Fix multiple bugs with ctld's UCL parsing

* Don't segfault when parsing a misformatted auth-group section
* If the config file specifies a chap section within a target but no
auth-group, create a new anonymous auth-group. That matches the
behavior with non-UCL config files.
* Protect some potential segfaults with assertions

PR: 274380
MFC after: 1 week
Sponsored by: Axcient
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D43198

Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

Fix an early return in ctld UCL parser

If the UCL ctld parser encountered a port that used the CTL
ioctl device, it fell into a special case that had an erroneous
early return. This caused all configuration in the target
following the port attribute to be skipped. Fix this by replacing
the return with a continue so that the rest of the config is
parsed correctly.

Sponsored by: Dell EMC Isilon
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D31703
Reviewed by: bapt

Add network QoS support for PCP to iscsi target.

Mak the Ethernet PCP codepoint configurable
for L2 local traffic, to allow lower latency for
iSCSI block IO. This addresses the target
side only.

Reviewed by: mav, trasz, bcr
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D26740

Add DSCP support for network QoS to iscsi target.

In order to prioritize iSCSI traffic across a network,
DSCP can be used. In order not to rely on "ipfw setdscp"
or in-network reclassification, this adds the dscp value
directly to the portal group (where TCP sessions are accepted).

The incoming iSCSI session is first handled by ctld for any
CHAP authentication and the socket is then handed off to the
in-kernel iscsi driver without modification of the socket
parameters. Simply setting up the socket in ctld is sufficient
to keep sending outgoing iSCSI related traffic with the
configured DSCP value.

Reviewed by: mav, trasz
MFC after: 2 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D26385

ctld: Fix a memory leak in uclparse_conf().

PR: 246596
Submitted by: Patryk <patrykkotlowski@gmail.com>
MFC after: 1 week

Rework CTL frontend & backend options to use nv(3), allow creating multiple
ioctl frontend ports.

This revision introduces two changes to CTL:
- Changes the way options are passed to CTL_LUN_REQ and CTL_PORT_REQ ioctls.
Removes ctl_be_arg structure and associated logic and replaces it with
nv(3)-based logic for passing in and out arguments.
- Allows creating multiple ioctl frontend ports using either ctladm(8) or
ctld(8).
New frontend ports are represented by /dev/cam/ctl<pp>.<vp> nodes, eg /dev/cam/ctl5.3.
Those device nodes respond only to CTL_IO ioctl.

New command-line options for ctladm:
# creates new ioctl frontend port with using free pp and vp=0
ctladm port -c
# creates new ioctl frontend port with pp=10 and vp=0
ctladm port -c -O pp=10
# creates new ioctl frontend port with pp=11 and vp=12
ctladm port -c -O pp=11 -O vp=12
# removes port with number 4 (it's a "targ_port" number, not pp number)
ctladm port -r -p 4

New syntax for ctl.conf:
target ... {
port ioctl/<pp>
...
}

target ... {
port ioctl/<pp>/<vp>
...

Note: Most of this work was made by jceel@, thank you.

Submitted by: jceel
Reworked by: myself
Reviewed by: mav (earlier versions and recently during the rework)
Obtained from: FreeNAS and TrueOS
Relnotes: Yes
Sponsored by: iXsystems Inc.
Differential Revision: https://reviews.freebsd.org/D9299

Add missing SPDX tags for ctld(8).

MFC after: 2 weeks

Fix ctld segfaulting when using ucl conf file format and having duplicated
lun or target

Submitted by: Nikita Kozlov <nikita.kozlov at blade-group.com>
MFC after: 3 days
Sponsored by: blade
Differential Revision: https://reviews.freebsd.org/D12646

Add MAX_LUNS overflow safety checks.

While this MAX_LUNS limitation is too synthetic and should be removed,
it is better to enforce it while it is here.

MFC after: 2 weeks

Check value returned from ucl_parser_add_file().

Reviewed by: trasz
Approved by: trasz (mentor)
MFC after: 1 month
Sponsored by: iXsystems, Inc.

Add an additional, libucl-based configuration file parser to ctld.

Default ctld behavior remains unchanged - libucl parser can be selected
explicitly by adding -u switch to ctld command line.

Reviewed by: trasz
Approved by: trasz (mentor)
MFC after: 1 month
Relnotes: yes
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D4534