W55MH32 MACRAW模式实现arp请求

本篇总结

在 W55MH32 上通过 MACRAW 模式发送广播 ARP 请求，将目标 IP 地址解析为 MAC 地址，并解析 ARP Probe/请求/响应三种报文。

硬件平台：本例程基于 W55MH32L-EVB 开发板运行。

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W55MH32 的优势

W55MH32 的 TOE 引擎原生支持 MACRAW 模式，用户可直接构建以太网帧并通过 Socket0 收发，无需软件实现完整的以太网驱动。MACRAW 模式绕过 TCP/IP 协议栈，适合实现 ARP 等二层协议。

while (1)
{
    do_arp(SOCKET_ID, ethernet_buf, dest_ip);
}

void do_arp(uint8_t sn, uint8_t *buf, uint8_t *dest_ip)
{
  uint16_t rlen       = 0;
  uint16_t local_port = 5000;
  uint16_t cnt        = 0;

  switch (getSn_SR(sn))
  {
  case SOCK_CLOSED:
      close(sn);
      socket(sn, Sn_MR_MACRAW, local_port, 0x00);
      break;
  case SOCK_MACRAW:
      arp_request(sn, local_port, dest_ip);

      while (1)
      {
          if ((rlen = getSn_RX_RSR(sn)) > 0)
          {
              arp_reply(sn, buf, rlen);
              break;
          }
          if (cnt > 1000)
          {
              printf("Request Time out.\r\n");
              cnt = 0;
              break;
          }
          else
          {
              cnt++;
              delay_ms(5);
          }
      }
      break;
  }
  if (arp_succ_flag)
      while (1);
}

void arp_request(uint8_t sn, uint16_t port, uint8_t *dest_ip)
{
  uint16_t i;
  uint8_t  broadcast_addr[4] = {0xff, 0xff, 0xff, 0xff};

  for (i = 0; i < 6; i++)
  {
      pARPMSG.dst_mac[i] = 0xff; // Broadcast address in an Ethernet frame
      pARPMSG.tgt_mac[i] = 0x00;
      if (i < 4)
      {
          pARPMSG.tgt_ip[i] = dest_ip[i];
      }
  }
  getSHAR(pARPMSG.src_mac);              // Fill in the source MAC address of the link layer
  getSHAR(pARPMSG.sender_mac);           // Fill in the MAC address of the sender in ARP
  getSIPR(pARPMSG.sender_ip);            // Enter the IP address of the sender in ARP
  pARPMSG.msg_type = htons(ARP_TYPE);    // ARP type
  pARPMSG.hw_type  = htons(ETHER_TYPE);  // Ethernet type
  pARPMSG.pro_type = htons(PRO_TYPE);    // IP
  pARPMSG.hw_size  = HW_SIZE;            // 6
  pARPMSG.pro_size = PRO_SIZE;           // 4
  pARPMSG.opcode   = htons(ARP_REQUEST); // request: 0x0001;  reply: 0x0002

  if (sendto(sn, (uint8_t *)&pARPMSG, sizeof(pARPMSG), broadcast_addr, port) != sizeof(pARPMSG))
  {
      printf("Fail to send arp request packet.\r\n");
  }
  else
  {
      if (pARPMSG.opcode == htons(ARP_REQUEST))
      {
          printf("Who has %d.%d.%d.%d ?  Tell %d.%d.%d.%d\r\n",
                  pARPMSG.tgt_ip[0], pARPMSG.tgt_ip[1], pARPMSG.tgt_ip[2], pARPMSG.tgt_ip[3],
                  pARPMSG.sender_ip[0], pARPMSG.sender_ip[1], pARPMSG.sender_ip[2], pARPMSG.sender_ip[3]);
      }
      else
      {
          printf("Opcode has wrong value. check opcode!\r\n");
      }
  }
}

void arp_reply(uint8_t sn, uint8_t *buff, uint16_t rlen)
{
    uint8_t  destip[4];
    uint16_t destport;
    uint8_t  ret_arp_reply[128];
    uint8_t  i;

    recvfrom(sn, (uint8_t *)buff, rlen, destip, &destport);

    if (buff[12] == ARP_TYPE_HI && buff[13] == ARP_TYPE_LO)
    {
        aAPRMSG = (ARPMSG *)buff;
        if ((aAPRMSG->opcode) == htons(ARP_REPLY))
        {
            for (i = 0; i < 4; i++)
            {
                if (aAPRMSG->tgt_ip[i] != pARPMSG.tgt_ip[i])
                {
                    break;
                }
                arp_succ_flag = 1;
            }
            memset(ret_arp_reply, 0x00, 128);
            sprintf((char *)ret_arp_reply, "%d.%d.%d.%d is at %.2x.%.2x.%.2x.%.2x.%.2x.%.2x\r\n",
                    aAPRMSG->sender_ip[0], aAPRMSG->sender_ip[1], aAPRMSG->sender_ip[2], aAPRMSG->sender_ip[3],
                    aAPRMSG->sender_mac[0], aAPRMSG->sender_mac[1], aAPRMSG->sender_mac[2], aAPRMSG->sender_mac[3],
                    aAPRMSG->sender_mac[4], aAPRMSG->sender_mac[5]);

            printf("%d.%d.%d.%d is at %.2x.%.2x.%.2x.%.2x.%.2x.%.2x\r\n",
                    aAPRMSG->sender_ip[0], aAPRMSG->sender_ip[1], aAPRMSG->sender_ip[2], aAPRMSG->sender_ip[3],
                    aAPRMSG->sender_mac[0], aAPRMSG->sender_mac[1], aAPRMSG->sender_mac[2], aAPRMSG->sender_mac[3],
                    aAPRMSG->sender_mac[4], aAPRMSG->sender_mac[5]);
        }
        else if ((aAPRMSG->opcode) == htons(ARP_REQUEST))
        {
            printf("Who has %d.%d.%d.%d ? Tell %.2x.%.2x.%.2x.%.2x.%.2x.%.2x\r\n",
                    aAPRMSG->tgt_ip[0], aAPRMSG->tgt_ip[1], aAPRMSG->tgt_ip[2], aAPRMSG->tgt_ip[3],
                    aAPRMSG->sender_mac[0], aAPRMSG->sender_mac[1], aAPRMSG->sender_mac[2], aAPRMSG->sender_mac[3],
                    aAPRMSG->sender_mac[4], aAPRMSG->sender_mac[5]);
        }
    }
    else
    {
        // printf("This message is not ARP reply: opcode is not 0x02!\r\n");
    }
}

注意事项

• MACRAW 模式仅 Socket0 支持，其他 Socket 无法使用
• ARP 请求以广播方式发送，目标设备收到后单播回复
• ARP 报文总长 28 字节，加上以太网帧头 14 字节共 42 字节
• ARP 仅在同一局域网内工作，无法跨越路由器