C코드 : connect 타임 아웃

int connectWithTimeout(int fd,struct sockaddr *remote, int len, int secs, int *err)
{
	int saveflags,ret,back_err;
	fd_set fd_w;
	struct timeval timeout;
 
	saveflags = fcntl(fd,F_GETFL,0);
	if(saveflags<0) 
	{
		perror("fcntl1");
		*err=errno;
		return -1;
	}

	/* Set non blocking */
	if( fcntl(fd,F_SETFL,saveflags|O_NONBLOCK)<0 ) 
	{
		perror("fcntl2");
		*err=errno;
		return -1;
	}

	/* This will return immediately */
	*err = connect(fd,remote,len);
	back_err=errno;

	/* restore flags */
	if( fcntl(fd,F_SETFL,saveflags)<0 ) 
	{
		perror("fcntl3");
		*err=errno;
		return -1;
	}

	/* return unless the connection was successful or the connect is
	still in progress. */
	if(*err<0 && back_err!=EINPROGRESS) 
	{
		perror("connect");
		*err=errno;
		return -1;
	}


	timeout.tv_sec = (long)secs;
	timeout.tv_usec = 0L;

	FD_ZERO(&fd_w);
	FD_SET(fd,&fd_w);

	*err= select(FD_SETSIZE,NULL,&fd_w,NULL,&timeout);
	if(*err<0) 
	{
		perror("select");
		*err=errno;
		return -1;
	}

	/* 0 means it timeout out & no fds changed */
	if(*err==0) 
	{
		perror("timeout...");
		*err=ETIMEDOUT;
		return -1;
	}

	/* Get the return code from the connect */
	len= sizeof(ret);
	*err= getsockopt(fd,SOL_SOCKET,SO_ERROR,&ret,&len);
	if(*err<0) 
	{
		perror("getsockopt");
		*err=errno;
		return -1;
	}

	/* ret=0 means success, otherwise it contains the errno */
	if(ret) 
	{
		*err=ret;
		return -1;
	}
	*err=0;
	return 0;
}