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 r326834, r326853

r326834:
dhclient(8): Don't shift through the sign bit of a signed int

PR: 208007
Submitted by: Michael McConville <mmcco@mykolab.com>

r326853:
dhclient(8): raise WARNS to 3

Mostly had to fix a lot of signed/unsigned comparison warnings

Sponsored by: Spectra Logic Corp

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

MFp4 @229481:

Currently it was allowed to send any UDP packets from unprivileged process and
possibly any packets because /dev/bpf was open for writing.

Move sending packets to privileged process. Unprivileged process has no longer
access to not connected UDP socket and has only access to /dev/bpf in read-only
mode.

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4 @229476,229478:

Make use of two fields: rfdesc and wfdesc to keep bpf descriptor open for
reading only in rfdesc and bpf descriptor open for writing only in wfdesc.
In the end they will be used by two different processes.

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4 @229473:

No caller checks send_packet() return value, so make it void.

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4 @229472:

Use the same type for 'from' and 'to' argument in send_packet().

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4 @229471:

Remove unused argument from assemble_hw_header().

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4 @229470:

Remove unused argument from send_packet().

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

MFp4: @229469:

Garbage-collect dead prototypes.

Reviewed by: brooks
Sponsored by: The FreeBSD Foundation

When acquiring a lease, record the value of the BOOTP siaddr field
contained in the DHCP offer, and write it out to the lease file
as an unquoted value of the "next-server" keyword. The value is ignored
when the lease is read back by dhclient, however other applications
are free to parse it.

The intent behind this change is to allow easier interoperability
with automated installation systems e.g. Cobbler, Foreman, Razor;
FreeBSD installation kernels can automatically probe the network
to discover deployment servers. There are no plans to MFC this
change unless a backport is specifically requested.

The syntax of the "next-server <ip>" lease keyword is intended to be
identical to that used by the ISC DHCPD server in its configuration files.
The required defines are already present in dhclient but were unused before
this change. (Note: This is NOT the same as Option 66, tftp-server-name).

It has been exercised in a university protocol testbed environment, with
Cobbler and an mfsBSD image containing pc-sysinstall (driven by Cobbler
Cheetah templates). The SYSLINUX memdisk driver is used to boot mfsBSD.
Currently this approach requires that a dedicated system profile has
been created for the node where FreeBSD is to be deployed. If this
is not present, the pc-sysinstall wrapper will be unable to obtain
a node configuration. There is code in progress to allow mfsBSD images
to obtain the required hints from the memdisk environment by parsing
the MBFT ACPI chunk. This is non-standard as it is not linked into
the platform's ACPI RSDT.

Reviewed by: des

Revert r239356 and use an alternate algorithm.

First, don't exit when the link goes down on an interface. Instead,
teach dhclient to track changes in link state and to enter the reboot
state when the link on an interface goes up causing dhclient to attempt
to renew its existing lease.

Second, remove the change I added to clear the old lease when dhclient
exits due to an error (such as ifconfig down). If an interface is
using autoconfiguration it should keep its autoconfiguration as much as
possible. If the next time it needs a configuration it is able to reuse
the previous autoconfiguration, then leaving the settings intact allows
existing connections to survive temporary outages, etc.

PR: bin/166656
MFC after: 1 month

Make dhclient use a pid file. Modify the rc script accordingly; while
there, clean it up and add some error checks.

Glanced at by: brooks@
MFC after: 3 weeks

Make dhclient use bootpc (68) as the source port for unicast DHCPREQUEST
packets instead of allowing the protocol stack to pick a random source port.

This fixes the behaviour where dhclient would never transition from RENEWING
to BOUND without going through REBINDING in networks which are paranoid about
DHCP spoofing, such as most mainstream cable-broadband ISP networks.

Reviewed by: brooks
Obtained from: OpenBSD (partly - I'm not convinced their solution can work)
MFC after: 1 week (pending re approval)

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).