nbd_opt_extended_headers(3)         LIBNBD         nbd_opt_extended_headers(3)


NAME
       nbd_opt_extended_headers - request the server to enable extended
       headers

SYNOPSIS
        #include <libnbd.h>

        int nbd_opt_extended_headers (
              struct nbd_handle *h
            );

DESCRIPTION
       Request that the server use extended headers, by sending
       "NBD_OPT_EXTENDED_HEADERS".  This can only be used if
       nbd_set_opt_mode(3) enabled option mode; furthermore, libnbd defaults
       to automatically requesting this unless you use
       nbd_set_request_extended_headers(3) or
       nbd_set_request_structured_replies(3) prior to connecting.  This
       function is mainly useful for integration testing of corner cases in
       server handling.

       This function returns true if the server replies with success, false if
       the server replies with an error, and fails only if the server does not
       reply (such as for a loss of connection).  Note that some servers fail
       a second request as redundant; libnbd assumes that once one request has
       succeeded, then extended headers are supported (as visible by
       nbd_get_extended_headers_negotiated(3)) regardless if later calls to
       this function return false.  If this function returns true, the use of
       structured replies is implied.

RETURN VALUE
       This call returns a boolean value.

ERRORS
       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).

HANDLE STATE
       nbd_opt_extended_headers can be called when the handle is in the
       following state:

        <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>
        | Handle created, before connecting   | <?> error                |
        | Connecting                          | <?> error                |
        | Connecting & handshaking (opt_mode) | <?> allowed              |
        | Connected to the server             | <?> error                |
        | Connection shut down                | <?> error                |
        | Handle dead                         | <?> error                |
        <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>

VERSION
       This function first appeared in libnbd 1.18.

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

        #define LIBNBD_HAVE_NBD_OPT_EXTENDED_HEADERS 1

SEE ALSO
       nbd_aio_opt_extended_headers(3), nbd_create(3),
       nbd_get_extended_headers_negotiated(3), nbd_opt_go(3),
       nbd_set_opt_mode(3), nbd_set_request_extended_headers(3),
       nbd_set_request_structured_replies(3), libnbd(3).

AUTHORS
       Eric Blake

       Richard W.M. Jones

COPYRIGHT
       Copyright Red Hat

LICENSE
       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

libnbd-1.20.0                     2024-05-31       nbd_opt_extended_headers(3)