// SPDX-License-Identifier: GPL-2.0-only

/*

 *  Copied from Linux Monitor (LiMon) - Networking.

 *

 *  Copyright 1994 - 2000 Neil Russell.

 *  Copyright 2000 Roland Borde

 *  Copyright 2000 Paolo Scaffardi

 *  Copyright 2000-2002 Wolfgang Denk, wd@denx.de

 */

#include <env.h>

#include <log.h>

#include <net.h>

#include <vsprintf.h>

#include <linux/delay.h>

#include "arp.h"

struct in_addr net_arp_wait_packet_ip;

static struct in_addr net_arp_wait_reply_ip;

/* MAC address of waiting packet's destination */

uchar        *arp_wait_packet_ethaddr;

int   arp_wait_tx_packet_size;

ulong   arp_wait_timer_start;

int   arp_wait_try;

uchar        *arp_tx_packet; /* THE ARP transmit packet */

static uchar  arp_tx_packet_buf[PKTSIZE_ALIGN + PKTALIGN];

void arp_init(void)

{

  /* XXX problem with bss workaround */

  arp_wait_packet_ethaddr = NULL;

  net_arp_wait_packet_ip.s_addr = 0;

  net_arp_wait_reply_ip.s_addr = 0;

  arp_wait_tx_packet_size = 0;

  arp_tx_packet = &arp_tx_packet_buf[0] + (PKTALIGN - 1);

  arp_tx_packet -= (ulong)arp_tx_packet % PKTALIGN;

}

void arp_raw_request(struct in_addr source_ip, const uchar *target_ethaddr,

  struct in_addr target_ip)

{

  uchar *pkt;

  struct arp_hdr *arp;

  int eth_hdr_size;

  debug_cond(DEBUG_DEV_PKT, "ARP broadcast %d\n", arp_wait_try);

  pkt = arp_tx_packet;

  eth_hdr_size = net_set_ether(pkt, net_bcast_ethaddr, PROT_ARP);

  pkt += eth_hdr_size;

  arp = (struct arp_hdr *)pkt;

  arp->ar_hrd = htons(ARP_ETHER);

  arp->ar_pro = htons(PROT_IP);

  arp->ar_hln = ARP_HLEN;

  arp->ar_pln = ARP_PLEN;

  arp->ar_op = htons(ARPOP_REQUEST);

  memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);  /* source ET addr */

  net_write_ip(&arp->ar_spa, source_ip);   /* source IP addr */

  memcpy(&arp->ar_tha, target_ethaddr, ARP_HLEN);  /* target ET addr */

  net_write_ip(&arp->ar_tpa, target_ip);   /* target IP addr */

  net_send_packet(arp_tx_packet, eth_hdr_size + ARP_HDR_SIZE);

}

void arp_request(void)

{

  if ((net_arp_wait_packet_ip.s_addr & net_netmask.s_addr) !=

      (net_ip.s_addr & net_netmask.s_addr)) {

    if (net_gateway.s_addr == 0) {

      puts("## Warning: gatewayip needed but not set\n");

      net_arp_wait_reply_ip = net_arp_wait_packet_ip;

    } else {

      net_arp_wait_reply_ip = net_gateway;

    }

  } else {

    net_arp_wait_reply_ip = net_arp_wait_packet_ip;

  }

  arp_raw_request(net_ip, net_null_ethaddr, net_arp_wait_reply_ip);

}

int arp_timeout_check(void)

{

  ulong t;

  if (!arp_is_waiting())

    return 0;

  t = get_timer(0);

  /* check for arp timeout */

  if ((t - arp_wait_timer_start) > CONFIG_ARP_TIMEOUT) {

    arp_wait_try++;

    if (arp_wait_try >= CONFIG_NET_RETRY_COUNT) {

      puts("\nARP Retry count exceeded; starting again\n");

      arp_wait_try = 0;

      net_set_state(NETLOOP_FAIL);

    } else {

      arp_wait_timer_start = t;

      arp_request();

    }

  }

  return 1;

}

void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)

{

  struct arp_hdr *arp;

  struct in_addr reply_ip_addr;

  int eth_hdr_size;

  uchar *tx_packet;

  /*

   * We have to deal with two types of ARP packets:

   * - REQUEST packets will be answered by sending  our

   *   IP address - if we know it.

   * - REPLY packates are expected only after we asked

   *   for the TFTP server's or the gateway's ethernet

   *   address; so if we receive such a packet, we set

   *   the server ethernet address

   */

  debug_cond(DEBUG_NET_PKT, "Got ARP\n");

  arp = (struct arp_hdr *)ip;

  if (len < ARP_HDR_SIZE) {

    printf("bad length %d < %d\n", len, ARP_HDR_SIZE);

    return;

  }

  if (ntohs(arp->ar_hrd) != ARP_ETHER)

    return;

  if (ntohs(arp->ar_pro) != PROT_IP)

    return;

  if (arp->ar_hln != ARP_HLEN)

    return;

  if (arp->ar_pln != ARP_PLEN)

    return;

  if (net_ip.s_addr == 0)

    return;

  if (net_read_ip(&arp->ar_tpa).s_addr != net_ip.s_addr)

    return;

  switch (ntohs(arp->ar_op)) {

  case ARPOP_REQUEST:

    /* reply with our IP address */

    debug_cond(DEBUG_DEV_PKT, "Got ARP REQUEST, return our IP\n");

    eth_hdr_size = net_update_ether(et, et->et_src, PROT_ARP);

    arp->ar_op = htons(ARPOP_REPLY);

    memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);

    net_copy_ip(&arp->ar_tpa, &arp->ar_spa);

    memcpy(&arp->ar_sha, net_ethaddr, ARP_HLEN);

    net_copy_ip(&arp->ar_spa, &net_ip);

#ifdef CONFIG_CMD_LINK_LOCAL

    /*

     * Work-around for brain-damaged Cisco equipment with

     *   arp-proxy enabled.

     *

     *   If the requesting IP is not on our subnet, wait 5ms to

     *   reply to ARP request so that our reply will overwrite

     *   the arp-proxy's instead of the other way around.

     */

    if ((net_read_ip(&arp->ar_tpa).s_addr & net_netmask.s_addr) !=

        (net_read_ip(&arp->ar_spa).s_addr & net_netmask.s_addr))

      udelay(5000);

#endif

    tx_packet = net_get_async_tx_pkt_buf();

    memcpy(tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);

    net_send_packet(tx_packet, eth_hdr_size + ARP_HDR_SIZE);

    return;

  case ARPOP_REPLY:   /* arp reply */

    /* are we waiting for a reply? */

    if (!arp_is_waiting())

      break;

    if (IS_ENABLED(CONFIG_KEEP_SERVERADDR) &&

        net_server_ip.s_addr == net_arp_wait_packet_ip.s_addr) {

      char buf[20];

      sprintf(buf, "%pM", &arp->ar_sha);

      env_set("serveraddr", buf);

    }

    reply_ip_addr = net_read_ip(&arp->ar_spa);

    /* matched waiting packet's address */

    if (reply_ip_addr.s_addr == net_arp_wait_reply_ip.s_addr) {

      debug_cond(DEBUG_DEV_PKT,

           "Got ARP REPLY, set eth addr (%pM)\n",

           arp->ar_data);

      /* save address for later use */

      if (arp_wait_packet_ethaddr != NULL)

        memcpy(arp_wait_packet_ethaddr,

               &arp->ar_sha, ARP_HLEN);

      net_get_arp_handler()((uchar *)arp, 0, reply_ip_addr,

                0, len);

      /* set the mac address in the waiting packet's header

         and transmit it */

      memcpy(((struct ethernet_hdr *)net_tx_packet)->et_dest,

             &arp->ar_sha, ARP_HLEN);

      net_send_packet(net_tx_packet, arp_wait_tx_packet_size);

      /* no arp request pending now */

      net_arp_wait_packet_ip.s_addr = 0;

      arp_wait_tx_packet_size = 0;

      arp_wait_packet_ethaddr = NULL;

    }

    return;

  default:

    debug("Unexpected ARP opcode 0x%x\n",

          ntohs(arp->ar_op));

    return;

  }

}

bool arp_is_waiting(void)

{

  return !!net_arp_wait_packet_ip.s_addr;

}