sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

net: clean up empty lines in .c and .h files

sys: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Fix Dummynet AQM packet marking function ecn_mark() and fq_codel /
fq_pie schedulers packet classification functions in layer2 (bridge mode).

Dummynet AQM packet marking function ecn_mark() and fq_codel/fq_pie
schedulers packet classification functions (fq_codel_classify_flow()
and fq_pie_classify_flow()) assume mbuf is pointing at L3 (IP)
packet. However, this assumption is incorrect if ipfw/dummynet is
used to manage layer2 traffic (bridge mode) since mbuf will point
at L2 frame. This patch solves this problem by identifying the
source of the frame/packet (L2 or L3) and adding ETHER_HDR_LEN
offset when converting an mbuf pointer to ip pointer if the traffic
is from layer2. More specifically, in dummynet packet tagging
function, tag_mbuf(), iphdr_off is set to ETHER_HDR_LEN if the
traffic is from layer2 and set to zero otherwise. Whenever an access
to IP header is required, mtodo(m, dn_tag_get(m)->iphdr_off) is
used instead of mtod(m, struct ip *) to correctly convert mbuf
pointer to ip pointer in both L2 and L3 traffic.

Submitted by: lstewart
MFC after: 2 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D12506

Import Dummynet AQM version 0.2.1 (CoDel, FQ-CoDel, PIE and FQ-PIE).

Centre for Advanced Internet Architectures

Implementing AQM in FreeBSD

* Overview <http://caia.swin.edu.au/freebsd/aqm/index.html>

* Articles, Papers and Presentations
<http://caia.swin.edu.au/freebsd/aqm/papers.html>

* Patches and Tools <http://caia.swin.edu.au/freebsd/aqm/downloads.html>

Overview

Recent years have seen a resurgence of interest in better managing
the depth of bottleneck queues in routers, switches and other places
that get congested. Solutions include transport protocol enhancements
at the end-hosts (such as delay-based or hybrid congestion control
schemes) and active queue management (AQM) schemes applied within
bottleneck queues.

The notion of AQM has been around since at least the late 1990s
(e.g. RFC 2309). In recent years the proliferation of oversized
buffers in all sorts of network devices (aka bufferbloat) has
stimulated keen community interest in four new AQM schemes -- CoDel,
FQ-CoDel, PIE and FQ-PIE.

The IETF AQM working group is looking to document these schemes,
and independent implementations are a corner-stone of the IETF's
process for confirming the clarity of publicly available protocol
descriptions. While significant development work on all three schemes
has occured in the Linux kernel, there is very little in FreeBSD.

Project Goals

This project began in late 2015, and aims to design and implement
functionally-correct versions of CoDel, FQ-CoDel, PIE and FQ_PIE
in FreeBSD (with code BSD-licensed as much as practical). We have
chosen to do this as extensions to FreeBSD's ipfw/dummynet firewall
and traffic shaper. Implementation of these AQM schemes in FreeBSD
will:
* Demonstrate whether the publicly available documentation is
sufficient to enable independent, functionally equivalent implementations

* Provide a broader suite of AQM options for sections the networking
community that rely on FreeBSD platforms

Program Members:

* Rasool Al Saadi (developer)

* Grenville Armitage (project lead)

Acknowledgements:

This project has been made possible in part by a gift from the
Comcast Innovation Fund.

Submitted by: Rasool Al-Saadi <ralsaadi@swin.edu.au>
X-No objection: core
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D6388

fix various warnings (signed/unsigned, printf types, unused arguments)

Revert one chunk from commit 285362, which introduced an off-by-one error
in computing a shift index. The error was due to the use of mixed
fls() / __fls() functions in another implementation of qfq.
To avoid that the problem occurs again, properly document which
incarnation of the function we need.
Note that the bug only affects QFQ in FreeBSD head from last july, as
the patch was not merged to other versions.

assorted algorithmic fixes from Paolo Valente (one of my qfq coauthors):
- use 1ULL to avoid shift truncations
- recompute the sum of weight dynamically to provide better fairness
- fix an erroneous constant in the computation of the slot
- preserve timestamp correctness when the old timestamp is stale.

o Create directory sys/netpfil, where all packet filters should
reside, and move there ipfw(4) and pf(4).

o Move most modified parts of pf out of contrib.

Actual movements:

sys/contrib/pf/net/*.c -> sys/netpfil/pf/
sys/contrib/pf/net/*.h -> sys/net/
contrib/pf/pfctl/*.c -> sbin/pfctl
contrib/pf/pfctl/*.h -> sbin/pfctl
contrib/pf/pfctl/pfctl.8 -> sbin/pfctl
contrib/pf/pfctl/*.4 -> share/man/man4
contrib/pf/pfctl/*.5 -> share/man/man5

sys/netinet/ipfw -> sys/netpfil/ipfw

The arguable movement is pf/net/*.h -> sys/net. There are
future plans to refactor pf includes, so I decided not to
break things twice.

Not modified bits of pf left in contrib: authpf, ftp-proxy,
tftp-proxy, pflogd.

The ipfw(4) movement is planned to be merged to stable/9,
to make head and stable match.

Discussed with: bz, luigi