linux网络编程之用socket实现简单客户端和服务端的通信（基于UDP）

单客户端和服务端的通信（基于UDP）   代码

服务端代码socket3.c

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<netdb.h>
#include<errno.h> 
#define PORT 8888
#define MAX_MSG_SIZE 1024 
int main(void)
{   
	int sockfd, addrlen, n;   
	struct sockaddr_in addr;   
	char msg[MAX_MSG_SIZE];   
	sockfd = socket(AF_INET, SOCK_DGRAM, 0);   
	if (sockfd < 0)   
	{      
		fprintf(stderr, "socket failed\n");      
		exit(EXIT_FAILURE);   
	}   
	addrlen = sizeof(struct sockaddr_in);  
	bzero(&addr, addrlen);   
	addr.sin_family = AF_INET;   
	addr.sin_addr.s_addr = htonl(INADDR_ANY);  
	addr.sin_port = htons(PORT);  
	if (bind(sockfd, (struct sockaddr*)(&addr), addrlen) < 0)  
	{    
		fprintf(stderr, "bind fail\n");   
		exit(EXIT_FAILURE); 
	}  
	puts("bind success");  
	while (1) 
	{     
		bzero(msg, MAX_MSG_SIZE);   
		n = recvfrom(sockfd, msg, sizeof(msg), 0, (struct sockaddr *)(&addr), &addrlen);   
		fprintf(stdout, "Recevie message from client is %s\n", msg); 
		fgets(msg, MAX_MSG_SIZE,stdin);  
		printf("Server endpoint input message %s\n", msg);   
		sendto(sockfd, msg, n, 0,(struct sockaddr *)(&addr), addrlen); 
	}   
	close(sockfd);  
	exit(EXIT_SUCCESS);
}

客户端代码socket4.c

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<string.h> 
#define MAX_BUF_SIZE 1024
#define PORT 8888 
int main() 
{  
	int sockfd, addrlen, n;  
	char buffer[MAX_BUF_SIZE]; 
	struct sockaddr_in addr; 
	sockfd = socket(AF_INET, SOCK_DGRAM, 0); 
	if (sockfd < 0)  
	{   
		fprintf(stderr, "socket falied\n");    
		exit(EXIT_FAILURE);
	}   
	addrlen = sizeof(struct sockaddr_in);  
	bzero(&addr, addrlen); 
	addr.sin_family = AF_INET;   
	addr.sin_port = htons(PORT); 
	addr.sin_addr.s_addr = htonl(INADDR_ANY);  
	puts("socket success"); 
	while(1)  
	{    
		bzero(buffer, MAX_BUF_SIZE);    
		fgets(buffer, MAX_BUF_SIZE, stdin); 
		sendto(sockfd, buffer, strlen(buffer), 0, (struct sockaddr *)(&addr), addrlen);      
		printf("client send msg is %s\n", buffer);    
		n = recvfrom(sockfd, buffer, strlen(buffer), 0, (struct sockaddr *)(&addr), &addrlen);     
		fprintf(stdout, "clinet Receive message from server is %s\n", buffer);  
	}  
	close(sockfd);   
	exit(0);  
	return 0;
}

　　运行结果截图如下：

5、总结

服务端：socket->bind->(sendto 、revcfrom)

客户端：socket->(sendto 、revcfrom)

upd不是面相连接的，这个是和tcp本质区别，数据可能会乱序，重复。