s390x: refactor error handling for CSCH handler
[qemu/kevin.git] / nbd / client.c
blobcd5a2c80ac577fb2b1c00f306cb0fb45b8d36c59
1 /*
2 * Copyright (C) 2016-2017 Red Hat, Inc.
3 * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
5 * Network Block Device Client Side
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.
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.
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/>.
20 #include "qemu/osdep.h"
21 #include "qapi/error.h"
22 #include "trace.h"
23 #include "nbd-internal.h"
25 static int nbd_errno_to_system_errno(int err)
27 int ret;
28 switch (err) {
29 case NBD_SUCCESS:
30 ret = 0;
31 break;
32 case NBD_EPERM:
33 ret = EPERM;
34 break;
35 case NBD_EIO:
36 ret = EIO;
37 break;
38 case NBD_ENOMEM:
39 ret = ENOMEM;
40 break;
41 case NBD_ENOSPC:
42 ret = ENOSPC;
43 break;
44 case NBD_ESHUTDOWN:
45 ret = ESHUTDOWN;
46 break;
47 default:
48 trace_nbd_unknown_error(err);
49 /* fallthrough */
50 case NBD_EINVAL:
51 ret = EINVAL;
52 break;
54 return ret;
57 /* Definitions for opaque data types */
59 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
61 /* That's all folks */
63 /* Basic flow for negotiation
65 Server Client
66 Negotiate
70 Server Client
71 Negotiate #1
72 Option
73 Negotiate #2
75 ----
77 followed by
79 Server Client
80 Request
81 Response
82 Request
83 Response
84 ...
85 ...
86 Request (type == 2)
90 /* Send an option request.
92 * The request is for option @opt, with @data containing @len bytes of
93 * additional payload for the request (@len may be -1 to treat @data as
94 * a C string; and @data may be NULL if @len is 0).
95 * Return 0 if successful, -1 with errp set if it is impossible to
96 * continue. */
97 static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
98 uint32_t len, const char *data,
99 Error **errp)
101 nbd_option req;
102 QEMU_BUILD_BUG_ON(sizeof(req) != 16);
104 if (len == -1) {
105 req.length = len = strlen(data);
107 trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
109 stq_be_p(&req.magic, NBD_OPTS_MAGIC);
110 stl_be_p(&req.option, opt);
111 stl_be_p(&req.length, len);
113 if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
114 error_prepend(errp, "Failed to send option request header");
115 return -1;
118 if (len && nbd_write(ioc, (char *) data, len, errp) < 0) {
119 error_prepend(errp, "Failed to send option request data");
120 return -1;
123 return 0;
126 /* Send NBD_OPT_ABORT as a courtesy to let the server know that we are
127 * not going to attempt further negotiation. */
128 static void nbd_send_opt_abort(QIOChannel *ioc)
130 /* Technically, a compliant server is supposed to reply to us; but
131 * older servers disconnected instead. At any rate, we're allowed
132 * to disconnect without waiting for the server reply, so we don't
133 * even care if the request makes it to the server, let alone
134 * waiting around for whether the server replies. */
135 nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL);
139 /* Receive the header of an option reply, which should match the given
140 * opt. Read through the length field, but NOT the length bytes of
141 * payload. Return 0 if successful, -1 with errp set if it is
142 * impossible to continue. */
143 static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
144 nbd_opt_reply *reply, Error **errp)
146 QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
147 if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) {
148 error_prepend(errp, "failed to read option reply");
149 nbd_send_opt_abort(ioc);
150 return -1;
152 be64_to_cpus(&reply->magic);
153 be32_to_cpus(&reply->option);
154 be32_to_cpus(&reply->type);
155 be32_to_cpus(&reply->length);
157 trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
158 reply->type, nbd_rep_lookup(reply->type),
159 reply->length);
161 if (reply->magic != NBD_REP_MAGIC) {
162 error_setg(errp, "Unexpected option reply magic");
163 nbd_send_opt_abort(ioc);
164 return -1;
166 if (reply->option != opt) {
167 error_setg(errp, "Unexpected option type %x expected %x",
168 reply->option, opt);
169 nbd_send_opt_abort(ioc);
170 return -1;
172 return 0;
175 /* If reply represents success, return 1 without further action.
176 * If reply represents an error, consume the optional payload of
177 * the packet on ioc. Then return 0 for unsupported (so the client
178 * can fall back to other approaches), or -1 with errp set for other
179 * errors.
181 static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
182 Error **errp)
184 char *msg = NULL;
185 int result = -1;
187 if (!(reply->type & (1 << 31))) {
188 return 1;
191 if (reply->length) {
192 if (reply->length > NBD_MAX_BUFFER_SIZE) {
193 error_setg(errp, "server error 0x%" PRIx32
194 " (%s) message is too long",
195 reply->type, nbd_rep_lookup(reply->type));
196 goto cleanup;
198 msg = g_malloc(reply->length + 1);
199 if (nbd_read(ioc, msg, reply->length, errp) < 0) {
200 error_prepend(errp, "failed to read option error 0x%" PRIx32
201 " (%s) message",
202 reply->type, nbd_rep_lookup(reply->type));
203 goto cleanup;
205 msg[reply->length] = '\0';
208 switch (reply->type) {
209 case NBD_REP_ERR_UNSUP:
210 trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
211 result = 0;
212 goto cleanup;
214 case NBD_REP_ERR_POLICY:
215 error_setg(errp, "Denied by server for option %" PRIx32 " (%s)",
216 reply->option, nbd_opt_lookup(reply->option));
217 break;
219 case NBD_REP_ERR_INVALID:
220 error_setg(errp, "Invalid data length for option %" PRIx32 " (%s)",
221 reply->option, nbd_opt_lookup(reply->option));
222 break;
224 case NBD_REP_ERR_PLATFORM:
225 error_setg(errp, "Server lacks support for option %" PRIx32 " (%s)",
226 reply->option, nbd_opt_lookup(reply->option));
227 break;
229 case NBD_REP_ERR_TLS_REQD:
230 error_setg(errp, "TLS negotiation required before option %" PRIx32
231 " (%s)", reply->option, nbd_opt_lookup(reply->option));
232 break;
234 case NBD_REP_ERR_UNKNOWN:
235 error_setg(errp, "Requested export not available");
236 break;
238 case NBD_REP_ERR_SHUTDOWN:
239 error_setg(errp, "Server shutting down before option %" PRIx32 " (%s)",
240 reply->option, nbd_opt_lookup(reply->option));
241 break;
243 case NBD_REP_ERR_BLOCK_SIZE_REQD:
244 error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIx32
245 " (%s)", reply->option, nbd_opt_lookup(reply->option));
246 break;
248 default:
249 error_setg(errp, "Unknown error code when asking for option %" PRIx32
250 " (%s)", reply->option, nbd_opt_lookup(reply->option));
251 break;
254 if (msg) {
255 error_append_hint(errp, "server reported: %s\n", msg);
258 cleanup:
259 g_free(msg);
260 if (result < 0) {
261 nbd_send_opt_abort(ioc);
263 return result;
266 /* Process another portion of the NBD_OPT_LIST reply. Set *@match if
267 * the current reply matches @want or if the server does not support
268 * NBD_OPT_LIST, otherwise leave @match alone. Return 0 if iteration
269 * is complete, positive if more replies are expected, or negative
270 * with @errp set if an unrecoverable error occurred. */
271 static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
272 Error **errp)
274 nbd_opt_reply reply;
275 uint32_t len;
276 uint32_t namelen;
277 char name[NBD_MAX_NAME_SIZE + 1];
278 int error;
280 if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
281 return -1;
283 error = nbd_handle_reply_err(ioc, &reply, errp);
284 if (error <= 0) {
285 /* The server did not support NBD_OPT_LIST, so set *match on
286 * the assumption that any name will be accepted. */
287 *match = true;
288 return error;
290 len = reply.length;
292 if (reply.type == NBD_REP_ACK) {
293 if (len != 0) {
294 error_setg(errp, "length too long for option end");
295 nbd_send_opt_abort(ioc);
296 return -1;
298 return 0;
299 } else if (reply.type != NBD_REP_SERVER) {
300 error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
301 reply.type, NBD_REP_SERVER);
302 nbd_send_opt_abort(ioc);
303 return -1;
306 if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
307 error_setg(errp, "incorrect option length %" PRIu32, len);
308 nbd_send_opt_abort(ioc);
309 return -1;
311 if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) {
312 error_prepend(errp, "failed to read option name length");
313 nbd_send_opt_abort(ioc);
314 return -1;
316 namelen = be32_to_cpu(namelen);
317 len -= sizeof(namelen);
318 if (len < namelen) {
319 error_setg(errp, "incorrect option name length");
320 nbd_send_opt_abort(ioc);
321 return -1;
323 if (namelen != strlen(want)) {
324 if (nbd_drop(ioc, len, errp) < 0) {
325 error_prepend(errp, "failed to skip export name with wrong length");
326 nbd_send_opt_abort(ioc);
327 return -1;
329 return 1;
332 assert(namelen < sizeof(name));
333 if (nbd_read(ioc, name, namelen, errp) < 0) {
334 error_prepend(errp, "failed to read export name");
335 nbd_send_opt_abort(ioc);
336 return -1;
338 name[namelen] = '\0';
339 len -= namelen;
340 if (nbd_drop(ioc, len, errp) < 0) {
341 error_prepend(errp, "failed to read export description");
342 nbd_send_opt_abort(ioc);
343 return -1;
345 if (!strcmp(name, want)) {
346 *match = true;
348 return 1;
352 /* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be
353 * used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and
354 * NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to
355 * go (with @info populated). */
356 static int nbd_opt_go(QIOChannel *ioc, const char *wantname,
357 NBDExportInfo *info, Error **errp)
359 nbd_opt_reply reply;
360 uint32_t len = strlen(wantname);
361 uint16_t type;
362 int error;
363 char *buf;
365 /* The protocol requires that the server send NBD_INFO_EXPORT with
366 * a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so
367 * flags still 0 is a witness of a broken server. */
368 info->flags = 0;
370 trace_nbd_opt_go_start(wantname);
371 buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
372 stl_be_p(buf, len);
373 memcpy(buf + 4, wantname, len);
374 /* At most one request, everything else up to server */
375 stw_be_p(buf + 4 + len, info->request_sizes);
376 if (info->request_sizes) {
377 stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE);
379 error = nbd_send_option_request(ioc, NBD_OPT_GO,
380 4 + len + 2 + 2 * info->request_sizes,
381 buf, errp);
382 g_free(buf);
383 if (error < 0) {
384 return -1;
387 while (1) {
388 if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) {
389 return -1;
391 error = nbd_handle_reply_err(ioc, &reply, errp);
392 if (error <= 0) {
393 return error;
395 len = reply.length;
397 if (reply.type == NBD_REP_ACK) {
398 /* Server is done sending info and moved into transmission
399 phase, but make sure it sent flags */
400 if (len) {
401 error_setg(errp, "server sent invalid NBD_REP_ACK");
402 return -1;
404 if (!info->flags) {
405 error_setg(errp, "broken server omitted NBD_INFO_EXPORT");
406 return -1;
408 trace_nbd_opt_go_success();
409 return 1;
411 if (reply.type != NBD_REP_INFO) {
412 error_setg(errp, "unexpected reply type %" PRIx32
413 " (%s), expected %x",
414 reply.type, nbd_rep_lookup(reply.type), NBD_REP_INFO);
415 nbd_send_opt_abort(ioc);
416 return -1;
418 if (len < sizeof(type)) {
419 error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short",
420 len);
421 nbd_send_opt_abort(ioc);
422 return -1;
424 if (nbd_read(ioc, &type, sizeof(type), errp) < 0) {
425 error_prepend(errp, "failed to read info type");
426 nbd_send_opt_abort(ioc);
427 return -1;
429 len -= sizeof(type);
430 be16_to_cpus(&type);
431 switch (type) {
432 case NBD_INFO_EXPORT:
433 if (len != sizeof(info->size) + sizeof(info->flags)) {
434 error_setg(errp, "remaining export info len %" PRIu32
435 " is unexpected size", len);
436 nbd_send_opt_abort(ioc);
437 return -1;
439 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
440 error_prepend(errp, "failed to read info size");
441 nbd_send_opt_abort(ioc);
442 return -1;
444 be64_to_cpus(&info->size);
445 if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
446 error_prepend(errp, "failed to read info flags");
447 nbd_send_opt_abort(ioc);
448 return -1;
450 be16_to_cpus(&info->flags);
451 trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
452 break;
454 case NBD_INFO_BLOCK_SIZE:
455 if (len != sizeof(info->min_block) * 3) {
456 error_setg(errp, "remaining export info len %" PRIu32
457 " is unexpected size", len);
458 nbd_send_opt_abort(ioc);
459 return -1;
461 if (nbd_read(ioc, &info->min_block, sizeof(info->min_block),
462 errp) < 0) {
463 error_prepend(errp, "failed to read info minimum block size");
464 nbd_send_opt_abort(ioc);
465 return -1;
467 be32_to_cpus(&info->min_block);
468 if (!is_power_of_2(info->min_block)) {
469 error_setg(errp, "server minimum block size %" PRId32
470 "is not a power of two", info->min_block);
471 nbd_send_opt_abort(ioc);
472 return -1;
474 if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block),
475 errp) < 0) {
476 error_prepend(errp, "failed to read info preferred block size");
477 nbd_send_opt_abort(ioc);
478 return -1;
480 be32_to_cpus(&info->opt_block);
481 if (!is_power_of_2(info->opt_block) ||
482 info->opt_block < info->min_block) {
483 error_setg(errp, "server preferred block size %" PRId32
484 "is not valid", info->opt_block);
485 nbd_send_opt_abort(ioc);
486 return -1;
488 if (nbd_read(ioc, &info->max_block, sizeof(info->max_block),
489 errp) < 0) {
490 error_prepend(errp, "failed to read info maximum block size");
491 nbd_send_opt_abort(ioc);
492 return -1;
494 be32_to_cpus(&info->max_block);
495 trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block,
496 info->max_block);
497 break;
499 default:
500 trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type));
501 if (nbd_drop(ioc, len, errp) < 0) {
502 error_prepend(errp, "Failed to read info payload");
503 nbd_send_opt_abort(ioc);
504 return -1;
506 break;
511 /* Return -1 on failure, 0 if wantname is an available export. */
512 static int nbd_receive_query_exports(QIOChannel *ioc,
513 const char *wantname,
514 Error **errp)
516 bool foundExport = false;
518 trace_nbd_receive_query_exports_start(wantname);
519 if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
520 return -1;
523 while (1) {
524 int ret = nbd_receive_list(ioc, wantname, &foundExport, errp);
526 if (ret < 0) {
527 /* Server gave unexpected reply */
528 return -1;
529 } else if (ret == 0) {
530 /* Done iterating. */
531 if (!foundExport) {
532 error_setg(errp, "No export with name '%s' available",
533 wantname);
534 nbd_send_opt_abort(ioc);
535 return -1;
537 trace_nbd_receive_query_exports_success(wantname);
538 return 0;
543 static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
544 QCryptoTLSCreds *tlscreds,
545 const char *hostname, Error **errp)
547 nbd_opt_reply reply;
548 QIOChannelTLS *tioc;
549 struct NBDTLSHandshakeData data = { 0 };
551 trace_nbd_receive_starttls_request();
552 if (nbd_send_option_request(ioc, NBD_OPT_STARTTLS, 0, NULL, errp) < 0) {
553 return NULL;
556 trace_nbd_receive_starttls_reply();
557 if (nbd_receive_option_reply(ioc, NBD_OPT_STARTTLS, &reply, errp) < 0) {
558 return NULL;
561 if (reply.type != NBD_REP_ACK) {
562 error_setg(errp, "Server rejected request to start TLS %" PRIx32,
563 reply.type);
564 nbd_send_opt_abort(ioc);
565 return NULL;
568 if (reply.length != 0) {
569 error_setg(errp, "Start TLS response was not zero %" PRIu32,
570 reply.length);
571 nbd_send_opt_abort(ioc);
572 return NULL;
575 trace_nbd_receive_starttls_new_client();
576 tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
577 if (!tioc) {
578 return NULL;
580 qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
581 data.loop = g_main_loop_new(g_main_context_default(), FALSE);
582 trace_nbd_receive_starttls_tls_handshake();
583 qio_channel_tls_handshake(tioc,
584 nbd_tls_handshake,
585 &data,
586 NULL);
588 if (!data.complete) {
589 g_main_loop_run(data.loop);
591 g_main_loop_unref(data.loop);
592 if (data.error) {
593 error_propagate(errp, data.error);
594 object_unref(OBJECT(tioc));
595 return NULL;
598 return QIO_CHANNEL(tioc);
602 int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
603 QCryptoTLSCreds *tlscreds, const char *hostname,
604 QIOChannel **outioc, NBDExportInfo *info,
605 Error **errp)
607 char buf[256];
608 uint64_t magic;
609 int rc;
610 bool zeroes = true;
612 trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
614 rc = -EINVAL;
616 if (outioc) {
617 *outioc = NULL;
619 if (tlscreds && !outioc) {
620 error_setg(errp, "Output I/O channel required for TLS");
621 goto fail;
624 if (nbd_read(ioc, buf, 8, errp) < 0) {
625 error_prepend(errp, "Failed to read data");
626 goto fail;
629 buf[8] = '\0';
630 if (strlen(buf) == 0) {
631 error_setg(errp, "Server connection closed unexpectedly");
632 goto fail;
635 magic = ldq_be_p(buf);
636 trace_nbd_receive_negotiate_magic(magic);
638 if (memcmp(buf, "NBDMAGIC", 8) != 0) {
639 error_setg(errp, "Invalid magic received");
640 goto fail;
643 if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
644 error_prepend(errp, "Failed to read magic");
645 goto fail;
647 magic = be64_to_cpu(magic);
648 trace_nbd_receive_negotiate_magic(magic);
650 if (magic == NBD_OPTS_MAGIC) {
651 uint32_t clientflags = 0;
652 uint16_t globalflags;
653 bool fixedNewStyle = false;
655 if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) {
656 error_prepend(errp, "Failed to read server flags");
657 goto fail;
659 globalflags = be16_to_cpu(globalflags);
660 trace_nbd_receive_negotiate_server_flags(globalflags);
661 if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) {
662 fixedNewStyle = true;
663 clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
665 if (globalflags & NBD_FLAG_NO_ZEROES) {
666 zeroes = false;
667 clientflags |= NBD_FLAG_C_NO_ZEROES;
669 /* client requested flags */
670 clientflags = cpu_to_be32(clientflags);
671 if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) {
672 error_prepend(errp, "Failed to send clientflags field");
673 goto fail;
675 if (tlscreds) {
676 if (fixedNewStyle) {
677 *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
678 if (!*outioc) {
679 goto fail;
681 ioc = *outioc;
682 } else {
683 error_setg(errp, "Server does not support STARTTLS");
684 goto fail;
687 if (!name) {
688 trace_nbd_receive_negotiate_default_name();
689 name = "";
691 if (fixedNewStyle) {
692 int result;
694 /* Try NBD_OPT_GO first - if it works, we are done (it
695 * also gives us a good message if the server requires
696 * TLS). If it is not available, fall back to
697 * NBD_OPT_LIST for nicer error messages about a missing
698 * export, then use NBD_OPT_EXPORT_NAME. */
699 result = nbd_opt_go(ioc, name, info, errp);
700 if (result < 0) {
701 goto fail;
703 if (result > 0) {
704 return 0;
706 /* Check our desired export is present in the
707 * server export list. Since NBD_OPT_EXPORT_NAME
708 * cannot return an error message, running this
709 * query gives us better error reporting if the
710 * export name is not available.
712 if (nbd_receive_query_exports(ioc, name, errp) < 0) {
713 goto fail;
716 /* write the export name request */
717 if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
718 errp) < 0) {
719 goto fail;
722 /* Read the response */
723 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
724 error_prepend(errp, "Failed to read export length");
725 goto fail;
727 be64_to_cpus(&info->size);
729 if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
730 error_prepend(errp, "Failed to read export flags");
731 goto fail;
733 be16_to_cpus(&info->flags);
734 } else if (magic == NBD_CLIENT_MAGIC) {
735 uint32_t oldflags;
737 if (name) {
738 error_setg(errp, "Server does not support export names");
739 goto fail;
741 if (tlscreds) {
742 error_setg(errp, "Server does not support STARTTLS");
743 goto fail;
746 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
747 error_prepend(errp, "Failed to read export length");
748 goto fail;
750 be64_to_cpus(&info->size);
752 if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
753 error_prepend(errp, "Failed to read export flags");
754 goto fail;
756 be32_to_cpus(&oldflags);
757 if (oldflags & ~0xffff) {
758 error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
759 goto fail;
761 info->flags = oldflags;
762 } else {
763 error_setg(errp, "Bad magic received");
764 goto fail;
767 trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
768 if (zeroes && nbd_drop(ioc, 124, errp) < 0) {
769 error_prepend(errp, "Failed to read reserved block");
770 goto fail;
772 rc = 0;
774 fail:
775 return rc;
778 #ifdef __linux__
779 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
780 Error **errp)
782 unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block);
783 unsigned long sectors = info->size / sector_size;
785 /* FIXME: Once the kernel module is patched to honor block sizes,
786 * and to advertise that fact to user space, we should update the
787 * hand-off to the kernel to use any block sizes we learned. */
788 assert(!info->request_sizes);
789 if (info->size / sector_size != sectors) {
790 error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel",
791 info->size);
792 return -E2BIG;
795 trace_nbd_init_set_socket();
797 if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {
798 int serrno = errno;
799 error_setg(errp, "Failed to set NBD socket");
800 return -serrno;
803 trace_nbd_init_set_block_size(sector_size);
805 if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) {
806 int serrno = errno;
807 error_setg(errp, "Failed setting NBD block size");
808 return -serrno;
811 trace_nbd_init_set_size(sectors);
812 if (info->size % sector_size) {
813 trace_nbd_init_trailing_bytes(info->size % sector_size);
816 if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {
817 int serrno = errno;
818 error_setg(errp, "Failed setting size (in blocks)");
819 return -serrno;
822 if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) {
823 if (errno == ENOTTY) {
824 int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0;
825 trace_nbd_init_set_readonly();
827 if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
828 int serrno = errno;
829 error_setg(errp, "Failed setting read-only attribute");
830 return -serrno;
832 } else {
833 int serrno = errno;
834 error_setg(errp, "Failed setting flags");
835 return -serrno;
839 trace_nbd_init_finish();
841 return 0;
844 int nbd_client(int fd)
846 int ret;
847 int serrno;
849 trace_nbd_client_loop();
851 ret = ioctl(fd, NBD_DO_IT);
852 if (ret < 0 && errno == EPIPE) {
853 /* NBD_DO_IT normally returns EPIPE when someone has disconnected
854 * the socket via NBD_DISCONNECT. We do not want to return 1 in
855 * that case.
857 ret = 0;
859 serrno = errno;
861 trace_nbd_client_loop_ret(ret, strerror(serrno));
863 trace_nbd_client_clear_queue();
864 ioctl(fd, NBD_CLEAR_QUE);
866 trace_nbd_client_clear_socket();
867 ioctl(fd, NBD_CLEAR_SOCK);
869 errno = serrno;
870 return ret;
873 int nbd_disconnect(int fd)
875 ioctl(fd, NBD_CLEAR_QUE);
876 ioctl(fd, NBD_DISCONNECT);
877 ioctl(fd, NBD_CLEAR_SOCK);
878 return 0;
881 #else
882 int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info,
883 Error **errp)
885 error_setg(errp, "nbd_init is only supported on Linux");
886 return -ENOTSUP;
889 int nbd_client(int fd)
891 return -ENOTSUP;
893 int nbd_disconnect(int fd)
895 return -ENOTSUP;
897 #endif
899 int nbd_send_request(QIOChannel *ioc, NBDRequest *request)
901 uint8_t buf[NBD_REQUEST_SIZE];
903 trace_nbd_send_request(request->from, request->len, request->handle,
904 request->flags, request->type,
905 nbd_cmd_lookup(request->type));
907 stl_be_p(buf, NBD_REQUEST_MAGIC);
908 stw_be_p(buf + 4, request->flags);
909 stw_be_p(buf + 6, request->type);
910 stq_be_p(buf + 8, request->handle);
911 stq_be_p(buf + 16, request->from);
912 stl_be_p(buf + 24, request->len);
914 return nbd_write(ioc, buf, sizeof(buf), NULL);
917 /* nbd_receive_reply
918 * Returns 1 on success
919 * 0 on eof, when no data was read (errp is not set)
920 * negative errno on failure (errp is set)
922 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
924 uint8_t buf[NBD_REPLY_SIZE];
925 uint32_t magic;
926 int ret;
928 ret = nbd_read_eof(ioc, buf, sizeof(buf), errp);
929 if (ret <= 0) {
930 return ret;
933 /* Reply
934 [ 0 .. 3] magic (NBD_SIMPLE_REPLY_MAGIC)
935 [ 4 .. 7] error (0 == no error)
936 [ 7 .. 15] handle
939 magic = ldl_be_p(buf);
940 reply->error = ldl_be_p(buf + 4);
941 reply->handle = ldq_be_p(buf + 8);
943 reply->error = nbd_errno_to_system_errno(reply->error);
945 if (reply->error == ESHUTDOWN) {
946 /* This works even on mingw which lacks a native ESHUTDOWN */
947 error_setg(errp, "server shutting down");
948 return -EINVAL;
950 trace_nbd_receive_reply(magic, reply->error, reply->handle);
952 if (magic != NBD_SIMPLE_REPLY_MAGIC) {
953 error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
954 return -EINVAL;
957 return 1;