nbd_set_request_structured_replies - control use of structured replies


 #include <libnbd.h>

 int nbd_set_request_structured_replies (
       struct nbd_handle *h, bool request


By default, libnbd tries to negotiate structured replies with the server, as this protocol extension must be in use before nbd_can_meta_context(3) or nbd_can_df(3) can return true. However, for integration testing, it can be useful to clear this flag rather than find a way to alter the server to fail the negotiation request. It is also useful to set this to false prior to using nbd_set_opt_mode(3) if it is desired to control when to send nbd_opt_structured_reply(3) during negotiation.

Note that setting this knob to false also disables any automatic request for extended headers.


If the call is successful the function returns 0.


On error -1 is returned.

Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

The following parameters must not be NULL: h. For more information see "Non-NULL parameters" in libnbd(3).


nbd_set_request_structured_replies can be called when the handle is in the following state:

 │ Handle created, before connecting   │ ✅ allowed              │
 │ Connecting                          │ ❌ error                │
 │ Connecting & handshaking (opt_mode) │ ❌ error                │
 │ Connected to the server             │ ❌ error                │
 │ Connection shut down                │ ❌ error                │
 │ Handle dead                         │ ❌ error                │


This function first appeared in libnbd 1.2.

If you need to test if this function is available at compile time check if the following macro is defined:



nbd_can_df(3), nbd_can_meta_context(3), nbd_create(3), nbd_get_request_structured_replies(3), nbd_get_structured_replies_negotiated(3), nbd_opt_structured_reply(3), nbd_set_handshake_flags(3), nbd_set_opt_mode(3), nbd_set_request_extended_headers(3), nbd_set_strict_mode(3), libnbd(3).


Eric Blake

Richard W.M. Jones


Copyright Red Hat


This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA