[openssl-users] Issue with select after SSL_get_wfd

Grace Priscilla Jero grace.priscilla at gmail.com
Fri Feb 16 03:35:55 UTC 2018

Hi All,

I want to know the status of the SSL_WRITE for DTLS on UDP on a
non-blocking socket. Only if the other end does the recvfrom I want to
continue with subsequent SSL_WRITE.

Below is what I have tried.

//Making the socket blocking - if I dont do below then select call hangs

if (wfd = SSL_get_wfd(ssl))
            flags = fcntl(wfd, F_GETFL);
            flags &= ~O_NONBLOCK;
            fcntl(a_wfd, F_SETFL, flags);

                FD_SET(wfd, &write_fds);
len = SSL_write(          ssl,

i = select(wfd+1, NULL, &write_fds, 0, 0);

The other side has not yet done the SSL_read but i is "1".
Is their something wrong with this?

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