nbd_get_structured_replies_negotiated - see if structured replies are in use


 #include <libnbd.h>

 int nbd_get_structured_replies_negotiated (
       struct nbd_handle *h


After connecting you may call this to find out if the connection is using structured replies. Note that this setting is sticky; this can return true even after a second nbd_opt_structured_reply(3) returns false because the server detected a duplicate request.

Note that if the connection negotiates extended headers, this function returns true (as extended headers imply structured replies) even if no explicit request for structured replies was attempted.


This call returns a boolean value.


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_get_structured_replies_negotiated can be called when the handle is in the following states:

 │ Handle created, before connecting   │ ❌ error                │
 │ Connecting                          │ ❌ error                │
 │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
 │ Connected to the server             │ ✅ allowed              │
 │ Connection shut down                │ ✅ allowed              │
 │ 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_create(3), nbd_get_extended_headers_negotiated(3), nbd_get_protocol(3), nbd_get_request_structured_replies(3), nbd_opt_extended_headers(3), nbd_opt_structured_reply(3), nbd_set_request_structured_replies(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.

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