TCP程序简单示例

最新推荐文章于 2024-11-09 17:46:22 发布

tanyouliang

最新推荐文章于 2024-11-09 17:46:22 发布

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分类专栏： Linux系统文章标签： tcp buffer struct socket stream null

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本文介绍了一个简单的TCP服务器和客户端程序的实现方法。服务器监听指定端口并响应客户端连接请求，向客户端发送欢迎消息，并读取客户端发来的消息；客户端则尝试连接服务器并接收服务器的消息，再向服务器发送字符串消息。

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

#define PORT 1234
#define MAXSOCKFD 10

int main(int argc,char **argv)
{
	int sockfd,newsockfd,is_connected[MAXSOCKFD],fd;
	struct sockaddr_in addr;
	int addr_len = sizeof(struct sockaddr_in);
	fd_set readfds;
	char buffer[256];
	char msg[] = "Welcome to server";

	if(sockfd = socket(AF_INET,SOCK_STREAM,0) < 0){
		perror("socket");
		exit(1);
	}

	//fill in struct sockaddr_in
	addr.sin_family = AF_INET;
	addr.sin_port = htons(PORT);
	addr.sin_addr.s_addr = htonl(INADDR_ANY);
	
	if(bind(sockfd,(struct sockaddr *)&addr,(socklen_t)sizeof(addr)) < 0){
		perror("bind");
		exit(1);
	}

	if(listen(sockfd,3) < 0){
		perror("listen");
		exit(1);
	}

	//clean up connect status flags
	for(fd = 0;fd < MAXSOCKFD;fd++)
		is_connected[fd] = 0;

	while(1){
		FD_ZERO(&readfds);
		FD_SET(sockfd,&readfds);

		for(fd = 0;fd < MAXSOCKFD;fd++){
			if(is_connected[fd])
				FD_SET(fd,&readfds);
		}

		if(!select(MAXSOCKFD,&readfds,NULL,NULL,NULL))
			continue;

		//estimate whether have new connect or new message
		for(fd = 0;fd < MAXSOCKFD;fd++){
			if(FD_ISSET(fd,&readfds)){
				if(sockfd == fd){
					//new connect
					if((newsockfd = accept(sockfd,(struct sockaddr *)&addr,&addr_len)) < 0)
						perror("accept");
					//send msg to clent
					write(newsockfd,msg,sizeof(msg));
					is_connected[newsockfd] = 1;
					printf("connect from %s\n",inet_ntoa(addr.sin_addr));

				}else{
					//new message
					bzero(buffer,sizeof(buffer));
					if(read(fd,buffer,sizeof(buffer)) <= 0){
						//the connect break off,clean up connet status
						printf("connection closed.\n");
						is_connected[fd] = 0;
						close(fd);
					}else
						printf("%s",buffer);
				}
			}
		}
	}
}




//client.c


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



#define PORT 1234
#define SERVER_IP "192.168.7.109"

int main(int argc,char **argv)
{
	int sockfd;
	struct sockaddr_in addr;
	char buffer[256];

	if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0){
		perror("socket");
		exit(1);
	}

	//fill in struct  sockaddr_in
	bzero(&addr,sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_port = htons(PORT);
	addr.sin_addr.s_addr = inet_addr(SERVER_IP);

	//attempt to connect
	if(connect(sockfd,(struct sockaddr *)&addr,sizeof(addr)) < 0){
		perror("connect");
		exit(1);
	}

	//accept messages from server
	recv(sockfd,buffer,sizeof(buffer),0);
	printf("%s\n",buffer);
	while(1){
		bzero(buffer,sizeof(buffer));
		//read string from stdin
		read(0,buffer,sizeof(buffer));
		//send string to server
		if(send(sockfd,buffer,sizeof(buffer),0) < 0){
			perror("send");
			exit(1);
		}

	}
}