| /** |
| * \addtogroup uip |
| * @{ |
| */ |
| |
| /** |
| * \defgroup uiparp uIP Address Resolution Protocol |
| * @{ |
| * |
| * 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. |
| */ |
| |
| /** |
| * \file |
| * Implementation of the ARP Address Resolution Protocol. |
| * \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. |
| * |
| * This file is part of the uIP TCP/IP stack. |
| * |
| * $Id: uip_arp.c,v 1.15 2005/02/23 22:40:40 oliverschmidt Exp $ |
| * |
| */ |
| |
| |
| #include "uip_arp.h" |
| |
| #include <string.h> |
| |
| struct arp_hdr { |
| struct uip_eth_hdr ethhdr; |
| u16_t hwtype; |
| u16_t protocol; |
| u8_t hwlen; |
| u8_t protolen; |
| u16_t opcode; |
| struct uip_eth_addr shwaddr; |
| u16_t sipaddr[2]; |
| struct uip_eth_addr dhwaddr; |
| u16_t dipaddr[2]; |
| }; |
| |
| struct ethip_hdr { |
| struct uip_eth_hdr ethhdr; |
| /* IP header. */ |
| u8_t vhl, |
| tos, |
| len[2], |
| ipid[2], |
| ipoffset[2], |
| ttl, |
| proto; |
| u16_t ipchksum; |
| u16_t srcipaddr[2], |
| destipaddr[2]; |
| }; |
| |
| #define ARP_REQUEST 1 |
| #define ARP_REPLY 2 |
| |
| #define ARP_HWTYPE_ETH 1 |
| |
| struct arp_entry { |
| u16_t ipaddr[2]; |
| struct uip_eth_addr ethaddr; |
| u8_t time; |
| }; |
| |
| static const struct uip_eth_addr broadcast_ethaddr = |
| {{0xff,0xff,0xff,0xff,0xff,0xff}}; |
| static const u16_t broadcast_ipaddr[2] = {0xffff,0xffff}; |
| |
| static struct arp_entry arp_table[UIP_ARPTAB_SIZE]; |
| static u16_t ipaddr[2]; |
| static u8_t i, c; |
| |
| static u8_t arptime; |
| static u8_t tmpage; |
| |
| #define BUF ((struct arp_hdr *)&uip_buf[0]) |
| #define IPBUF ((struct ethip_hdr *)&uip_buf[0]) |
| /*-----------------------------------------------------------------------------------*/ |
| /** |
| * Initialize the ARP module. |
| * |
| */ |
| /*-----------------------------------------------------------------------------------*/ |
| void |
| uip_arp_init(void) |
| { |
| for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
| memset(arp_table[i].ipaddr, 0, 4); |
| } |
| } |
| /*-----------------------------------------------------------------------------------*/ |
| /** |
| * 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; |
| |
| ++arptime; |
| for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
| tabptr = &arp_table[i]; |
| if((tabptr->ipaddr[0] | tabptr->ipaddr[1]) != 0 && |
| arptime - tabptr->time >= UIP_ARP_MAXAGE) { |
| memset(tabptr->ipaddr, 0, 4); |
| } |
| } |
| |
| } |
| /*-----------------------------------------------------------------------------------*/ |
| static void |
| uip_arp_update(u16_t *ipaddr, struct uip_eth_addr *ethaddr) |
| { |
| register struct arp_entry *tabptr; |
| /* 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 < UIP_ARPTAB_SIZE; ++i) { |
| |
| tabptr = &arp_table[i]; |
| /* Only check those entries that are actually in use. */ |
| if(tabptr->ipaddr[0] != 0 && |
| tabptr->ipaddr[1] != 0) { |
| |
| /* Check if the source IP address of the incoming packet matches |
| the IP address in this ARP table entry. */ |
| if(ipaddr[0] == tabptr->ipaddr[0] && |
| ipaddr[1] == tabptr->ipaddr[1]) { |
| |
| /* An old entry found, update this and return. */ |
| memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6); |
| tabptr->time = 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 < UIP_ARPTAB_SIZE; ++i) { |
| tabptr = &arp_table[i]; |
| if(tabptr->ipaddr[0] == 0 && |
| tabptr->ipaddr[1] == 0) { |
| break; |
| } |
| } |
| |
| /* If no unused entry is found, we try to find the oldest entry and |
| throw it away. */ |
| if(i == UIP_ARPTAB_SIZE) { |
| tmpage = 0; |
| c = 0; |
| for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
| tabptr = &arp_table[i]; |
| if(arptime - tabptr->time > tmpage) { |
| tmpage = arptime - tabptr->time; |
| c = i; |
| } |
| } |
| i = c; |
| tabptr = &arp_table[i]; |
| } |
| |
| /* Now, i is the ARP table entry which we will fill with the new |
| information. */ |
| memcpy(tabptr->ipaddr, ipaddr, 4); |
| memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6); |
| tabptr->time = arptime; |
| } |
| /*-----------------------------------------------------------------------------------*/ |
| /** |
| * ARP processing for incoming IP packets |
| * |
| * This function should be called by the device driver when an IP |
| * packet has been received. The function will check if the address is |
| * in the ARP cache, and if so the ARP cache entry will be |
| * refreshed. If no ARP cache entry was found, a new one is created. |
| * |
| * This function expects an IP packet with a prepended Ethernet header |
| * in the uip_buf[] buffer, and the length of the packet in the global |
| * variable uip_len. |
| */ |
| /*-----------------------------------------------------------------------------------*/ |
| #if 0 |
| void |
| uip_arp_ipin(void) |
| { |
| uip_len -= sizeof(struct uip_eth_hdr); |
| |
| /* Only insert/update an entry if the source IP address of the |
| incoming IP packet comes from a host on the local network. */ |
| if((IPBUF->srcipaddr[0] & uip_netmask[0]) != |
| (uip_hostaddr[0] & uip_netmask[0])) { |
| return; |
| } |
| if((IPBUF->srcipaddr[1] & uip_netmask[1]) != |
| (uip_hostaddr[1] & uip_netmask[1])) { |
| return; |
| } |
| uip_arp_update(IPBUF->srcipaddr, &(IPBUF->ethhdr.src)); |
| |
| return; |
| } |
| #endif /* 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 uip_buf[] buffer. |
| * |
| * When the function returns, the value of the global variable uip_len |
| * indicates whether the device driver should send out a packet or |
| * not. If uip_len is zero, no packet should be sent. If uip_len is |
| * non-zero, it contains the length of the outbound packet that is |
| * present in the uip_buf[] buffer. |
| * |
| * This function expects an ARP packet with a prepended Ethernet |
| * header in the uip_buf[] buffer, and the length of the packet in the |
| * global variable uip_len. |
| */ |
| /*-----------------------------------------------------------------------------------*/ |
| void |
| uip_arp_arpin(void) |
| { |
| |
| if(uip_len < sizeof(struct arp_hdr)) { |
| uip_len = 0; |
| return; |
| } |
| uip_len = 0; |
| |
| switch(BUF->opcode) { |
| case HTONS(ARP_REQUEST): |
| /* ARP request. If it asked for our address, we send out a |
| reply. */ |
| /* if(BUF->dipaddr[0] == uip_hostaddr[0] && |
| BUF->dipaddr[1] == uip_hostaddr[1]) {*/ |
| if(uip_ipaddr_cmp(BUF->dipaddr, uip_hostaddr)) { |
| /* 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(BUF->sipaddr, &BUF->shwaddr); |
| |
| /* The reply opcode is 2. */ |
| BUF->opcode = HTONS(2); |
| |
| memcpy(BUF->dhwaddr.addr, BUF->shwaddr.addr, 6); |
| memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6); |
| memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
| memcpy(BUF->ethhdr.dest.addr, BUF->dhwaddr.addr, 6); |
| |
| BUF->dipaddr[0] = BUF->sipaddr[0]; |
| BUF->dipaddr[1] = BUF->sipaddr[1]; |
| BUF->sipaddr[0] = uip_hostaddr[0]; |
| BUF->sipaddr[1] = uip_hostaddr[1]; |
| |
| BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP); |
| uip_len = sizeof(struct arp_hdr); |
| } |
| break; |
| case HTONS(ARP_REPLY): |
| /* ARP reply. We insert or update the ARP table if it was meant |
| for us. */ |
| /* if(BUF->dipaddr[0] == uip_hostaddr[0] && |
| BUF->dipaddr[1] == uip_hostaddr[1]) {*/ |
| if(uip_ipaddr_cmp(BUF->dipaddr, uip_hostaddr)) { |
| uip_arp_update(BUF->sipaddr, &BUF->shwaddr); |
| } |
| break; |
| } |
| |
| return; |
| } |
| /*-----------------------------------------------------------------------------------*/ |
| /** |
| * 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 uip_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 uip_buf[] |
| * buffer, and the length of the packet is in the global variable |
| * uip_len. |
| */ |
| /*-----------------------------------------------------------------------------------*/ |
| void |
| uip_arp_out(void) |
| { |
| struct arp_entry *tabptr; |
| |
| /* 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(uip_ipaddr_cmp(IPBUF->destipaddr, broadcast_ipaddr)) { |
| memcpy(IPBUF->ethhdr.dest.addr, broadcast_ethaddr.addr, 6); |
| } else { |
| /* Check if the destination address is on the local network. */ |
| if(!uip_ipaddr_maskcmp(IPBUF->destipaddr, uip_hostaddr, uip_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, uip_draddr); |
| } else { |
| /* Else, we use the destination IP address. */ |
| uip_ipaddr_copy(ipaddr, IPBUF->destipaddr); |
| } |
| |
| for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
| tabptr = &arp_table[i]; |
| if(uip_ipaddr_cmp(ipaddr, tabptr->ipaddr)) { |
| break; |
| } |
| } |
| |
| if(i == UIP_ARPTAB_SIZE) { |
| /* The destination address was not in our ARP table, so we |
| overwrite the IP packet with an ARP request. */ |
| |
| memset(BUF->ethhdr.dest.addr, 0xff, 6); |
| memset(BUF->dhwaddr.addr, 0x00, 6); |
| memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
| memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6); |
| |
| uip_ipaddr_copy(BUF->dipaddr, ipaddr); |
| uip_ipaddr_copy(BUF->sipaddr, uip_hostaddr); |
| BUF->opcode = HTONS(ARP_REQUEST); /* ARP request. */ |
| BUF->hwtype = HTONS(ARP_HWTYPE_ETH); |
| BUF->protocol = HTONS(UIP_ETHTYPE_IP); |
| BUF->hwlen = 6; |
| BUF->protolen = 4; |
| BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP); |
| |
| uip_appdata = &uip_buf[UIP_TCPIP_HLEN + UIP_LLH_LEN]; |
| |
| uip_len = sizeof(struct arp_hdr); |
| return; |
| } |
| |
| /* Build an ethernet header. */ |
| memcpy(IPBUF->ethhdr.dest.addr, tabptr->ethaddr.addr, 6); |
| } |
| memcpy(IPBUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
| |
| IPBUF->ethhdr.type = HTONS(UIP_ETHTYPE_IP); |
| |
| uip_len += sizeof(struct uip_eth_hdr); |
| } |
| /*-----------------------------------------------------------------------------------*/ |
| |
| /** @} */ |
| /** @} */ |