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         int eth_hdr_size;
  56
  57         debug("ARP broadcast %d\n", NetArpWaitTry);
  58
  59         pkt = NetTxPacket;
  60
  61         eth_hdr_size = NetSetEther(pkt, NetBcastAddr, PROT_ARP);
  62         pkt += eth_hdr_size;
  63
  64         arp = (struct arp_hdr *) pkt;
  65
  66         arp->ar_hrd = htons(ARP_ETHER);
  67         arp->ar_pro = htons(PROT_IP);
  68         arp->ar_hln = ARP_HLEN;
  69         arp->ar_pln = ARP_PLEN;
  70         arp->ar_op = htons(ARPOP_REQUEST);
  71
  72         /* source ET addr */
  73         memcpy(&arp->ar_sha, NetOurEther, ARP_HLEN);
  74         /* source IP addr */
  75         NetWriteIP(&arp->ar_spa, NetOurIP);
  76         /* dest ET addr = 0 */
  77         memset(&arp->ar_tha, 0, ARP_HLEN);
  78         if ((NetArpWaitPacketIP & NetOurSubnetMask) !=
  79             (NetOurIP & NetOurSubnetMask)) {
  80                 if (NetOurGatewayIP == 0) {
  81                         puts("## Warning: gatewayip needed but not set\n");
  82                         NetArpWaitReplyIP = NetArpWaitPacketIP;
  83                 } else {
  84                         NetArpWaitReplyIP = NetOurGatewayIP;
  85                 }
  86         } else {
  87                 NetArpWaitReplyIP = NetArpWaitPacketIP;
  88         }
  89
  90         NetWriteIP(&arp->ar_tpa, NetArpWaitReplyIP);
  91         (void) eth_send(NetTxPacket, eth_hdr_size + ARP_HDR_SIZE);
  92 }
  93
  94 void ArpTimeoutCheck(void)
  95 {
  96         ulong t;
  97
  98         if (!NetArpWaitPacketIP)
  99                 return;
 100
 101         t = get_timer(0);
 102
 103         /* check for arp timeout */
 104         if ((t - NetArpWaitTimerStart) > ARP_TIMEOUT) {
 105                 NetArpWaitTry++;
 106
 107                 if (NetArpWaitTry >= ARP_TIMEOUT_COUNT) {
 108                         puts("\nARP Retry count exceeded; starting again\n");
 109                         NetArpWaitTry = 0;
 110                         NetStartAgain();
 111                 } else {
 112                         NetArpWaitTimerStart = t;
 113                         ArpRequest();
 114                 }
 115         }
 116 }
 117
 118 void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 119 {
 120         struct arp_hdr *arp;
 121         IPaddr_t reply_ip_addr;
 122         uchar *pkt;
 123         int eth_hdr_size;
 124
 125         /*
 126          * We have to deal with two types of ARP packets:
 127          * - REQUEST packets will be answered by sending  our
 128          *   IP address - if we know it.
 129          * - REPLY packates are expected only after we asked
 130          *   for the TFTP server's or the gateway's ethernet
 131          *   address; so if we receive such a packet, we set
 132          *   the server ethernet address
 133          */
 134         debug("Got ARP\n");
 135
 136         arp = (struct arp_hdr *)ip;
 137         if (len < ARP_HDR_SIZE) {
 138                 printf("bad length %d < %d\n", len, ARP_HDR_SIZE);
 139                 return;
 140         }
 141         if (ntohs(arp->ar_hrd) != ARP_ETHER)
 142                 return;
 143         if (ntohs(arp->ar_pro) != PROT_IP)
 144                 return;
 145         if (arp->ar_hln != ARP_HLEN)
 146                 return;
 147         if (arp->ar_pln != ARP_PLEN)
 148                 return;
 149
 150         if (NetOurIP == 0)
 151                 return;
 152
 153         if (NetReadIP(&arp->ar_tpa) != NetOurIP)
 154                 return;
 155
 156         switch (ntohs(arp->ar_op)) {
 157         case ARPOP_REQUEST:
 158                 /* reply with our IP address */
 159                 debug("Got ARP REQUEST, return our IP\n");
 160                 pkt = (uchar *)et;
 161                 eth_hdr_size = NetSetEther(pkt, et->et_src, PROT_ARP);
 162                 pkt += eth_hdr_size;
 163                 arp->ar_op = htons(ARPOP_REPLY);
 164                 memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);
 165                 NetCopyIP(&arp->ar_tpa, &arp->ar_spa);
 166                 memcpy(&arp->ar_sha, NetOurEther, ARP_HLEN);
 167                 NetCopyIP(&arp->ar_spa, &NetOurIP);
 168                 (void) eth_send((uchar *)et, eth_hdr_size + ARP_HDR_SIZE);
 169                 return;
 170
 171         case ARPOP_REPLY:               /* arp reply */
 172                 /* are we waiting for a reply */
 173                 if (!NetArpWaitPacketIP || !NetArpWaitPacketMAC)
 174                         break;
 175
 176 #ifdef CONFIG_KEEP_SERVERADDR
 177                 if (NetServerIP == NetArpWaitPacketIP) {
 178                         char buf[20];
 179                         sprintf(buf, "%pM", arp->ar_sha);
 180                         setenv("serveraddr", buf);
 181                 }
 182 #endif
 183
 184                 reply_ip_addr = NetReadIP(&arp->ar_spa);
 185
 186                 /* matched waiting packet's address */
 187                 if (reply_ip_addr == NetArpWaitReplyIP) {
 188                         debug("Got ARP REPLY, set eth addr (%pM)\n",
 189                                 arp->ar_data);
 190
 191                         /* save address for later use */
 192                         memcpy(NetArpWaitPacketMAC,
 193                                 &arp->ar_sha, ARP_HLEN);
 194
 195 #ifdef CONFIG_NETCONSOLE
 196                         NetGetHandler()(0, 0, 0, 0, 0);
 197 #endif
 198                         /* modify header, and transmit it */
 199                         memcpy(((struct ethernet_hdr *)NetArpWaitTxPacket)->
 200                                 et_dest, NetArpWaitPacketMAC, ARP_HLEN);
 201                         (void) eth_send(NetArpWaitTxPacket,
 202                                         NetArpWaitTxPacketSize);
 203
 204                         /* no arp request pending now */
 205                         NetArpWaitPacketIP = 0;
 206                         NetArpWaitTxPacketSize = 0;
 207                         NetArpWaitPacketMAC = NULL;
 208
 209                 }
 210                 return;
 211         default:
 212                 debug("Unexpected ARP opcode 0x%x\n",
 213                       ntohs(arp->ar_op));
 214                 return;
 215         }
 216 }