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 #include <linux/delay.h>
  17
  18 #include "arp.h"
  19
  20 #ifndef CONFIG_ARP_TIMEOUT
  21 /* Milliseconds before trying ARP again */
  22 # define ARP_TIMEOUT            5000UL
  23 #else
  24 # define ARP_TIMEOUT            CONFIG_ARP_TIMEOUT
  25 #endif
  26
  27
  28 #ifndef CONFIG_NET_RETRY_COUNT
  29 # define ARP_TIMEOUT_COUNT      5       /* # of timeouts before giving up  */
  30 #else
  31 # define ARP_TIMEOUT_COUNT      CONFIG_NET_RETRY_COUNT
  32 #endif
  33
  34 struct in_addr net_arp_wait_packet_ip;
  35 static struct in_addr net_arp_wait_reply_ip;
  36 /* MAC address of waiting packet's destination */
  37 uchar          *arp_wait_packet_ethaddr;
  38 int             arp_wait_tx_packet_size;
  39 ulong           arp_wait_timer_start;
  40 int             arp_wait_try;
  41 uchar          *arp_tx_packet; /* THE ARP transmit packet */
  42 static uchar    arp_tx_packet_buf[PKTSIZE_ALIGN + PKTALIGN];
  43
  44 void arp_init(void)
  45 {
  46         /* XXX problem with bss workaround */
  47         arp_wait_packet_ethaddr = NULL;
  48         net_arp_wait_packet_ip.s_addr = 0;
  49         net_arp_wait_reply_ip.s_addr = 0;
  50         arp_wait_tx_packet_size = 0;
  51         arp_tx_packet = &arp_tx_packet_buf[0] + (PKTALIGN - 1);
  52         arp_tx_packet -= (ulong)arp_tx_packet % PKTALIGN;
  53 }
  54
  55 void arp_raw_request(struct in_addr source_ip, const uchar *target_ethaddr,
  56         struct in_addr target_ip)
  57 {
  58         uchar *pkt;
  59         struct arp_hdr *arp;
  60         int eth_hdr_size;
  61
  62         debug_cond(DEBUG_DEV_PKT, "ARP broadcast %d\n", arp_wait_try);
  63
  64         pkt = arp_tx_packet;
  65
  66         eth_hdr_size = net_set_ether(pkt, net_bcast_ethaddr, PROT_ARP);
  67         pkt += eth_hdr_size;
  68
  69         arp = (struct arp_hdr *)pkt;
  70
  71         arp->ar_hrd = htons(ARP_ETHER);
  72         arp->ar_pro = htons(PROT_IP);
  73         arp->ar_hln = ARP_HLEN;
  74         arp->ar_pln = ARP_PLEN;
  75         arp->ar_op = htons(ARPOP_REQUEST);
  76
  77         memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);    /* source ET addr */
  78         net_write_ip(&arp->ar_spa, source_ip);          /* source IP addr */
  79         memcpy(&arp->ar_tha, target_ethaddr, ARP_HLEN); /* target ET addr */
  80         net_write_ip(&arp->ar_tpa, target_ip);          /* target IP addr */
  81
  82         net_send_packet(arp_tx_packet, eth_hdr_size + ARP_HDR_SIZE);
  83 }
  84
  85 void arp_request(void)
  86 {
  87         if ((net_arp_wait_packet_ip.s_addr & net_netmask.s_addr) !=
  88             (net_ip.s_addr & net_netmask.s_addr)) {
  89                 if (net_gateway.s_addr == 0) {
  90                         puts("## Warning: gatewayip needed but not set\n");
  91                         net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  92                 } else {
  93                         net_arp_wait_reply_ip = net_gateway;
  94                 }
  95         } else {
  96                 net_arp_wait_reply_ip = net_arp_wait_packet_ip;
  97         }
  98
  99         arp_raw_request(net_ip, net_null_ethaddr, net_arp_wait_reply_ip);
 100 }
 101
 102 int arp_timeout_check(void)
 103 {
 104         ulong t;
 105
 106         if (!arp_is_waiting())
 107                 return 0;
 108
 109         t = get_timer(0);
 110
 111         /* check for arp timeout */
 112         if ((t - arp_wait_timer_start) > ARP_TIMEOUT) {
 113                 arp_wait_try++;
 114
 115                 if (arp_wait_try >= ARP_TIMEOUT_COUNT) {
 116                         puts("\nARP Retry count exceeded; starting again\n");
 117                         arp_wait_try = 0;
 118                         net_set_state(NETLOOP_FAIL);
 119                 } else {
 120                         arp_wait_timer_start = t;
 121                         arp_request();
 122                 }
 123         }
 124         return 1;
 125 }
 126
 127 void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 128 {
 129         struct arp_hdr *arp;
 130         struct in_addr reply_ip_addr;
 131         int eth_hdr_size;
 132         uchar *tx_packet;
 133
 134         /*
 135          * We have to deal with two types of ARP packets:
 136          * - REQUEST packets will be answered by sending  our
 137          *   IP address - if we know it.
 138          * - REPLY packates are expected only after we asked
 139          *   for the TFTP server's or the gateway's ethernet
 140          *   address; so if we receive such a packet, we set
 141          *   the server ethernet address
 142          */
 143         debug_cond(DEBUG_NET_PKT, "Got ARP\n");
 144
 145         arp = (struct arp_hdr *)ip;
 146         if (len < ARP_HDR_SIZE) {
 147                 printf("bad length %d < %d\n", len, ARP_HDR_SIZE);
 148                 return;
 149         }
 150         if (ntohs(arp->ar_hrd) != ARP_ETHER)
 151                 return;
 152         if (ntohs(arp->ar_pro) != PROT_IP)
 153                 return;
 154         if (arp->ar_hln != ARP_HLEN)
 155                 return;
 156         if (arp->ar_pln != ARP_PLEN)
 157                 return;
 158
 159         if (net_ip.s_addr == 0)
 160                 return;
 161
 162         if (net_read_ip(&arp->ar_tpa).s_addr != net_ip.s_addr)
 163                 return;
 164
 165         switch (ntohs(arp->ar_op)) {
 166         case ARPOP_REQUEST:
 167                 /* reply with our IP address */
 168                 debug_cond(DEBUG_DEV_PKT, "Got ARP REQUEST, return our IP\n");
 169                 eth_hdr_size = net_update_ether(et, et->et_src, PROT_ARP);
 170                 arp->ar_op = htons(ARPOP_REPLY);
 171                 memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);
 172                 net_copy_ip(&arp->ar_tpa, &arp->ar_spa);
 173                 memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);
 174                 net_copy_ip(&arp->ar_spa, &net_ip);
 175
 176 #ifdef CONFIG_CMD_LINK_LOCAL
 177                 /*
 178                  * Work-around for brain-damaged Cisco equipment with
 179                  *   arp-proxy enabled.
 180                  *
 181                  *   If the requesting IP is not on our subnet, wait 5ms to
 182                  *   reply to ARP request so that our reply will overwrite
 183                  *   the arp-proxy's instead of the other way around.
 184                  */
 185                 if ((net_read_ip(&arp->ar_tpa).s_addr & net_netmask.s_addr) !=
 186                     (net_read_ip(&arp->ar_spa).s_addr & net_netmask.s_addr))
 187                         udelay(5000);
 188 #endif
 189                 tx_packet = net_get_async_tx_pkt_buf();
 190                 memcpy(tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);
 191                 net_send_packet(tx_packet, eth_hdr_size + ARP_HDR_SIZE);
 192                 return;
 193
 194         case ARPOP_REPLY:               /* arp reply */
 195                 /* are we waiting for a reply? */
 196                 if (!arp_is_waiting())
 197                         break;
 198
 199 #ifdef CONFIG_KEEP_SERVERADDR
 200                 if (net_server_ip.s_addr == net_arp_wait_packet_ip.s_addr) {
 201                         char buf[20];
 202                         sprintf(buf, "%pM", &arp->ar_sha);
 203                         env_set("serveraddr", buf);
 204                 }
 205 #endif
 206
 207                 reply_ip_addr = net_read_ip(&arp->ar_spa);
 208
 209                 /* matched waiting packet's address */
 210                 if (reply_ip_addr.s_addr == net_arp_wait_reply_ip.s_addr) {
 211                         debug_cond(DEBUG_DEV_PKT,
 212                                    "Got ARP REPLY, set eth addr (%pM)\n",
 213                                    arp->ar_data);
 214
 215                         /* save address for later use */
 216                         if (arp_wait_packet_ethaddr != NULL)
 217                                 memcpy(arp_wait_packet_ethaddr,
 218                                        &arp->ar_sha, ARP_HLEN);
 219
 220                         net_get_arp_handler()((uchar *)arp, 0, reply_ip_addr,
 221                                               0, len);
 222
 223                         /* set the mac address in the waiting packet's header
 224                            and transmit it */
 225                         memcpy(((struct ethernet_hdr *)net_tx_packet)->et_dest,
 226                                &arp->ar_sha, ARP_HLEN);
 227                         net_send_packet(net_tx_packet, arp_wait_tx_packet_size);
 228
 229                         /* no arp request pending now */
 230                         net_arp_wait_packet_ip.s_addr = 0;
 231                         arp_wait_tx_packet_size = 0;
 232                         arp_wait_packet_ethaddr = NULL;
 233                 }
 234                 return;
 235         default:
 236                 debug("Unexpected ARP opcode 0x%x\n",
 237                       ntohs(arp->ar_op));
 238                 return;
 239         }
 240 }
 241
 242 bool arp_is_waiting(void)
 243 {
 244         return !!net_arp_wait_packet_ip.s_addr;
 245 }