linux socket如何检测断开

//服务端

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <netinet/in.h>

#include <sys/socket.h>

#include <sys/wait.h>

#define MYPORT 3490 /*定义用户连接端口*/

#define BACKLOG 10 /*多少等待连接控制*/

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

{

	int sockfd, new_fd;/* listen on sock_fd, new connection on new_fd*/

	struct sockaddr_in my_addr; /* my address information */

	struct sockaddr_in their_addr; /* connector's address information */

	int sin_size;

	if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)

	{

		perror("socket");

		exit(1);

	}



	int opt = 1;

	int len = sizeof(opt);

	setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, len);



	my_addr.sin_family = AF_INET; /* host byte order */

	my_addr.sin_port = htons(MYPORT); /* short, network byte order */

	my_addr.sin_addr.s_addr = INADDR_ANY; /* auto-fill with my IP */

	bzero(&(my_addr.sin_zero),0); /* zero the rest of the struct */



	if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))== -1) 

	{

		perror("bind");

		exit(1);

	}

	if (listen(sockfd, BACKLOG) == -1) {

		perror("listen");

		exit(1);

	}



	while(1) { /* main accept() loop */

		sin_size = sizeof(struct sockaddr_in);

		printf("while\n");

		if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) 

		{

			perror("accept");

			continue;

		}

		printf("server: got connection from %s\n", inet_ntoa(their_addr.sin_addr));



		while(1)

		{

			usleep(10000000);

			if (send(new_fd, "Hello, world!\n", 14, 0) == -1)

				perror("send");

		}

		close(new_fd);

		exit(0);



	}

	return 0;

}

//客户端

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <netinet/in.h>

#include <sys/socket.h>

#include <sys/wait.h>

#include <netdb.h>

#define PORT 3490 /* 客户机连接远程主机的端口 */

#define MAXDATASIZE 100 /* 每次可以接收的最大字节 */

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

{

	int sockfd, numbytes;

	char buf[MAXDATASIZE];

	struct hostent *he;

	struct sockaddr_in their_addr; /* connector's address information */

	if (argc != 2) 

	{

		fprintf(stderr,"usage: client hostname\n");

		exit(1);

	}

	if ((he=gethostbyname(argv[1])) == NULL) 

	{ /* get the host info */

		herror("gethostbyname");

		exit(1);

	}



	if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) 

	{

		perror("socket");

		exit(1);

	}



	their_addr.sin_family = AF_INET; /* host byte order */

	their_addr.sin_port = htons(PORT); /* short, network byte order */

	their_addr.sin_addr = *((struct in_addr *)(he->h_addr));

	bzero(&(their_addr.sin_zero),0); /* zero the rest of the struct */

	if (connect(sockfd, (struct sockaddr *)&their_addr,sizeof(struct sockaddr)) == -1) 

	{

		perror("connect");

		exit(1);

	}

	while(1)

	{

		printf("receiving......\n");

		if ((numbytes=recv(sockfd, buf, MAXDATASIZE, 0)) == -1) 

		{

			perror("recv");

			exit(1);

		}

		buf[numbytes] = '\0';

		printf("Received: %s\n",buf);

	}

	close(sockfd);

	return 0;

}

#include 

……

////KeepAlive实现

//下面代码要求有ACE,如果没有包含ACE,则请把用到的ACE函数改成linux相应的接口

int keepAlive = 1;//设定KeepAlive

int keepIdle = 5;//开始首次KeepAlive探测前的TCP空闭时间

int keepInterval = 5;//两次KeepAlive探测间的时间间隔

int keepCount = 3;//判定断开前的KeepAlive探测次数



if(setsockopt(s,SOL_SOCKET,SO_KEEPALIVE,(void*)&keepAlive,sizeof(keepAlive)) == -1)

{

        ACE_DEBUG ((LM_INFO,

        ACE_TEXT ("(%P|%t) setsockopt SO_KEEPALIVE error!\n")));



}



if(setsockopt(s,SOL_TCP,TCP_KEEPIDLE,(void *)&keepIdle,sizeof(keepIdle)) == -1)

{

        ACE_DEBUG ((LM_INFO,

        ACE_TEXT ("(%P|%t) setsockopt TCP_KEEPIDLE error!\n")));

}



if(setsockopt(s,SOL_TCP,TCP_KEEPINTVL,(void *)&keepInterval,sizeof(keepInterval)) == -1)

{

        ACE_DEBUG ((LM_INFO,

        ACE_TEXT ("(%P|%t) setsockopt TCP_KEEPINTVL error!\n")));

}



if(setsockopt(s,SOL_TCP,TCP_KEEPCNT,(void *)&keepCount,sizeof(keepCount)) == -1)

{

        ACE_DEBUG ((LM_INFO,

        ACE_TEXT ("(%P|%t)setsockopt TCP_KEEPCNT error!\n")));

}