一点细节关于linux下tcp断开连接时的情况

最新推荐文章于 2024-06-22 20:49:51 发布

原创最新推荐文章于 2024-06-22 20:49:51 发布 · 2.4k 阅读

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#linux #tcp #stream #server #null #socket

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本文探讨了服务器端口在客户端先断开连接与服务器自行关闭两种情况下的使用状态，重点解释了TIME_WAIT状态及其对端口可用性的影响。

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如果客户端先断开连接，server端再断开，那么server端占用的端口号立马可以用。

但是客户端未断开情况下，server自行关闭，那么占用的端口将进入TIME_WAIT状态而暂时不可使用。

因为主动断开那边会出现TIME_WAIT，而被动断开则不会吗

echoserv.c

#include "mytcplib.h"

static void servecho(int connfd, const struct sockaddr_in *cliaddr);

int main(int argc, char **argv)
{
	int sockfd, connfd;
	int childpid;
	int len;
	struct sockaddr_in servaddr, cliaddr;
		
	sockfd = Socket(AF_INET, SOCK_STREAM, 0);
	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(8081);
	servaddr.sin_addr.s_addr = INADDR_ANY;

	Bind(sockfd, (SA *)&servaddr, sizeof(servaddr));

	Listen(sockfd, LISTENQ);
	
	for(;;)
	{
		len = sizeof(cliaddr);
		connfd = Accept(sockfd, (SA *)&cliaddr, &len);
		if((childpid = fork()) == 0)
		{
			close(sockfd);
			servecho(connfd,  &cliaddr);
			close(connfd);
			exit(0);
		}
		else
		{
			waitpid(NULL, NULL, NULL);
			close(connfd);
		}

	}
	

}


void servecho(int connfd, const struct sockaddr_in *cliaddr)
{
	char recv[1024];
	int n;
	printf("connection from ip: %s at port: %d\n",
		 inet_ntoa(cliaddr->sin_addr),ntohs(cliaddr->sin_port));

	while((n = read(connfd, recv, sizeof(recv))) > 0)
	{
		//if(errno == EINTR)
		//	continue;
	
		printf("Received %d bytes , %s\n", n, recv);
		write(connfd, recv, strlen(recv));
		memset(recv, 0, sizeof(recv));
	}
	printf("Disconnected!\n");
}

echocli,c

#include "mytcplib.h"

static void cliecho(int sockfd)
{
}

int main(int argc, char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;
	char buff[1024];
	int n;

	sockfd = Socket(AF_INET, SOCK_STREAM, 0);
	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(8081);
	inet_pton(AF_INET, argv[1], &servaddr.sin_addr);
	
	Connect(sockfd, (SA *)&servaddr, sizeof(servaddr));
	memset(buff, 0, sizeof(buff));
	while(fgets(buff, sizeof(buff), stdin) != NULL)
	{
		printf("%s", buff);
		buff[strlen(buff) - 1] = 0;
		write(sockfd, buff, strlen(buff));
		n = read(sockfd, buff, sizeof(buff));
	//printf("%d\n",n);
		snprintf(buff + n, 50 ,"Received %d bytes.\n", n);
	
		write(1, buff, strlen(buff));
		memset(buff, 0, sizeof(buff));
	}
	close(sockfd);
	exit(0);

}