MFC r313979:

[ifconfig] fix a memory leak!

MFC r326276:

various: 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.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use nitems() from sys/param.h.

MFC after: 2 weeks.

Replace N #defines with nitems to simplify ifconfig code slightly

MFC after: 1 week

Add an option to limit the number of source MACs that can be behind a bridge
interface. Once the limit is reached packets with unknown source addresses are
dropped until an existing host cache entry expires or is removed. Useful to
use with the STICKY cache option.

Sponsored by: miniSuperHappyDevHouse NZ

Add a bridge interface flag called PRIVATE where any private port can not
communicate with another private port.

All unicast/broadcast/multicast layer2 traffic is blocked so it works much the
same way as using firewall rules but scales better and is generally easier as
firewall packages usually do not allow ARP blocking.

An example usage would be having a number of customers on separate vlans
bridged with a server network. All the vlans are marked private, they can all
communicate with the server network unhindered, but can not exchange any
traffic whatsoever with each other.

Approved by: re (rwatson)

Add the vlan tag to the bridge route table. This allows a vlan trunk to be
bridged, previously legitimate traffic was not passed as the bridge could not
tell that it was on a different Ethernet segment.

All non-tagged traffic is treated as vlan1 as per IEEE 802.1Q-2003

These days P2P means peer-2-peer (also well known from serveral filesharing
protocols) while PointToPoint has been PtP links. Change the variables
accordingly while the code is still fresh and undocumented.

Requested by: bz

Show the MAC address cache size and timeout.

Keep the command name the same as the values display name in ifconfig.

Sync with the OpenBSD port of RSTP
- use flags rather than sperate ioctls for edge, p2p
- implement p2p and autop2p flags
- define large pathcost constant as ULL
- show bridgeid and rootid in ifconfig

Obtained from: Reyk Floeter <reyk@openbsd.org>

Add a new address cache type called sticky. On an interface marked sticky any
address learned by the bridge is made permanent, the address will not age out
and most importantly will not migrate to another interface.

This can be used to stop mac address poisoning or clients roaming in much the
same way as static entries without the hassle of preloading the table.

Bring in support for the Rapid Spanning Tree Protocol (802.1w).

RSTP provides faster spanning tree convergence, the protocol will exchange
information with neighboring switches to quickly transition to forwarding
without creating loops. The code will default to RSTP mode but will downgrade
any port connected to a legacy STP network so is fully backward compatible.

Reviewed by: syrinx
Tested by: syrinx

Add support for creating span ports so that one can snoop bridged traffic
from another interface/machine/network.

Obtained from: OpenBSD
MFC after: 2 weeks

Display the status of the spanning tree for each port.

member: xl0 flags=7<LEARNING,DISCOVER,STP>
member: gem0 flags=7<LEARNING,DISCOVER,STP>
to:
member: xl0 flags=7<LEARNING,DISCOVER,STP>
port 3 priority 128 path cost 55 forwarding
member: gem0 flags=7<LEARNING,DISCOVER,STP>
port 1 priority 128 path cost 55 learning

Add if_bridge, which provides more advanced Ethernet bridging and 802.1d
spanning tree support.

Based on Jason Wright's bridge driver from OpenBSD, and modified by Jason R.
Thorpe in NetBSD.

Reviewed by: mlaier, bms, green
Silence from: -net
Approved by: mlaier (mentor)
Obtained from: NetBSD