1nbd_get_tls_negotiated(3)           LIBNBD           nbd_get_tls_negotiated(3)
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NAME

6       nbd_get_tls_negotiated - find out if TLS was negotiated on a connection
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SYNOPSIS

9        #include <libnbd.h>
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11        int nbd_get_tls_negotiated (
12              struct nbd_handle *h
13            );
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DESCRIPTION

16       After connecting you may call this to find out if the connection is
17       using TLS.
18
19       This is normally useful only if you set the TLS request mode to
20       "LIBNBD_TLS_ALLOW" (see nbd_set_tls(3)), because in this mode we try to
21       use TLS but fall back to unencrypted if it was not available.  This
22       function will tell you if TLS was negotiated or not.
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24       In "LIBNBD_TLS_REQUIRE" mode (the most secure) the connection would
25       have failed if TLS could not be negotiated.  With "LIBNBD_TLS_DISABLE"
26       mode, TLS is not tried automatically; but if the NBD server uses the
27       less-common "SELECTIVETLS" mode, this function reports whether a manual
28       nbd_opt_starttls(3) enabled TLS or if the connection is still
29       plaintext.
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RETURN VALUE

32       This call returns a boolean value.
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ERRORS

35       On error -1 is returned.
36
37       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
38       of the error.
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40       The following parameters must not be NULL: "h".  For more information
41       see "Non-NULL parameters" in libnbd(3).
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HANDLE STATE

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

48       This function first appeared in libnbd 1.2.
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50       If you need to test if this function is available at compile time check
51       if the following macro is defined:
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53        #define LIBNBD_HAVE_NBD_GET_TLS_NEGOTIATED 1
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SEE ALSO

56       nbd_create(3), nbd_get_tls(3), nbd_opt_starttls(3), nbd_set_tls(3),
57       libnbd(3).
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AUTHORS

60       Eric Blake
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62       Richard W.M. Jones
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65       Copyright Red Hat
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LICENSE

68       This library is free software; you can redistribute it and/or modify it
69       under the terms of the GNU Lesser General Public License as published
70       by the Free Software Foundation; either version 2 of the License, or
71       (at your option) any later version.
72
73       This library is distributed in the hope that it will be useful, but
74       WITHOUT ANY WARRANTY; without even the implied warranty of
75       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
76       Lesser General Public License for more details.
77
78       You should have received a copy of the GNU Lesser General Public
79       License along with this library; if not, write to the Free Software
80       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
81       02110-1301 USA
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85libnbd-1.16.5                     2023-09-26         nbd_get_tls_negotiated(3)
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