+=head1 RETURN VALUES
+
+SSL_CTX_set_tmp_dh_callback() and SSL_set_tmp_dh_callback() do not return
+diagnostic output.
+
+SSL_CTX_set_tmp_dh() and SSL_set_tmp_dh() do return 1 on success and 0
+on failure. Check the error queue to find out the reason of failure.
+