;
ARPBUF->ah_protolen = 4;
uip_arp_dump(ARPBUF);
ETHBUF->type = HTONS(UIP_ETHTYPE_ARP);
dev->d_len = sizeof(struct arp_hdr) + UIP_LLH_LEN;
return;
}
/* Build an ethernet header. */
memcpy(ETHBUF->dest, tabptr->at_ethaddr.ether_addr_octet, ETHER_ADDR_LEN);
}
/* Finish populating the ethernet header */
memcpy(ETHBUF->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN);
ETHBUF->type = HTONS(UIP_ETHTYPE_IP);
dev->d_len += UIP_LLH_LEN;
}
#endif /* CONFIG_NET */
