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nbd: Improve error messages
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This patch makes use of the Error object for nbd_receive_negotiate() so
that errors during negotiation look nicer.

Furthermore, this patch adds an additional error message if the received
magic was wrong, but would be correct for the other protocol version,
respectively: So if an export name was specified, but the NBD server
magic corresponds to an old handshake, this condition is explicitly
signaled to the user, and vice versa.

As these messages are now part of the "Could not open image" error
message, additional filtering has to be employed in iotest 083, which
this patch does as well.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@XanClic @kevmw
XanClic authored and kevmw committed Feb 6, 2015
1 parent a231cb2 commit 1ce5284
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Showing 8 changed files with 55 additions and 58 deletions.
4 changes: 2 additions & 2 deletions block/nbd-client.c
View file
Expand Up @@ -373,7 +373,7 @@ void nbd_client_session_close(NbdClientSession *client)
}

int nbd_client_session_init(NbdClientSession *client, BlockDriverState *bs,
int sock, const char *export)
int sock, const char *export, Error **errp)
{
int ret;

Expand All @@ -382,7 +382,7 @@ int nbd_client_session_init(NbdClientSession *client, BlockDriverState *bs,
qemu_set_block(sock);
ret = nbd_receive_negotiate(sock, export,
&client->nbdflags, &client->size,
&client->blocksize);
&client->blocksize, errp);
if (ret < 0) {
logout("Failed to negotiate with the NBD server\n");
closesocket(sock);
Expand Down
2 changes: 1 addition & 1 deletion block/nbd-client.h
View file
Expand Up @@ -36,7 +36,7 @@ typedef struct NbdClientSession {
} NbdClientSession;

int nbd_client_session_init(NbdClientSession *client, BlockDriverState *bs,
int sock, const char *export_name);
int sock, const char *export_name, Error **errp);
void nbd_client_session_close(NbdClientSession *client);

int nbd_client_session_co_discard(NbdClientSession *client, int64_t sector_num,
Expand Down
2 changes: 1 addition & 1 deletion block/nbd.c
View file
Expand Up @@ -271,7 +271,7 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
}

/* NBD handshake */
result = nbd_client_session_init(&s->client, bs, sock, export);
result = nbd_client_session_init(&s->client, bs, sock, export, errp);
g_free(export);
return result;
}
Expand Down
2 changes: 1 addition & 1 deletion include/block/nbd.h
View file
Expand Up @@ -75,7 +75,7 @@ enum {

ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, size_t *blocksize);
off_t *size, size_t *blocksize, Error **errp);
int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize);
ssize_t nbd_send_request(int csock, struct nbd_request *request);
ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply);
Expand Down
42 changes: 25 additions & 17 deletions nbd.c
View file
Expand Up @@ -494,7 +494,7 @@ static int nbd_send_negotiate(NBDClient *client)
}

int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, size_t *blocksize)
off_t *size, size_t *blocksize, Error **errp)
{
char buf[256];
uint64_t magic, s;
Expand All @@ -506,13 +506,13 @@ int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
rc = -EINVAL;

if (read_sync(csock, buf, 8) != 8) {
LOG("read failed");
error_setg(errp, "Failed to read data");
goto fail;
}

buf[8] = '\0';
if (strlen(buf) == 0) {
LOG("server connection closed");
error_setg(errp, "Server connection closed unexpectedly");
goto fail;
}

Expand All @@ -527,12 +527,12 @@ int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
qemu_isprint(buf[7]) ? buf[7] : '.');

if (memcmp(buf, "NBDMAGIC", 8) != 0) {
LOG("Invalid magic received");
error_setg(errp, "Invalid magic received");
goto fail;
}

if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
error_setg(errp, "Failed to read magic");
goto fail;
}
magic = be64_to_cpu(magic);
Expand All @@ -545,52 +545,60 @@ int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,

TRACE("Checking magic (opts_magic)");
if (magic != NBD_OPTS_MAGIC) {
LOG("Bad magic received");
if (magic == NBD_CLIENT_MAGIC) {
error_setg(errp, "Server does not support export names");
} else {
error_setg(errp, "Bad magic received");
}
goto fail;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("flags read failed");
error_setg(errp, "Failed to read server flags");
goto fail;
}
*flags = be16_to_cpu(tmp) << 16;
/* reserved for future use */
if (write_sync(csock, &reserved, sizeof(reserved)) !=
sizeof(reserved)) {
LOG("write failed (reserved)");
error_setg(errp, "Failed to read reserved field");
goto fail;
}
/* write the export name */
magic = cpu_to_be64(magic);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (magic)");
error_setg(errp, "Failed to send export name magic");
goto fail;
}
opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (opt)");
error_setg(errp, "Failed to send export name option number");
goto fail;
}
namesize = cpu_to_be32(strlen(name));
if (write_sync(csock, &namesize, sizeof(namesize)) !=
sizeof(namesize)) {
LOG("write failed (namesize)");
error_setg(errp, "Failed to send export name length");
goto fail;
}
if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
LOG("write failed (name)");
error_setg(errp, "Failed to send export name");
goto fail;
}
} else {
TRACE("Checking magic (cli_magic)");

if (magic != NBD_CLIENT_MAGIC) {
LOG("Bad magic received");
if (magic == NBD_OPTS_MAGIC) {
error_setg(errp, "Server requires an export name");
} else {
error_setg(errp, "Bad magic received");
}
goto fail;
}
}

if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
LOG("read failed");
error_setg(errp, "Failed to read export length");
goto fail;
}
*size = be64_to_cpu(s);
Expand All @@ -599,19 +607,19 @@ int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,

if (!name) {
if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
LOG("read failed (flags)");
error_setg(errp, "Failed to read export flags");
goto fail;
}
*flags = be32_to_cpup(flags);
} else {
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed (tmp)");
error_setg(errp, "Failed to read export flags");
goto fail;
}
*flags |= be32_to_cpu(tmp);
}
if (read_sync(csock, &buf, 124) != 124) {
LOG("read failed (buf)");
error_setg(errp, "Failed to read reserved block");
goto fail;
}
rc = 0;
Expand Down
7 changes: 6 additions & 1 deletion qemu-nbd.c
View file
Expand Up @@ -284,15 +284,20 @@ static void *nbd_client_thread(void *arg)
int fd, sock;
int ret;
pthread_t show_parts_thread;
Error *local_error = NULL;

sock = unix_socket_outgoing(sockpath);
if (sock < 0) {
goto out;
}

ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
&size, &blocksize);
&size, &blocksize, &local_error);
if (ret < 0) {
if (local_error) {
fprintf(stderr, "%s\n", error_get_pretty(local_error));
error_free(local_error);
}
goto out_socket;
}

Expand Down
3 changes: 2 additions & 1 deletion tests/qemu-iotests/083
View file
Expand Up @@ -56,7 +56,8 @@ filter_nbd() {
#
# Filter out the TCP port number since this changes between runs.
sed -e 's#^.*nbd\.c:.*##g' \
-e 's#nbd:127\.0\.0\.1:[^:]*:#nbd:127\.0\.0\.1:PORT:#g'
-e 's#nbd:127\.0\.0\.1:[^:]*:#nbd:127\.0\.0\.1:PORT:#g' \
-e 's#\(exportname=foo\|PORT\): Failed to .*$#\1#'
}

check_disconnect() {
Expand Down
51 changes: 17 additions & 34 deletions tests/qemu-iotests/083.out
View file
@@ -1,62 +1,52 @@
QA output created by 083
=== Check disconnect before neg1 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect after neg1 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 8 neg1 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 16 neg1 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect before export ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect after export ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 4 export ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 12 export ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 16 export ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect before neg2 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect after neg2 ===
Expand All @@ -66,14 +56,12 @@ read failed: Input/output error

=== Check disconnect 8 neg2 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect 10 neg2 ===


qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT:exportname=foo
no file open, try 'help open'

=== Check disconnect before request ===
Expand Down Expand Up @@ -119,32 +107,27 @@ read 512/512 bytes at offset 0

=== Check disconnect before neg-classic ===


qemu-io: can't open device nbd:127.0.0.1:PORT: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT
no file open, try 'help open'

=== Check disconnect 8 neg-classic ===


qemu-io: can't open device nbd:127.0.0.1:PORT: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT
no file open, try 'help open'

=== Check disconnect 16 neg-classic ===


qemu-io: can't open device nbd:127.0.0.1:PORT: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT
no file open, try 'help open'

=== Check disconnect 24 neg-classic ===


qemu-io: can't open device nbd:127.0.0.1:PORT: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT
no file open, try 'help open'

=== Check disconnect 28 neg-classic ===


qemu-io: can't open device nbd:127.0.0.1:PORT: Could not open image: Invalid argument
qemu-io: can't open device nbd:127.0.0.1:PORT
no file open, try 'help open'

=== Check disconnect after neg-classic ===
Expand Down

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