net/arp.c

   1 /*
   2  *      Copied from Linux Monitor (LiMon) - Networking.
   3  *
   4  *      Copyright 1994 - 2000 Neil Russell.
   5  *      (See License)
   6  *      Copyright 2000 Roland Borde
   7  *      Copyright 2000 Paolo Scaffardi
   8  *      Copyright 2000-2002 Wolfgang Denk, wd@denx.de
   9  */
  10
  11 #include <common.h>
  12
  13 #include "arp.h"
  14
  15 #ifndef CONFIG_ARP_TIMEOUT
  16 /* Milliseconds before trying ARP again */
  17 # define ARP_TIMEOUT            5000UL
  18 #else
  19 # define ARP_TIMEOUT            CONFIG_ARP_TIMEOUT
  20 #endif
  21
  22
  23 #ifndef CONFIG_NET_RETRY_COUNT
  24 # define ARP_TIMEOUT_COUNT      5       /* # of timeouts before giving up  */
  25 #else
  26 # define ARP_TIMEOUT_COUNT      CONFIG_NET_RETRY_COUNT
  27 #endif
  28
  29 IPaddr_t        NetArpWaitPacketIP;
  30 IPaddr_t        NetArpWaitReplyIP;
  31 /* MAC address of waiting packet's destination */
  32 uchar          *NetArpWaitPacketMAC;
  33 /* THE transmit packet */
  34 uchar          *NetArpWaitTxPacket;
  35 int             NetArpWaitTxPacketSize;
  36 uchar           NetArpWaitPacketBuf[PKTSIZE_ALIGN + PKTALIGN];
  37 ulong           NetArpWaitTimerStart;
  38 int             NetArpWaitTry;
  39
  40 void ArpInit(void)
  41 {
  42         /* XXX problem with bss workaround */
  43         NetArpWaitPacketMAC = NULL;
  44         NetArpWaitPacketIP = 0;
  45         NetArpWaitReplyIP = 0;
  46         NetArpWaitTxPacket = &NetArpWaitPacketBuf[0] + (PKTALIGN - 1);
  47         NetArpWaitTxPacket -= (ulong)NetArpWaitTxPacket % PKTALIGN;
  48         NetArpWaitTxPacketSize = 0;
  49 }
  50
  51 void ArpRequest(void)
  52 {
  53         uchar *pkt;
  54         struct arp_hdr *arp;
  55
  56         debug("ARP broadcast %d\n", NetArpWaitTry);
  57
  58         pkt = NetTxPacket;
  59
  60         pkt += NetSetEther(pkt, NetBcastAddr, PROT_ARP);
  61
  62         arp = (struct arp_hdr *) pkt;
  63
  64         arp->ar_hrd = htons(ARP_ETHER);
  65         arp->ar_pro = htons(PROT_IP);
  66         arp->ar_hln = 6;
  67         arp->ar_pln = 4;
  68         arp->ar_op = htons(ARPOP_REQUEST);
  69
  70         /* source ET addr */
  71         memcpy(&arp->ar_data[0], NetOurEther, 6);
  72         /* source IP addr */
  73         NetWriteIP((uchar *) &arp->ar_data[6], NetOurIP);
  74         /* dest ET addr = 0 */
  75         memset(&arp->ar_data[10], '\0', 6);
  76         if ((NetArpWaitPacketIP & NetOurSubnetMask) !=
  77             (NetOurIP & NetOurSubnetMask)) {
  78                 if (NetOurGatewayIP == 0) {
  79                         puts("## Warning: gatewayip needed but not set\n");
  80                         NetArpWaitReplyIP = NetArpWaitPacketIP;
  81                 } else {
  82                         NetArpWaitReplyIP = NetOurGatewayIP;
  83                 }
  84         } else {
  85                 NetArpWaitReplyIP = NetArpWaitPacketIP;
  86         }
  87
  88         NetWriteIP((uchar *) &arp->ar_data[16], NetArpWaitReplyIP);
  89         (void) eth_send(NetTxPacket, (pkt - NetTxPacket) + ARP_HDR_SIZE);
  90 }
  91
  92 void ArpTimeoutCheck(void)
  93 {
  94         ulong t;
  95
  96         if (!NetArpWaitPacketIP)
  97                 return;
  98
  99         t = get_timer(0);
 100
 101         /* check for arp timeout */
 102         if ((t - NetArpWaitTimerStart) > ARP_TIMEOUT) {
 103                 NetArpWaitTry++;
 104
 105                 if (NetArpWaitTry >= ARP_TIMEOUT_COUNT) {
 106                         puts("\nARP Retry count exceeded; starting again\n");
 107                         NetArpWaitTry = 0;
 108                         NetStartAgain();
 109                 } else {
 110                         NetArpWaitTimerStart = t;
 111                         ArpRequest();
 112                 }
 113         }
 114 }
 115
 116 void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 117 {
 118         struct arp_hdr *arp;
 119         IPaddr_t tmp;
 120         uchar *pkt;
 121
 122         /*
 123          * We have to deal with two types of ARP packets:
 124          * - REQUEST packets will be answered by sending  our
 125          *   IP address - if we know it.
 126          * - REPLY packates are expected only after we asked
 127          *   for the TFTP server's or the gateway's ethernet
 128          *   address; so if we receive such a packet, we set
 129          *   the server ethernet address
 130          */
 131         debug("Got ARP\n");
 132
 133         arp = (struct arp_hdr *)ip;
 134         if (len < ARP_HDR_SIZE) {
 135                 printf("bad length %d < %d\n", len, ARP_HDR_SIZE);
 136                 return;
 137         }
 138         if (ntohs(arp->ar_hrd) != ARP_ETHER)
 139                 return;
 140         if (ntohs(arp->ar_pro) != PROT_IP)
 141                 return;
 142         if (arp->ar_hln != 6)
 143                 return;
 144         if (arp->ar_pln != 4)
 145                 return;
 146
 147         if (NetOurIP == 0)
 148                 return;
 149
 150         if (NetReadIP(&arp->ar_data[16]) != NetOurIP)
 151                 return;
 152
 153         switch (ntohs(arp->ar_op)) {
 154         case ARPOP_REQUEST:
 155                 /* reply with our IP address */
 156                 debug("Got ARP REQUEST, return our IP\n");
 157                 pkt = (uchar *)et;
 158                 pkt += NetSetEther(pkt, et->et_src, PROT_ARP);
 159                 arp->ar_op = htons(ARPOP_REPLY);
 160                 memcpy(&arp->ar_data[10], &arp->ar_data[0], 6);
 161                 NetCopyIP(&arp->ar_data[16], &arp->ar_data[6]);
 162                 memcpy(&arp->ar_data[0], NetOurEther, 6);
 163                 NetCopyIP(&arp->ar_data[6], &NetOurIP);
 164                 (void) eth_send((uchar *)et,
 165                                 (pkt - (uchar *)et) + ARP_HDR_SIZE);
 166                 return;
 167
 168         case ARPOP_REPLY:               /* arp reply */
 169                 /* are we waiting for a reply */
 170                 if (!NetArpWaitPacketIP || !NetArpWaitPacketMAC)
 171                         break;
 172
 173 #ifdef CONFIG_KEEP_SERVERADDR
 174                 if (NetServerIP == NetArpWaitPacketIP) {
 175                         char buf[20];
 176                         sprintf(buf, "%pM", arp->ar_data);
 177                         setenv("serveraddr", buf);
 178                 }
 179 #endif
 180
 181                 tmp = NetReadIP(&arp->ar_data[6]);
 182
 183                 /* matched waiting packet's address */
 184                 if (tmp == NetArpWaitReplyIP) {
 185                         debug("Got ARP REPLY, set eth addr (%pM)\n",
 186                                 arp->ar_data);
 187
 188                         /* save address for later use */
 189                         memcpy(NetArpWaitPacketMAC,
 190                                &arp->ar_data[0], 6);
 191
 192 #ifdef CONFIG_NETCONSOLE
 193                         NetGetHandler()(0, 0, 0, 0, 0);
 194 #endif
 195                         /* modify header, and transmit it */
 196                         memcpy(((struct ethernet_hdr *)NetArpWaitTxPacket)->
 197                                 et_dest, NetArpWaitPacketMAC, 6);
 198                         (void) eth_send(NetArpWaitTxPacket,
 199                                         NetArpWaitTxPacketSize);
 200
 201                         /* no arp request pending now */
 202                         NetArpWaitPacketIP = 0;
 203                         NetArpWaitTxPacketSize = 0;
 204                         NetArpWaitPacketMAC = NULL;
 205
 206                 }
 207                 return;
 208         default:
 209                 debug("Unexpected ARP opcode 0x%x\n",
 210                       ntohs(arp->ar_op));
 211                 return;
 212         }
 213 }