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