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