qemu-nbd: Disallow listing exports

oVirt uses random URLs to expose images temporarily via HTTPS. We would like to integrated qemu-nbd in the same system, proving a user an easy and uniform way to access an image - either using HTTPS:

    https://server:54322/images/dc72d3cc-b933-45e8-89a2-e028e1c2ef3d

Or using NBD over TLS:

    nbd://server:10809/dc72d3cc-b933-45e8-89a2-e028e1c2ef3d

Unfortunatly, qemu-nbd allows listing exports by default. Allowing anyone to find the secret export using easy to guess port number.

These patches:
- add --nolist option to qemu-nbd, disabling NBD_OPT_LIST command.
- add some infrastructure ot iotests.py
- and use the new infrastructure to add test the new option using nbd-client.

Adding dependency on nbd-client may be probelematic, but I think qemu-nbd should have tests ensuring compatibility with other tools.

Nir Soffer (3):
nbd: Add option to disallow listing exports
iotests.py: Add helper for running commands
qemu-iotests: Test new qemu-nbd --nolist option

 blockdev-nbd.c                |  2 +-
 include/block/nbd.h           |  1 +
 nbd/server.c                  |  7 +++++++
 qemu-nbd.c                    |  9 ++++++++-
 qemu-nbd.texi                 |  2 ++
 tests/qemu-iotests/214        | 46 +++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/214.out    |  2 ++
 tests/qemu-iotests/group      |  1 +
 tests/qemu-iotests/iotests.py | 18 +++++++++++++++++
 9 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100755 tests/qemu-iotests/214
 create mode 100644 tests/qemu-iotests/214.out

2.14.3