NAME

       nbd_get_protocol - return the NBD protocol variant

SYNOPSIS

        #include <libnbd.h>

        const char * nbd_get_protocol (struct nbd_handle *h);

DESCRIPTION

       Return the NBD protocol variant in use on the connection.  At the moment this returns one
       of the strings "oldstyle", "newstyle" or "newstyle-fixed".  Other strings might be
       returned in the future.  Most modern NBD servers use "newstyle-fixed".

       This call does not block, because it returns data that is saved in the handle from the NBD
       protocol handshake.

RETURN VALUE

       This call returns a statically allocated string, valid for the lifetime of the process or
       until libnbd is unloaded by dlclose(3).  You must not try to free the string.

ERRORS

       On error "NULL" is returned.

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

HANDLE STATE

       The handle must be negotiating, or connected with the server, or shut down, otherwise this
       call will return an error.

VERSION

       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:

        #define LIBNBD_HAVE_NBD_GET_PROTOCOL 1

SEE ALSO

       nbd_create(3), nbd_get_block_size(3), nbd_get_handshake_flags(3),
       nbd_get_structured_replies_negotiated(3), nbd_get_tls_negotiated(3), libnbd(3).

AUTHORS

       Eric Blake

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2019-2021 Red Hat Inc.

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