MFC r336195: unbreak dhclient(8) option 26 processing

Make dhclient(8) verify if new MTU (option 26) differs from current one
and skip unneeded MTU change. This check eliminates infinite loop
of MTU change / link flap / lease verification / MTU change / link flap etc.
in case of some NIC drivers like em(4) or igb(4).

PR: 229432
Approved by: mav (mentor)

MFC r329754:

dhclient: raise WARNS to 4

Mostly const-correctness fixes. There were also some variable-shadowing,
unused variable, and a couple of sockaddr type-correctness changes. I also had
trouble with cast-align warnings. I was able to prove that one of them was a
false positive. But ultimately I had to disable the warning program-wide to
deal with the others.

Reviewed by: cem
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D14460

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

MFC r305306:

dhclient: add support for interface-mtu (26)

Make dhclient set interface MTU if it was provided.

This version implements MTU setting in dhclient itself before it runs
dhclient-script.

PR: 206721

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

MFC r311160, r311210, r311288, r311292, r311298, r311340

r311160:
misc minor fixes in mpr(4)

sys/dev/mpr/mpr_sas.c
* Fix a potential null pointer dereference (CID 1305731)
* Check for overrun of the ccb_scsiio.cdb_io.cdb_bytes buffer (CID
1211934)

sys/dev/mpr/mpr_sas_lsi.c
* Nullify a dangling pointer in mprsas_get_sata_identify
* Fix a memory leak in mprsas_SSU_to_SATA_devices (CID 1211935)

Reported by: Coverity (partially)
CID: 1305731 1211934 1211935
Reviewed by: slm
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D8880

r311210:
Quell Coverity for diskinfo(8)

* CID 1198994: Don't run the speed disk on a disk with no sectors
* CID 1011442: Don't call close(2) if open(2) fails
* CID 1011161: Use snprintf instead of sprintf
* CID 1009825: Check the return value of lseek

Reported by: Coverity
CID: 1198994 1011442 1011161 1009825
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r311288:
Delete dead code in chat(8)

It's always been dead, ever since first import in 1994. It's still dead in
OpenBSD's version, too.

Reported by: Coverity
CID: 270586
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r311292:
Remove dead code in rpc_parse.c

It's been dead ever since it was imported from TI-RPC in 1995. The dead
code is still present in Illumos today, but was removed from NetBSD in 2006.

Reported by: Coverity
CID: 270097
Obtained from: NetBSD
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r311298:
Remove dead code in dhclient(8)

The offending code has been dead ever since the import from OpenBSD in
r195805. OpenBSD later deleted that entire function.

Reported by: Coverity
CID: 500059
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r311340:
Misc Coverity fixes for tail(1)

CID 1006402: Initialize stack variable
CID 271580: Don't leak memory when ENOMEM.

Reported by: Coverity
CID: 271580 1006402
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

MFC r309027:

Allocate a struct ifreq rather than using a (wrong) computed size for
the BIOCSETIF ioctl.

The kernel always copies an entire struct ifreq and IPv4 addresses will
always fit in an ifreq.

On systems with pointers larger than 64-bits, the computed size will be
less than the size of struct ifreq, potentially resulting in the kernel
attempting to copyin memory from outside the allocation.

Reviewed by: jhb
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D8445

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

Fix the logic to count the number of "live interfaces". With this change
dhclient now terminates when the underlying ifnet is destroyed (e.g.
on card eject).

Reviewed by: brooks
Approved by: re (kib)

Teach dhclient(8) about net80211 link (association) status.

Reviewed by: brooks
MFC after: 3 days

Add __FBSDID to all .c files in dhclient to aid in determining file
versions when dealing with user problems.

This commit was generated by cvs2svn to compensate for changes in r147072,
which included commits to RCS files with non-trunk default branches.

Import the OpenBSD dhclient as shipped with OpenBSD-3.7 (the tag
OPENBSD_3_7).