carp: support VRRPv3

Allow carp(4) to use the VRRPv3 protocol (RFC 5798). We can distinguish carp and
VRRP based on the protocol version number (carp is 2, VRRPv3 is 3), and support
both from the carp(4) code.

Reviewed by: glebius
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D44774

Remove $FreeBSD$: two-line .h pattern

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

carp: support unicast

Allow users to configure the address to send carp messages to. This
allows carp to be used in unicast mode, which is useful in certain
virtual configurations (e.g. AWS, VMWare ESXi, ...)

Reviewed by: melifaro
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D38940

carp: add netlink interface

Allow carp configuration information to be supplied and retrieved via
netlink.

Reviewed by: melifaro
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D39048

libifconfig: Correct some typos in source code comments

- s/occured/occurred/
- s/the the/the/

MFC after: 3 days

libifconfig: Overhaul ifconfig_media_* interfaces

Define an ifmedia_t type to use for ifmedia words.

Add ifconfig_media_lookup_* functions to lookup ifmedia words by name.

Get media options as an array of option names rather than formatting it
as a comma-delimited list into a buffer.

Sprinkle const on static the static description tables for peace of
mind.

Don't need to zero memory allocated by calloc.

Reviewed by: kp
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D29029

libifconfig: Add a function to get down reason

For use in ifconfig.

Reviewed by: kp
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D28991

Move list_cloners to libifconfig

Move list_cloners() from ifconfig(8) to libifconfig(3) where it can be
reused by other consumers.

Reviewed by: kp
Differential Revision: https://reviews.freebsd.org/D26858

Move ifconfig SFP status functionality into libifconfig

libifconfig_sfp.h provides an API in libifconfig for querying SFP module
properties, operational status, and vendor strings, as well as descriptions
of the various fields, string conversions, and other useful helpers for
implementing user interfaces.

SFP module status is obtained by reading registers via an I2C interface.
Descriptions of these registers and the values therein have been collected
in a Lua table which is used to generate all the boilerplace C headers and
source files for accessing these values, their names, and descriptions.
The generated code is fully commented and readable.

This is the first use of libifconfig in ifconfig itself. For now, the
scope remains very limited. Over time, more of ifconfig will be replaced
with libifconfig.

Some minor changes to the formatting of ifconfig output have been made:
- Module memory hex dumps are indented one extra space as a result of using
hexdump(3) instead of a bespoke hex dump function.
- Media descriptions have an added two-character short-name in parenthesis.
- QSFP modules were incorrectly displaying TX bias current as power. Now
TX channels display bias current, and this change has been made for both
SFP and QSFP modules for consistency.

A Lua binding for libifconfig including this functionality is implemented
but has not been included in this commit. The plan is for it to be
committed after dynamic module loading has been enabled in flua.

Reviewed by: kp, melifaro
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D25494

libifconfig: Add function to get bridge status

The new function operates similarly to ifconfig_lagg_get_lagg_status and
likewise is accompanied by a function to free the bridge status data structure.

I have included in this patch the relocation of some strings describing STP
parameters and the PV2ID macro from ifconfig into net/if_bridgevar.h as they
are useful for consumers of libifconfig.

Reviewed by: kp, melifaro, mmacy
Approved by: mmacy (mentor)
MFC after: 1 week
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D25460

libifconfig: multiple feature additions

Added the ability to:

* Create virtual interfaces
* Create vlan interfaces
* Get interface fib
* Get interface groups
* Get interface status
* Get nd6 info
* Get media status
* Get additional ifaddr info in a convenient struct
* Get vhids
* Get carp info
* Get lagg and laggport status
* Iterate over all interfaces and ifaddrs

And add more examples, too.

Note that this is a backwards-incompatible change. But that's ok, because it's
a private library.

MFC after: 3 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D14463

libifconfig: allow to get original interface name via ifconfig_get_orig_name()

Uses the same method as in tools/tools/ifinfo/ifinfo.c
(via net.link.generic sysctl).

Tested with modified wlandebug(8).

Differential Revision: https://reviews.freebsd.org/D12554

libifconfig: style(9) fixes

Also switch from BSD 3-clause to 2-clause license where possible, and
consolidate duplicate 3-clause license into one.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
Reviewed by: cem, kp
Differential Revision: https://reviews.freebsd.org/D7764

Renaming libifc to libifconfig in response to feedback on initial commit of
this library. Sticking to 'libifconfig' (and 'ifconfig_' as function prefix)
should reduce chances of namespace collisions, make it more clear what the
library does, and be more in line with existing libraries.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
Differential Revision: https://reviews.freebsd.org/D7742
Reviewed by: cem, kp