code11_1.cpp

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <pthread.h>
/*超时连接函数*/
int timeout_connect(const char * ip,int port,int time)
{
	int ret = 0;
	struct sockaddr_in address;
	bzero(&address,sizeof(address));
	address.sin_family = AF_INET;
	inet_pton(AF_INET,ip,&address.sin_addr);
	address.sin_port = htons(port);

	int sockfd = socket(PF_INET,SOCK_STREAM,0);
	assert(sockfd != -1);
	/*通过选项SO_RCVTIMEO和SO_SNDTIMEO所设置的超时时间的类型是
	 * timeval，这和selecte系统所调用的超时参数类型相同*/
	struct timeval timeout;
	timeout.tv_sec = time;
	timeout.tv_usec = 0;
	socklen_t len = sizeof(timeout);
	ret = setsockopt(sockfd,SOL_SOCKET,SO_SNDTIMEO,&timeout,len);
	assert(ret != -1);

	ret = connect(sockfd,(struct sockaddr *)&address,sizeof(address));
	if(ret != -1)
	{
		/*超时对应的错误是EINPROGRESS,下面这个条件如果成立，我们就可以
		 * 处理定时任务了*/
		if(errno == EINPROGRESS)
		{
			printf("connecting timeout,process timeout logic\n");
			return -1;
		}
		printf("error occur when connecting to server\n");
		return -1;
	}
	return sockfd;

}
int main(int argc,char *argv[])
{
	if(argc <= 2)
	{
		printf("usage: %s ip_address port_number\n",basename(argv[0]));
		return 1;
	}
	const char *ip = argv[1];
	int port = atoi(argv[2]);
	int sockfd = timeout_connect(ip,port,10);
	if(sockfd <= 0)
		return 1;
	close(sockfd);
	return 0;
}