[Linux]检测socket异常断开--keepalive

参考文献:

http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/#usingkeepalive

http://blog.csdn.net/jwybobo2007/article/details/6162784

#include<stdlib.h>
#include<stdio.h>
#include<netinet/in.h>
#include<netinet/tcp.h>
#include<netdb.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<unistd.h>
#include<fcntl.h>
#include<errno.h>
#include<string.h>

int main(const int argc,char* const argv[])
{
	int socket_fd;
	struct sockaddr_in name;
	struct hostent *hostinfo;
	socket_fd = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
	name.sin_family = AF_INET;
	hostinfo = gethostbyname(argv[1]);
	if(hostinfo == NULL) return -1;
	name.sin_addr = *((struct in_addr*)hostinfo->h_addr);
	name.sin_port = htons(atoi(argv[2]));
	if(connect(socket_fd,(struct sockaddr*)&name,sizeof(name))==-1) return -2;
	
	char buf[1024];
	ssize_t count;
	int sock_flag;
	int times=0;
	sock_flag = fcntl(socket_fd,F_GETFL);
	fcntl(socket_fd,F_SETFL,sock_flag|O_NONBLOCK);	
	//write(socket_fd,"GET /\n",strlen("GET /\n"));
	
	int keepalive = 1;
	int keepidle = 5;
	int keepinterval = 3;
	int keepcount = 2;
	if(setsockopt(socket_fd,SOL_SOCKET,SO_KEEPALIVE,&keepalive,sizeof(keepalive))<0) return -3;
	if(setsockopt(socket_fd,SOL_TCP,TCP_KEEPIDLE,&keepidle,sizeof(keepidle))<0) return -4;
	if(setsockopt(socket_fd,SOL_TCP,TCP_KEEPINTVL,&keepinterval,sizeof(keepinterval))<0) return -5;
	if(setsockopt(socket_fd,SOL_TCP,TCP_KEEPCNT,&keepcount,sizeof(keepcount))<0) return -6;
	
	while(true)
	{
		count=read(socket_fd,buf,1024);
		if(count>0) write(STDOUT_FILENO,buf,count);
		else if(count==-1 && errno==EAGAIN) 
		{
			printf("%dth sleep 1s\n",++times);	
			sleep(1);
		}
		else
		{
			printf("count=%d,errno=%d\n",count,errno);
			break;
		}
	}
	return 0;
}