xref: /openbmc/qemu/include/block/nbd.h (revision 4c7c0d24)
1 /*
2  *  Copyright Red Hat
3  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
4  *
5  *  Network Block Device
6  *
7  *  This program is free software; you can redistribute it and/or modify
8  *  it under the terms of the GNU General Public License as published by
9  *  the Free Software Foundation; under version 2 of the License.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 #ifndef NBD_H
21 #define NBD_H
22 
23 #include "block/export.h"
24 #include "io/channel-socket.h"
25 #include "crypto/tlscreds.h"
26 #include "qapi/error.h"
27 #include "qemu/bswap.h"
28 
29 typedef struct NBDExport NBDExport;
30 typedef struct NBDClient NBDClient;
31 typedef struct NBDClientConnection NBDClientConnection;
32 typedef struct NBDMetaContexts NBDMetaContexts;
33 
34 extern const BlockExportDriver blk_exp_nbd;
35 
36 /*
37  * NBD_DEFAULT_HANDSHAKE_MAX_SECS: Number of seconds in which client must
38  * succeed at NBD_OPT_GO before being forcefully dropped as too slow.
39  */
40 #define NBD_DEFAULT_HANDSHAKE_MAX_SECS 10
41 
42 /*
43  * NBD_DEFAULT_MAX_CONNECTIONS: Number of client sockets to allow at
44  * once; must be large enough to allow a MULTI_CONN-aware client like
45  * nbdcopy to create its typical number of 8-16 sockets.
46  */
47 #define NBD_DEFAULT_MAX_CONNECTIONS 100
48 
49 /* Handshake phase structs - this struct is passed on the wire */
50 
51 typedef struct NBDOption {
52     uint64_t magic; /* NBD_OPTS_MAGIC */
53     uint32_t option; /* NBD_OPT_* */
54     uint32_t length;
55 } QEMU_PACKED NBDOption;
56 
57 typedef struct NBDOptionReply {
58     uint64_t magic; /* NBD_REP_MAGIC */
59     uint32_t option; /* NBD_OPT_* */
60     uint32_t type; /* NBD_REP_* */
61     uint32_t length;
62 } QEMU_PACKED NBDOptionReply;
63 
64 typedef struct NBDOptionReplyMetaContext {
65     NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
66     uint32_t context_id;
67     /* metadata context name follows */
68 } QEMU_PACKED NBDOptionReplyMetaContext;
69 
70 /* Track results of negotiation */
71 typedef enum NBDMode {
72     /* Keep this list in a continuum of increasing features. */
73     NBD_MODE_OLDSTYLE,     /* server lacks newstyle negotiation */
74     NBD_MODE_EXPORT_NAME,  /* newstyle but only OPT_EXPORT_NAME safe */
75     NBD_MODE_SIMPLE,       /* newstyle but only simple replies */
76     NBD_MODE_STRUCTURED,   /* newstyle, structured replies enabled */
77     NBD_MODE_EXTENDED,     /* newstyle, extended headers enabled */
78 } NBDMode;
79 
80 /* Transmission phase structs */
81 
82 /*
83  * Note: NBDRequest is _NOT_ the same as the network representation of an NBD
84  * request!
85  */
86 typedef struct NBDRequest {
87     uint64_t cookie;
88     uint64_t from;  /* Offset touched by the command */
89     uint64_t len;   /* Effect length; 32 bit limit without extended headers */
90     uint16_t flags; /* NBD_CMD_FLAG_* */
91     uint16_t type;  /* NBD_CMD_* */
92     NBDMode mode;   /* Determines which network representation to use */
93     NBDMetaContexts *contexts; /* Used by NBD_CMD_BLOCK_STATUS */
94 } NBDRequest;
95 
96 typedef struct NBDSimpleReply {
97     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
98     uint32_t error;
99     uint64_t cookie;
100 } QEMU_PACKED NBDSimpleReply;
101 
102 /* Header of all structured replies */
103 typedef struct NBDStructuredReplyChunk {
104     uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
105     uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
106     uint16_t type;   /* NBD_REPLY_TYPE_* */
107     uint64_t cookie; /* request handle */
108     uint32_t length; /* length of payload */
109 } QEMU_PACKED NBDStructuredReplyChunk;
110 
111 typedef struct NBDExtendedReplyChunk {
112     uint32_t magic;  /* NBD_EXTENDED_REPLY_MAGIC */
113     uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
114     uint16_t type;   /* NBD_REPLY_TYPE_* */
115     uint64_t cookie; /* request handle */
116     uint64_t offset; /* request offset */
117     uint64_t length; /* length of payload */
118 } QEMU_PACKED NBDExtendedReplyChunk;
119 
120 typedef union NBDReply {
121     NBDSimpleReply simple;
122     NBDStructuredReplyChunk structured;
123     NBDExtendedReplyChunk extended;
124     struct {
125         /*
126          * @magic and @cookie fields have the same offset and size in all
127          * forms of replies, so let them be accessible without ".simple.",
128          * ".structured.", or ".extended." specifications.
129          */
130         uint32_t magic;
131         uint32_t _skip;
132         uint64_t cookie;
133     };
134 } NBDReply;
135 QEMU_BUILD_BUG_ON(offsetof(NBDReply, simple.cookie) !=
136                   offsetof(NBDReply, cookie));
137 QEMU_BUILD_BUG_ON(offsetof(NBDReply, structured.cookie) !=
138                   offsetof(NBDReply, cookie));
139 QEMU_BUILD_BUG_ON(offsetof(NBDReply, extended.cookie) !=
140                   offsetof(NBDReply, cookie));
141 
142 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
143 typedef struct NBDStructuredReadData {
144     /* header's .length >= 9 */
145     uint64_t offset;
146     /* At least one byte of data payload follows, calculated from h.length */
147 } QEMU_PACKED NBDStructuredReadData;
148 
149 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
150 typedef struct NBDStructuredReadHole {
151     /* header's length == 12 */
152     uint64_t offset;
153     uint32_t length;
154 } QEMU_PACKED NBDStructuredReadHole;
155 
156 /* Header of all NBD_REPLY_TYPE_ERROR* errors */
157 typedef struct NBDStructuredError {
158     /* header's length >= 6 */
159     uint32_t error;
160     uint16_t message_length;
161 } QEMU_PACKED NBDStructuredError;
162 
163 /* Header of NBD_REPLY_TYPE_BLOCK_STATUS */
164 typedef struct NBDStructuredMeta {
165     /* header's length >= 12 (at least one extent) */
166     uint32_t context_id;
167     /* NBDExtent32 extents[] follows, array length implied by header */
168 } QEMU_PACKED NBDStructuredMeta;
169 
170 /* Extent array element for NBD_REPLY_TYPE_BLOCK_STATUS */
171 typedef struct NBDExtent32 {
172     uint32_t length;
173     uint32_t flags; /* NBD_STATE_* */
174 } QEMU_PACKED NBDExtent32;
175 
176 /* Header of NBD_REPLY_TYPE_BLOCK_STATUS_EXT */
177 typedef struct NBDExtendedMeta {
178     /* header's length >= 24 (at least one extent) */
179     uint32_t context_id;
180     uint32_t count; /* header length must be count * 16 + 8 */
181     /* NBDExtent64 extents[count] follows */
182 } QEMU_PACKED NBDExtendedMeta;
183 
184 /* Extent array element for NBD_REPLY_TYPE_BLOCK_STATUS_EXT */
185 typedef struct NBDExtent64 {
186     uint64_t length;
187     uint64_t flags; /* NBD_STATE_* */
188 } QEMU_PACKED NBDExtent64;
189 
190 /* Client payload for limiting NBD_CMD_BLOCK_STATUS reply */
191 typedef struct NBDBlockStatusPayload {
192     uint64_t effect_length;
193     /* uint32_t ids[] follows, array length implied by header */
194 } QEMU_PACKED NBDBlockStatusPayload;
195 
196 /* Transmission (export) flags: sent from server to client during handshake,
197    but describe what will happen during transmission */
198 enum {
199     NBD_FLAG_HAS_FLAGS_BIT          =  0, /* Flags are there */
200     NBD_FLAG_READ_ONLY_BIT          =  1, /* Device is read-only */
201     NBD_FLAG_SEND_FLUSH_BIT         =  2, /* Send FLUSH */
202     NBD_FLAG_SEND_FUA_BIT           =  3, /* Send FUA (Force Unit Access) */
203     NBD_FLAG_ROTATIONAL_BIT         =  4, /* Use elevator algorithm -
204                                              rotational media */
205     NBD_FLAG_SEND_TRIM_BIT          =  5, /* Send TRIM (discard) */
206     NBD_FLAG_SEND_WRITE_ZEROES_BIT  =  6, /* Send WRITE_ZEROES */
207     NBD_FLAG_SEND_DF_BIT            =  7, /* Send DF (Do not Fragment) */
208     NBD_FLAG_CAN_MULTI_CONN_BIT     =  8, /* Multi-client cache consistent */
209     NBD_FLAG_SEND_RESIZE_BIT        =  9, /* Send resize */
210     NBD_FLAG_SEND_CACHE_BIT         = 10, /* Send CACHE (prefetch) */
211     NBD_FLAG_SEND_FAST_ZERO_BIT     = 11, /* FAST_ZERO flag for WRITE_ZEROES */
212     NBD_FLAG_BLOCK_STAT_PAYLOAD_BIT = 12, /* PAYLOAD flag for BLOCK_STATUS */
213 };
214 
215 #define NBD_FLAG_HAS_FLAGS          (1 << NBD_FLAG_HAS_FLAGS_BIT)
216 #define NBD_FLAG_READ_ONLY          (1 << NBD_FLAG_READ_ONLY_BIT)
217 #define NBD_FLAG_SEND_FLUSH         (1 << NBD_FLAG_SEND_FLUSH_BIT)
218 #define NBD_FLAG_SEND_FUA           (1 << NBD_FLAG_SEND_FUA_BIT)
219 #define NBD_FLAG_ROTATIONAL         (1 << NBD_FLAG_ROTATIONAL_BIT)
220 #define NBD_FLAG_SEND_TRIM          (1 << NBD_FLAG_SEND_TRIM_BIT)
221 #define NBD_FLAG_SEND_WRITE_ZEROES  (1 << NBD_FLAG_SEND_WRITE_ZEROES_BIT)
222 #define NBD_FLAG_SEND_DF            (1 << NBD_FLAG_SEND_DF_BIT)
223 #define NBD_FLAG_CAN_MULTI_CONN     (1 << NBD_FLAG_CAN_MULTI_CONN_BIT)
224 #define NBD_FLAG_SEND_RESIZE        (1 << NBD_FLAG_SEND_RESIZE_BIT)
225 #define NBD_FLAG_SEND_CACHE         (1 << NBD_FLAG_SEND_CACHE_BIT)
226 #define NBD_FLAG_SEND_FAST_ZERO     (1 << NBD_FLAG_SEND_FAST_ZERO_BIT)
227 #define NBD_FLAG_BLOCK_STAT_PAYLOAD (1 << NBD_FLAG_BLOCK_STAT_PAYLOAD_BIT)
228 
229 /* New-style handshake (global) flags, sent from server to client, and
230    control what will happen during handshake phase. */
231 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
232 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
233 
234 /* New-style client flags, sent from client to server to control what happens
235    during handshake phase. */
236 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
237 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
238 
239 /* Option requests. */
240 #define NBD_OPT_EXPORT_NAME       (1)
241 #define NBD_OPT_ABORT             (2)
242 #define NBD_OPT_LIST              (3)
243 /* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
244 #define NBD_OPT_STARTTLS          (5)
245 #define NBD_OPT_INFO              (6)
246 #define NBD_OPT_GO                (7)
247 #define NBD_OPT_STRUCTURED_REPLY  (8)
248 #define NBD_OPT_LIST_META_CONTEXT (9)
249 #define NBD_OPT_SET_META_CONTEXT  (10)
250 #define NBD_OPT_EXTENDED_HEADERS  (11)
251 
252 /* Option reply types. */
253 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
254 
255 #define NBD_REP_ACK             (1)    /* Data sending finished. */
256 #define NBD_REP_SERVER          (2)    /* Export description. */
257 #define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
258 #define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
259 
260 #define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
261 #define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
262 #define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
263 #define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
264 #define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
265 #define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
266 #define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
267 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
268 #define NBD_REP_ERR_TOO_BIG         NBD_REP_ERR(9)  /* Payload size overflow */
269 #define NBD_REP_ERR_EXT_HEADER_REQD NBD_REP_ERR(10) /* Need extended headers */
270 
271 /* Info types, used during NBD_REP_INFO */
272 #define NBD_INFO_EXPORT         0
273 #define NBD_INFO_NAME           1
274 #define NBD_INFO_DESCRIPTION    2
275 #define NBD_INFO_BLOCK_SIZE     3
276 
277 /* Request flags, sent from client to server during transmission phase */
278 #define NBD_CMD_FLAG_FUA         (1 << 0) /* 'force unit access' during write */
279 #define NBD_CMD_FLAG_NO_HOLE     (1 << 1) /* don't punch hole on zero run */
280 #define NBD_CMD_FLAG_DF          (1 << 2) /* don't fragment structured read */
281 #define NBD_CMD_FLAG_REQ_ONE     (1 << 3) \
282     /* only one extent in BLOCK_STATUS reply chunk */
283 #define NBD_CMD_FLAG_FAST_ZERO   (1 << 4) /* fail if WRITE_ZEROES is not fast */
284 #define NBD_CMD_FLAG_PAYLOAD_LEN (1 << 5) \
285     /* length describes payload, not effect; only with ext header */
286 
287 /* Supported request types */
288 enum {
289     NBD_CMD_READ = 0,
290     NBD_CMD_WRITE = 1,
291     NBD_CMD_DISC = 2,
292     NBD_CMD_FLUSH = 3,
293     NBD_CMD_TRIM = 4,
294     NBD_CMD_CACHE = 5,
295     NBD_CMD_WRITE_ZEROES = 6,
296     NBD_CMD_BLOCK_STATUS = 7,
297 };
298 
299 #define NBD_DEFAULT_PORT	10809
300 
301 /* Maximum size of a single READ/WRITE data buffer */
302 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
303 
304 /*
305  * Maximum size of a protocol string (export name, metadata context name,
306  * etc.).  Use malloc rather than stack allocation for storage of a
307  * string.
308  */
309 #define NBD_MAX_STRING_SIZE 4096
310 
311 /* Two types of request structures, a given client will only use 1 */
312 #define NBD_REQUEST_MAGIC           0x25609513
313 #define NBD_EXTENDED_REQUEST_MAGIC  0x21e41c71
314 
315 /*
316  * Three types of reply structures, but what a client expects depends
317  * on NBD_OPT_STRUCTURED_REPLY and NBD_OPT_EXTENDED_HEADERS.
318  */
319 #define NBD_SIMPLE_REPLY_MAGIC      0x67446698
320 #define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
321 #define NBD_EXTENDED_REPLY_MAGIC    0x6e8a278c
322 
323 /* Chunk reply flags (for structured and extended replies) */
324 #define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
325 
326 /* Chunk reply types */
327 #define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
328 
329 #define NBD_REPLY_TYPE_NONE              0
330 #define NBD_REPLY_TYPE_OFFSET_DATA       1
331 #define NBD_REPLY_TYPE_OFFSET_HOLE       2
332 #define NBD_REPLY_TYPE_BLOCK_STATUS      5
333 #define NBD_REPLY_TYPE_BLOCK_STATUS_EXT  6
334 #define NBD_REPLY_TYPE_ERROR             NBD_REPLY_ERR(1)
335 #define NBD_REPLY_TYPE_ERROR_OFFSET      NBD_REPLY_ERR(2)
336 
337 /* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */
338 #define NBD_STATE_HOLE (1 << 0)
339 #define NBD_STATE_ZERO (1 << 1)
340 
341 /* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
342 #define NBD_STATE_DIRTY (1 << 0)
343 
344 /* No flags needed for qemu:allocation-depth in NBD_REPLY_TYPE_BLOCK_STATUS */
345 
346 static inline bool nbd_reply_type_is_error(int type)
347 {
348     return type & (1 << 15);
349 }
350 
351 /* NBD errors are based on errno numbers, so there is a 1:1 mapping,
352  * but only a limited set of errno values is specified in the protocol.
353  * Everything else is squashed to EINVAL.
354  */
355 #define NBD_SUCCESS    0
356 #define NBD_EPERM      1
357 #define NBD_EIO        5
358 #define NBD_ENOMEM     12
359 #define NBD_EINVAL     22
360 #define NBD_ENOSPC     28
361 #define NBD_EOVERFLOW  75
362 #define NBD_ENOTSUP    95
363 #define NBD_ESHUTDOWN  108
364 
365 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
366 typedef struct NBDExportInfo {
367     /* Set by client before nbd_receive_negotiate() */
368     bool request_sizes;
369     char *x_dirty_bitmap;
370 
371     /* Set by client before nbd_receive_negotiate(), or by server results
372      * during nbd_receive_export_list() */
373     char *name; /* must be non-NULL */
374 
375     /* In-out fields, set by client before nbd_receive_negotiate() and
376      * updated by server results during nbd_receive_negotiate() */
377     NBDMode mode; /* input maximum mode tolerated; output actual mode chosen */
378     bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
379 
380     /* Set by server results during nbd_receive_negotiate() and
381      * nbd_receive_export_list() */
382     uint64_t size;
383     uint16_t flags;
384     uint32_t min_block;
385     uint32_t opt_block;
386     uint32_t max_block;
387 
388     uint32_t context_id;
389 
390     /* Set by server results during nbd_receive_export_list() */
391     char *description;
392     int n_contexts;
393     char **contexts;
394 } NBDExportInfo;
395 
396 int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
397                           const char *hostname, QIOChannel **outioc,
398                           NBDExportInfo *info, Error **errp);
399 void nbd_free_export_list(NBDExportInfo *info, int count);
400 int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
401                             const char *hostname, NBDExportInfo **info,
402                             Error **errp);
403 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
404              Error **errp);
405 int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
406 int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc,
407                                    NBDReply *reply, NBDMode mode,
408                                    Error **errp);
409 int nbd_client(int fd);
410 int nbd_disconnect(int fd);
411 int nbd_errno_to_system_errno(int err);
412 
413 void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
414 
415 AioContext *nbd_export_aio_context(NBDExport *exp);
416 NBDExport *nbd_export_find(const char *name);
417 
418 void nbd_client_new(QIOChannelSocket *sioc,
419                     uint32_t handshake_max_secs,
420                     QCryptoTLSCreds *tlscreds,
421                     const char *tlsauthz,
422                     void (*close_fn)(NBDClient *, bool),
423                     void *owner);
424 void *nbd_client_owner(NBDClient *client);
425 void nbd_client_get(NBDClient *client);
426 void nbd_client_put(NBDClient *client);
427 
428 void nbd_server_is_qemu_nbd(int max_connections);
429 bool nbd_server_is_running(void);
430 int nbd_server_max_connections(void);
431 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
432                       const char *tls_authz, uint32_t max_connections,
433                       Error **errp);
434 void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
435 
436 /* nbd_read
437  * Reads @size bytes from @ioc. Returns 0 on success.
438  */
439 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
440                            const char *desc, Error **errp)
441 {
442     ERRP_GUARD();
443     int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
444 
445     if (ret < 0) {
446         if (desc) {
447             error_prepend(errp, "Failed to read %s: ", desc);
448         }
449         return ret;
450     }
451 
452     return 0;
453 }
454 
455 #define DEF_NBD_READ_N(bits)                                            \
456 static inline int nbd_read##bits(QIOChannel *ioc,                       \
457                                  uint##bits##_t *val,                   \
458                                  const char *desc, Error **errp)        \
459 {                                                                       \
460     int ret = nbd_read(ioc, val, sizeof(*val), desc, errp);             \
461     if (ret < 0) {                                                      \
462         return ret;                                                     \
463     }                                                                   \
464     *val = be##bits##_to_cpu(*val);                                     \
465     return 0;                                                           \
466 }
467 
468 DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
469 DEF_NBD_READ_N(32) /* Defines nbd_read32(). */
470 DEF_NBD_READ_N(64) /* Defines nbd_read64(). */
471 
472 #undef DEF_NBD_READ_N
473 
474 static inline bool nbd_reply_is_simple(NBDReply *reply)
475 {
476     return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
477 }
478 
479 static inline bool nbd_reply_is_structured(NBDReply *reply)
480 {
481     return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
482 }
483 
484 const char *nbd_reply_type_lookup(uint16_t type);
485 const char *nbd_opt_lookup(uint32_t opt);
486 const char *nbd_rep_lookup(uint32_t rep);
487 const char *nbd_info_lookup(uint16_t info);
488 const char *nbd_cmd_lookup(uint16_t info);
489 const char *nbd_err_lookup(int err);
490 const char *nbd_mode_lookup(NBDMode mode);
491 
492 /* nbd/client-connection.c */
493 void nbd_client_connection_enable_retry(NBDClientConnection *conn);
494 
495 NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
496                                                bool do_negotiation,
497                                                const char *export_name,
498                                                const char *x_dirty_bitmap,
499                                                QCryptoTLSCreds *tlscreds,
500                                                const char *tlshostname);
501 void nbd_client_connection_release(NBDClientConnection *conn);
502 
503 QIOChannel *coroutine_fn
504 nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
505                             bool blocking, Error **errp);
506 
507 void nbd_co_establish_connection_cancel(NBDClientConnection *conn);
508 
509 #endif
510