嵌入式第三十五天(网络编程(UDP))

一.目的

Linux下的网络编程:目的:不同主机进程间通信

解决问题:

1.主机与主机之间物理层面必须互通

2.进程与进程间在软件层面必须互通

二.相关概念

三.编程

1.流程

2.相关函数接口

3.示例

使用UPD实现全双工通信:

cs 复制代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<pthread.h>

int socketfd;
struct sockaddr_in client_addr;
socklen_t addr_len = sizeof(client_addr);

void *send_message(void *arg)
{
    while(1)
    {
        char buff[1024];
        fgets(buff,sizeof(buff),stdin);
        buff[strlen(buff) - 1] = '\0';

        sendto(socketfd,buff,strlen(buff),0,(struct sockaddr*)&client_addr,addr_len);
        if(strcmp(buff,"quiet") == 0)
        {
            break;
        }
    }
    pthread_exit(NULL);
}

void *recv_message(void *arg)
{
    while(1)
    {
        char buff[1024];
        int ret = recvfrom(socketfd,buff,sizeof(buff),0,(struct sockaddr*)&client_addr,&addr_len);

        if(ret > 0)
        {
            buff[ret] = '\0';
            printf("客户端:%s\n",buff);
            
            if(strcmp(buff,"quiet") == 0)
            {
                break;
            }
        }
    }
    pthread_exit(NULL);
}

int main(int argc,const char *argv[])
{
    struct sockaddr_in seraddr;
    pthread_t send_thread;
    pthread_t recv_thread;

    socketfd = socket(AF_INET,SOCK_DGRAM,0);
    if(socketfd < 0)
    {
        perror("socket error");
        return -1;
    }

    memset(&seraddr,0,sizeof(seraddr));
    seraddr.sin_family = AF_INET;
    seraddr.sin_port = htons(50000);
    seraddr.sin_addr.s_addr = inet_addr("192.168.19.129");

    int ret = bind(socketfd,(struct sockaddr*)&seraddr,sizeof(seraddr));
    if(ret < 0)
    {
        perror("bind errorr");
        return -1;
    }

    char buff[1024];
    recvfrom(socketfd,buff,sizeof(buff),0,(struct sockaddr*)&client_addr,&addr_len);
    printf("客户端已连接\n");

    pthread_create(&send_thread,NULL,send_message,NULL);
    pthread_create(&recv_thread,NULL,recv_message,NULL);

    pthread_join(send_thread,NULL);
    pthread_join(recv_thread,NULL);

    close(socketfd);

    return 0;
}

cs 复制代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<pthread.h>

int client_socket;
struct sockaddr_in seraddr;

void *send_message(void *arg)
{
    while(1)
    {
        char buff[1024] = {0};
        fgets(buff,sizeof(buff),stdin);
        buff[strlen(buff) - 1] = '\0';

        sendto(client_socket,buff,strlen(buff),0,(struct sockaddr*)&seraddr,sizeof(seraddr));

        if(strcmp(buff,"quiet") == 0)
        {
            break;
        }
    }
    pthread_exit(NULL);
}

void *recv_message(void *arg)
{
    int ret;
    socklen_t addr_len = sizeof(seraddr);
    while(1)
    {
        char buff[1024] = {0};
        ret = recvfrom(client_socket,buff,sizeof(buff),0,(struct sockaddr*)&seraddr,&addr_len);
        if(ret > 0)
        {
            buff[ret] = '\0';
            printf("服务端:%s\n",buff);

            if(strcmp(buff,"quiet") == 0)
            {
                break;
            }
        }
    }
    pthread_exit(NULL);
}

int main(int argc,const char *argv[])
{
    pthread_t send_thread;
    pthread_t recv_thread;

    if((client_socket = socket(AF_INET,SOCK_DGRAM,0)) < 0)
    {
        perror("sockeet error");
        return 0;
    }

    memset(&seraddr,0,sizeof(seraddr));
    seraddr.sin_family = AF_INET;
    seraddr.sin_port = htons(50000);
    seraddr.sin_addr.s_addr = inet_addr("192.168.19.129");

    printf("客户端启动\n");

    sendto(client_socket,"",0,0,(struct sockaddr*)&seraddr,sizeof(seraddr));

    pthread_create(&send_thread,NULL,send_message,NULL);
    pthread_create(&recv_thread,NULL,recv_message,NULL);

    pthread_join(send_thread,NULL);
    pthread_join(recv_thread,NULL);

    close(client_socket);

    return 0;
}

补充:

UDP特点: