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-rw-r--r--nbd/client.c1512
1 files changed, 1512 insertions, 0 deletions
diff --git a/nbd/client.c b/nbd/client.c
new file mode 100644
index 000000000..30d5383cb
--- /dev/null
+++ b/nbd/client.c
@@ -0,0 +1,1512 @@
+/*
+ * Copyright (C) 2016-2019 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 "qemu/queue.h"
+#include "trace.h"
+#include "nbd-internal.h"
+#include "qemu/cutils.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)
+{
+ ERRP_GUARD();
+ 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), "option reply", errp) < 0) {
+ 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), where @strict determines if only
+ * ERR_UNSUP or all errors fit that category, or -1 with errp set for
+ * other errors.
+ */
+static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
+ bool strict, Error **errp)
+{
+ ERRP_GUARD();
+ g_autofree char *msg = NULL;
+
+ 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 err;
+ }
+ msg = g_malloc(reply->length + 1);
+ if (nbd_read(ioc, msg, reply->length, NULL, errp) < 0) {
+ error_prepend(errp, "Failed to read option error %" PRIu32
+ " (%s) message: ",
+ reply->type, nbd_rep_lookup(reply->type));
+ goto err;
+ }
+ msg[reply->length] = '\0';
+ trace_nbd_server_error_msg(reply->type,
+ nbd_reply_type_lookup(reply->type), msg);
+ }
+
+ if (reply->type == NBD_REP_ERR_UNSUP || !strict) {
+ trace_nbd_reply_err_ignored(reply->option,
+ nbd_opt_lookup(reply->option),
+ reply->type, nbd_rep_lookup(reply->type));
+ return 0;
+ }
+
+ switch (reply->type) {
+ 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));
+ error_append_hint(errp, "Did you forget a valid tls-creds?\n");
+ 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);
+ }
+
+ err:
+ nbd_send_opt_abort(ioc);
+ return -1;
+}
+
+/* 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)
+{
+ NBDOptionReply reply;
+ uint32_t len;
+ uint32_t namelen;
+ g_autofree char *local_name = NULL;
+ g_autofree 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, true, 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_read32(ioc, &namelen, "option name length", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ len -= sizeof(namelen);
+ if (len < namelen || namelen > NBD_MAX_STRING_SIZE) {
+ error_setg(errp, "incorrect name length in server's list response");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+
+ local_name = g_malloc(namelen + 1);
+ if (nbd_read(ioc, local_name, namelen, "export name", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ local_name[namelen] = '\0';
+ len -= namelen;
+ if (len) {
+ if (len > NBD_MAX_STRING_SIZE) {
+ error_setg(errp, "incorrect description length in server's "
+ "list response");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ local_desc = g_malloc(len + 1);
+ if (nbd_read(ioc, local_desc, len, "export description", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ local_desc[len] = '\0';
+ }
+
+ trace_nbd_receive_list(local_name, local_desc ?: "");
+ *name = g_steal_pointer(&local_name);
+ if (description) {
+ *description = g_steal_pointer(&local_desc);
+ }
+ return 1;
+}
+
+
+/*
+ * nbd_opt_info_or_go:
+ * Send option for NBD_OPT_INFO or NBD_OPT_GO and parse the reply.
+ * Returns -1 if the option proves the export @info->name cannot be
+ * used, 0 if the option 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 the rest of @info populated).
+ */
+static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
+ NBDExportInfo *info, Error **errp)
+{
+ ERRP_GUARD();
+ NBDOptionReply reply;
+ uint32_t len = strlen(info->name);
+ 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;
+
+ assert(opt == NBD_OPT_GO || opt == NBD_OPT_INFO);
+ trace_nbd_opt_info_go_start(nbd_opt_lookup(opt), info->name);
+ buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
+ stl_be_p(buf, len);
+ memcpy(buf + 4, info->name, 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, opt,
+ 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, opt, &reply, errp) < 0) {
+ return -1;
+ }
+ error = nbd_handle_reply_err(ioc, &reply, true, 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 for NBD_OPT_GO, 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_info_go_success(nbd_opt_lookup(opt));
+ 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_read16(ioc, &type, "info type", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ len -= sizeof(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_read64(ioc, &info->size, "info size", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ if (nbd_read16(ioc, &info->flags, "info flags", errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ if (info->min_block &&
+ !QEMU_IS_ALIGNED(info->size, info->min_block)) {
+ error_setg(errp, "export size %" PRIu64 " is not multiple of "
+ "minimum block size %" PRIu32, info->size,
+ info->min_block);
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ 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_read32(ioc, &info->min_block, "info minimum block size",
+ errp) < 0) {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ 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_read32(ioc, &info->opt_block, "info preferred block size",
+ errp) < 0)
+ {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ 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_read32(ioc, &info->max_block, "info maximum block size",
+ errp) < 0)
+ {
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ 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_info_block_size(info->min_block, info->opt_block,
+ info->max_block);
+ break;
+
+ default:
+ /*
+ * Not worth the bother to check if NBD_INFO_NAME or
+ * NBD_INFO_DESCRIPTION exceed NBD_MAX_STRING_SIZE.
+ */
+ trace_nbd_opt_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.
+ * @strict controls whether ERR_UNSUP or all errors produce 0 status.
+ * 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, bool strict,
+ 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, strict, 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, true, 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_send_meta_query:
+ * Send 0 or 1 set/list meta context queries.
+ * Return 0 on success, -1 with errp set for any error
+ */
+static int nbd_send_meta_query(QIOChannel *ioc, uint32_t opt,
+ const char *export, const char *query,
+ Error **errp)
+{
+ int ret;
+ uint32_t export_len = strlen(export);
+ uint32_t queries = !!query;
+ uint32_t query_len = 0;
+ uint32_t data_len;
+ char *data;
+ char *p;
+
+ data_len = sizeof(export_len) + export_len + sizeof(queries);
+ assert(export_len <= NBD_MAX_STRING_SIZE);
+ if (query) {
+ query_len = strlen(query);
+ data_len += sizeof(query_len) + query_len;
+ assert(query_len <= NBD_MAX_STRING_SIZE);
+ } else {
+ assert(opt == NBD_OPT_LIST_META_CONTEXT);
+ }
+ p = data = g_malloc(data_len);
+
+ trace_nbd_opt_meta_request(nbd_opt_lookup(opt), query ?: "(all)", export);
+ stl_be_p(p, export_len);
+ memcpy(p += sizeof(export_len), export, export_len);
+ stl_be_p(p += export_len, queries);
+ if (query) {
+ stl_be_p(p += sizeof(queries), query_len);
+ memcpy(p += sizeof(query_len), query, query_len);
+ }
+
+ ret = nbd_send_option_request(ioc, opt, data_len, data, errp);
+ g_free(data);
+ return ret;
+}
+
+/*
+ * nbd_receive_one_meta_context:
+ * Called in a loop to receive and trace one set/list meta context reply.
+ * Pass non-NULL @name or @id to collect results back to the caller, which
+ * must eventually call g_free().
+ * return 1 if name is set and iteration must continue,
+ * 0 if iteration is complete (including if option is unsupported),
+ * -1 with errp set for any error
+ */
+static int nbd_receive_one_meta_context(QIOChannel *ioc,
+ uint32_t opt,
+ char **name,
+ uint32_t *id,
+ Error **errp)
+{
+ int ret;
+ NBDOptionReply reply;
+ char *local_name = NULL;
+ uint32_t local_id;
+
+ if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
+ return -1;
+ }
+
+ ret = nbd_handle_reply_err(ioc, &reply, false, errp);
+ if (ret <= 0) {
+ return ret;
+ }
+
+ if (reply.type == NBD_REP_ACK) {
+ if (reply.length != 0) {
+ error_setg(errp, "Unexpected length to ACK response");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ return 0;
+ } else if (reply.type != NBD_REP_META_CONTEXT) {
+ error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)",
+ reply.type, nbd_rep_lookup(reply.type),
+ NBD_REP_META_CONTEXT, nbd_rep_lookup(NBD_REP_META_CONTEXT));
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+
+ if (reply.length <= sizeof(local_id) ||
+ reply.length > NBD_MAX_BUFFER_SIZE) {
+ error_setg(errp, "Failed to negotiate meta context, server "
+ "answered with unexpected length %" PRIu32,
+ reply.length);
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+
+ if (nbd_read32(ioc, &local_id, "context id", errp) < 0) {
+ return -1;
+ }
+
+ reply.length -= sizeof(local_id);
+ local_name = g_malloc(reply.length + 1);
+ if (nbd_read(ioc, local_name, reply.length, "context name", errp) < 0) {
+ g_free(local_name);
+ return -1;
+ }
+ local_name[reply.length] = '\0';
+ trace_nbd_opt_meta_reply(nbd_opt_lookup(opt), local_name, local_id);
+
+ if (name) {
+ *name = local_name;
+ } else {
+ g_free(local_name);
+ }
+ if (id) {
+ *id = local_id;
+ }
+ return 1;
+}
+
+/*
+ * nbd_negotiate_simple_meta_context:
+ * Request the server to set the meta context for export @info->name
+ * using @info->x_dirty_bitmap with a fallback to "base:allocation",
+ * setting @info->context_id to the resulting id. Fail if the server
+ * responds with more than one context or with a context different
+ * than the query.
+ * return 1 for successful negotiation,
+ * 0 if operation is unsupported,
+ * -1 with errp set for any other error
+ */
+static int nbd_negotiate_simple_meta_context(QIOChannel *ioc,
+ NBDExportInfo *info,
+ Error **errp)
+{
+ /*
+ * TODO: Removing the x_dirty_bitmap hack will mean refactoring
+ * this function to request and store ids for multiple contexts
+ * (both base:allocation and a dirty bitmap), at which point this
+ * function should lose the term _simple.
+ */
+ int ret;
+ const char *context = info->x_dirty_bitmap ?: "base:allocation";
+ bool received = false;
+ char *name = NULL;
+
+ if (nbd_send_meta_query(ioc, NBD_OPT_SET_META_CONTEXT,
+ info->name, context, errp) < 0) {
+ return -1;
+ }
+
+ ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT,
+ &name, &info->context_id, errp);
+ if (ret < 0) {
+ return -1;
+ }
+ if (ret == 1) {
+ 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);
+ received = true;
+
+ ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT,
+ NULL, NULL, errp);
+ if (ret < 0) {
+ return -1;
+ }
+ }
+ if (ret != 0) {
+ error_setg(errp, "Server answered with more than one context");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ return received;
+}
+
+/*
+ * nbd_list_meta_contexts:
+ * Request the server to list all meta contexts for export @info->name.
+ * return 0 if list is complete (even if empty),
+ * -1 with errp set for any error
+ */
+static int nbd_list_meta_contexts(QIOChannel *ioc,
+ NBDExportInfo *info,
+ Error **errp)
+{
+ int ret;
+ int seen_any = false;
+ int seen_qemu = false;
+
+ if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT,
+ info->name, NULL, errp) < 0) {
+ return -1;
+ }
+
+ while (1) {
+ char *context;
+
+ ret = nbd_receive_one_meta_context(ioc, NBD_OPT_LIST_META_CONTEXT,
+ &context, NULL, errp);
+ if (ret == 0 && seen_any && !seen_qemu) {
+ /*
+ * Work around qemu 3.0 bug: the server forgot to send
+ * "qemu:" replies to 0 queries. If we saw at least one
+ * reply (probably base:allocation), but none of them were
+ * qemu:, then run a more specific query to make sure.
+ */
+ seen_qemu = true;
+ if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT,
+ info->name, "qemu:", errp) < 0) {
+ return -1;
+ }
+ continue;
+ }
+ if (ret <= 0) {
+ return ret;
+ }
+ seen_any = true;
+ seen_qemu |= strstart(context, "qemu:", NULL);
+ info->contexts = g_renew(char *, info->contexts, ++info->n_contexts);
+ info->contexts[info->n_contexts - 1] = context;
+ }
+}
+
+/*
+ * nbd_start_negotiate:
+ * Start the handshake to the server. After a positive return, the server
+ * is ready to accept additional NBD_OPT requests.
+ * Returns: negative errno: failure talking to server
+ * 0: server is oldstyle, must call nbd_negotiate_finish_oldstyle
+ * 1: server is newstyle, but can only accept EXPORT_NAME
+ * 2: server is newstyle, but lacks structured replies
+ * 3: server is newstyle and set up for structured replies
+ */
+static int nbd_start_negotiate(AioContext *aio_context, QIOChannel *ioc,
+ QCryptoTLSCreds *tlscreds,
+ const char *hostname, QIOChannel **outioc,
+ bool structured_reply, bool *zeroes,
+ Error **errp)
+{
+ ERRP_GUARD();
+ uint64_t magic;
+
+ trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>");
+
+ if (zeroes) {
+ *zeroes = true;
+ }
+ if (outioc) {
+ *outioc = NULL;
+ }
+ if (tlscreds && !outioc) {
+ error_setg(errp, "Output I/O channel required for TLS");
+ return -EINVAL;
+ }
+
+ if (nbd_read64(ioc, &magic, "initial magic", errp) < 0) {
+ return -EINVAL;
+ }
+ trace_nbd_receive_negotiate_magic(magic);
+
+ if (magic != NBD_INIT_MAGIC) {
+ error_setg(errp, "Bad initial magic received: 0x%" PRIx64, magic);
+ return -EINVAL;
+ }
+
+ if (nbd_read64(ioc, &magic, "server magic", errp) < 0) {
+ return -EINVAL;
+ }
+ trace_nbd_receive_negotiate_magic(magic);
+
+ if (magic == NBD_OPTS_MAGIC) {
+ uint32_t clientflags = 0;
+ uint16_t globalflags;
+ bool fixedNewStyle = false;
+
+ if (nbd_read16(ioc, &globalflags, "server flags", errp) < 0) {
+ return -EINVAL;
+ }
+ 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) {
+ if (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: ");
+ return -EINVAL;
+ }
+ if (tlscreds) {
+ if (fixedNewStyle) {
+ *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
+ if (!*outioc) {
+ return -EINVAL;
+ }
+ ioc = *outioc;
+ if (aio_context) {
+ qio_channel_set_blocking(ioc, false, NULL);
+ qio_channel_attach_aio_context(ioc, aio_context);
+ }
+ } else {
+ error_setg(errp, "Server does not support STARTTLS");
+ return -EINVAL;
+ }
+ }
+ if (fixedNewStyle) {
+ int result = 0;
+
+ if (structured_reply) {
+ result = nbd_request_simple_option(ioc,
+ NBD_OPT_STRUCTURED_REPLY,
+ false, errp);
+ if (result < 0) {
+ return -EINVAL;
+ }
+ }
+ return 2 + result;
+ } else {
+ return 1;
+ }
+ } else if (magic == NBD_CLIENT_MAGIC) {
+ if (tlscreds) {
+ error_setg(errp, "Server does not support STARTTLS");
+ return -EINVAL;
+ }
+ return 0;
+ } else {
+ error_setg(errp, "Bad server magic received: 0x%" PRIx64, magic);
+ return -EINVAL;
+ }
+}
+
+/*
+ * nbd_negotiate_finish_oldstyle:
+ * Populate @info with the size and export flags from an oldstyle server,
+ * but does not consume 124 bytes of reserved zero padding.
+ * Returns 0 on success, -1 with @errp set on failure
+ */
+static int nbd_negotiate_finish_oldstyle(QIOChannel *ioc, NBDExportInfo *info,
+ Error **errp)
+{
+ uint32_t oldflags;
+
+ if (nbd_read64(ioc, &info->size, "export length", errp) < 0) {
+ return -EINVAL;
+ }
+
+ if (nbd_read32(ioc, &oldflags, "export flags", errp) < 0) {
+ return -EINVAL;
+ }
+ if (oldflags & ~0xffff) {
+ error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
+ return -EINVAL;
+ }
+ info->flags = oldflags;
+ return 0;
+}
+
+/*
+ * nbd_receive_negotiate:
+ * Connect to server, complete negotiation, and move into transmission phase.
+ * Returns: negative errno: failure talking to server
+ * 0: server is connected
+ */
+int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc,
+ QCryptoTLSCreds *tlscreds,
+ const char *hostname, QIOChannel **outioc,
+ NBDExportInfo *info, Error **errp)
+{
+ ERRP_GUARD();
+ int result;
+ bool zeroes;
+ bool base_allocation = info->base_allocation;
+
+ assert(info->name && strlen(info->name) <= NBD_MAX_STRING_SIZE);
+ trace_nbd_receive_negotiate_name(info->name);
+
+ result = nbd_start_negotiate(aio_context, ioc, tlscreds, hostname, outioc,
+ info->structured_reply, &zeroes, errp);
+
+ info->structured_reply = false;
+ info->base_allocation = false;
+ if (tlscreds && *outioc) {
+ ioc = *outioc;
+ }
+
+ switch (result) {
+ case 3: /* newstyle, with structured replies */
+ info->structured_reply = true;
+ if (base_allocation) {
+ result = nbd_negotiate_simple_meta_context(ioc, info, errp);
+ if (result < 0) {
+ return -EINVAL;
+ }
+ info->base_allocation = result == 1;
+ }
+ /* fall through */
+ case 2: /* newstyle, try OPT_GO */
+ /* 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_info_or_go(ioc, NBD_OPT_GO, info, errp);
+ if (result < 0) {
+ return -EINVAL;
+ }
+ 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, info->name, errp) < 0) {
+ return -EINVAL;
+ }
+ /* fall through */
+ case 1: /* newstyle, but limited to EXPORT_NAME */
+ /* write the export name request */
+ if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, info->name,
+ errp) < 0) {
+ return -EINVAL;
+ }
+
+ /* Read the response */
+ if (nbd_read64(ioc, &info->size, "export length", errp) < 0) {
+ return -EINVAL;
+ }
+
+ if (nbd_read16(ioc, &info->flags, "export flags", errp) < 0) {
+ return -EINVAL;
+ }
+ break;
+ case 0: /* oldstyle, parse length and flags */
+ if (*info->name) {
+ error_setg(errp, "Server does not support non-empty export names");
+ return -EINVAL;
+ }
+ if (nbd_negotiate_finish_oldstyle(ioc, info, errp) < 0) {
+ return -EINVAL;
+ }
+ break;
+ default:
+ return result;
+ }
+
+ 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: ");
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/* Clean up result of nbd_receive_export_list */
+void nbd_free_export_list(NBDExportInfo *info, int count)
+{
+ int i, j;
+
+ if (!info) {
+ return;
+ }
+
+ for (i = 0; i < count; i++) {
+ g_free(info[i].name);
+ g_free(info[i].description);
+ for (j = 0; j < info[i].n_contexts; j++) {
+ g_free(info[i].contexts[j]);
+ }
+ g_free(info[i].contexts);
+ }
+ g_free(info);
+}
+
+/*
+ * nbd_receive_export_list:
+ * Query details about a server's exports, then disconnect without
+ * going into transmission phase. Return a count of the exports listed
+ * in @info by the server, or -1 on error. Caller must free @info using
+ * nbd_free_export_list().
+ */
+int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
+ const char *hostname, NBDExportInfo **info,
+ Error **errp)
+{
+ int result;
+ int count = 0;
+ int i;
+ int rc;
+ int ret = -1;
+ NBDExportInfo *array = NULL;
+ QIOChannel *sioc = NULL;
+
+ *info = NULL;
+ result = nbd_start_negotiate(NULL, ioc, tlscreds, hostname, &sioc, true,
+ NULL, errp);
+ if (tlscreds && sioc) {
+ ioc = sioc;
+ }
+
+ switch (result) {
+ case 2:
+ case 3:
+ /* newstyle - use NBD_OPT_LIST to populate array, then try
+ * NBD_OPT_INFO on each array member. If structured replies
+ * are enabled, also try NBD_OPT_LIST_META_CONTEXT. */
+ if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
+ goto out;
+ }
+ while (1) {
+ char *name;
+ char *desc;
+
+ rc = nbd_receive_list(ioc, &name, &desc, errp);
+ if (rc < 0) {
+ goto out;
+ } else if (rc == 0) {
+ break;
+ }
+ array = g_renew(NBDExportInfo, array, ++count);
+ memset(&array[count - 1], 0, sizeof(*array));
+ array[count - 1].name = name;
+ array[count - 1].description = desc;
+ array[count - 1].structured_reply = result == 3;
+ }
+
+ for (i = 0; i < count; i++) {
+ array[i].request_sizes = true;
+ rc = nbd_opt_info_or_go(ioc, NBD_OPT_INFO, &array[i], errp);
+ if (rc < 0) {
+ goto out;
+ } else if (rc == 0) {
+ /*
+ * Pointless to try rest of loop. If OPT_INFO doesn't work,
+ * it's unlikely that meta contexts work either
+ */
+ break;
+ }
+
+ if (result == 3 &&
+ nbd_list_meta_contexts(ioc, &array[i], errp) < 0) {
+ goto out;
+ }
+ }
+
+ /* Send NBD_OPT_ABORT as a courtesy before hanging up */
+ nbd_send_opt_abort(ioc);
+ break;
+ case 1: /* newstyle, but limited to EXPORT_NAME */
+ error_setg(errp, "Server does not support export lists");
+ /* We can't even send NBD_OPT_ABORT, so merely hang up */
+ goto out;
+ case 0: /* oldstyle, parse length and flags */
+ array = g_new0(NBDExportInfo, 1);
+ array->name = g_strdup("");
+ count = 1;
+
+ if (nbd_negotiate_finish_oldstyle(ioc, array, errp) < 0) {
+ goto out;
+ }
+
+ /* Send NBD_CMD_DISC as a courtesy to the server, but ignore all
+ * errors now that we have the information we wanted. */
+ if (nbd_drop(ioc, 124, NULL) == 0) {
+ NBDRequest request = { .type = NBD_CMD_DISC };
+
+ nbd_send_request(ioc, &request);
+ }
+ break;
+ default:
+ goto out;
+ }
+
+ *info = array;
+ array = NULL;
+ ret = count;
+
+ out:
+ qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+ qio_channel_close(ioc, NULL);
+ object_unref(OBJECT(sioc));
+ nbd_free_export_list(array, count);
+ return ret;
+}
+
+#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), "reply", 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), "structured chunk",
+ 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_read_eof
+ * Tries to read @size bytes from @ioc.
+ * Returns 1 on success
+ * 0 on eof, when no data was read (errp is not set)
+ * negative errno on failure (errp is set)
+ */
+static inline int coroutine_fn
+nbd_read_eof(BlockDriverState *bs, QIOChannel *ioc, void *buffer, size_t size,
+ Error **errp)
+{
+ bool partial = false;
+
+ assert(size);
+ while (size > 0) {
+ struct iovec iov = { .iov_base = buffer, .iov_len = size };
+ ssize_t len;
+
+ len = qio_channel_readv(ioc, &iov, 1, errp);
+ if (len == QIO_CHANNEL_ERR_BLOCK) {
+ qio_channel_yield(ioc, G_IO_IN);
+ continue;
+ } else if (len < 0) {
+ return -EIO;
+ } else if (len == 0) {
+ if (partial) {
+ error_setg(errp,
+ "Unexpected end-of-file before all bytes were read");
+ return -EIO;
+ } else {
+ return 0;
+ }
+ }
+
+ partial = true;
+ size -= len;
+ buffer = (uint8_t*) buffer + len;
+ }
+ return 1;
+}
+
+/* nbd_receive_reply
+ *
+ * Decreases bs->in_flight while waiting for a new reply. This yield is where
+ * we wait indefinitely and the coroutine must be able to be safely reentered
+ * for nbd_client_attach_aio_context().
+ *
+ * Returns 1 on success
+ * 0 on eof, when no data was read (errp is not set)
+ * negative errno on failure (errp is set)
+ */
+int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc,
+ NBDReply *reply, Error **errp)
+{
+ int ret;
+ const char *type;
+
+ ret = nbd_read_eof(bs, 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;
+}
+