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091d0bf3c9
qemu/nbd/client.c
Eric Blake 091d0bf3c9 nbd/client: Refactor nbd_receive_list() 
Right now, nbd_receive_list() is only called by
nbd_receive_query_exports(), which in turn is only called if the
server lacks NBD_OPT_GO but has working option negotiation, and is
merely used as a quality-of-implementation trick since servers
can't give decent errors for NBD_OPT_EXPORT_NAME.  However, servers
that lack NBD_OPT_GO are becoming increasingly rare (nbdkit was a
latecomer, in Aug 2018, but qemu has been such a server since commit
f37708f6 in July 2017 and released in 2.10), so it no longer makes
sense to micro-optimize that function for performance.

Furthermore, when debugging a server's implementation, tracing the
full reply (both names and descriptions) is useful, not to mention
that upcoming patches adding 'qemu-nbd --list' will want to collect
that data.  And when you consider that a server can send an export
name up to the NBD protocol length limit of 4k; but our current
NBD_MAX_NAME_SIZE is only 256, we can't trace all valid server
names without more storage, but 4k is large enough that the heap
is better than the stack for long names.

Thus, I'm changing the division of labor, with nbd_receive_list()
now always malloc'ing a result on success (the malloc is bounded
by the fact that we reject servers with a reply length larger
than 32M), and moving the comparison to 'wantname' to the caller.

There is a minor change in behavior where a server with 0 exports
(an immediate NBD_REP_ACK reply) is now no longer distinguished
from a server without LIST support (NBD_REP_ERR_UNSUP); this
information could be preserved with a complication to the calling
contract to provide a bit more information, but I didn't see the
point.  After all, the worst that can happen if our guess at a
match is wrong is that the caller will get a cryptic disconnect
when NBD_OPT_EXPORT_NAME fails (which is no different from what
would happen if we had not tried LIST), while treating an empty
list as immediate failure would prevent connecting to really old
servers that really did lack LIST.  Besides, NBD servers with 0
exports are rare (qemu can do it when using QMP nbd-server-start
without nbd-server-add - but qemu understands NBD_OPT_GO and
thus won't tickle this change in behavior).

Fix the spelling of foundExport to match coding standards while
in the area.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190117193658.16413-9-eblake@redhat.com>
2019-01-21 15:49:52 -06:00

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/*
* Copyright (C) 2016-2018 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Client Side
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "trace.h"
#include "nbd-internal.h"
/* Definitions for opaque data types */
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
/* That's all folks */
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
Response
...
...
Request (type == 2)
*/
/* Send an option request.
*
* The request is for option @opt, with @data containing @len bytes of
* additional payload for the request (@len may be -1 to treat @data as
* a C string; and @data may be NULL if @len is 0).
* Return 0 if successful, -1 with errp set if it is impossible to
* continue. */
static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
uint32_t len, const char *data,
Error **errp)
{
NBDOption req;
QEMU_BUILD_BUG_ON(sizeof(req) != 16);
if (len == -1) {
req.length = len = strlen(data);
}
trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
stq_be_p(&req.magic, NBD_OPTS_MAGIC);
stl_be_p(&req.option, opt);
stl_be_p(&req.length, len);
if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
error_prepend(errp, "Failed to send option request header: ");
return -1;
}
if (len && nbd_write(ioc, (char *) data, len, errp) < 0) {
error_prepend(errp, "Failed to send option request data: ");
return -1;
}
return 0;
}
/* Send NBD_OPT_ABORT as a courtesy to let the server know that we are
* not going to attempt further negotiation. */
static void nbd_send_opt_abort(QIOChannel *ioc)
{
/* Technically, a compliant server is supposed to reply to us; but
* older servers disconnected instead. At any rate, we're allowed
* to disconnect without waiting for the server reply, so we don't
* even care if the request makes it to the server, let alone
* waiting around for whether the server replies. */
nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL);
}
/* Receive the header of an option reply, which should match the given
* opt. Read through the length field, but NOT the length bytes of
* payload. Return 0 if successful, -1 with errp set if it is
* impossible to continue. */
static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
NBDOptionReply *reply, Error **errp)
{
QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) {
error_prepend(errp, "failed to read option reply: ");
nbd_send_opt_abort(ioc);
return -1;
}
reply->magic = be64_to_cpu(reply->magic);
reply->option = be32_to_cpu(reply->option);
reply->type = be32_to_cpu(reply->type);
reply->length = be32_to_cpu(reply->length);
trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
reply->type, nbd_rep_lookup(reply->type),
reply->length);
if (reply->magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option reply magic");
nbd_send_opt_abort(ioc);
return -1;
}
if (reply->option != opt) {
error_setg(errp, "Unexpected option type %u (%s), expected %u (%s)",
reply->option, nbd_opt_lookup(reply->option),
opt, nbd_opt_lookup(opt));
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
}
/* If reply represents success, return 1 without further action.
* If reply represents an error, consume the optional payload of
* the packet on ioc. Then return 0 for unsupported (so the client
* can fall back to other approaches), or -1 with errp set for other
* errors.
*/
static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
Error **errp)
{
char *msg = NULL;
int result = -1;
if (!(reply->type & (1 << 31))) {
return 1;
}
if (reply->length) {
if (reply->length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "server error %" PRIu32
" (%s) message is too long",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg = g_malloc(reply->length + 1);
if (nbd_read(ioc, msg, reply->length, errp) < 0) {
error_prepend(errp, "failed to read option error %" PRIu32
" (%s) message: ",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg[reply->length] = '\0';
trace_nbd_server_error_msg(reply->type,
nbd_reply_type_lookup(reply->type), msg);
}
switch (reply->type) {
case NBD_REP_ERR_UNSUP:
trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
result = 0;
goto cleanup;
case NBD_REP_ERR_POLICY:
error_setg(errp, "Denied by server for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_INVALID:
error_setg(errp, "Invalid parameters for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_PLATFORM:
error_setg(errp, "Server lacks support for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_TLS_REQD:
error_setg(errp, "TLS negotiation required before option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_UNKNOWN:
error_setg(errp, "Requested export not available");
break;
case NBD_REP_ERR_SHUTDOWN:
error_setg(errp, "Server shutting down before option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_BLOCK_SIZE_REQD:
error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
default:
error_setg(errp, "Unknown error code when asking for option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
}
if (msg) {
error_append_hint(errp, "server reported: %s\n", msg);
}
cleanup:
g_free(msg);
if (result < 0) {
nbd_send_opt_abort(ioc);
}
return result;
}
/* nbd_receive_list:
* Process another portion of the NBD_OPT_LIST reply, populating any
* name received into *@name. If @description is non-NULL, and the
* server provided a description, that is also populated. The caller
* must eventually call g_free() on success.
* Returns 1 if name and description were set and iteration must continue,
* 0 if iteration is complete (including if OPT_LIST unsupported),
* -1 with @errp set if an unrecoverable error occurred.
*/
static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
Error **errp)
{
int ret = -1;
NBDOptionReply reply;
uint32_t len;
uint32_t namelen;
char *local_name = NULL;
char *local_desc = NULL;
int error;
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
len = reply.length;
if (reply.type == NBD_REP_ACK) {
if (len != 0) {
error_setg(errp, "length too long for option end");
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
} else if (reply.type != NBD_REP_SERVER) {
error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_SERVER, nbd_rep_lookup(NBD_REP_SERVER));
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "incorrect option length %" PRIu32, len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) {
error_prepend(errp, "failed to read option name length: ");
nbd_send_opt_abort(ioc);
return -1;
}
namelen = be32_to_cpu(namelen);
len -= sizeof(namelen);
if (len < namelen) {
error_setg(errp, "incorrect option name length");
nbd_send_opt_abort(ioc);
return -1;
}
local_name = g_malloc(namelen + 1);
if (nbd_read(ioc, local_name, namelen, errp) < 0) {
error_prepend(errp, "failed to read export name: ");
nbd_send_opt_abort(ioc);
goto out;
}
local_name[namelen] = '\0';
len -= namelen;
if (len) {
local_desc = g_malloc(len + 1);
if (nbd_read(ioc, local_desc, len, errp) < 0) {
error_prepend(errp, "failed to read export description: ");
nbd_send_opt_abort(ioc);
goto out;
}
local_desc[len] = '\0';
}
trace_nbd_receive_list(local_name, local_desc ?: "");
*name = local_name;
local_name = NULL;
if (description) {
*description = local_desc;
local_desc = NULL;
}
ret = 1;
out:
g_free(local_name);
g_free(local_desc);
return ret;
}
/* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be
* used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and
* NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to
* go (with @info populated). */
static int nbd_opt_go(QIOChannel *ioc, const char *wantname,
NBDExportInfo *info, Error **errp)
{
NBDOptionReply reply;
uint32_t len = strlen(wantname);
uint16_t type;
int error;
char *buf;
/* The protocol requires that the server send NBD_INFO_EXPORT with
* a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so
* flags still 0 is a witness of a broken server. */
info->flags = 0;
trace_nbd_opt_go_start(wantname);
buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
stl_be_p(buf, len);
memcpy(buf + 4, wantname, len);
/* At most one request, everything else up to server */
stw_be_p(buf + 4 + len, info->request_sizes);
if (info->request_sizes) {
stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE);
}
error = nbd_send_option_request(ioc, NBD_OPT_GO,
4 + len + 2 + 2 * info->request_sizes,
buf, errp);
g_free(buf);
if (error < 0) {
return -1;
}
while (1) {
if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
len = reply.length;
if (reply.type == NBD_REP_ACK) {
/* Server is done sending info and moved into transmission
phase, but make sure it sent flags */
if (len) {
error_setg(errp, "server sent invalid NBD_REP_ACK");
return -1;
}
if (!info->flags) {
error_setg(errp, "broken server omitted NBD_INFO_EXPORT");
return -1;
}
trace_nbd_opt_go_success();
return 1;
}
if (reply.type != NBD_REP_INFO) {
error_setg(errp, "unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_INFO, nbd_rep_lookup(NBD_REP_INFO));
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(type)) {
error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short",
len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &type, sizeof(type), errp) < 0) {
error_prepend(errp, "failed to read info type: ");
nbd_send_opt_abort(ioc);
return -1;
}
len -= sizeof(type);
type = be16_to_cpu(type);
switch (type) {
case NBD_INFO_EXPORT:
if (len != sizeof(info->size) + sizeof(info->flags)) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "failed to read info size: ");
nbd_send_opt_abort(ioc);
return -1;
}
info->size = be64_to_cpu(info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "failed to read info flags: ");
nbd_send_opt_abort(ioc);
return -1;
}
info->flags = be16_to_cpu(info->flags);
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
break;
case NBD_INFO_BLOCK_SIZE:
if (len != sizeof(info->min_block) * 3) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->min_block, sizeof(info->min_block),
errp) < 0) {
error_prepend(errp, "failed to read info minimum block size: ");
nbd_send_opt_abort(ioc);
return -1;
}
info->min_block = be32_to_cpu(info->min_block);
if (!is_power_of_2(info->min_block)) {
error_setg(errp, "server minimum block size %" PRIu32
" is not a power of two", info->min_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block),
errp) < 0) {
error_prepend(errp,
"failed to read info preferred block size: ");
nbd_send_opt_abort(ioc);
return -1;
}
info->opt_block = be32_to_cpu(info->opt_block);
if (!is_power_of_2(info->opt_block) ||
info->opt_block < info->min_block) {
error_setg(errp, "server preferred block size %" PRIu32
" is not valid", info->opt_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->max_block, sizeof(info->max_block),
errp) < 0) {
error_prepend(errp, "failed to read info maximum block size: ");
nbd_send_opt_abort(ioc);
return -1;
}
info->max_block = be32_to_cpu(info->max_block);
if (info->max_block < info->min_block) {
error_setg(errp, "server maximum block size %" PRIu32
" is not valid", info->max_block);
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block,
info->max_block);
break;
default:
trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type));
if (nbd_drop(ioc, len, errp) < 0) {
error_prepend(errp, "Failed to read info payload: ");
nbd_send_opt_abort(ioc);
return -1;
}
break;
}
}
}
/* Return -1 on failure, 0 if wantname is an available export. */
static int nbd_receive_query_exports(QIOChannel *ioc,
const char *wantname,
Error **errp)
{
bool list_empty = true;
bool found_export = false;
trace_nbd_receive_query_exports_start(wantname);
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
return -1;
}
while (1) {
char *name;
int ret = nbd_receive_list(ioc, &name, NULL, errp);
if (ret < 0) {
/* Server gave unexpected reply */
return -1;
} else if (ret == 0) {
/* Done iterating. */
if (list_empty) {
/*
* We don't have enough context to tell a server that
* sent an empty list apart from a server that does
* not support the list command; but as this function
* is just used to trigger a nicer error message
* before trying NBD_OPT_EXPORT_NAME, assume the
* export is available.
*/
return 0;
} else if (!found_export) {
error_setg(errp, "No export with name '%s' available",
wantname);
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_receive_query_exports_success(wantname);
return 0;
}
list_empty = false;
if (!strcmp(name, wantname)) {
found_export = true;
}
g_free(name);
}
}
/* nbd_request_simple_option: Send an option request, and parse the reply
* return 1 for successful negotiation,
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
{
NBDOptionReply reply;
int error;
if (nbd_send_option_request(ioc, opt, 0, NULL, errp) < 0) {
return -1;
}
if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Server answered option %d (%s) with unexpected "
"reply %" PRIu32 " (%s)", opt, nbd_opt_lookup(opt),
reply.type, nbd_rep_lookup(reply.type));
nbd_send_opt_abort(ioc);
return -1;
}
if (reply.length != 0) {
error_setg(errp, "Option %d ('%s') response length is %" PRIu32
" (it should be zero)", opt, nbd_opt_lookup(opt),
reply.length);
nbd_send_opt_abort(ioc);
return -1;
}
return 1;
}
static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
const char *hostname, Error **errp)
{
int ret;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, errp);
if (ret <= 0) {
if (ret == 0) {
error_setg(errp, "Server don't support STARTTLS option");
nbd_send_opt_abort(ioc);
}
return NULL;
}
trace_nbd_receive_starttls_new_client();
tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
if (!tioc) {
return NULL;
}
qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
data.loop = g_main_loop_new(g_main_context_default(), FALSE);
trace_nbd_receive_starttls_tls_handshake();
qio_channel_tls_handshake(tioc,
nbd_tls_handshake,
&data,
NULL,
NULL);
if (!data.complete) {
g_main_loop_run(data.loop);
}
g_main_loop_unref(data.loop);
if (data.error) {
error_propagate(errp, data.error);
object_unref(OBJECT(tioc));
return NULL;
}
return QIO_CHANNEL(tioc);
}
/* nbd_negotiate_simple_meta_context:
* Set one meta context. Simple means that reply must contain zero (not
* negotiated) or one (negotiated) contexts. More contexts would be considered
* as a protocol error. It's also implied that meta-data query equals queried
* context name, so, if server replies with something different than @context,
* it is considered an error too.
* return 1 for successful negotiation, context_id is set
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
static int nbd_negotiate_simple_meta_context(QIOChannel *ioc,
const char *export,
const char *context,
uint32_t *context_id,
Error **errp)
{
int ret;
NBDOptionReply reply;
uint32_t received_id = 0;
bool received = false;
uint32_t export_len = strlen(export);
uint32_t context_len = strlen(context);
uint32_t data_len = sizeof(export_len) + export_len +
sizeof(uint32_t) + /* number of queries */
sizeof(context_len) + context_len;
char *data = g_malloc(data_len);
char *p = data;
trace_nbd_opt_meta_request(context, export);
stl_be_p(p, export_len);
memcpy(p += sizeof(export_len), export, export_len);
stl_be_p(p += export_len, 1);
stl_be_p(p += sizeof(uint32_t), context_len);
memcpy(p += sizeof(context_len), context, context_len);
ret = nbd_send_option_request(ioc, NBD_OPT_SET_META_CONTEXT, data_len, data,
errp);
g_free(data);
if (ret < 0) {
return ret;
}
if (nbd_receive_option_reply(ioc, NBD_OPT_SET_META_CONTEXT, &reply,
errp) < 0)
{
return -1;
}
ret = nbd_handle_reply_err(ioc, &reply, errp);
if (ret <= 0) {
return ret;
}
if (reply.type == NBD_REP_META_CONTEXT) {
char *name;
if (reply.length != sizeof(received_id) + context_len) {
error_setg(errp, "Failed to negotiate meta context '%s', server "
"answered with unexpected length %" PRIu32, context,
reply.length);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &received_id, sizeof(received_id), errp) < 0) {
return -1;
}
received_id = be32_to_cpu(received_id);
reply.length -= sizeof(received_id);
name = g_malloc(reply.length + 1);
if (nbd_read(ioc, name, reply.length, errp) < 0) {
g_free(name);
return -1;
}
name[reply.length] = '\0';
if (strcmp(context, name)) {
error_setg(errp, "Failed to negotiate meta context '%s', server "
"answered with different context '%s'", context,
name);
g_free(name);
nbd_send_opt_abort(ioc);
return -1;
}
g_free(name);
trace_nbd_opt_meta_reply(context, received_id);
received = true;
/* receive NBD_REP_ACK */
if (nbd_receive_option_reply(ioc, NBD_OPT_SET_META_CONTEXT, &reply,
errp) < 0)
{
return -1;
}
ret = nbd_handle_reply_err(ioc, &reply, errp);
if (ret <= 0) {
return ret;
}
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_ACK, nbd_rep_lookup(NBD_REP_ACK));
nbd_send_opt_abort(ioc);
return -1;
}
if (reply.length) {
error_setg(errp, "Unexpected length to ACK response");
nbd_send_opt_abort(ioc);
return -1;
}
if (received) {
*context_id = received_id;
return 1;
}
return 0;
}
int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
QCryptoTLSCreds *tlscreds, const char *hostname,
QIOChannel **outioc, NBDExportInfo *info,
Error **errp)
{
uint64_t magic;
int rc;
bool zeroes = true;
bool structured_reply = info->structured_reply;
bool base_allocation = info->base_allocation;
trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
info->structured_reply = false;
info->base_allocation = false;
rc = -EINVAL;
if (outioc) {
*outioc = NULL;
}
if (tlscreds && !outioc) {
error_setg(errp, "Output I/O channel required for TLS");
goto fail;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read initial magic: ");
goto fail;
}
magic = be64_to_cpu(magic);
trace_nbd_receive_negotiate_magic(magic);
if (magic != NBD_INIT_MAGIC) {
error_setg(errp, "Bad initial magic received: 0x%" PRIx64, magic);
goto fail;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read server magic: ");
goto fail;
}
magic = be64_to_cpu(magic);
trace_nbd_receive_negotiate_magic(magic);
if (magic == NBD_OPTS_MAGIC) {
uint32_t clientflags = 0;
uint16_t globalflags;
bool fixedNewStyle = false;
if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) {
error_prepend(errp, "Failed to read server flags: ");
goto fail;
}
globalflags = be16_to_cpu(globalflags);
trace_nbd_receive_negotiate_server_flags(globalflags);
if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) {
fixedNewStyle = true;
clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (globalflags & NBD_FLAG_NO_ZEROES) {
zeroes = false;
clientflags |= NBD_FLAG_C_NO_ZEROES;
}
/* client requested flags */
clientflags = cpu_to_be32(clientflags);
if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) {
error_prepend(errp, "Failed to send clientflags field: ");
goto fail;
}
if (tlscreds) {
if (fixedNewStyle) {
*outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
if (!*outioc) {
goto fail;
}
ioc = *outioc;
} else {
error_setg(errp, "Server does not support STARTTLS");
goto fail;
}
}
if (!name) {
trace_nbd_receive_negotiate_default_name();
name = "";
}
if (fixedNewStyle) {
int result;
if (structured_reply) {
result = nbd_request_simple_option(ioc,
NBD_OPT_STRUCTURED_REPLY,
errp);
if (result < 0) {
goto fail;
}
info->structured_reply = result == 1;
}
if (info->structured_reply && base_allocation) {
result = nbd_negotiate_simple_meta_context(
ioc, name, info->x_dirty_bitmap ?: "base:allocation",
&info->meta_base_allocation_id, errp);
if (result < 0) {
goto fail;
}
info->base_allocation = result == 1;
}
/* Try NBD_OPT_GO first - if it works, we are done (it
* also gives us a good message if the server requires
* TLS). If it is not available, fall back to
* NBD_OPT_LIST for nicer error messages about a missing
* export, then use NBD_OPT_EXPORT_NAME. */
result = nbd_opt_go(ioc, name, info, errp);
if (result < 0) {
goto fail;
}
if (result > 0) {
return 0;
}
/* Check our desired export is present in the
* server export list. Since NBD_OPT_EXPORT_NAME
* cannot return an error message, running this
* query gives us better error reporting if the
* export name is not available.
*/
if (nbd_receive_query_exports(ioc, name, errp) < 0) {
goto fail;
}
}
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
errp) < 0) {
goto fail;
}
/* Read the response */
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length: ");
goto fail;
}
info->size = be64_to_cpu(info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "Failed to read export flags: ");
goto fail;
}
info->flags = be16_to_cpu(info->flags);
} else if (magic == NBD_CLIENT_MAGIC) {
uint32_t oldflags;
if (name) {
error_setg(errp, "Server does not support export names");
goto fail;
}
if (tlscreds) {
error_setg(errp, "Server does not support STARTTLS");
goto fail;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length: ");
goto fail;
}
info->size = be64_to_cpu(info->size);
if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
error_prepend(errp, "Failed to read export flags: ");
goto fail;
}
oldflags = be32_to_cpu(oldflags);
if (oldflags & ~0xffff) {
error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
goto fail;
}
info->flags = oldflags;
} else {
error_setg(errp, "Bad server magic received: 0x%" PRIx64, magic);
goto fail;
}
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
if (zeroes && nbd_drop(ioc, 124, errp) < 0) {
error_prepend(errp, "Failed to read reserved block: ");
goto fail;
}
rc = 0;
fail:
return rc;
}
#ifdef __linux__
int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
Error **errp)
{
unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block);
unsigned long sectors = info->size / sector_size;
/* FIXME: Once the kernel module is patched to honor block sizes,
* and to advertise that fact to user space, we should update the
* hand-off to the kernel to use any block sizes we learned. */
assert(!info->request_sizes);
if (info->size / sector_size != sectors) {
error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel",
info->size);
return -E2BIG;
}
trace_nbd_init_set_socket();
if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {
int serrno = errno;
error_setg(errp, "Failed to set NBD socket");
return -serrno;
}
trace_nbd_init_set_block_size(sector_size);
if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting NBD block size");
return -serrno;
}
trace_nbd_init_set_size(sectors);
if (info->size % sector_size) {
trace_nbd_init_trailing_bytes(info->size % sector_size);
}
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting size (in blocks)");
return -serrno;
}
if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) {
if (errno == ENOTTY) {
int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0;
trace_nbd_init_set_readonly();
if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting read-only attribute");
return -serrno;
}
} else {
int serrno = errno;
error_setg(errp, "Failed setting flags");
return -serrno;
}
}
trace_nbd_init_finish();
return 0;
}
int nbd_client(int fd)
{
int ret;
int serrno;
trace_nbd_client_loop();
ret = ioctl(fd, NBD_DO_IT);
if (ret < 0 && errno == EPIPE) {
/* NBD_DO_IT normally returns EPIPE when someone has disconnected
* the socket via NBD_DISCONNECT. We do not want to return 1 in
* that case.
*/
ret = 0;
}
serrno = errno;
trace_nbd_client_loop_ret(ret, strerror(serrno));
trace_nbd_client_clear_queue();
ioctl(fd, NBD_CLEAR_QUE);
trace_nbd_client_clear_socket();
ioctl(fd, NBD_CLEAR_SOCK);
errno = serrno;
return ret;
}
int nbd_disconnect(int fd)
{
ioctl(fd, NBD_CLEAR_QUE);
ioctl(fd, NBD_DISCONNECT);
ioctl(fd, NBD_CLEAR_SOCK);
return 0;
}
#endif /* __linux__ */
int nbd_send_request(QIOChannel *ioc, NBDRequest *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
trace_nbd_send_request(request->from, request->len, request->handle,
request->flags, request->type,
nbd_cmd_lookup(request->type));
stl_be_p(buf, NBD_REQUEST_MAGIC);
stw_be_p(buf + 4, request->flags);
stw_be_p(buf + 6, request->type);
stq_be_p(buf + 8, request->handle);
stq_be_p(buf + 16, request->from);
stl_be_p(buf + 24, request->len);
return nbd_write(ioc, buf, sizeof(buf), NULL);
}
/* nbd_receive_simple_reply
* Read simple reply except magic field (which should be already read).
* Payload is not read (payload is possible for CMD_READ, but here we even
* don't know whether it take place or not).
*/
static int nbd_receive_simple_reply(QIOChannel *ioc, NBDSimpleReply *reply,
Error **errp)
{
int ret;
assert(reply->magic == NBD_SIMPLE_REPLY_MAGIC);
ret = nbd_read(ioc, (uint8_t *)reply + sizeof(reply->magic),
sizeof(*reply) - sizeof(reply->magic), errp);
if (ret < 0) {
return ret;
}
reply->error = be32_to_cpu(reply->error);
reply->handle = be64_to_cpu(reply->handle);
return 0;
}
/* nbd_receive_structured_reply_chunk
* Read structured reply chunk except magic field (which should be already
* read).
* Payload is not read.
*/
static int nbd_receive_structured_reply_chunk(QIOChannel *ioc,
NBDStructuredReplyChunk *chunk,
Error **errp)
{
int ret;
assert(chunk->magic == NBD_STRUCTURED_REPLY_MAGIC);
ret = nbd_read(ioc, (uint8_t *)chunk + sizeof(chunk->magic),
sizeof(*chunk) - sizeof(chunk->magic), errp);
if (ret < 0) {
return ret;
}
chunk->flags = be16_to_cpu(chunk->flags);
chunk->type = be16_to_cpu(chunk->type);
chunk->handle = be64_to_cpu(chunk->handle);
chunk->length = be32_to_cpu(chunk->length);
return 0;
}
/* nbd_receive_reply
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
{
int ret;
const char *type;
ret = nbd_read_eof(ioc, &reply->magic, sizeof(reply->magic), errp);
if (ret <= 0) {
return ret;
}
reply->magic = be32_to_cpu(reply->magic);
switch (reply->magic) {
case NBD_SIMPLE_REPLY_MAGIC:
ret = nbd_receive_simple_reply(ioc, &reply->simple, errp);
if (ret < 0) {
break;
}
trace_nbd_receive_simple_reply(reply->simple.error,
nbd_err_lookup(reply->simple.error),
reply->handle);
break;
case NBD_STRUCTURED_REPLY_MAGIC:
ret = nbd_receive_structured_reply_chunk(ioc, &reply->structured, errp);
if (ret < 0) {
break;
}
type = nbd_reply_type_lookup(reply->structured.type);
trace_nbd_receive_structured_reply_chunk(reply->structured.flags,
reply->structured.type, type,
reply->structured.handle,
reply->structured.length);
break;
default:
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", reply->magic);
return -EINVAL;
}
if (ret < 0) {
return ret;
}
return 1;
}
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