NBD_OPT_EXPORT_NAME is lousy: it requires us to close the connection
rather than report an error. Upstream NBD recently added NBD_OPT_GO
as the improved version of the option that does what we want, along
with NBD_OPT_INFO that returns the same information but does not
transition to transmission phase.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
nbd/server.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 109 insertions(+), 13 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index 379df8c..e68e83c 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -233,17 +233,19 @@ static int nbd_negotiate_send_rep(QIOChannel *ioc,
uint32_t type, uint32_t opt)
return nbd_negotiate_send_rep_len(ioc, type, opt, 0);
}
-/* Send an NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
+/* Send the common part of an NBD_REP_SERVER reply for the given option,
+ * and include extra_len in the advertised payload.
* Return -errno to kill connection, 0 to continue negotiation */
-static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
+static int nbd_negotiate_send_rep_server(QIOChannel *ioc, NBDExport *exp,
+ uint32_t opt, uint32_t extra_len)
{
uint32_t len;
int rc;
TRACE("Advertising export name '%s'", exp->name ? exp->name : "");
len = strlen(exp->name);
- rc = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST,
- len + sizeof(len));
+ rc = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, opt,
+ len + sizeof(len) + extra_len);
if (rc < 0) {
return rc;
}
@@ -261,6 +263,15 @@ static int nbd_negotiate_send_rep_list(QIOChannel *ioc,
NBDExport *exp)
return 0;
}
+/* Send an NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
+ * Return -errno to kill connection, 0 to continue negotiation. */
+static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
+{
+ return nbd_negotiate_send_rep_server(ioc, exp, NBD_OPT_LIST, 0);
+}
+
+/* Send a sequence of replies to NBD_OPT_LIST.
+ * Return -errno to kill connection, 0 to continue negotiation. */
static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
{
NBDExport *exp;
@@ -283,6 +294,8 @@ static int nbd_negotiate_handle_list(NBDClient *client,
uint32_t length)
return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
}
+/* Send a reply to NBD_OPT_EXPORT_NAME.
+ * Return -errno to kill connection, 0 to end negotiation. */
static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
{
int rc = -EINVAL;
@@ -318,6 +331,73 @@ fail:
}
+/* Handle NBD_OPT_INFO and NBD_OPT_GO.
+ * Return -errno to kill connection, 0 if ready for next option, and 1
+ * to move into transmission phase. */
+static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,
+ uint32_t opt, uint16_t myflags)
+{
+ int rc;
+ char name[NBD_MAX_NAME_SIZE + 1];
+ NBDExport *exp;
+ uint64_t size;
+ uint16_t flags;
+
+ /* Client sends:
+ [20 .. xx] export name (length bytes)
+ */
+ TRACE("Checking length");
+ if (length >= sizeof(name)) {
+ if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
+ return -EIO;
+ }
+ return nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_INVALID, opt);
+ }
+ if (nbd_negotiate_read(client->ioc, name, length) != length) {
+ LOG("read failed");
+ return -EIO;
+ }
+ name[length] = '\0';
+
+ TRACE("Client requested info on export '%s'", name);
+
+ exp = nbd_export_find(name);
+ if (!exp) {
+ return nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_UNKNOWN, opt);
+ }
+
+ QEMU_BUILD_BUG_ON(NBD_FINAL_REPLY_SIZE != sizeof(size) + sizeof(flags));
+ rc = nbd_negotiate_send_rep_server(client->ioc, exp, opt,
+ NBD_FINAL_REPLY_SIZE);
+ if (rc < 0) {
+ return rc;
+ }
+
+ assert((exp->nbdflags & ~65535) == 0);
+ size = cpu_to_be64(exp->size);
+ flags = cpu_to_be16(exp->nbdflags | myflags);
+
+ if (nbd_negotiate_write(client->ioc, &size, sizeof(size)) !=
+ sizeof(size)) {
+ LOG("write failed");
+ return -EIO;
+ }
+ if (nbd_negotiate_write(client->ioc, &flags, sizeof(flags)) !=
+ sizeof(flags)) {
+ LOG("write failed");
+ return -EIO;
+ }
+
+ if (opt == NBD_OPT_GO) {
+ client->exp = exp;
+ QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
+ nbd_export_get(client->exp);
+ rc = 1;
+ }
+ return rc;
+}
+
+
static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
uint32_t length)
{
@@ -366,7 +446,10 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient
*client,
}
-static int nbd_negotiate_options(NBDClient *client)
+/* Loop over all client options, during fixed newstyle negotiation.
+ * Return -errno to kill connection, 0 on successful NBD_OPT_EXPORT_NAME,
+ * 1 on successful NBD_OPT_GO. */
+static int nbd_negotiate_options(NBDClient *client, uint16_t myflags)
{
uint32_t flags;
bool fixedNewstyle = false;
@@ -480,6 +563,16 @@ static int nbd_negotiate_options(NBDClient *client)
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, length);
+ case NBD_OPT_INFO:
+ case NBD_OPT_GO:
+ ret = nbd_negotiate_handle_info(client, length, clientflags,
+ myflags);
+ if (ret) {
+ assert(ret < 0 || clientflags == NBD_OPT_GO);
+ return ret;
+ }
+ break;
+
case NBD_OPT_STARTTLS:
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
@@ -584,18 +677,21 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData
*data)
LOG("write failed");
goto fail;
}
- rc = nbd_negotiate_options(client);
- if (rc != 0) {
+ rc = nbd_negotiate_options(client, myflags);
+ if (rc < 0) {
LOG("option negotiation failed");
goto fail;
}
- stq_be_p(buf + 18, client->exp->size);
- stw_be_p(buf + 26, client->exp->nbdflags | myflags);
- len = client->no_zeroes ? 10 : sizeof(buf) - 18;
- if (nbd_negotiate_write(client->ioc, buf + 18, len) != len) {
- LOG("write failed");
- goto fail;
+ if (!rc) {
+ /* If options ended with NBD_OPT_GO, we already sent this. */
+ stq_be_p(buf + 18, client->exp->size);
+ stw_be_p(buf + 26, client->exp->nbdflags | myflags);
+ len = client->no_zeroes ? 10 : sizeof(buf) - 18;
+ if (nbd_negotiate_write(client->ioc, buf + 18, len) != len) {
+ LOG("write failed");
+ goto fail;
+ }
}
}
--
2.5.5
