Libguestfs - May 2016 - [PATCH] protocol: Ignore rest of option when replying with error

We must consume the payload of any option received, whether or
not we can answer the option successfully, in order to be in
sync for reading the next option.  This is particularly true
once clients start using NBD_OPT_GO, as long as we don't happen
to service that option.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 src/connections.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/connections.c b/src/connections.c
index 0c93f35..840e315 100644
--- a/src/connections.c
+++ b/src/connections.c
@@ -334,6 +334,10 @@ _negotiate_handshake_newstyle_options (struct connection
*conn)
         if (send_newstyle_option_reply (conn, option, NBD_REP_ERR_INVALID)
             == -1)
           return -1;
+        if (xread (conn->sockin, data, optlen) == -1) {
+          nbdkit_error ("read: %m");
+          return -1;
+        }
         continue;
       }

@@ -351,6 +355,10 @@ _negotiate_handshake_newstyle_options (struct connection
*conn)
       /* Unknown option. */
       if (send_newstyle_option_reply (conn, option, NBD_REP_ERR_UNSUP) == -1)
         return -1;
+      if (xread (conn->sockin, data, optlen) == -1) {
+        nbdkit_error ("read: %m");
+        return -1;
+      }
     }

     /* Note, since it's not very clear from the protocol doc, that the
-- 
2.5.5

On Fri, May 20, 2016 at 08:04:05AM -0600, Eric Blake
wrote:
> We must consume the payload of any option received, whether or
> not we can answer the option successfully, in order to be in
> sync for reading the next option.  This is particularly true
> once clients start using NBD_OPT_GO, as long as we don't happen
> to service that option.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
Thanks Eric, I have pushed this.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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