W55MH32 IPRAW模式实现ping功能

本篇总结

基于 W55MH32 的 IPRAW 模式手动构建 ICMP Echo 报文实现 ping 功能，统计请求、回复与丢包数量。

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 IPRAW 模式，用户可直接构建 ICMP 报文并通过 IPRAW Socket 发送，无需软件实现完整的 IP 协议栈。IP 头由硬件自动封装，用户只需关注 ICMP 报文内容。

while (1)
{
    do_ping(SOCKET_ID, dest_ip, ping_num);
}

void ping_count(uint8_t s, uint16_t pCount, uint8_t *addr)
{
    uint16_t rlen, cnt, i;
    cnt = 0;

    for (i = 0; i < pCount + 1; i++)
    {
        if (i != 0)
        {
            // Output count number
            printf("No.%d  ", i);
        }
        switch (getSn_SR(s))
        {
        case SOCK_CLOSED:
            close(s);
            // Create Socket
            IINCHIP_WRITE(WZTOE_Sn_PROTO(s), IPPROTO_ICMP);
            if (socket(s, Sn_MR_IPRAW, 3000, 0) != 0)
            {
            }
            // Check socket register
            while (getSn_SR(s) != SOCK_IPRAW);
            break;
        case SOCK_IPRAW:
            ping_request(s, addr);
            req++;
            while (1)
            {
                if ((rlen = getSn_RX_RSR(s)) > 0)
                {
                    ping_reply(s, addr, rlen);
                    rep++;
                    if (ping_reply_received)
                        break;
                }
                if ((cnt > 1000))
                {
                    printf("Request Time out\r\n\r\n");
                    cnt = 0;
                    break;
                }
                else
                {
                    cnt++;
                    delay_ms(5);
                }
            }
            break;
        default:
            break;
        }
        if (req >= pCount)
        {
            printf("Ping Request = %d, Ping Reply = %d, Lost = %d\r\n", req, rep, req - rep);
        }
    }
}

void ping_request(uint8_t s, uint8_t *addr)
{
    uint16_t i;
    ping_reply_received = 0;
    PingRequest.Type    = PING_REQUEST;
    PingRequest.Code    = CODE_ZERO;
    PingRequest.ID      = htons(RandomID++);
    PingRequest.SeqNum  = htons(RandomSeqNum++);
    for (i = 0; i < BUF_LEN; i++)
    {
        PingRequest.Data[i] = (i) % 8;
    }
    PingRequest.CheckSum = 0;

    PingRequest.CheckSum = htons(checksum((uint8_t *)&PingRequest, sizeof(PingRequest)));

    if (sendto(s, (uint8_t *)&PingRequest, sizeof(PingRequest), addr, 3000) == 0)
    {
        printf("Fail to send ping-reply packet\r\n");
    }
    else
    {
        printf("Ping:%d.%d.%d.%d\r\n", (addr[0]), (addr[1]), (addr[2]), (addr[3]));
    }
}

void ping_reply(uint8_t s, uint8_t *addr, uint16_t rlen)
{
    uint16_t tmp_checksum;
    uint16_t len;
    uint16_t i;
    uint8_t  data_buf[136];

    uint16_t port = 3000;
    PINGMSGR PingReply;
    len = recvfrom(s, data_buf, rlen, addr, &port);

    if (data_buf[0] == PING_REPLY)
    {
        PingReply.Type     = data_buf[0];
        PingReply.Code     = data_buf[1];
        PingReply.CheckSum = (data_buf[3] << 8) + data_buf[2];
        PingReply.ID       = (data_buf[5] << 8) + data_buf[4];
        PingReply.SeqNum   = (data_buf[7] << 8) + data_buf[6];

        for (i = 0; i < len - 8; i++)
        {
            PingReply.Data[i] = data_buf[8 + i];
        }
        tmp_checksum = ~checksum(data_buf, len);
        if (tmp_checksum != 0xffff)
            printf("tmp_checksum = %x\r\n", tmp_checksum);

        else
        {
            printf("Reply from %3d.%3d.%3d.%3d ID=%x Byte=%d\r\n\r\n",
                   (addr[0]), (addr[1]), (addr[2]), (addr[3]),
                   htons(PingReply.ID), (rlen + 6));
            ping_reply_received = 1;
        }
    }
    else if (data_buf[0] == PING_REQUEST)
    {
        PingReply.Code     = data_buf[1];
        PingReply.Type     = data_buf[2];
        PingReply.CheckSum = (data_buf[3] << 8) + data_buf[2];
        PingReply.ID       = (data_buf[5] << 8) + data_buf[4];
        PingReply.SeqNum   = (data_buf[7] << 8) + data_buf[6];
        for (i = 0; i < len - 8; i++)
        {
            PingReply.Data[i] = data_buf[8 + i];
        }
        tmp_checksum       = PingReply.CheckSum;
        PingReply.CheckSum = 0;
        if (tmp_checksum != PingReply.CheckSum)
        {
            printf(" \n CheckSum is in correct %x shold be %x \n",
                   (tmp_checksum), htons(PingReply.CheckSum));
        }
        else
        {
        }
        printf("  Request from %d.%d.%d.%d  ID:%x SeqNum:%x  :data size %d bytes\r\n",
                (addr[0]), (addr[1]), (addr[2]), (addr[3]),
                (PingReply.ID), (PingReply.SeqNum), (rlen + 6));
        ping_reply_received = 1;
    }
    else
    {
        printf(" Unkonwn msg. \n");
    }
}

校验和验证关键

接收回复时，通过 ~checksum(data_buf, len) 对整个数据包校验，结果应为 0xffff 表示校验通过。校验通过后设置 ping_reply_received = 1，使 ping_count() 状态机跳出等待循环。

实现要点

IPRAW 模式下使用 socket(s, Sn_MR_IPRAW, 3000, 0) 创建 Socket，并通过 IINCHIP_WRITE(WZTOE_Sn_PROTO(s), IPPROTO_ICMP) 设置协议为 ICMP。校验和计算必须正确，否则目标主机会丢弃报文。