diff options
| -rw-r--r-- | nbd/client.c | 126 | ||||
| -rw-r--r-- | nbd/nbd-internal.h | 3 | ||||
| -rw-r--r-- | nbd/trace-events | 3 |
3 files changed, 130 insertions, 2 deletions
diff --git a/nbd/client.c b/nbd/client.c index a443e51aa0..1e98ca9613 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -350,6 +350,114 @@ static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match, } +/* 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) +{ + nbd_opt_reply 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 + 1); + stl_be_p(buf, len); + memcpy(buf + 4, wantname, len); + /* No requests, live with whatever server sends */ + stw_be_p(buf + 4 + len, 0); + if (nbd_send_option_request(ioc, NBD_OPT_GO, len + 6, buf, errp) < 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"); + nbd_send_opt_abort(ioc); + return -1; + } + if (!info->flags) { + error_setg(errp, "broken server omitted NBD_INFO_EXPORT"); + nbd_send_opt_abort(ioc); + return -1; + } + trace_nbd_opt_go_success(); + return 1; + } + if (reply.type != NBD_REP_INFO) { + error_setg(errp, "unexpected reply type %" PRIx32 ", expected %x", + reply.type, 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); + be16_to_cpus(&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; + } + be64_to_cpus(&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; + } + be16_to_cpus(&info->flags); + trace_nbd_receive_negotiate_size_flags(info->size, info->flags); + 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, @@ -531,11 +639,25 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, name = ""; } if (fixedNewStyle) { + int result; + + /* 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 good error reporting if the - * server required TLS + * query gives us better error reporting if the + * export name is not available. */ if (nbd_receive_query_exports(ioc, name, errp) < 0) { goto fail; diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h index bf95601ff5..4065bc68ac 100644 --- a/nbd/nbd-internal.h +++ b/nbd/nbd-internal.h @@ -37,8 +37,11 @@ * https://github.com/yoe/nbd/blob/master/doc/proto.md */ +/* Size of all NBD_OPT_*, without payload */ #define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4) +/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */ #define NBD_REPLY_SIZE (4 + 4 + 8) + #define NBD_REQUEST_MAGIC 0x25609513 #define NBD_REPLY_MAGIC 0x67446698 #define NBD_OPTS_MAGIC 0x49484156454F5054LL diff --git a/nbd/trace-events b/nbd/trace-events index 5230c61ab1..bd09fab375 100644 --- a/nbd/trace-events +++ b/nbd/trace-events @@ -3,6 +3,9 @@ nbd_unknown_error(int err) "Squashing unexpected error %d to EINVAL" nbd_send_option_request(uint32_t opt, const char *name, uint32_t len) "Sending option request %" PRIu32" (%s), len %" PRIu32 nbd_receive_option_reply(uint32_t option, const char *optname, uint32_t type, const char *typename, uint32_t length) "Received option reply %" PRIx32" (%s), type %" PRIx32" (%s), len %" PRIu32 nbd_reply_err_unsup(uint32_t option, const char *name) "server doesn't understand request %" PRIx32 " (%s), attempting fallback" +nbd_opt_go_start(const char *name) "Attempting NBD_OPT_GO for export '%s'" +nbd_opt_go_success(void) "Export is good to go" +nbd_opt_go_info_unknown(int info, const char *name) "Ignoring unknown info %d (%s)" nbd_receive_query_exports_start(const char *wantname) "Querying export list for '%s'" nbd_receive_query_exports_success(const char *wantname) "Found desired export name '%s'" nbd_receive_starttls_request(void) "Requesting TLS from server" |