nbd_connect_uri(3)

1nbd_connect_uri(3)                  LIBNBD                  nbd_connect_uri(3)
2
3
4

NAME

6       nbd_connect_uri - connect to NBD URI
7

SYNOPSIS

9        #include <libnbd.h>
10
11        int nbd_connect_uri (struct nbd_handle *h, const char *uri);
12

DESCRIPTION

14       Connect (synchronously) to an NBD server and export by specifying the
15       NBD URI.  This call parses the URI and may call nbd_set_export_name(3)
16       and nbd_set_tls(3) and other calls as needed, followed by
17       nbd_connect_tcp(3) or nbd_connect_unix(3).  This call returns when the
18       connection has been made.
19
20   Example URIs supported
21       "nbd://example.com"
22           Connect over TCP, unencrypted, to "example.com" port 10809.
23
24       "nbds://example.com"
25           Connect over TCP with TLS, to "example.com" port 10809.  If the
26           server does not support TLS then this will fail.
27
28       "nbd+unix:///foo?socket=/tmp/nbd.sock"
29           Connect over the Unix domain socket /tmp/nbd.sock to an NBD server
30           running locally.  The export name is set to "foo" (note without any
31           leading "/" character).
32
33       "nbd+vsock:///"
34           In this scenario libnbd is running in a virtual machine.  Connect
35           over "AF_VSOCK" to an NBD server running on the hypervisor.
36
37   Supported URI formats
38       The following schemes are supported in the current version of libnbd:
39
40       "nbd:"
41           Connect over TCP without using TLS.
42
43       "nbds:"
44           Connect over TCP.  TLS is required and the connection will fail if
45           the server does not support TLS.
46
47       "nbd+unix:"
48       "nbds+unix:"
49           Connect over a Unix domain socket, without or with TLS
50           respectively.  The "socket" parameter is required.
51
52       "nbd+vsock:"
53       "nbds+vsock:"
54           Connect over the "AF_VSOCK" transport, without or with TLS
55           respectively.
56
57       The authority part of the URI ("[username@][servername][:port]") is
58       parsed depending on the transport.  For TCP it specifies the server to
59       connect to and optional port number.  For "+unix" it should not be
60       present.  For "+vsock" the server name is the numeric CID (eg. 2 to
61       connect to the host), and the optional port number may be present.  If
62       the "username" is present it is used for TLS authentication.
63
64       For all transports, an export name may be present, parsed in accordance
65       with the NBD URI specification.
66
67       Finally the query part of the URI can contain:
68
69       socket=SOCKET
70           Specifies the Unix domain socket to connect on.  Must be present
71           for the "+unix" transport and must not be present for the other
72           transports.
73
74       tls-psk-file=PSKFILE
75           Set the PSK file.  See nbd_set_tls_psk_file(3).  Note this is not
76           allowed by default - see next section.
77
78   Disable URI features
79       For security reasons you might want to disable certain URI features.
80       Pre-filtering URIs is error-prone and should not be attempted.  Instead
81       use the libnbd APIs below to control what can appear in URIs.  Note you
82       must call these functions on the same handle before calling
83       "nbd_connect_uri" or nbd_aio_connect_uri(3).
84
85       TCP, Unix domain socket or "AF_VSOCK" transports
86           Default: all allowed
87
88           To select which transports are allowed call
89           nbd_set_uri_allow_transports(3).
90
91       TLS Default: both non-TLS and TLS connections allowed
92
93           To force TLS off or on in URIs call nbd_set_uri_allow_tls(3).
94
95       Connect to Unix domain socket in the local filesystem
96           Default: allowed
97
98           To prevent this you must disable the "+unix" transport using
99           nbd_set_uri_allow_transports(3).
100
101       Read from local files
102           Default: denied
103
104           To allow URIs to contain references to local files (eg. for
105           parameters like "tls-psk-file") call
106           nbd_set_uri_allow_local_file(3).
107
108   Optional features
109       This call will fail if libnbd was not compiled with libxml2; you can
110       test whether this is the case with nbd_supports_uri(3).
111
112       Support for URIs that require TLS will fail if libnbd was not compiled
113       with gnutls; you can test whether this is the case with
114       nbd_supports_tls(3).
115

RETURN VALUE

117       If the call is successful the function returns 0.
118

ERRORS

120       On error "-1" is returned.
121
122       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
123       of the error.
124

HANDLE STATE

126       The handle must be newly created, otherwise this call will return an
127       error.
128

VERSION

130       This function first appeared in libnbd 1.0.
131
132       If you need to test if this function is available at compile time check
133       if the following macro is defined:
134
135        #define LIBNBD_HAVE_NBD_CONNECT_URI 1
136

AUTHORS

142       Eric Blake
143
144       Richard W.M. Jones
145

COPYRIGHT

147       Copyright (C) 2019 Red Hat Inc.
148

LICENSE

150       This library is free software; you can redistribute it and/or modify it
151       under the terms of the GNU Lesser General Public License as published
152       by the Free Software Foundation; either version 2 of the License, or
153       (at your option) any later version.
154
155       This library is distributed in the hope that it will be useful, but
156       WITHOUT ANY WARRANTY; without even the implied warranty of
157       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
158       Lesser General Public License for more details.
159
160       You should have received a copy of the GNU Lesser General Public
161       License along with this library; if not, write to the Free Software
162       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
163       02110-1301 USA
164
165
166
167libnbd-1.2.1                      2019-11-14                nbd_connect_uri(3)