/* 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;
}
/* 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)
{
nbd_option 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;
}
/* 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,
nbd_opt_reply *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;
}
be64_to_cpus(&reply->magic);
be32_to_cpus(&reply->option);
be32_to_cpus(&reply->type);
be32_to_cpus(&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 %x expected %x",
reply->option, 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, nbd_opt_reply *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 0x%" PRIx32
" (%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 0x%" PRIx32
" (%s) message",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg[reply->length] = '\0';
}
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 %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_INVALID:
error_setg(errp, "Invalid data length for option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_PLATFORM:
error_setg(errp, "Server lacks support for option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_TLS_REQD:
error_setg(errp, "TLS negotiation required before option %" PRIx32
" (%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 %" PRIx32 " (%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 %" PRIx32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
default:
error_setg(errp, "Unknown error code when asking for option %" PRIx32
" (%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;
}
