Ilya Krylov
123
Diff: uitility/uip_arp.c
- Revision:
- 0:5350a66d5279
diff -r 000000000000 -r 5350a66d5279 uitility/uip_arp.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/uitility/uip_arp.c Mon Sep 15 11:12:30 2014 +0000
@@ -0,0 +1,417 @@
+/**
+ * \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 1.8 2006/06/02 23:36:21 adam 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(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(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);
+}
+
+/*-----------------------------------------------------------------------------------*/
+/** @} */
+/** @} */