int conn_nonb(int sockfd, const struct sockaddr_in *saptr, socklen_t salen, int nsec)
{
int flags, n, error, code;
socklen_t len;
fd_set wset;
struct timeval tval;
flags = fcntl(sockfd, F_GETFL, 0);
fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
error = 0;
if ((n == connect(sockfd, saptr, salen)) == 0) {
goto done;
} else if (n < 0 && errno != EINPROGRESS){
return (-1);
}
/* Do whatever we want while the connect is taking place */
FD_ZERO(&wset);
FD_SET(sockfd, &wset);
tval.tv_sec = nsec;
tval.tv_usec = 0;
if ((n = select(sockfd+1, NULL, &wset,
NULL, nsec ? &tval : NULL)) == 0) {
close(sockfd); /* timeout */
errno = ETIMEDOUT;
return (-1);
}
if (FD_ISSET(sockfd, &wset)) {
len = sizeof(error);
code = getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len);
/* 如果發生錯誤，Solaris實現的getsockopt返回-1，
* 把pending error設置給errno. Berkeley實現的
* getsockopt返回0, pending error返回給error.
* 我們需要處理這兩種情況 */
if (code < 0 || error) {
close(sockfd);
if (error)
errno = error;
return (-1);
}
} else {
fprintf(stderr, "select error: sockfd not set");
exit(0);
}
done:
fcntl(sockfd, F_SETFL, flags); /* restore file status flags */
return (0);
}