functional if libcurl is built against OpenSSL
\fICURLOPT_DEBUGFUNCTION\fP in the last void * argument. This pointer is not
used by libcurl, it is only passed to the callback.
.IP CURLOPT_SSL_CTX_FUNCTION
+This option does only function for libcurl powered by OpenSSL. If libcurl was
+built against another SSL library, this functionality is absent.
+
Function pointer that should match the following prototype: \fBCURLcode
sslctxfun(CURL *curl, void *sslctx, void *parm);\fP This function gets called
by libcurl just before the initialization of an SSL connection after having