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nbd: negotiate with named exports 

Allow negotiation to receive the name of the requested export from
the client.  Passing a NULL export to nbd_client_new will cause
the server to send the extended negotiation header.  The exp field
is then filled during negotiation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-08-23 14:57:11 +02:00
parent ee0a19ec2a
commit 6b8c01e781
1 changed files with 150 additions and 19 deletions
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169
nbd.c
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@ -238,11 +238,23 @@ int unix_socket_outgoing(const char *path)
return unix_connect(path);
}
/* Basic flow
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
@ -250,20 +262,112 @@ int unix_socket_outgoing(const char *path)
...
...
Request (type == 2)
*/
static int nbd_receive_options(NBDClient *client)
{
int csock = client->sock;
char name[256];
uint32_t tmp, length;
uint64_t magic;
int rc;
/* Client sends:
[ 0 .. 3] reserved (0)
[ 4 .. 11] NBD_OPTS_MAGIC
[12 .. 15] NBD_OPT_EXPORT_NAME
[16 .. 19] length
[20 .. xx] export name (length bytes)
*/
rc = -EINVAL;
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed");
goto fail;
}
TRACE("Checking reserved");
if (tmp != 0) {
LOG("Bad reserved received");
goto fail;
}
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
goto fail;
}
TRACE("Checking reserved");
if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
LOG("Bad magic received");
goto fail;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed");
goto fail;
}
TRACE("Checking option");
if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
LOG("Bad option received");
goto fail;
}
if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
LOG("read failed");
goto fail;
}
TRACE("Checking length");
length = be32_to_cpu(length);
if (length > 255) {
LOG("Bad length received");
goto fail;
}
if (read_sync(csock, name, length) != length) {
LOG("read failed");
goto fail;
}
name[length] = '\0';
client->exp = nbd_export_find(name);
if (!client->exp) {
LOG("export not found");
goto fail;
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
TRACE("Option negotiation succeeded.");
rc = 0;
fail:
return rc;
}
static int nbd_send_negotiate(NBDClient *client)
{
int csock = client->sock;
char buf[8 + 8 + 8 + 128];
int rc;
const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
/* Negotiate
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
/* Negotiation header without options:
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
[16 .. 23] size
[24 .. 27] flags
[28 .. 151] reserved (0)
[24 .. 25] server flags (0)
[24 .. 27] export flags
[28 .. 151] reserved (0)
Negotiation header with options, part 1:
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_OPTS_MAGIC)
[16 .. 17] server flags (0)
part 2 (after options are sent):
[18 .. 25] size
[26 .. 27] export flags
[28 .. 151] reserved (0)
*/
socket_set_block(csock);
@ -271,16 +375,39 @@ static int nbd_send_negotiate(NBDClient *client)
TRACE("Beginning negotiation.");
memcpy(buf, "NBDMAGIC", 8);
cpu_to_be64w((uint64_t*)(buf + 8), NBD_CLIENT_MAGIC);
cpu_to_be64w((uint64_t*)(buf + 16), client->exp->size);
cpu_to_be32w((uint32_t*)(buf + 24),
client->exp->nbdflags | NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
if (client->exp) {
assert ((client->exp->nbdflags & ~65535) == 0);
cpu_to_be64w((uint64_t*)(buf + 8), NBD_CLIENT_MAGIC);
cpu_to_be64w((uint64_t*)(buf + 16), client->exp->size);
cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
} else {
cpu_to_be64w((uint64_t*)(buf + 8), NBD_OPTS_MAGIC);
}
memset(buf + 28, 0, 124);
if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
LOG("write failed");
goto fail;
if (client->exp) {
if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
LOG("write failed");
goto fail;
}
} else {
if (write_sync(csock, buf, 18) != 18) {
LOG("write failed");
goto fail;
}
rc = nbd_receive_options(client);
if (rc < 0) {
LOG("option negotiation failed");
goto fail;
}
assert ((client->exp->nbdflags & ~65535) == 0);
cpu_to_be64w((uint64_t*)(buf + 18), client->exp->size);
cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
if (write_sync(csock, buf + 18, sizeof(buf) - 18) != sizeof(buf) - 18) {
LOG("write failed");
goto fail;
}
}
TRACE("Negotiation succeeded.");
@ -673,8 +800,10 @@ void nbd_client_put(NBDClient *client)
qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL);
close(client->sock);
client->sock = -1;
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
}
g_free(client);
}
}
@ -1100,7 +1229,9 @@ NBDClient *nbd_client_new(NBDExport *exp, int csock,
qemu_co_mutex_init(&client->send_lock);
qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client);
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
nbd_export_get(exp);
if (exp) {
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
nbd_export_get(exp);
}
return client;
}