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UNIX® Network Programming Volume 1, Third Edition
16.3 Nonblocking connect
#include "unp.h"
int
connect_nonb(int sockfd, const SA *saptr, socklen_t salen, int nsec)
{
int flags, n, error;
socklen_t len;
fd_set rset, wset;
struct timeval tval;
flags = Fcntl(sockfd, F_GETFL, 0);
Fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
error = 0;
if ( (n = connect(sockfd, (struct sockaddr *) saptr, salen)) < 0)
if (errno != EINPROGRESS)
return(-1);
/* Do whatever we want while the connect is taking place. */
if (n == 0)
goto done; /* connect completed immediately */
FD_ZERO(&rset);
FD_SET(sockfd, &rset);
wset = rset;
tval.tv_sec = nsec;
tval.tv_usec = 0;
if ( (n = Select(sockfd+1, &rset, &wset, NULL,
nsec ? &tval : NULL)) == 0) {
close(sockfd); /* timeout */
errno = ETIMEDOUT;
return(-1);
}
if (FD_ISSET(sockfd, &rset) || FD_ISSET(sockfd, &wset)) {
len = sizeof(error);
if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len) < 0)
return(-1); /* Solaris pending error */
} else
err_quit("select error: sockfd not set");
done:
Fcntl(sockfd, F_SETFL, flags); /* restore file status flags */
if (error) {
close(sockfd); /* just in case */
errno = error;
return(-1);
}
return(0);
}
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