net/arp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      Copied from Linux Monitor (LiMon) - Networking.
   4  *
   5  *      Copyright 1994 - 2000 Neil Russell.
   6  *      (See License)
   7  *      Copyright 2000 Roland Borde
   8  *      Copyright 2000 Paolo Scaffardi
   9  *      Copyright 2000-2002 Wolfgang Denk, [email protected]
  10  */
  11
  12 #include <common.h>
  13 #include <env.h>
  14 #include <net.h>
  15
  16 #include "arp.h"
  17
  18 #ifndef CONFIG_ARP_TIMEOUT
  19 /* Milliseconds before trying ARP again */
  20 # define ARP_TIMEOUT            5000UL
  21 #else
  22 # define ARP_TIMEOUT            CONFIG_ARP_TIMEOUT
  23 #endif
  24
  25
  26 #ifndef CONFIG_NET_RETRY_COUNT
  27 # define ARP_TIMEOUT_COUNT      5       /* # of timeouts before giving up  */
  28 #else
  29 # define ARP_TIMEOUT_COUNT      CONFIG_NET_RETRY_COUNT
  30 #endif
  31
  32 struct in_addr net_arp_wait_packet_ip;
  33 static struct in_addr net_arp_wait_reply_ip;
  34 /* MAC address of waiting packet's destination */
  35 uchar          *arp_wait_packet_ethaddr;
  36 int             arp_wait_tx_packet_size;
  37 ulong           arp_wait_timer_start;
  38 int             arp_wait_try;
  39 uchar          *arp_tx_packet; /* THE ARP transmit packet */
  40 static uchar    arp_tx_packet_buf[PKTSIZE_ALIGN + PKTALIGN];
  41
  42 void arp_init(void)
  43 {
  44         /* XXX problem with bss workaround */
  45         arp_wait_packet_ethaddr = NULL;
  46         net_arp_wait_packet_ip.s_addr = 0;
  47         net_arp_wait_reply_ip.s_addr = 0;
  48         arp_wait_tx_packet_size = 0;
  49         arp_tx_packet = &arp_tx_packet_buf[0] + (PKTALIGN - 1);
  50         arp_tx_packet -= (ulong)arp_tx_packet % PKTALIGN;
  51 }
  52
  53 void arp_raw_request(struct in_addr source_ip, const uchar *target_ethaddr,
  54         struct in_addr target_ip)
  55 {
  56         uchar *pkt;
  57         struct arp_hdr *arp;
  58         int eth_hdr_size;
  59
  60         debug_cond(DEBUG_DEV_PKT, "ARP broadcast %d\n", arp_wait_try);
  61
  62         pkt = arp_tx_packet;
  63
  64         eth_hdr_size = net_set_ether(pkt, net_bcast_ethaddr, PROT_ARP);
  65         pkt += eth_hdr_size;
  66
  67         arp = (struct arp_hdr *)pkt;
  68
  69         arp->ar_hrd = htons(ARP_ETHER);
  70         arp->ar_pro = htons(PROT_IP);
  71         arp->ar_hln = ARP_HLEN;
  72         arp->ar_pln = ARP_PLEN;
  73         arp->ar_op = htons(ARPOP_REQUEST);
  74
  75         memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);    /* source ET addr */
  76         net_write_ip(&arp->ar_spa, source_ip);          /* source IP addr */
  77         memcpy(&arp->ar_tha, target_ethaddr, ARP_HLEN); /* target ET addr */
  78         net_write_ip(&arp->ar_tpa, target_ip);          /* target IP addr */
  79
  80         net_send_packet(arp_tx_packet, eth_hdr_size + ARP_HDR_SIZE);
  81 }
  82
  83 void arp_request(void)
  84 {
  85         if ((net_arp_wait_packet_ip.s_addr & net_netmask.s_addr) !=
  86             (net_ip.s_addr & net_netmask.s_addr)) {
  87                 if (net_gateway.s_addr == 0) {
  88                         puts("## Warning: gatewayip needed but not set\n");
  89                         net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  90                 } else {
  91                         net_arp_wait_reply_ip = net_gateway;
  92                 }
  93         } else {
  94                 net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  95         }
  96
  97         arp_raw_request(net_ip, net_null_ethaddr, net_arp_wait_reply_ip);
  98 }
  99
 100 int arp_timeout_check(void)
 101 {
 102         ulong t;
 103
 104         if (!arp_is_waiting())
 105                 return 0;
 106
 107         t = get_timer(0);
 108
 109         /* check for arp timeout */
 110         if ((t - arp_wait_timer_start) > ARP_TIMEOUT) {
 111                 arp_wait_try++;
 112
 113                 if (arp_wait_try >= ARP_TIMEOUT_COUNT) {
 114                         puts("\nARP Retry count exceeded; starting again\n");
 115                         arp_wait_try = 0;
 116                         net_set_state(NETLOOP_FAIL);
 117                 } else {
 118                         arp_wait_timer_start = t;
 119                         arp_request();
 120                 }
 121         }
 122         return 1;
 123 }
 124
 125 void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 126 {
 127         struct arp_hdr *arp;
 128         struct in_addr reply_ip_addr;
 129         int eth_hdr_size;
 130         uchar *tx_packet;
 131
 132         /*
 133          * We have to deal with two types of ARP packets:
 134          * - REQUEST packets will be answered by sending  our
 135          *   IP address - if we know it.
 136          * - REPLY packates are expected only after we asked
 137          *   for the TFTP server's or the gateway's ethernet
 138          *   address; so if we receive such a packet, we set
 139          *   the server ethernet address
 140          */
 141         debug_cond(DEBUG_NET_PKT, "Got ARP\n");
 142
 143         arp = (struct arp_hdr *)ip;
 144         if (len < ARP_HDR_SIZE) {
 145                 printf("bad length %d < %d\n", len, ARP_HDR_SIZE);
 146                 return;
 147         }
 148         if (ntohs(arp->ar_hrd) != ARP_ETHER)
 149                 return;
 150         if (ntohs(arp->ar_pro) != PROT_IP)
 151                 return;
 152         if (arp->ar_hln != ARP_HLEN)
 153                 return;
 154         if (arp->ar_pln != ARP_PLEN)
 155                 return;
 156
 157         if (net_ip.s_addr == 0)
 158                 return;
 159
 160         if (net_read_ip(&arp->ar_tpa).s_addr != net_ip.s_addr)
 161                 return;
 162
 163         switch (ntohs(arp->ar_op)) {
 164         case ARPOP_REQUEST:
 165                 /* reply with our IP address */
 166                 debug_cond(DEBUG_DEV_PKT, "Got ARP REQUEST, return our IP\n");
 167                 eth_hdr_size = net_update_ether(et, et->et_src, PROT_ARP);
 168                 arp->ar_op = htons(ARPOP_REPLY);
 169                 memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);
 170                 net_copy_ip(&arp->ar_tpa, &arp->ar_spa);
 171                 memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);
 172                 net_copy_ip(&arp->ar_spa, &net_ip);
 173
 174 #ifdef CONFIG_CMD_LINK_LOCAL
 175                 /*
 176                  * Work-around for brain-damaged Cisco equipment with
 177                  *   arp-proxy enabled.
 178                  *
 179                  *   If the requesting IP is not on our subnet, wait 5ms to
 180                  *   reply to ARP request so that our reply will overwrite
 181                  *   the arp-proxy's instead of the other way around.
 182                  */
 183                 if ((net_read_ip(&arp->ar_tpa).s_addr & net_netmask.s_addr) !=
 184                     (net_read_ip(&arp->ar_spa).s_addr & net_netmask.s_addr))
 185                         udelay(5000);
 186 #endif
 187                 tx_packet = net_get_async_tx_pkt_buf();
 188                 memcpy(tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);
 189                 net_send_packet(tx_packet, eth_hdr_size + ARP_HDR_SIZE);
 190                 return;
 191
 192         case ARPOP_REPLY:               /* arp reply */
 193                 /* are we waiting for a reply? */
 194                 if (!arp_is_waiting())
 195                         break;
 196
 197 #ifdef CONFIG_KEEP_SERVERADDR
 198                 if (net_server_ip.s_addr == net_arp_wait_packet_ip.s_addr) {
 199                         char buf[20];
 200                         sprintf(buf, "%pM", &arp->ar_sha);
 201                         env_set("serveraddr", buf);
 202                 }
 203 #endif
 204
 205                 reply_ip_addr = net_read_ip(&arp->ar_spa);
 206
 207                 /* matched waiting packet's address */
 208                 if (reply_ip_addr.s_addr == net_arp_wait_reply_ip.s_addr) {
 209                         debug_cond(DEBUG_DEV_PKT,
 210                                    "Got ARP REPLY, set eth addr (%pM)\n",
 211                                    arp->ar_data);
 212
 213                         /* save address for later use */
 214                         if (arp_wait_packet_ethaddr != NULL)
 215                                 memcpy(arp_wait_packet_ethaddr,
 216                                        &arp->ar_sha, ARP_HLEN);
 217
 218                         net_get_arp_handler()((uchar *)arp, 0, reply_ip_addr,
 219                                               0, len);
 220
 221                         /* set the mac address in the waiting packet's header
 222                            and transmit it */
 223                         memcpy(((struct ethernet_hdr *)net_tx_packet)->et_dest,
 224                                &arp->ar_sha, ARP_HLEN);
 225                         net_send_packet(net_tx_packet, arp_wait_tx_packet_size);
 226
 227                         /* no arp request pending now */
 228                         net_arp_wait_packet_ip.s_addr = 0;
 229                         arp_wait_tx_packet_size = 0;
 230                         arp_wait_packet_ethaddr = NULL;
 231                 }
 232                 return;
 233         default:
 234                 debug("Unexpected ARP opcode 0x%x\n",
 235                       ntohs(arp->ar_op));
 236                 return;
 237         }
 238 }
 239
 240 bool arp_is_waiting(void)
 241 {
 242         return !!net_arp_wait_packet_ip.s_addr;
 243 }