similar to: [PATCH] Add support for newstyle NBD protocol (RHBZ#1297100).

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.

We should have only one NBD protocol file. Let's make nbdkit's version the canonical one, and use it in libnbd. 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.

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.

More nbd-protocol.h improvements Eric Blake (2): common/protocol: Switch nbdmagic to uint64_t common/protocol: Declare additional constants common/protocol/nbd-protocol.h | 16 ++++++++++------ server/protocol-handshake-newstyle.c | 2 +- server/protocol-handshake-oldstyle.c | 2 +- plugins/nbd/nbd-standalone.c | 2 +- tests/test-layers.c | 2 +- 5 files

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

This time around, the numbers are indeed looking better than in v1; and I like the interface better. Eric Blake (2): server: Prefer send() over write() server: Group related transmission send()s server/internal.h | 7 +++- server/connections.c | 51 +++++++++++++++++++++++++--- server/crypto.c | 11 ++++--

v1 was here: https://www.redhat.com/archives/libguestfs/2020-February/msg00081.html v2 replaces struct connection *conn = GET_CONN; with GET_CONN; which sets conn implicitly and asserts that it is non-NULL. If we actually want to test if conn is non-NULL or behave differently, then you must use threadlocal_get_conn() instead, and some existing uses do that. Rich.

The third patch is a large but mechanical change which gets rid of passing around struct connection * entirely within the server, preferring instead to reference the connection through thread-local storage. I hope this is a gateway to simplifying other parts of the code. Rich.

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

Diff against libnbd’s copy of this file, and change this one until it matches. --- common/protocol/nbd-protocol.h | 76 +++++++++++++++++----------- server/protocol-handshake-newstyle.c | 26 +++++----- server/protocol-handshake-oldstyle.c | 4 +- server/protocol.c | 25 ++++----- tests/test-layers.c | 14 ++--- 5 files changed, 81 insertions(+), 64

Patch 1 played with an early draft of Rich's Fedora 30 libnbd package: https://bugzilla.redhat.com/show_bug.cgi?id=1713767#c17 Note that comment 21 provides a newer package 0.1.1-1 with a different API; and that libnbd has more unreleased API changes in the pipeline (whether that will be called 0.2 or 0.1.2); so we'll have to tweak things based on what is actually available in distros.

libnbd-0.1.2-1 is now available in Fedora 29/30 updates-testing, although it was not compiled against libxml2 so it lacks uri support (I ended up testing patch 4 with a self-built libnbd). Diffs since v1 - rebase to master, bump from libnbd 0.1 to 0.1.2, add URI support, better timing results Still not done - patch 5 needs associated tests Eric Blake (5): nbd: Check for libnbd nbd:

Updated based on other changes that have happened in the meantime: - rely more on cleanup.h (throughout) - split structured read for easier review (patch 2 and 3 were combined in v1) - rely on nbdkit not leaking a server's partial answer (patch 3) - add tests (patch 5) - other bug fixes I found while testing it - drop EOVERFLOW patch for now; it will be separate once upstream NBD protocol

Since the v1 series (0/4, at [1]), I've applied patches 1 and 2, rewritten patch 3 [Forbid NUL in export and context names] into patch 4 here, patch 4 there turned into patch 6 here, and everything else here is new. [1]https://www.redhat.com/archives/libguestfs/2019-September/msg00180.html I don't know if there is a handy reusable function for checking whether a string contains valid

libnbd-0.1.4-1 is now available in Fedora 29/30 updates testing. Diffs since v2 - rebase to master, bump from libnbd 0.1.2 to 0.1.3+, add tests to TLS usage which flushed out the need to turn relative pathnames into absolute, doc tweaks Now that the testsuite covers TLS and libnbd has been fixed to provide the things I found lacking when developing v2, I'm leaning towards pushing this on

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)

I'm hoping to implement .extents for the nbd plugin; this is a prerequisite. I'm not sure about patch 3 - if we like it, I'll squash it to 2, if we don't, I think we are okay just dropping it. I'm also wondering if we have to worry about malicious plugins that don't populate the entire .pread buffer in an effort to get nbdkit to expose portions of the heap; my patch 7 loses

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.

I'm still working on the interleaving (and Rich reminded me on IRC that we still don't have THREAD_MODEL_PARALLEL working anywhere yet, anyways). Since nbdkit doesn't really have a parallel plugin yet, my testing on that front will have to use qemu-nbd as the original server, as well as qemu-io as the driver (qemu-io's aio_read and aio_write commands can be used to trigger