- I did a cleanup of the internal generic SSL layer and how the various SSL

libraries are supported. Starting now, each underlying SSL library support
  code does a set of defines for the 16 functions the generic layer (sslgen.c)
  uses (all these new function defines use the prefix "curlssl_"). This
  greatly simplified the generic layer in readability by involving much less
  #ifdefs and other preprocessor stuff and should make it easier for people to
  make libcurl work with new SSL libraries.

  Hopefully I can later on document these 16 functions somewhat as well.

  I also made most of the internal SSL-dependent functions (using Curl_ssl_
  prefix) #defined to nothing when no SSL support is requested - previously
  they would unnecessarily call mostly empty functions.

lib/ssluse.c

@@ -1936,6 +1936,16 @@ Curl_ossl_connect(struct connectdata *conn,
   return CURLE_OK;
 }
 
+bool Curl_ossl_data_pending(const struct connectdata *conn,
+                            int connindex)
+{
+  if(conn->ssl[connindex].handle)
+    /* SSL is in use */
+    return (bool)(0 != SSL_pending(conn->ssl[connindex].handle));
+  else
+    return FALSE;
+}
+
 /* return number of sent (non-SSL) bytes */
 ssize_t Curl_ossl_send(struct connectdata *conn,
                        int sockindex,