similar to: [nbdkit PATCH] connections: Be less noisy when client sends NBD_OPT_ABORT

qemu is about to add 'qemu-nbd --list', which exercises NBD_OPT_LIST and NBD_OPT_INFO to give the user as much detail as possible about an export without actually connecting to it. For that to display more than the export name when nbdkit is the server, we need to implement NBD_OPT_INFO. Thankfully, the NBD spec intentionally made the command very similar to NBD_OPT_GO, to the point that

--- src/connections.c | 233 +++++++++++++++++++++++++++++++++++++--------- src/protocol.h | 27 ++++-- 2 files changed, 209 insertions(+), 51 deletions(-) diff --git a/src/connections.c b/src/connections.c index ba6e91d..4e9b191 100644 --- a/src/connections.c +++ b/src/connections.c @@ -75,7 +75,9 @@ struct connection { void **handles; size_t nr_handles; + uint32_t cflags;

Fuzzing with afl found a bug where a 27 byte client sequence can cause nbdkit to report a strange error message: $ printf %s $'000\1IHAVEOPT000\6'$'000\7'$'000\1x00' | tr 0 '\0' | ./nbdkit -s memory size=1m >/dev/null nbdkit: memory: error: client exceeded maximum number of options (32) The culprit? The client is hanging up on a message boundary, so

The code handling the NBD protocol was located in the same file as the code handling connections, for not really any reason except historical. This is quite a large code movement which splits out the protocol code into four new files: server/protocol-handshake.c initial handshake server/protocol-handshake-newstyle.c " " (newstyle)

On Fri, Aug 14, 2020 at 05:00:25PM -0500, Eric Blake wrote: > diff --git a/lib/internal.h b/lib/internal.h > index 5f495fb..03baacd 100644 > --- a/lib/internal.h > +++ b/lib/internal.h > @@ -101,6 +101,7 @@ struct nbd_handle { > > /* Option negotiation mode. */ > bool opt_mode; > + uint8_t current_opt; Be nice to add a comment here about what current_opt can

Experimental and only very lightly tested so far. Rich.

With some crufty sed scripts we can generate functions that map from NBD protocol flags (eg. NBD_CMD_READ) to strings ("NBD_CMD_READ"). This works on GNU sed and with FreeBSD, also with GNU sed's --posix option, so I guess the sed code is POSIX-compatible. Rich.

On Mon, Jun 12, 2023 at 07:27:52PM +0100, Richard W.M. Jones wrote: > This change avoids the following harmless but annoying warning on the > normal exit path: > > libnbd: debug: nbd1: nbd_opt_abort: enter: > libnbd: debug: nbd1: nbd_opt_abort: leave: error="nbd_opt_abort: invalid state: READY: the handle must be negotiating: Invalid argument" > --- > info/main.c |

This is only lightly tested (against just qemu NBD client), and the code might be structured a little better as the _negotiate_handshake_newstyle_options function has now grown to be huge. Anyway works for me. Rich.

There's no substantial difference over v1, I simply fixed a few whitespace issues, moved one struct around and tidied up the comments. Rich.

It is finally time to introduce our first negotiating option command. With this change, we can now enter NEWSTYLE.START more than once; as such, it needs to know whether it is the first entry (proceed with gflags/cflags, TLS, and structured reply) or a later entry (all nbd_opt_* will cause an IssueCommand event to kick the state machine out of NEGOTIATING, at which point we want to jump to the

This is about the simplest implementation of NBD Structured Replies (SR) that we can do right now. It accepts NBD_OPT_STRUCTURED_REPLIES when negotiated by the client, but only sends back the simplest possible SR when required to by NBD_CMD_READ. The rest of the time it will send back simple replies as before. We do not modify the plugin API so plugins are unable to send complex SRs. Also we

These are a couple of patches in preparation for the Block Status implementation. While the patches (especially the second one) are very large they are really just elementary code motion. Rich.

If a plugin's .open or .get_size or .can_write fails, right now that is fatal to the connection. When nbdkit was first implemented, this made sense (there was no way to report errors to oldstyle or NBD_OPT_EXPORT_NAME). But now that newstyle is around, it's rather abrupt to hang up on the client, and better is to return an error to NBD_OPT_GO, and let the client choose what to do (most

None are supported at present, so this always returns an empty list. --- docs/nbdkit-protocol.pod | 4 ++ server/protocol.h | 2 + server/connections.c | 84 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 90 insertions(+) diff --git a/docs/nbdkit-protocol.pod b/docs/nbdkit-protocol.pod index 68438fa..4c65e00 100644 --- a/docs/nbdkit-protocol.pod +++

On 7/20/20 9:43 AM, Richard W.M. Jones wrote: > A major missing feature of this library was the ability to list > exports from an NBD server. This implements the feature by adding a > new handle mode and additional functions for querying the list of > export names. > --- > .gitignore | 1 + > examples/Makefile.am | 14

Since commit 86fdb48c6a5362d66865493d9d2172166f99722e we have stored the connection object in thread-local storage. In this very large, but mostly mechanical change we stop passing the connection pointer around everywhere, and instead use the value stored in thread-local storage. This assumes a 1-1 mapping between the connection and the current thread which is true in *most* places.

Up to nbdkit 1.22, we never advertised large export lists, so a client had no real reason to give more than 32 NBD_OPT_ commands before finally selecting an export or quitting, and we were justified in dropping indecisive chatty clients as being a waste of server resources. But now that we support .list_exports, it is reasonable for a client (such as 'qemu-nbd --list' or 'nbdinfo

Well, I'm not quite done (I still want to get nbdinfo to work on a single nbd connection for all cases when reading the heads of the file is not required), but I'm happy with patches 1-11, and 12-13 show where I'm headed for getting NBD_OPT_INFO to work. Posting now to see if some of the earlier patches are ready to commit while I continue working on the latter half. Eric Blake (13):

This generates small functions which map from various integer NBD protocol flags to the string equivalent. eg: name_of_nbd_cmd (NBD_CMD_READ) ---> "NBD_CMD_READ" This commit uses some hairy sed scripting to ensure that we don't add any more dependencies to nbdkit. --- src/protocol.h | 9 +++++++ .gitignore | 1 + src/Makefile.am | 17