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

Add a ``log'' command for logging specific information.
Add an ``UPTIME'' variable to indicate the bundle uptime.

It's now possible to put something like this in ppp.linkdown
for a server setup:

MYADDR:
log Session closing: User USER, address HISADDR, up UPTIME

Fixed some memory leakage with commands that expand words.
Made some functions static.
Fixed a diagnostic bug (iface add .... SIOCDIFADDR)

Convert IIJ copyrights to BSD copyrights.

Approved by: Toshiharu OHNO <tohno@sirius.ocn.ne.jp>

Understand environment variables in commands

Submitted by: Mark Knight <markk@knigma.org>

$Id$ -> $FreeBSD$

Allow multiple systems (config labels) on the command
line and in the ``load'' & ``dial'' commands. The last
label loaded becomes the current label name.
Only require a label for -auto mode.

Give ``load'' optional context. It's now possible to
``link 1,2,3 load label'' for people that want to set
up their links in a more mpd-like manner.

MFMP: Make ppp multilink capable.
See the file README.changes, and re-read the man page.

Fix prototypes.
Remove extraneous decls.
Add ``const'' to several places.
Allow ``make NOALIAS=1'' to remove IP aliasing.
Merge with OpenBSD - only the Makefiles vary.

We can now survive a compile with
-Wall -Wbad-function-cast -Wcast-align -Wcast-qual
-Winline -Wmissing-declarations -Wmissing-prototypes
-Wnested-externs -Wpointer-arith -Wredundant-decls
-Wshadow -Wstrict-prototypes -Wwrite-strings -Wchar-subscripts
(although the Makefile just contains -Wall).

Finish the security improvements:
o Add "allow" command:
"allow users a b c" gives access to users a, b and c.
"allow modes auto" gives those users access to auto mode only.
"allow users *" and "allow modes *" are accepted.
No users and all modes are allowed by default.
UID 0 can do anything.
o Set the current label with the "load" and "dial" commands
so that the call to ppp.linkdown makes sense.
o Up the verison number.
o Don't OR MODE_AUTO for -background and -ddial.
o Don't OR MODE_INTER when we get a diagnostic connection.
o Allow up to 40 args per line (was 20).
o "set ifaddr" only changes the interface in AUTO mode (with other
modes, it happens after IPCP negotiation).
o Sort command descriptions in the man page.
o Support -dedicated mode where we just talk ppp forever (no login etc).

Introduce ID0 logging.
Stay as the invoking uid as much as possible.
Execution as a normal user is still forbidden for now,
so these changes are pretty ineffective.
The next commit will implement the modifications suggested
on -hackers a number of days ago.

Cosmetic (no functional changes):
o Add missing $Id$s
o Move extern decls from .c -> .h files
o Staticize
o Remove #includes from .h files
o style(9)ify includes
o bcopy -> memcpy
bzero -> memset
bcmp -> memcmp
index -> strchr
rindex -> strrchr
o Move timeout.h -> timer.h (making it consistent w/ timer.c)
o Add -Wmissing-prototypes

Make the code format more in line with style(9).
Update loadalias to use the new libalias api.
Update to version 1.1.

Overhaul ppp:
o Use syslog
o Remove references to stdout/stderr (incl perror())
o Introduce VarTerm - the interactive terminal or zero
o Allow "set timeout" to affect current session
o Change "set debug" to "set log"
o Allow "set log [+|-]flag"
o Make MSEXT and PASSWDAUTH stuff the default
o Move all #ifdef DEBUG stuff into the code - this
shouldn't be too much overhead. It's now controlled
with "set log +debug"
o Add "set log command, debug, tun, warn, error, alert"
o Remove cdefs.h, and assume an ansi compiler.
o Improve all diagnostic output
o Don't trap SIGSEGV
o SIGHUP now terminates again (log files are controlled
by syslog)
o Call CloseModem() when changing devices
o Fix parsing of third arg of "delete"

I think this fixes the "magic is same" problems that some
people have been experiencing.
The man page is being rewritten. It'll follow soon.

De-couple ppp from libalias. If libalias isn't there, the
alias commands simply won't work. Only root may specify the
location of the alias lib (otherwise, it's hard-coded).

Make logprintf silently fail if LogOpen hasn't been called.

Suggested by: eivind

Revert $FreeBSD$ to $Id$

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Final cleanup for now. -Wall is now silent. A couple of bogons found.