传输层-UDP介绍

一、基于UDP协议的程序

二、测试用例

1、服务端代码

cpp 复制代码

//udp_server.c内容

#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<arpa/inet.h>

#define handle_error(cmd,result)\
    if (result < 0)             \
    {                           \
        perror(cmd);            \
        return -1;              \
    }                           \

int main(int argc, char const *argv[])
{
    //使用udp协议完成客户端和服务端的通讯
    //EOF作为关闭的信号
    struct sockaddr_in server_addr,client_addr;
    int sockfd,tmep_result;
    char* buf=malloc(sizeof(char)*1024);

    //清空
    memset(&server_addr,0,sizeof(server_addr));
    memset(&client_addr,0,sizeof(client_addr));
    //填写服务端地址
    server_addr.sin_family=AF_INET;
    //填写ip地址 0.0.0.0
    server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    //填写端口号
    server_addr.sin_port = htons(6666);

    //udp编程
    //1、创建socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);
    handle_error("socket",sockfd);
    //2、服务端绑定地址
    socklen_t server_len = sizeof(server_addr);
    socklen_t client_len = sizeof(client_len);
    tmep_result = bind(sockfd,(struct sockaddr*)&server_addr,server_len);
    handle_error("bind",tmep_result);

    //直接就可以收发数据
    do
    {
        //接收数据到缓存
        memset(buf,0,1024);
        //接收数据
        tmep_result = recvfrom(sockfd,buf,1024,0,(struct sockaddr *)&client_addr,&client_len);
        handle_error("recvfrom",tmep_result);
        if (strncmp(buf,"EOF",3) != 0)
        {
            printf("接收到客户端%s %d信息:%s\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port),buf);
            strcpy(buf,"OK\n");
        }
        else
        {
            printf("收到结束信息，准备关闭\n");
        }
        //回复数据
        tmep_result = sendto(sockfd,buf,4,0,(struct sockaddr*)&client_addr,client_len);
        handle_error("sendto",tmep_result);

    } while (strncmp(buf,"EOF",3));

    

    return 0;
}

2、客户端代码

cpp 复制代码

//udp_client.c 内容

#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<arpa/inet.h>
#include<unistd.h>

#define handle_error(cmd,result)\
    if (result < 0)             \
    {                           \
        perror(cmd);            \
        return -1;              \
    }                           \

int main(int argc, char const *argv[])
{
    //使用udp协议完成客户端和服务端的通讯
    //EOF作为关闭的信号
    struct sockaddr_in server_addr,client_addr;
    int sockfd,tmep_result;
    char* buf=malloc(sizeof(char)*1024);

    //清空
    memset(&server_addr,0,sizeof(server_addr));
    memset(&client_addr,0,sizeof(client_addr));
    //填写服务端地址
    server_addr.sin_family=AF_INET;
    //填写ip地址 0.0.0.0
    server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    //填写端口号
    server_addr.sin_port = htons(6666);

    //udp编程
    //1、创建socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);
    handle_error("socket",sockfd);
    //2、客户端不需要绑定地址
    socklen_t server_len = sizeof(server_addr);
    socklen_t client_len = sizeof(client_len);

    //直接就可以收发数据
    do
    {
        printf("请输入要发送的信息:\n");
        //从控制台读取数据
        int buf_len = read(STDIN_FILENO,buf,1023);
        tmep_result = sendto(sockfd,buf,buf_len,0,(struct sockaddr *)&server_addr,server_len);
        handle_error("sendto",tmep_result);
        //清空缓存区用来接收数据
        memset(buf,0,1024);
        tmep_result = recvfrom(sockfd,buf,1024,0,NULL,NULL);
        handle_error("recvfrom",tmep_result);
        if (strncmp(buf,"EOF",3) != 0)
        {
            printf("收到服务端%s %d返回的数据%s\n",inet_ntoa(server_addr.sin_addr),ntohs(server_addr.sin_port),buf);
        }
        

    } while (strncmp(buf,"EOF",3));

    free(buf);

    return 0;
}

makfile

cpp 复制代码

udp_server:udp_server.c
	-$(CC) -o $@ $^ -lpthread

udp_client:udp_client.c
	-$(CC) -o $@ $^ -lpthread