W6300使用TFTP协议读取文件内容

本篇总结

在 W6300 上实现 TFTP 客户端，从 TFTP 服务器读取文本文件内容。

硬件平台：本例程基于 W6300-EVB-M4 开发板运行。

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W6300 的优势

W6300 SDK 内置了 TFTP 客户端库，报文组包/解包、超时重传、状态管理全部由库函数处理。你只需要：注册超时定时器 → 调用 TFTP_init() → 发送读请求 TFTP_read_request() → 主循环调用 TFTP_run() 驱动状态机。

wiz_add_timer(tftp_timeout_handler, 1000);
do_tftp_client(SOCKET_ID, ethernet_buf);
wiz_delete_timer(tftp_timeout_handler);

#define TFTP_RECEIVE_WORD_COUNT ((MAX_MTU_SIZE + sizeof(uint32_t) - 1U) / sizeof(uint32_t))

static uint32_t s_tftp_receive_storage[TFTP_RECEIVE_WORD_COUNT];

void do_tftp_client(uint8_t sn, uint8_t *buff)
{
    uint32_t tftp_server_ip = inet_addr((uint8_t *)TFTP_SERVER_IP);
    int tftp_state;

    /* W5500-compatible signature; keep the proven W6300-aligned receive storage. */
    (void)buff;

    dbg_level = 0;
    TFTP_init(sn, (uint8_t *)s_tftp_receive_storage);

    printf("tftp server ip: %s, file name: %s\r\n", TFTP_SERVER_IP, TFTP_SERVER_FILE_NAME);
    printf("send request\r\n");
    TFTP_read_request(tftp_server_ip, (uint8_t *)TFTP_SERVER_FILE_NAME);

    while (1)
    {
        tftp_state = TFTP_run();

        if (tftp_state == TFTP_SUCCESS)
        {
            printf("tftp read success, file name: %s\r\n", TFTP_SERVER_FILE_NAME);
            printf("\r\n========== File Content Start ==========\r\n");
            printf("%s", (char *)s_tftp_receive_storage + 4);
            printf("\r\n========== File Content End ==========\r\n");
            break;
        }
        else if (tftp_state == TFTP_FAIL)
        {
            printf("tftp read fail, file name: %s\r\n", TFTP_SERVER_FILE_NAME);
            break;
        }

        wiz_user_delay_ms(1U);
    }

    TFTP_exit();
}

void TFTP_init(uint8_t socket, uint8_t *buf)
{
    init_tftp();

    g_tftp_socket  = open_tftp_socket(socket);
    g_tftp_rcv_buf = buf;
}

static void init_tftp(void)
{
    g_filename[0] = 0;

    set_server_ip(0);
    set_server_port(0);
    set_local_port(0);

    set_tftp_state(STATE_NONE);
    set_block_number(0);

    // timeout flag
    g_resend_flag  = 0;
    tftp_retry_cnt = tftp_time_cnt = 0;
    g_progress_state = TFTP_PROGRESS;
}

void TFTP_read_request(uint32_t server_ip, uint8_t *filename)
{
    set_server_ip(server_ip);

    g_progress_state = TFTP_PROGRESS;
    send_tftp_rrq(filename, (uint8_t *)TRANS_BINARY, &default_tftp_opt, 1);
}

int TFTP_run(void)
{
    int32_t len;
    uint16_t from_port;
    uint32_t from_ip;

    /* Timeout Process */
    if (g_resend_flag)
    {
        if (tftp_time_cnt >= g_timeout)
        {
            switch (get_tftp_state())
            {
            case STATE_WRQ:
                break;

            case STATE_RRQ:
                send_tftp_rrq(g_filename, (uint8_t *)TRANS_BINARY, &default_tftp_opt, 1);
                break;

            case STATE_OACK:
            case STATE_DATA:
                send_tftp_ack(get_block_number());
                break;

            case STATE_ACK:
                break;

            default:
                break;
            }

            tftp_time_cnt = 0;
            tftp_retry_cnt++;

            if (tftp_retry_cnt >= 5)
            {
                init_tftp();
                g_progress_state = TFTP_FAIL;
            }
        }
    }

    /* Receive Packet Process */
    len = recv_udp_packet(g_tftp_socket, g_tftp_rcv_buf, MAX_MTU_SIZE, &from_ip, &from_port);
    if (len < 0)
    {
        return g_progress_state;
    }

    recv_tftp_packet(g_tftp_rcv_buf, (uint32_t)len, from_ip, from_port);

    return g_progress_state;
}

static void recv_tftp_packet(uint8_t *packet, uint32_t packet_len, uint32_t from_ip, uint16_t from_port)
{
    uint16_t opcode;

    if ((packet == NULL) || (packet_len < 2U))
    {
        return;
    }

    /* Verify Server IP */
    if (from_ip != get_server_ip())
    {
        return;
    }

    opcode = tftp_read_be16(packet);

    /* Set Server Port */
    if ((get_tftp_state() == STATE_WRQ) || (get_tftp_state() == STATE_RRQ))
    {
        set_server_port(from_port);
    }

    switch (opcode)
    {
    case TFTP_RRQ:
        recv_tftp_rrq(packet, packet_len);
        break;
    case TFTP_WRQ:
        recv_tftp_wrq(packet, packet_len);
        break;
    case TFTP_DATA:
        recv_tftp_data(packet, packet_len);
        break;
    case TFTP_ACK:
        recv_tftp_ack(packet, packet_len);
        break;
    case TFTP_OACK:
        recv_tftp_oack(packet, packet_len);
        break;
    case TFTP_ERROR:
        recv_tftp_error(packet, packet_len);
        break;

    default:
        break;
    }
}

超时重传机制

TFTP 基于 UDP 不保证可靠传输，需在应用层实现超时重传。当 g_resend_flag 置位且计时到达 g_timeout 时，根据当前状态重发对应报文（RRQ 或 ACK）。重试次数累计达到 5 次仍未成功，则调用 init_tftp() 复位并置 TFTP_FAIL。W6300 平台的 tftp_timeout_handler 通过软件定时器链表每秒调用一次。

请注意

测试实例需要 PC 端和 W6300 处于同一网段。首先打开 Tftpd32，选择 TFTP 目录和服务器地址。服务器地址必须与程序对应，并且 TFTP 目录下必须有程序中读取的文件。