search for: option_repli

Instead of repeating a check for valid reply headers in each sub-state machine, let's have a common helper function do all the work. Additionally, a central location will make it easier to uniformly capture any NBD_REP_ERR message payloads. --- generator/generator | 8 +-- generator/states-newstyle-opt-go.c | 40 +++----------

I'm still playing with ideas on how to split rstate from wstate (so that we can send a request without waiting for POLLIN to complete a pending reply), but this is some preliminary refactoring I found useful. I also fixed a couple of bugs while in the area (already pushed). There's a question of whether we want nbd_handle to be nearly 5k, or if we should instead keep it small and add one

This isn't quite finished because not all of the tests or examples have been updated, but it demonstrates an idea: Should we forget about the concept of having multiple connections managed under a single handle? In this patch there is a single ‘struct nbd_handle *’ which manages a single state machine and connection (and therefore no nbd_connection). To connect to a multi-conn server you must

Proposal for new APIs to list exports. The general shape of the API can probably best be seen from the examples/list-exports.c example. Rich.

Some of these affect attempts to connect to older qemu-nbd versions, some of them were triggered by manual edits to qemu-nbd source code to provoke various other compliant (if uncommon) server behaviors. Eric Blake (4): starttls: Skip error payload if falling back to unencrypted states: Reject payload to NBD_REP_ACK meta-context: Skip error payload if server lacks meta_context states: Add

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 +++ examples/list-exports.c | 108 +++++++++++++++++++

On 6/14/19 4:54 PM, Eric Blake wrote: > Similar to the earlier patch for structured reply errors, it's worth > logging (at least through debug) any error messages that the server > sends alongside NBD_REP_ERR. And given our earlier changes, it > doesn't really impact the size of struct nbd_handle. > --- > +++ b/generator/states-newstyle.c > @@ -77,6 +77,35 @@

Similar to the earlier patch for structured reply errors, it's worth logging (at least through debug) any error messages that the server sends alongside NBD_REP_ERR. And given our earlier changes, it doesn't really impact the size of struct nbd_handle. --- generator/states-newstyle-opt-go.c | 5 ++-- .../states-newstyle-opt-set-meta-context.c | 6 +++-

Simple refactoring. --- generator/states-newstyle-opt-export-name.c | 12 +++++------ generator/states-newstyle-opt-go.c | 13 ++++++------ generator/states-oldstyle.c | 10 +++------- lib/flags.c | 22 +++++++++++++++++++++ lib/internal.h | 5 +++++ 5 files changed, 42 insertions(+), 20 deletions(-) diff

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 ()

Drop the SET designation, so that we can reuse these states for OPT_LIST_META_CONTEXT in the next patch. --- generator/Makefile.am | 4 +-- generator/state_machine.ml | 6 ++--- ...t.c => states-newstyle-opt-meta-context.c} | 26 +++++++++---------- .../states-newstyle-opt-structured-reply.c | 4 +-- generator/states-newstyle.c

I'm posting this now, as I'm at the end of a workday and I got things working for manual experimentation. Still to do: - write interop tests for qemu-nbd and nbdkit (including my proposed patch addition of qemu-nbd -A to show qemu:allocation-depth) - figure out if we can make 'nbdinfo --map' use the new API to automatically select all contexts advertised by the server Eric Blake

Any server that sends a reply to NBD_OPT_* or NBD_CMD_* longer than the maximum length we are willing to use for NBD_CMD_{READ,WRITE} is probably broken; it is not worth waiting for read() to wait for that many bytes to arrive from the server to bring the connection back into sync for the next operation, so just declare it dead. It may be possible to provoke nbdkit into being such a server when

Per recent discussion here: https://www.redhat.com/archives/libguestfs/2019-May/thread.html#00175

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

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

An incremental improvement on top of listing exports. I still think it's worth experimenting with revisiting how our API for list mode should actually work [1] (so that we can reuse a single connection for both grabbing the list and finally using NBD_OPT_GO), but this change was easier to whip together while still thinking about that. [1]

Most of the states were calling SET_NEXT_STATE(%.DEAD) then using return -1 on error, to reflect the fact that they had also called set_error() and wanted the caller to notice the failure. Unfortunately, the state machine engine refuses to run the entry code of the next state when the current state returned -1, which meant the DEAD state entry code never runs. A concrete example of the problems

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

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