HI3861学习笔记（22）——UDP客户端

作者: Leung_ManWah | 来源:发表于2022-03-15 18:11 被阅读0次

一、TCP与UDP优缺点

1、TCP面向连接（如打电话要先拨号建立连接）;UDP是无连接的，即发送数据之前不需要建立连接。

2、TCP提供可靠的服务。也就是说，通过TCP连接传送的数据，无差错，不丢失，不重复，且按序到达;UDP尽最大努力交付，即不保证可靠交付。
TCP通过校验和，重传控制，序号标识，滑动窗口、确认应答实现可靠传输。如丢包时的重发控制，还可以对次序乱掉的分包进行顺序控制。

3、UDP具有较好的实时性，工作效率比TCP高，适用于对高速传输和实时性有较高的通信或广播通信。

4、每一条TCP连接只能是点到点的;UDP支持一对一，一对多，多对一和多对多的交互通信。

5、TCP对系统资源要求较多，UDP对系统资源要求较少。

二、API说明

以下 UDP 接口位于 vendor\hisi\hi3861\hi3861\third_party\lwip_sack\include\sockets.h。

业务BUILD.gn中包含路径

include_dirs = [
        "//utils/native/lite/include",
        "//kernel/liteos_m/components/cmsis/2.0",
        "//base/iot_hardware/interfaces/kits/wifiiot_lite",
        "//foundation/communication/interfaces/kits/wifi_lite/wifiservice",
        "//vendor/hisi/hi3861/hi3861/third_party/lwip_sack/include/",
    ]

socket()
bind()
accept()
shutdown()
getpeername()
getsockopt()＆setsockopt()
close()
read()，readv()，write()，writev()
recv()
send()，sendmsg()，sendto()
select()
fcntl()

三、UDP客户端

3.1 主要流程

3.1.1 第一步：新建socket

在网络编程中所需要进行的第一件事情就是创建一个socket，无论是客户端还是服务器端，都需要创建一个socket，该函数返回socket文件描述符，类似于文件描述符。socket是一个结构体，被创建在内核中。

//在sock_fd 进行监听，在 new_fd 接收新的链接
int sock_fd;

//创建socket
if((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
    perror("create socket failed!\r\n");
    exit(1);
}

3.1.2 第二步：配置将要连接的服务器信息（端口和IP）

按道理服务器的地址选择 255.255.255.255，意思是不指定局域网内的某一设备，局域网所有的设备如果监听了这个端口号，那么都可以收到hi3861发来的消息。但是实际好像就只能填UDP服务器的地址，而已只能发送，不能接收。

#define UDP_PROT  8888

int addr_length;

//服务器的地址信息
struct sockaddr_in send_addr;
socklen_t addr_length = sizeof(send_addr);

//初始化预连接的服务端地址
send_addr.sin_family = AF_INET;
send_addr.sin_port = htons(UDP_PROT);
send_addr.sin_addr.s_addr = inet_addr("192.168.31.225");
addr_length = sizeof(send_addr);

3.1.3 第三步：发送数据

sendto() 用来将数据由指定的socket传给对方主机。参数s为已建好连线的socket。参数msg指向欲连线的数据内容，参数flags一般设0。

static const char *send_data = "Hello! I'm BearPi-HM_Nano UDP Client!\r\n";

//发送数据到服务远端
sendto(sock_fd, send_data, strlen(send_data), 0, (struct sockaddr *)&send_addr, addr_length);

3.1.4 第四步：接收数据

char recvBuf[512];

while (1)
{
    bzero(recvBuf, sizeof(recvBuf));
    ...

    //线程休眠一段时间
    sleep(10);

    //接收服务端返回的字符串
    recvfrom(sock_fd, recvBuf, sizeof(recvBuf), 0, (struct sockaddr *)&send_addr, &addr_length);
    printf("%s:%d=>%s\n", inet_ntoa(send_addr.sin_addr), ntohs(send_addr.sin_port), recvBuf);
}

3.2 配置SSID和密码连接WIFI创建TCP客户端

wifi_connect.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "lwip/netif.h"
#include "lwip/netifapi.h"
#include "lwip/ip4_addr.h"
#include "lwip/api_shell.h"

#include "cmsis_os2.h"
#include "hos_types.h"
#include "wifi_device.h"
#include "wifiiot_errno.h"
#include "ohos_init.h"

#define DEF_TIMEOUT 15
#define ONE_SECOND 1

#define SELECT_WIFI_SECURITYTYPE WIFI_SEC_TYPE_PSK  

static void WiFiInit(void);
static void WaitSacnResult(void);
static int WaitConnectResult(void);
static void OnWifiScanStateChangedHandler(int state, int size);
static void OnWifiConnectionChangedHandler(int state, WifiLinkedInfo *info);
static void OnHotspotStaJoinHandler(StationInfo *info);
static void OnHotspotStateChangedHandler(int state);
static void OnHotspotStaLeaveHandler(StationInfo *info);

static int g_staScanSuccess = 0;
static int g_ConnectSuccess = 0;
static int ssid_count = 0;
WifiEvent g_wifiEventHandler = {0};
WifiErrorCode error;

#define SELECT_WLAN_PORT "wlan0"

int WifiConnect(const char *ssid, const char *psk)
{
    WifiScanInfo *info = NULL;
    unsigned int size = WIFI_SCAN_HOTSPOT_LIMIT;
    static struct netif *g_lwip_netif = NULL;

    osDelay(200);
    printf("<--System Init-->\r\n");

    //初始化WIFI
    WiFiInit();

    //使能WIFI
    if (EnableWifi() != WIFI_SUCCESS)
    {
        printf("EnableWifi failed, error = %d\r\n", error);
        return -1;
    }

    //判断WIFI是否激活
    if (IsWifiActive() == 0)
    {
        printf("Wifi station is not actived.\r\n");
        return -1;
    }

    //分配空间，保存WiFi信息
    info = malloc(sizeof(WifiScanInfo) * WIFI_SCAN_HOTSPOT_LIMIT);
    if (info == NULL)
    {
        return -1;
    }
    //轮询查找WiFi列表
    do{
        //重置标志位
        ssid_count = 0;
        g_staScanSuccess = 0;

        //开始扫描
        Scan();

        //等待扫描结果
        WaitSacnResult();

        //获取扫描列表
        error = GetScanInfoList(info, &size);

    }while(g_staScanSuccess != 1);
    //打印WiFi列表
    printf("********************\r\n");
    for(uint8_t i = 0; i < ssid_count; i++)
    {
        printf("no:%03d, ssid:%-30s, rssi:%5d\r\n", i+1, info[i].ssid, info[i].rssi/100);
    }
    printf("********************\r\n");
    
    //连接指定的WiFi热点
    for(uint8_t i = 0; i < ssid_count; i++)
    {
        if (strcmp(ssid, info[i].ssid) == 0)
        {
            int result;

            printf("Select:%3d wireless, Waiting...\r\n", i+1);

            //拷贝要连接的热点信息
            WifiDeviceConfig select_ap_config = {0};
            strcpy(select_ap_config.ssid, info[i].ssid);
            strcpy(select_ap_config.preSharedKey, psk);
            select_ap_config.securityType = SELECT_WIFI_SECURITYTYPE;

            if (AddDeviceConfig(&select_ap_config, &result) == WIFI_SUCCESS)
            {
                if (ConnectTo(result) == WIFI_SUCCESS && WaitConnectResult() == 1)
                {
                    printf("WiFi connect succeed!\r\n");
                    g_lwip_netif = netifapi_netif_find(SELECT_WLAN_PORT);
                    break;
                }
            }
        }

        if(i == ssid_count-1)
        {
            printf("ERROR: No wifi as expected\r\n");
            while(1) osDelay(100);
        }
    }
     //启动DHCP
    if (g_lwip_netif)
    {
        dhcp_start(g_lwip_netif);
        printf("begain to dhcp\r\n");
    }


    //等待DHCP
    for(;;)
    {
        if(dhcp_is_bound(g_lwip_netif) == ERR_OK)
        {
            printf("<-- DHCP state:OK -->\r\n");

            //打印获取到的IP信息
            netifapi_netif_common(g_lwip_netif, dhcp_clients_info_show, NULL);
            break;
        }

        printf("<-- DHCP state:Inprogress -->\r\n");
        osDelay(100);
    }

    osDelay(100);

    return 0;
}

static void WiFiInit(void)
{
    printf("<--Wifi Init-->\r\n");
    g_wifiEventHandler.OnWifiScanStateChanged = OnWifiScanStateChangedHandler;
    g_wifiEventHandler.OnWifiConnectionChanged = OnWifiConnectionChangedHandler;
    g_wifiEventHandler.OnHotspotStaJoin = OnHotspotStaJoinHandler;
    g_wifiEventHandler.OnHotspotStaLeave = OnHotspotStaLeaveHandler;
    g_wifiEventHandler.OnHotspotStateChanged = OnHotspotStateChangedHandler;
    error = RegisterWifiEvent(&g_wifiEventHandler);
    if (error != WIFI_SUCCESS)
    {
        printf("register wifi event fail!\r\n");
    }
    else
    {
        printf("register wifi event succeed!\r\n");
    }
}

static void OnWifiScanStateChangedHandler(int state, int size)
{
    if (size > 0)
    {
        ssid_count = size;
        g_staScanSuccess = 1;
    }
    printf("callback function for wifi scan:%d, %d\r\n", state, size);
    return;
}

static void OnWifiConnectionChangedHandler(int state, WifiLinkedInfo *info)
{
    if (info == NULL)
    {
        printf("WifiConnectionChanged:info is null, stat is %d.\n", state);
    }
    else
    {
        if (state == WIFI_STATE_AVALIABLE)
        {
            g_ConnectSuccess = 1;
        }
        else
        {
            g_ConnectSuccess = 0;
        }
    }
}

static void OnHotspotStaJoinHandler(StationInfo *info)
{
    (void)info;
    printf("STA join AP\n");
    return;
}

static void OnHotspotStaLeaveHandler(StationInfo *info)
{
    (void)info;
    printf("HotspotStaLeave:info is null.\n");
    return;
}

static void OnHotspotStateChangedHandler(int state)
{
    printf("HotspotStateChanged:state is %d.\n", state);
    return;
}

static void WaitSacnResult(void)
{
    int scanTimeout = DEF_TIMEOUT;
    while (scanTimeout > 0)
    {
        sleep(ONE_SECOND);
        scanTimeout--;
        if (g_staScanSuccess == 1)
        {
            printf("WaitSacnResult:wait success[%d]s\n", (DEF_TIMEOUT - scanTimeout));
            break;
        }
    }
    if (scanTimeout <= 0)
    {
        printf("WaitSacnResult:timeout!\n");
    }
}

static int WaitConnectResult(void)
{
    int ConnectTimeout = DEF_TIMEOUT;
    while (ConnectTimeout > 0)
    {
        sleep(ONE_SECOND);
        ConnectTimeout--;
        if (g_ConnectSuccess == 1)
        {
            printf("WaitConnectResult:wait success[%d]s\n", (DEF_TIMEOUT - ConnectTimeout));
            break;
        }
    }
    if (ConnectTimeout <= 0)
    {
        printf("WaitConnectResult:timeout!\n");
        return 0;
    }

    return 1;
}

wifi_connect.h

#ifndef __WIFI_CONNECT_H__
#define __WIFI_CONNECT_H__

int WifiConnect(const char *ssid,const char *psk);

#endif /* __WIFI_CONNECT_H__ */

四、完整代码

编译时在业务BUILD.gn中包含路径

static_library("myapp") {
    sources = [
        "wifi_connect.c",
        "hello_world.c"
    ]
    cflags = [ "-Wno-unused-variable" ]
    cflags += [ "-Wno-unused-but-set-variable" ]
    cflags += [ "-Wno-unused-parameter" ]
    include_dirs = [
        "//utils/native/lite/include",
        "//kernel/liteos_m/components/cmsis/2.0",
        "//base/iot_hardware/interfaces/kits/wifiiot_lite",
        "//foundation/communication/interfaces/kits/wifi_lite/wifiservice",
        "//vendor/hisi/hi3861/hi3861/third_party/lwip_sack/include/",
    ]
}

hello_world.c

#include <stdio.h>
#include <unistd.h>

#include "ohos_init.h"
#include "cmsis_os2.h"

#include "wifi_device.h"
#include "lwip/netifapi.h"
#include "lwip/api_shell.h"
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include "lwip/sockets.h"
#include "wifi_connect.h"

#define UDP_PROT 3333

//在sock_fd 进行监听，在 new_fd 接收新的链接
int sock_fd;

int addr_length;
static const char *send_data = "Hello! I'm BearPi-HM_Nano UDP Client!\r\n";

//服务器的地址信息
struct sockaddr_in send_addr;

static void UDPClientTask(void)
{
    socklen_t addr_length = sizeof(send_addr);
    char recvBuf[512];

    //连接Wifi
    WifiConnect("406", "82069909");

    //创建socket
    if ((sock_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)) == -1)
    {
        perror("create socket failed!\r\n");
        exit(1);
    }

    //初始化预连接的服务端地址
    send_addr.sin_family = AF_INET;
    send_addr.sin_port = htons(UDP_PROT);
    send_addr.sin_addr.s_addr = inet_addr("192.168.31.225");
    addr_length = sizeof(send_addr);

    while (1)
    {
        bzero(recvBuf, sizeof(recvBuf));

        //发送数据到服务远端
        sendto(sock_fd, send_data, strlen(send_data), 0, (struct sockaddr *)&send_addr, addr_length);

        //线程休眠一段时间
        sleep(10);

        //接收服务端返回的字符串
        recvfrom(sock_fd, recvBuf, sizeof(recvBuf), 0, (struct sockaddr *)&send_addr, &addr_length);
        printf("%s:%d=>%s\n", inet_ntoa(send_addr.sin_addr), ntohs(send_addr.sin_port), recvBuf);
    }

    //关闭这个 socket
    closesocket(sock_fd);
}

static void UDPClientDemo(void)
{
    osThreadAttr_t attr;

    attr.name = "UDPClientTask";
    attr.attr_bits = 0U;
    attr.cb_mem = NULL;
    attr.cb_size = 0U;
    attr.stack_mem = NULL;
    attr.stack_size = 10240;
    attr.priority = osPriorityNormal;

    if (osThreadNew((osThreadFunc_t)UDPClientTask, NULL, &attr) == NULL)
    {
        printf("[UDPClientDemo] Falied to create UDPClientTask!\n");
    }
}

APP_FEATURE_INIT(UDPClientDemo);

查看打印：

• 由 Leung 写于 2022 年 3 月 15 日

HI3861学习笔记（22）——UDP客户端

一、TCP与UDP优缺点

二、API说明

三、UDP客户端

3.1 主要流程

3.1.1 第一步：新建socket

3.1.2 第二步：配置将要连接的服务器信息（端口和IP）

3.1.3 第三步：发送数据

3.1.4 第四步：接收数据

3.2 配置SSID和密码连接WIFI创建TCP客户端

四、完整代码

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