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