On Wed, Sep 12, 2007, Jim Marshall wrote:
> I have setup my BIO to be non-blocking in my server. In my server I want
> to use 'select' to detect when there is a connection available, but for
> some reason it is not working. either select returns '-1' with errno set
> to EINTR or select returns 0, but it has not waited for 2 seconds for a
> connection. Maybe someone can give me an idea what I am doing wrong?
>
> here is the code I am using:
>
> void startListening(BIO* sock) {
> int acceptSock = BIO_get_fd(sock, NULL);
> int waitVal = 0;
> fd_set rfds, wfds, efds;
> struct timeval tv;
> /* Wait up to two seconds. */
> tv.tv_sec = 2;
> tv.tv_usec = 0;
> /* This is just one of the tests I have tried */
> FD_ZERO(&rfds);
> FD_SET(acceptSock, &rfds);
> FD_ZERO(&wfds);
> FD_SET(acceptSock, &wfds);
> FD_ZERO(&rfds);
> FD_SET(acceptSock, &efds);
> do {
> /* see if we have any activity on the socket */
> waitVal = select(acceptSock, &rfds, &wfds, &efds, &tv);
> if (waitVal < 0)
> {
> char* err = strerror(errno);
> printf("select error: %s\n", err);
> fflush(stdout);
> return;
> } if (waitVal > 0) {
> BIO_do_accept(sock)
> handleAccept(sock);
> }
> } while (waitVal == 0);
> ...
> }
>
> If I change this code to do a 'BIO_do_accept' and the call 'sleep(1)'
> when 'BIO_do_accept' returns -1 and errno is EAGAIN it seems to work
> fine. But that means my server could be sleeping when a request come in.
>
> Any thoughts?
>
> Thanks
> Jim
>
> p.s.
> The BIO passed into the function above is created like this:
>
> ret = BIO_new_accept(hostString);
> if (ret != NULL)
> {
> /* set the accept socket to non-blocking */
> BIO_set_nbio_accept(ret, 1);
> /* set sockets created from this accept socket to
> non-blocking */
> BIO_set_nbio(ret, 1);
> BIO_set_bind_mode(ret, BIO_BIND_REUSEADDR);
> /* bind & listen */
> val = BIO_do_accept(ret)
> ...
>
> it is returned to a calling function which in turn calls startListening.
>
Well you should loop round calling BIO_do_accept() in the startListening()
function and not call it outside. Check the return value and if >0 a
connection has occurred and you can process it.
If <=0 check the status with BIO_should_retry() if that returns 0 some error
has occurred.
If BIO_should_retry() is true get the fd from the BIO and wait for a
connection condition: what you wait for depends on the OS but select (or
similar) for a read condition is typical.
Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
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