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, wd@denx.de
  10  */
  11
  12 #include <common.h>
  13 #include <env.h>
  14 #include <log.h>
  15 #include <net.h>
  16
  17 #include "arp.h"
  18
  19 #ifndef CONFIG_ARP_TIMEOUT
  20 /* Milliseconds before trying ARP again */
  21 # define ARP_TIMEOUT            5000UL
  22 #else
  23 # define ARP_TIMEOUT            CONFIG_ARP_TIMEOUT
  24 #endif
  25
  26
  27 #ifndef CONFIG_NET_RETRY_COUNT
  28 # define ARP_TIMEOUT_COUNT      5       /* # of timeouts before giving up  */
  29 #else
  30 # define ARP_TIMEOUT_COUNT      CONFIG_NET_RETRY_COUNT
  31 #endif
  32
  33 struct in_addr net_arp_wait_packet_ip;
  34 static struct in_addr net_arp_wait_reply_ip;
  35 /* MAC address of waiting packet's destination */
  36 uchar          *arp_wait_packet_ethaddr;
  37 int             arp_wait_tx_packet_size;
  38 ulong           arp_wait_timer_start;
  39 int             arp_wait_try;
  40 uchar          *arp_tx_packet; /* THE ARP transmit packet */
  41 static uchar    arp_tx_packet_buf[PKTSIZE_ALIGN + PKTALIGN];
  42
  43 void arp_init(void)
  44 {
  45         /* XXX problem with bss workaround */
  46         arp_wait_packet_ethaddr = NULL;
  47         net_arp_wait_packet_ip.s_addr = 0;
  48         net_arp_wait_reply_ip.s_addr = 0;
  49         arp_wait_tx_packet_size = 0;
  50         arp_tx_packet = &arp_tx_packet_buf[0] + (PKTALIGN - 1);
  51         arp_tx_packet -= (ulong)arp_tx_packet % PKTALIGN;
  52 }
  53
  54 void arp_raw_request(struct in_addr source_ip, const uchar *target_ethaddr,
  55         struct in_addr target_ip)
  56 {
  57         uchar *pkt;
  58         struct arp_hdr *arp;
  59         int eth_hdr_size;
  60
  61         debug_cond(DEBUG_DEV_PKT, "ARP broadcast %d\n", arp_wait_try);
  62
  63         pkt = arp_tx_packet;
  64
  65         eth_hdr_size = net_set_ether(pkt, net_bcast_ethaddr, PROT_ARP);
  66         pkt += eth_hdr_size;
  67
  68         arp = (struct arp_hdr *)pkt;
  69
  70         arp->ar_hrd = htons(ARP_ETHER);
  71         arp->ar_pro = htons(PROT_IP);
  72         arp->ar_hln = ARP_HLEN;
  73         arp->ar_pln = ARP_PLEN;
  74         arp->ar_op = htons(ARPOP_REQUEST);
  75
  76         memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);    /* source ET addr */
  77         net_write_ip(&arp->ar_spa, source_ip);          /* source IP addr */
  78         memcpy(&arp->ar_tha, target_ethaddr, ARP_HLEN); /* target ET addr */
  79         net_write_ip(&arp->ar_tpa, target_ip);          /* target IP addr */
  80
  81         net_send_packet(arp_tx_packet, eth_hdr_size + ARP_HDR_SIZE);
  82 }
  83
  84 void arp_request(void)
  85 {
  86         if ((net_arp_wait_packet_ip.s_addr & net_netmask.s_addr) !=
  87             (net_ip.s_addr & net_netmask.s_addr)) {
  88                 if (net_gateway.s_addr == 0) {
  89                         puts("## Warning: gatewayip needed but not set\n");
  90                         net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  91                 } else {
  92                         net_arp_wait_reply_ip = net_gateway;
  93                 }
  94         } else {
  95                 net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  96         }
  97
  98         arp_raw_request(net_ip, net_null_ethaddr, net_arp_wait_reply_ip);
  99 }
 100
 101 int arp_timeout_check(void)
 102 {
 103         ulong t;
 104
 105         if (!arp_is_waiting())
 106                 return 0;
 107
 108         t = get_timer(0);
 109
 110         /* check for arp timeout */
 111         if ((t - arp_wait_timer_start) > ARP_TIMEOUT) {
 112                 arp_wait_try++;
 113
 114                 if (arp_wait_try >= ARP_TIMEOUT_COUNT) {
 115                         puts("\nARP Retry count exceeded; starting again\n");
 116                         arp_wait_try = 0;
 117                         net_set_state(NETLOOP_FAIL);
 118                 } else {
 119                         arp_wait_timer_start = t;
 120                         arp_request();
 121                 }
 122         }
 123         return 1;
 124 }
 125
 126 void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 127 {
 128         struct arp_hdr *arp;
 129         struct in_addr reply_ip_addr;
 130         int eth_hdr_size;
 131         uchar *tx_packet;
 132
 133         /*
 134          * We have to deal with two types of ARP packets:
 135          * - REQUEST packets will be answered by sending  our
 136          *   IP address - if we know it.
 137          * - REPLY packates are expected only after we asked
 138          *   for the TFTP server's or the gateway's ethernet
 139          *   address; so if we receive such a packet, we set
 140          *   the server ethernet address
 141          */
 142         debug_cond(DEBUG_NET_PKT, "Got ARP\n");
 143
 144         arp = (struct arp_hdr *)ip;
 145         if (len < ARP_HDR_SIZE) {
 146                 printf("bad length %d < %d\n", len, ARP_HDR_SIZE);
 147                 return;
 148         }
 149         if (ntohs(arp->ar_hrd) != ARP_ETHER)
 150                 return;
 151         if (ntohs(arp->ar_pro) != PROT_IP)
 152                 return;
 153         if (arp->ar_hln != ARP_HLEN)
 154                 return;
 155         if (arp->ar_pln != ARP_PLEN)
 156                 return;
 157
 158         if (net_ip.s_addr == 0)
 159                 return;
 160
 161         if (net_read_ip(&arp->ar_tpa).s_addr != net_ip.s_addr)
 162                 return;
 163
 164         switch (ntohs(arp->ar_op)) {
 165         case ARPOP_REQUEST:
 166                 /* reply with our IP address */
 167                 debug_cond(DEBUG_DEV_PKT, "Got ARP REQUEST, return our IP\n");
 168                 eth_hdr_size = net_update_ether(et, et->et_src, PROT_ARP);
 169                 arp->ar_op = htons(ARPOP_REPLY);
 170                 memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);
 171                 net_copy_ip(&arp->ar_tpa, &arp->ar_spa);
 172                 memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);
 173                 net_copy_ip(&arp->ar_spa, &net_ip);
 174
 175 #ifdef CONFIG_CMD_LINK_LOCAL
 176                 /*
 177                  * Work-around for brain-damaged Cisco equipment with
 178                  *   arp-proxy enabled.
 179                  *
 180                  *   If the requesting IP is not on our subnet, wait 5ms to
 181                  *   reply to ARP request so that our reply will overwrite
 182                  *   the arp-proxy's instead of the other way around.
 183                  */
 184                 if ((net_read_ip(&arp->ar_tpa).s_addr & net_netmask.s_addr) !=
 185                     (net_read_ip(&arp->ar_spa).s_addr & net_netmask.s_addr))
 186                         udelay(5000);
 187 #endif
 188                 tx_packet = net_get_async_tx_pkt_buf();
 189                 memcpy(tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);
 190                 net_send_packet(tx_packet, eth_hdr_size + ARP_HDR_SIZE);
 191                 return;
 192
 193         case ARPOP_REPLY:               /* arp reply */
 194                 /* are we waiting for a reply? */
 195                 if (!arp_is_waiting())
 196                         break;
 197
 198 #ifdef CONFIG_KEEP_SERVERADDR
 199                 if (net_server_ip.s_addr == net_arp_wait_packet_ip.s_addr) {
 200                         char buf[20];
 201                         sprintf(buf, "%pM", &arp->ar_sha);
 202                         env_set("serveraddr", buf);
 203                 }
 204 #endif
 205
 206                 reply_ip_addr = net_read_ip(&arp->ar_spa);
 207
 208                 /* matched waiting packet's address */
 209                 if (reply_ip_addr.s_addr == net_arp_wait_reply_ip.s_addr) {
 210                         debug_cond(DEBUG_DEV_PKT,
 211                                    "Got ARP REPLY, set eth addr (%pM)\n",
 212                                    arp->ar_data);
 213
 214                         /* save address for later use */
 215                         if (arp_wait_packet_ethaddr != NULL)
 216                                 memcpy(arp_wait_packet_ethaddr,
 217                                        &arp->ar_sha, ARP_HLEN);
 218
 219                         net_get_arp_handler()((uchar *)arp, 0, reply_ip_addr,
 220                                               0, len);
 221
 222                         /* set the mac address in the waiting packet's header
 223                            and transmit it */
 224                         memcpy(((struct ethernet_hdr *)net_tx_packet)->et_dest,
 225                                &arp->ar_sha, ARP_HLEN);
 226                         net_send_packet(net_tx_packet, arp_wait_tx_packet_size);
 227
 228                         /* no arp request pending now */
 229                         net_arp_wait_packet_ip.s_addr = 0;
 230                         arp_wait_tx_packet_size = 0;
 231                         arp_wait_packet_ethaddr = NULL;
 232                 }
 233                 return;
 234         default:
 235                 debug("Unexpected ARP opcode 0x%x\n",
 236                       ntohs(arp->ar_op));
 237                 return;
 238         }
 239 }
 240
 241 bool arp_is_waiting(void)
 242 {
 243         return !!net_arp_wait_packet_ip.s_addr;
 244 }