LwIP之UDP发送和接收Demo

使用RT-Thread Studio基于rt-thread4.0.2构建的工程：

这里记录一下最基本的收发代码。

/*

 * Copyright (c) 2006-2019, RT-Thread Development Team

 *

 * SPDX-License-Identifier: Apache-2.0

 *

 * Change Logs:

 * Date           Author       Notes

 * 2020-02-20     ShineRoyal   the first version

 */

#include

#include

#include

#include

static const char *send_data = "GET /download/rt-thread.txt HTTP/1.1rn"

        "Host: www.rt-thread.orgrn"

        "User-Agent: rtthread/4.0.1 rttrnrn";

void udpclient(int argc, char **argv)

{

    int sock, port, count;

    struct hostent *host;

    struct sockaddr_in send_addr, recv_addr;

    const char *url;

    /* 接收到的参数小于 3 个 */

    if (argc < 3)

    {

        rt_kprintf("Usage: udpclient URL PORT [COUNT = 10]n");

        rt_kprintf("Like: tcpclient 192.168.12.44 5000n");

        return;

    }

    url = argv[1];

    port = strtoul(argv[2], 0, 10);

    if (argc > 3)

        count = strtoul(argv[3], 0, 10);

    else

        count = 10;

    /* 通过函数入口参数 url 获得 host 地址（如果是域名，会做域名解析） */

    host = (struct hostent *) gethostbyname(url);

    /* 创建一个 socket，类型是 SOCK_DGRAM，UDP 类型 */

    if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)

    {

        rt_kprintf("Socket errorn");

        return;

    }

    /* 初始化预连接的服务端地址 */

    send_addr.sin_family = AF_INET;

    send_addr.sin_port = htons(port);

    send_addr.sin_addr = *((struct in_addr *) host->h_addr);

    rt_memset(&(send_addr.sin_zero), 0, sizeof(send_addr.sin_zero));

    recv_addr.sin_family = AF_INET;

    recv_addr.sin_port = IPADDR_ANY;

    recv_addr.sin_addr = *((struct in_addr *) host->h_addr);

    rt_memset(&(recv_addr.sin_zero), 0, sizeof(recv_addr.sin_zero));

    /* 总计发送 count 次数据 */

    while (count)

    {

        /* 发送数据到服务远端 */

        sendto(sock, send_data, strlen(send_data), 0, (struct sockaddr * )&send_addr, sizeof(struct sockaddr));

        /* 线程休眠一段时间 */

        rt_thread_delay(50);

        char str[100];

        memset(str, 0, sizeof(str));

        recvfrom(sock, str, sizeof(str), 0, &recv_addr, sizeof(recv_addr));

        rt_kprintf("%s:%d=>%sn", inet_ntoa(recv_addr.sin_addr), ntohs(recv_addr.sin_port), str);

        /* 计数值减一 */

        count--;

    }

    /* 关闭这个 socket */

    closesocket(sock);

}

MSH_CMD_EXPORT(udpclient, udpclient);

收发情况如下：