New features

New nbdkit-ssh-plugin(1) which lets you turn any disk image on a remote Unix server accessible by ssh into an NBD source.

New nbdkit-rate-filter(1) for bandwidth-limiting connections. Either single connections or the whole server can be bandwidth-limited, and the limit can be dynamically changed at runtime.

New nbdkit-readahead-filter(1) improves performance when reading sequentially from plugins with a high request overhead like curl.

New nbdkit-linuxdisk-plugin(1) lets you create complete ext2, ext3 or ext4 filesystems in a GPT partitioned disk image, from a local directory. This can be attached to existing Linux VMs or used to create new ones from scratch.

New nbdkit-noextents-filter(1) can make sparse disks appear fully allocated.

Plugins can now be written in the Rust programming language, see nbdkit-rust-plugin(3).

The old nbdkit-xz-plugin has been removed. Use

 nbdkit --filter=xz file file.xz

as a replacement. This filter can be placed on top of other plugins such as curl (for decompressing a remote web URL).

"NBD_CMD_BLOCK_STATUS" has been implemented allowing clients to query which parts of the disk are allocated, holes or zeroes. Plugins and filters have been extended to supply this information in many cases. This required adding minimal support for NBD protocol Structured Replies, "NBD_CMD_FLAG_REQ_ONE" and "NBD_CMD_FLAG_DF". (Thanks to Eric Blake for extensive help with this one.)

nbdkit-vddk-plugin(1) has been updated to VDDK 6.7, but now also works back as far as VDDK 5.1.1. It supports extents, flush and FUA. Also added: new flags "single-link" and "unbuffered". (Thanks to Martin Kletzander).

The line "All rights reserved." was removed from the license, with the agreement of all nbdkit contributors. Note this does not change the license.

"nbdkit_error" errors are printed in red when writing to the terminal, making them much easier to see.

"nbdkit_parse_size" rejects negative values, eg. "nbdkit memory size=-100" (Nikolay Ivanets).

nbdkit-curl-plugin(1) now supports cookies, password auth and proxies. It can also limit URLs to whitelisted protocols. This makes it broadly feature equivalent to and a replacement for the qemu curl block driver.

nbdkit-partitioning-plugin(1) can now create MBR logical partitions. Previously it only supported 4 MBR primary partitions and if you wanted more than that you had to use GPT.

nbdkit-partition-filter(1) also supports MBR logical partitions.

nbdkit-python-plugin(3) creates plugins which are compatible with Python >= 3.7.

Tests are now run under "MALLOC_CHECK_=1" and "MALLOC_PERTURB_=random". This causes some tests to crash (silently) because of a shutdown race which needs to be fixed.

Test shell scripts now have a generic "requires" function to skip tests if features are not present.

C99 type "bool" is now used in most places where appropriate.

The protocol and connections code in the server has been split up because the single file had grown very large. (Thanks to Eric Blake for helping with protocol issues).