similar to: ANNOUNCE: libnbd 1.4 - high performance NBD client library

Use the just-added nbd_opt_list_meta_context() API to give more details about each export (matching what 'qemu-nbd --list' already does). Note that this requires some shuffling: listing meta exports requires being in opt mode, but is easiest to do in list_one_export(), which requires setting opt_mode in more code paths, and deferring ready mode until the last possible minute during

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 the bare minimum needed to allow the user to take control over the rest of option negotiating. This patch adds several new API: nbd_set_opt_mode() - called during Created to enable the new mode nbd_get_opt_mode() - query whether opt mode is enabled nbd_opt_go() - used in Negotiating state to attempt to use export nbd_opt_abort() - used in Negotiating state to skip Connected state

With new-enough libnbd and our new dynamic-export mode, we can grab the export list from the server for replay to the client. Signed-off-by: Eric Blake <eblake@redhat.com> --- plugins/nbd/nbdkit-nbd-plugin.pod | 7 ++ tests/Makefile.am | 2 + plugins/nbd/nbd.c | 53 ++++++++++ tests/test-nbd-dynamic-content.sh | 2 +- tests/test-nbd-dynamic-list.sh

Squash this into opt_go? into opt_info? Standalone? Testing: why does python not throw an exception: $ ./run nbdsh Welcome to nbdsh, the shell for interacting with Network Block Device (NBD) servers. The ‘nbd’ module has already been imported and there is an open NBD handle called ‘h’. h.connect_tcp ("remote", "10809") # Connect to a remote server. h.get_size ()

On 8/11/20 12:38 PM, Eric Blake wrote: > On 8/11/20 12:12 PM, Richard W.M. Jones wrote: >> I think this needs extra documentation in docs/libnbd.pod because it's >> definitely not clear just from the rather thin manual page for >> set_opt_mode how it works.  docs/libnbd.pod is a good place for a >> broader description of how it works. > > Yes, good idea. >

This is the culmination of the previous patches' preparation work for using extended headers when possible. The new states in the state machine are copied extensively from our handling of OPT_STRUCTURED_REPLY. The next patch will then expose a new API nbd_opt_extended_headers() for manual control. At the same time I posted this patch, I had patches for qemu-nbd to support extended headers

Another series on top of my exportname filter, marking off another todo bullet point. With this, you can now use the NBD plugin as a transparent passthrough of all export names served by the remote server in both directions (list advertisement server to client, and export name from client to server). Eric Blake (3): nbd: Implement .default_export, .export_description nbd: Add

Right now, we require the user to supply potential metacontext names in advance, without knowing what the server actually supports until after the connection or nbd_opt_info call is complete. But the NBD protocol also supports a client being able to query what contexts a server supports, including where a client asks with a prefix and the server replies back with all answers that match the

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):

I'm pleased to announce a new high performance Network Block Device (NBD) client library called libnbd. It's written in C and there are also bindings available for Python, OCaml and (soon) Rust. 0.9.8 is the third pre-release before the stable 1.0 version where we freeze the API, so feedback on API-related issues is very welcome now. Download:

An upcoming commit will add the ability to query which meta contexts a server is advertising; but first we need to be able to present a different list of meta context requests in response to what we learn from the server. Add APIs for reviewing which requests have already been registered, as well as a way to reset the list of requests. This adds some testsuite coverage; and more will appear with

This continues the changes for adding NBD_OPT_LIST support. Now, instead of libnbd malloc'ing storage itself, the user passes a callback that can handle name/description pairs however it likes, and we get rid of the artificial cap at 10000 exports. However, the user will probably end up malloc'ing a list themselves, as we can't call nbd_set_export_name, or even request NBD_OPT_INFO

I think this needs extra documentation in docs/libnbd.pod because it's definitely not clear just from the rather thin manual page for set_opt_mode how it works. docs/libnbd.pod is a good place for a broader description of how it works. IIUC let me try to explain: we get through as far as the end of group OPT_STRUCTURED_REPLY before we check the opt flag, and then the remainder of opt

In v2: ack'ed preliminary patches have been pushed, and I've added a lot of testsuite coverage as well as putting the new API to use in nbdinfo. Eric Blake (2): api: Add nbd_opt_list_meta_context info: List available meta-contexts lib/internal.h | 1 + generator/API.ml | 84 ++++++++-

This continues the changes for adding NBD_OPT_LIST support. Now, instead of libnbd malloc'ing storage itself, the user passes a callback that can handle name/description pairs however it likes, and we get rid of the artificial cap at 10000 exports. However, the user will probably end up malloc'ing a list themselves, as we can't call nbd_set_export_name, or even request NBD_OPT_INFO

On 8/11/20 12:12 PM, Richard W.M. Jones wrote: > I think this needs extra documentation in docs/libnbd.pod because it's > definitely not clear just from the rather thin manual page for > set_opt_mode how it works. docs/libnbd.pod is a good place for a > broader description of how it works. Yes, good idea. State-wise, the existing flow was: Created - Progress only by command

When using nbdsh for scripting, it is convenient to let nbdsh fail with status 1 when encountering an API failure. However, doing so by letting the nbd.Error exception leak all the way causes ABRT (at least on Fedora 32 with abrt-python3-handler installed) to assume the program crashed from a programming error, and needlessly complicates clients to have to add try: blocks. Better is if nbdsh

When using nbdsh for scripting, it is convenient to let nbdsh fail with status 1 when encountering an API failure. However, doing so by letting the nbd.Error exception leak all the way causes ABRT (on Fedora 32 at least) to assume the program crashed from a programming error, and needlessly complicates clients to have to add try: blocks. Better is if nbdsh itself prints the same stack trace that

We discovered a possible Downgrade Attack in libnbd. Lifecycle --------- Reported: 2019-09-14 Fixed: 2019-09-16 Published: 2019-09-16 There is no CVE number assigned for this issue yet, but the bug is being categorized and processed by Red Hat's security team which may result in a CVE being published later. Description ----------- Libnbd includes the method nbd_set_tls(h,