spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

pf: Initial Ethernet level filtering code

This is the kernel side of stateless Ethernel level filtering for pf.

The primary use case for this is to enable captive portal functionality
to allow/deny access by MAC address, rather than per IP address.

Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D31737

pf: Introduce pf_nvbool()

Similar to the existing functions for strings and ints, this lets us
simplify some of the nvlist conversion code.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

pf: switch rule counters to pf_counter_u64

Reviewed by: kp
Sponsored by: Rubicon Communications, LLC ("Netgate")

pf: rename pf_state to pf_kstate

Indicate that this is a kernel-only structure, and make it easier to
distinguish from others used to communicate with userspace.

Reviewed by: mjg
MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D31096

pf: Move provider declaration to pf.h

This simplifies life a bit, by not requiring us to repease the
declaration for every file where we want static probe points.

It also makes the gcc6 build happy.

pf: Convenience function for optional (numeric) arguments

Add _opt() variants for the uint* functions. These functions set the
provided default value if the nvlist doesn't contain the relevant value.
This is helpful for optional values (e.g. when the API is extended to
add new fields).

While here simplify the header by also using macros to create the
prototypes for the macro-generated function implementations.

Reviewed by: scottl
MFC after: 2 weeks
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D30510

pf: Move nvlist conversion functions to pf_nv

Separate the conversion functions (between kernel structs and nvlists)
to pf_nv. This reduces the size of pf_ioctl.c, which is already quite
large and complex, a good bit. It also keeps all the fairly
straightforward conversion code together.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D30359

pf: Introduce DIOCCLRSTATESNV

Introduce an nvlist variant of DIOCCLRSTATES.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D30052

pf: Error tracing SDTs

Add additional DTrace static trace points to facilitate debugging
failing pf ioctl calls.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

pf: Implement nvlist variant of DIOCGETRULE

MFC after: 4 weeks
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D29559

pf: Introduce nvlist variant of DIOCADDRULE

This will make future extensions of the API much easier.
The intent is to remove support for DIOCADDRULE in FreeBSD 14.

Reviewed by: markj (previous version), glebius (previous version)
MFC after: 4 weeks
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D29557