Linux下UDP简单通信程序

最新推荐文章于 2022-04-12 17:34:36 发布

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最新推荐文章于 2022-04-12 17:34:36 发布

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分类专栏： linux unix 文章标签： linux udp socket

本文链接：https://blog.youkuaiyun.com/liupenghui_200/article/details/38759763

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本文详细介绍了使用UDP协议进行客户端与服务器之间的通信过程，包括socket创建、地址解析、数据发送与接收，并通过实例展示了如何实现双向通信。

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

#define MAXLINE 80
#define PORT 8888

int main(int argc, char *argv[])
{
	

	struct sockaddr_in server_addr, client_addr;
	int sock_fd;
	int addrlen;
	char str[MAXLINE];
	char buf[MAXLINE];
	char addr[INET_ADDRSTRLEN];

	if((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
	{
		perror("socket");
		exit(1);
	}
	bzero(&server_addr,sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORT);	
	if(inet_pton(AF_INET, argv[1], &server_addr.sin_addr) < 0)
	{
		perror("inet_pton");
		exit(1);
	}
	while(fgets(str,MAXLINE,stdin) != NULL)
	{
		addrlen = sizeof(client_addr);
		if(-1 == sendto(sock_fd, str, strlen(str) + 1, 0, (struct sockaddr *)&server_addr, sizeof(server_addr)))
		{
			perror("sendto");
			exit(1);
		}
		if(-1 == recvfrom(sock_fd, buf, MAXLINE, 0, (struct sockaddr *)&client_addr, &addrlen))
		{
			perror("recvfrom");
			exit(1);
		}
		inet_ntop(AF_INET, &client_addr.sin_addr, addr, sizeof(addr));
		printf("Response from %s port %d:%s\n", addr, ntohs(client_addr.sin_port), buf);
	}
}

/*server.c*/
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>

#define MAXLINE 80
#define PORT 8888

int main(int argc, char *argv[])
{
	struct sockaddr_in server_addr, client_addr;
	int i;
	int sock_fd;
	int recvlen;
	int addrlen;
	int buflen;
	char buf[MAXLINE];
	char str[INET_ADDRSTRLEN];
	
	if((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)  //第三个参数一般默认0 ，根据第二个参数socket类型即可判断不用特意指定协议
	{
		perror("sock");
		exit(1);
	}
	
	bzero(&server_addr,sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = INADDR_ANY;
	server_addr.sin_port = htons(PORT);
	
	if(bind(sock_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
	{
		perror("bind");
		close(sock_fd);
		exit(1);
	}
	while(1)
	{
		addrlen = sizeof(client_addr);
		if((recvlen = recvfrom(sock_fd, buf, MAXLINE, 0, (struct sockaddr *)&client_addr, &addrlen)) < 0)
		{
			perror("recvfrom");
			exit(1);
		}
		inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str));
		printf("client ip is %s at port %d:%s\n", str, ntohs(client_addr.sin_port), buf);
		for(i = 0; i < recvlen; i++)
		{
			buf[i] = toupper(buf[i]);
		}
		
		if(sendto(sock_fd, buf, recvlen, 0, (struct sockaddr *)&client_addr, addrlen) != recvlen)
		{
			perror("sendto");
			exit(1);
		}
	}
	
}

先打开一个Terminal 运行server 再打开一个Terminal 运行client ./client 127.0.0.1(服务器的ip地址)