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

Make ppp WARNS=5 clean

Remove unused calls to inet_addr()

o Clean up some #includes
o Bump version number to 3.0.4
o When talking to a RADIUS server, provide a NAS-Port-Type.

When the NAS-Port-Type is Ethernet, provide a NAS-Port value equal
to the SESSIONID from the environment in direct mode or the
NGM_PPPOE_SESSIONID message in other modes. If no SESSIONID is found,
default to the interface index in client mode or zero in server mode.

When the NAS-Port-Type is ISDN, set the NAS-Port to the minor number
of the physical device (ie, the N in /dev/i4brbchN).

This makes it easier for the RADIUS server to identify the client
WRT accounting data etc.

Prompted by: lsz8425 <lsz8425@mail.cd.hn.cn>

Merge the NETGRAPH branch into HEAD. tty devices now use netgraph's line
discipline to do the async escaping, but no other benefits are available yet.

Change ``ifdef HAVE_DES'' to ``ifndef NODES'' for consistency.

Make the Makefile a little more sane WRT RELEASE_CRUNCH.

Detect if a udp socket on STDIN_FILENO is connected by calling
getpeername() and don't set PASSIVE mode if it's is.

socket()s first argument should be a protocol family rather than an
address family.

socket's first argument is an address family, not a protocol family.

Handle hardware-imposed MTU/MRU limitations. PPPoE will no longer
allow MRU/MTU negotiations to exceed 1492.

Add an optional ``max'' specifier to ``set m[rt]u'', ie.

set mtu max 1480

Bump the ppp version number.

Sponsored by: Monzoon Networks AG and FreeBSD Services Limited

Use fstat to check if descriptor 0 is a socket.

Suggested by: julian

Handle being given a connect()ed udp descriptor as stdin rather
than assuming it's unconnected.

Change ``set cd'' so that its default value is device specific. The
default is still 1 second for ttys, but is now 6 seconds for i4b (ISDN)
devices and 5 seconds for ethernet (PPPoE) devices.

Rewrite the link descriptor transfer code in MP mode.

Previously, ppp attempted to bind() to a local domain tcp socket
based on the peer authname & enddisc. If it succeeded, it listen()ed
and became MP server. If it failed, it connect()ed and became MP
client. The server then select()ed on the descriptor, accept()ed
it and wrote its pid to it then read the link data & link file descriptor,
and finally sent an ack (``!''). The client would read() the server
pid, transfer the link lock to that pid, send the link data & descriptor
and read the ack. It would then close the descriptor and clean up.

There was a race between the bind() and listen() where someone could
attempt to connect() and fail.

This change removes the race. Now ppp makes the RCVBUF big enough on a
socket descriptor and attempts to bind() to a local domain *udp* socket
(same name as before). If it succeeds, it becomes MP server. If it
fails, it sets the SNDBUF and connect()s, becoming MP client. The server
select()s on the descriptor and recvmsg()s the message, insisting on at
least two descriptors (plus the link data). It uses the second descriptor
to write() its pid then read()s an ack (``!''). The client creates a
socketpair() and sendmsg()s the link data, link descriptor and one of
the socketpair descriptors. It then read()s the server pid from the
other socketpair descriptor, transfers any locks and write()s an ack.

Now, there can be no race, and a connect() failure indicates a stale
socket file.

This also fixes MP ppp over ethernet, where the struct msghdr was being
misconstructed when transferring the control socket descriptor.

Also, if we fail to send the link, don't hang around in a ``session
owner'' state, just do the setsid() and fork() if it's required to
disown a tty.

UDP idea suggested by: Chris Bennet from Mindspring at FreeBSDCon

Support PPPoE

Help (lots) from: julian, archie
Facilities from: ahebert@pubnix.net

Back out the bogus #ifdef __NetBSD__ #include <signal.h> lines.
The original report was due to a mis-installation of the NetBS
header files :-/

Submitted by: Kazuyoshi Kato <kazk@yyy.or.jp>

NetBSD has moved ``extern int errno;'' to signal.h :-/

Submitted by: Kazuyoshi Kato <kazk@yyy.or.jp>

$Id$ -> $FreeBSD$

Add ISDN support via isdnd & i4b. This requires version
0.81.1 of the i4b code - namely support of the I4B_VR_REQ
ioctl via the i4brbchX device.

Ppp controls the phone number, but idle timers and
SYNC/RAW decisions are still made by isdnd (in isdnd.rc).

This involves a new datalink state machine phase. The
``wait for carrier'' phase happens after dialing but
before logging in. The whole dial state should really
be abstracted so that each device type can deal with it
in its own way (thinking about PPPoE) - but that'll have
to wait.

The ``set cd'' symantics remain the same for tty devices,
but we now delay until we either get CD or timeout waiting
(at which time we drop the link if we require CD).

For i4b devices we always insist on carrier.

Thanks to hm@ for his help, and especially for pointing out
that I *don't* need to re-implement isdnd (that was a huge
waste of time !) :-]

Correct the way ppp transfers links on the server side in MP
mode by padding out the ``struct device'' to the maximum
device size.
Bump the ppp version number to indicate the transfer format
change.

This should make MP over tty and udp devices functional again.

Correct the ``ignoring sync/async'' warnings so that they show
up with the correct device type.
Reassign the correct tcpdevice or execdevice after transfering
a link in MP server mode.

Allow ``host:port/udp'' devices and support ``host:port/tcp'' as
being the same as the previous (still supported) ``host:port''
syntax for tcp socket devices.

A udp device uses synchronous ppp rather than async, and avoids
the double-retransmit overhead that comes with ppp over tcp (it's
usually a bad idea to transport IP over a reliable transport that
itself is using an unreliable transport). PPP over UDP provides
througput of ** 1.5Mb per second ** with all compression disabled,
maxing out a PPro/200 when running ppp twice, back-to-back.

This proves that PPPoE is plausable in userland....

This change adds a few more handler functions to struct device and
allows derivations of struct device (which may contain their own
data etc) to pass themselves through the unix domain socket for MP.
** At last **, struct physical has lost all the tty crud !

iov2physical() is now smart enough to restore the correct stack of
layers so that MP servers will work again.

The version number has bumped as our MP link transfer contents have
changed (they now may contain a `struct device').

Don't extract the protocol twice in MP mode (resulting in protocol
rejects for every MP packet). This was broken with my original
layering changes.

Add ``Physical'' and ``Sync'' log levels for logging the relevent
raw packets and add protocol-tracking LogDEBUG stuff in various
LayerPush & LayerPull functions.

Assign our physical device name for incoming tcp connections by
calling getpeername().

Assign our physical device name for incoming udp connections from
the address retrieved by the first recvfrom().