qemu-e2k/nbd/trace-events
Eric Blake ef8c887ee0 nbd/server: Fix structured read of length 0
The NBD spec was recently clarified to state that a read of length 0
should not be attempted by a compliant client; but that a server must
still handle it correctly in an unspecified manner (that is, either
a successful no-op or an error reply, but not a crash) [1].  However,
it also implies that NBD_REPLY_TYPE_OFFSET_DATA must have a non-zero
payload length, but our existing code was replying with a chunk
that a picky client could reject as invalid because it was missing
a payload (our own client implementation was recently patched to be
that picky, after first fixing it to not send 0-length requests).

We are already doing successful no-ops for 0-length writes and for
non-structured reads; so for consistency, we want structured reply
reads to also be a no-op.  The easiest way to do this is to return
a NBD_REPLY_TYPE_NONE chunk; this is best done via a new helper
function (especially since future patches for other structured
replies may benefit from using the same helper).

[1] https://github.com/NetworkBlockDevice/nbd/commit/ee926037

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171108215703.9295-8-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2017-11-09 10:25:11 -06:00

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# nbd/client.c
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 0x%" PRIx32" (%s), type 0x%" PRIx32" (%s), len %" PRIu32
nbd_reply_err_unsup(uint32_t option, const char *name) "server doesn't understand request 0x%" 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_opt_go_info_block_size(uint32_t minimum, uint32_t preferred, uint32_t maximum) "Block sizes are 0x%" PRIx32 ", 0x%" PRIx32 ", 0x%" PRIx32
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_new_client(void) "Setting up TLS"
nbd_receive_starttls_tls_handshake(void) "Starting TLS handshake"
nbd_receive_negotiate(void *tlscreds, const char *hostname) "Receiving negotiation tlscreds=%p hostname=%s"
nbd_receive_negotiate_magic(uint64_t magic) "Magic is 0x%" PRIx64
nbd_receive_negotiate_server_flags(uint32_t globalflags) "Global flags are 0x%" PRIx32
nbd_receive_negotiate_default_name(void) "Using default NBD export name \"\""
nbd_receive_negotiate_size_flags(uint64_t size, uint16_t flags) "Size is %" PRIu64 ", export flags 0x%" PRIx16
nbd_init_set_socket(void) "Setting NBD socket"
nbd_init_set_block_size(unsigned long block_size) "Setting block size to %lu"
nbd_init_set_size(unsigned long sectors) "Setting size to %lu block(s)"
nbd_init_trailing_bytes(int ignored_bytes) "Ignoring trailing %d bytes of export"
nbd_init_set_readonly(void) "Setting readonly attribute"
nbd_init_finish(void) "Negotiation ended"
nbd_client_loop(void) "Doing NBD loop"
nbd_client_loop_ret(int ret, const char *error) "NBD loop returned %d: %s"
nbd_client_clear_queue(void) "Clearing NBD queue"
nbd_client_clear_socket(void) "Clearing NBD socket"
nbd_send_request(uint64_t from, uint32_t len, uint64_t handle, uint16_t flags, uint16_t type, const char *name) "Sending request to server: { .from = %" PRIu64", .len = %" PRIu32 ", .handle = %" PRIu64 ", .flags = 0x%" PRIx16 ", .type = %" PRIu16 " (%s) }"
nbd_receive_simple_reply(int32_t error, const char *errname, uint64_t handle) "Got simple reply: { .error = %" PRId32 " (%s), handle = %" PRIu64" }"
nbd_receive_structured_reply_chunk(uint16_t flags, uint16_t type, const char *name, uint64_t handle, uint32_t length) "Got structured reply chunk: { flags = 0x%" PRIx16 ", type = %d (%s), handle = %" PRIu64 ", length = %" PRIu32 " }"
# nbd/common.c
nbd_unknown_error(int err) "Squashing unexpected error %d to EINVAL"
# nbd/server.c
nbd_negotiate_send_rep_len(uint32_t opt, const char *optname, uint32_t type, const char *typename, uint32_t len) "Reply opt=0x%" PRIx32 " (%s), type=0x%" PRIx32 " (%s), len=%" PRIu32
nbd_negotiate_send_rep_err(const char *msg) "sending error message \"%s\""
nbd_negotiate_send_rep_list(const char *name, const char *desc) "Advertising export name '%s' description '%s'"
nbd_negotiate_handle_export_name(void) "Checking length"
nbd_negotiate_handle_export_name_request(const char *name) "Client requested export '%s'"
nbd_negotiate_send_info(int info, const char *name, uint32_t length) "Sending NBD_REP_INFO type %d (%s) with remaining length %" PRIu32
nbd_negotiate_handle_info_requests(int requests) "Client requested %d items of info"
nbd_negotiate_handle_info_request(int request, const char *name) "Client requested info %d (%s)"
nbd_negotiate_handle_info_block_size(uint32_t minimum, uint32_t preferred, uint32_t maximum) "advertising minimum 0x%" PRIx32 ", preferred 0x%" PRIx32 ", maximum 0x%" PRIx32
nbd_negotiate_handle_starttls(void) "Setting up TLS"
nbd_negotiate_handle_starttls_handshake(void) "Starting TLS handshake"
nbd_negotiate_options_flags(uint32_t flags) "Received client flags 0x%" PRIx32
nbd_negotiate_options_check_magic(uint64_t magic) "Checking opts magic 0x%" PRIx64
nbd_negotiate_options_check_option(uint32_t option, const char *name) "Checking option 0x%" PRIx32 " (%s)"
nbd_negotiate_begin(void) "Beginning negotiation"
nbd_negotiate_old_style(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags 0x%x"
nbd_negotiate_new_style_size_flags(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags 0x%x"
nbd_negotiate_success(void) "Negotiation succeeded"
nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t type, uint64_t from, uint32_t len) "Got request: { magic = 0x%" PRIx32 ", .flags = 0x%" PRIx16 ", .type = 0x%" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }"
nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching clients to AIO context %p\n"
nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients from AIO context %p\n"
nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errname, int len) "Send simple reply: handle = %" PRIu64 ", error = %" PRIu32 " (%s), len = %d"
nbd_co_send_structured_done(uint64_t handle) "Send structured reply done: handle = %" PRIu64
nbd_co_send_structured_read(uint64_t handle, uint64_t offset, void *data, size_t size) "Send structured read data reply: handle = %" PRIu64 ", offset = %" PRIu64 ", data = %p, len = %zu"
nbd_co_send_structured_error(uint64_t handle, int err, const char *errname, const char *msg) "Send structured error reply: handle = %" PRIu64 ", error = %d (%s), msg = '%s'"
nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char *name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)"
nbd_co_receive_request_payload_received(uint64_t handle, uint32_t len) "Payload received: handle = %" PRIu64 ", len = %" PRIu32
nbd_co_receive_request_cmd_write(uint32_t len) "Reading %" PRIu32 " byte(s)"
nbd_trip(void) "Reading request"