$ find * -type f |xargs perl contrib/scripts/spdx.pl
  $ git rm contrib/scripts/spdx.pl

IPv6 router advertisement messages contain the following parameters
(RFC 4861):

 - Reachable time: 32-bit unsigned integer.  The time, in
   milliseconds, that a node assumes a neighbor is reachable after
   having received a reachability confirmation.  Used by the Neighbor
   Unreachability Detection algorithm.  A value of zero means
   unspecified (by this router).

 - Retrans Timer: 32-bit unsigned integer.  The time, in milliseconds,
   between retransmitted Neighbor Solicitation messages.  Used by
   address resolution and the Neighbor Unreachability Detection
   algorithm.   A value of zero means unspecified (by this router).

Currently NM ignores them; however, since it leaves accept_ra=1, the
kernel parses RAs and applies those parameters for us [1].

In the next commit kernel handling of RAs will be disabled, so let NM
set those neighbor-related parameters.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv6/ndisc.c?h=v5.2#n1353

We no longer add these. If you use Emacs, configure it yourself.

Also, due to our "smart-tab" usage the editor anyway does a subpar
job handling our tabs. However, on the upside every user can choose
whatever tab-width he/she prefers. If "smart-tabs" are used properly
(like we do), every tab-width will work.

No manual changes, just ran commands:

    F=($(git grep -l -e '-\*-'))
    sed '1 { /\/\* *-\*-  *[mM]ode.*\*\/$/d }'     -i "${F[@]}"
    sed '1,4 { /^\(#\|--\|dnl\) *-\*- [mM]ode/d }' -i "${F[@]}"

Check remaining lines with:

    git grep -e '-\*-'

The ultimate purpose of this is to cleanup our files and eventually use
SPDX license identifiers. For that, first get rid of the boilerplate lines.

In the past, the headers "linux/if.h" and "net/if.h" were incompatible.
That means, we can either include one or the other, but not both.
This is fixed in the meantime, however the issue still exists when
building against older kernel/glibc.

That means, including one of these headers from a header file
is problematic. In particular if it's a header like "nm-platform.h",
which itself is dragged in by many other headers.

Avoid that by not including these headers from "platform.h", but instead
from the source files where needed (or possibly from less popular header
files).

Currently there is no problem. However, this allows an unknowing user to
include <net/if.h> at the same time with "nm-platform.h", which is easy
to get wrong.

we use get_expiry() to compare two lifetimes. Note, that previously,
it would correctly truncate the calculated expiry at G_MAXINT32-1.

However, that means, that two different lifetimes that both lie
more than 68 years in the future would compare equal.

Fix that, but extending the range to int64, so that no overflow
can happen.

We first iterate over addresses that might have failed IPv6 DAD and
update the state in NMNDisc.

However, while we do that, don't yet invoke the changed signal.
Otherwise, we will invoke it multiple times (in case multiple addresses
failed). Instead, keep track of whether something changed, and handle
it once a bit later.

(cherry picked from commit f312620276a3756fbc00362b5330b30a05a18cc6)

Platform invokes change events while reading netlink events. However,
platform code is not re-entrant and calling into platform again is not
allowed (aside operations that do not process the netlink socket, like
lookup of the platform cache).

That basically means, we have to always process events in an idle
handler. That is not a too strong limitation, because we anyway don't
know the call context in which the platform event is emitted and we
should avoid unguarded recursive calls into platform.

Otherwise, we get hit an assertion/crash in nm-iface-helper:

     1  raise()
     2  abort()
     3  g_assertion_message()
     4  g_assertion_message_expr()
     5  do_delete_object()
     6  ip6_address_delete()
 >>> 7  nm_platform_ip6_address_delete()
     8  nm_platform_ip6_address_sync()
     9  nm_ip6_config_commit()
     10 ndisc_config_changed()
     11 ffi_call_unix64()
     12 ffi_call()
     13 g_cclosure_marshal_generic_va()
     14 _g_closure_invoke_va()
     15 g_signal_emit_valist()
     16 g_signal_emit()
 >>> 17 nm_ndisc_dad_failed()
     18 ffi_call_unix64()
     19 ffi_call()
     20 g_cclosure_marshal_generic()
     21 g_closure_invoke()
     22 signal_emit_unlocked_R()
     23 g_signal_emit_valist()
     24 g_signal_emit()
 >>> 25 nm_platform_cache_update_emit_signal()
     26 event_handler_recvmsgs()
     27 event_handler_read_netlink()
     28 delayed_action_handle_one()
     29 delayed_action_handle_all()
     30 do_delete_object()
     31 ip6_address_delete()
     32 nm_platform_ip6_address_delete()
     33 nm_platform_ip6_address_sync()
 >>> 34 nm_ip6_config_commit()
     35 ndisc_config_changed()
     36 ffi_call_unix64()
     37 ffi_call()
     38 g_cclosure_marshal_generic_va()
     39 _g_closure_invoke_va()
     40 g_signal_emit_valist()
     41 g_signal_emit()
     42 check_timestamps()
     43 receive_ra()
     44 ndp_call_eventfd_handler()
     45 ndp_callall_eventfd_handler()
     46 event_ready()
     47 g_main_context_dispatch()
     48 g_main_context_iterate.isra.22()
     49 g_main_loop_run()
 >>> 50 main()

NMPlatform already has a check to assert against recursive calls
in delayed_action_handle_all():

    g_return_val_if_fail (priv->delayed_action.is_handling == 0, FALSE);

    priv->delayed_action.is_handling++;
    ...
    priv->delayed_action.is_handling--;

Fixes: f85728ecff824b1fece43aba51d8171db2766ea2

https://bugzilla.redhat.com/show_bug.cgi?id=1546656

We encounter the same enum in 3 forms:

  - NMNDiscPreference in NetworkManager
  - "enum ndp_route_preference" in <ndp.h>
  - ICMPV6_ROUTER_PREF_* in <linux/icmpv6.h>

Move our enum to nm-core-utils.h, so that it can be used
by platform code as well (platform code should not include
ndisc/nm-ndisc.h).

Also, NMNDiscPreference was not numerically identical to their
native values (meaning: it shuffled the names and numbers).
Make them all numerically equal, so that they can be used in
the same context.
This means, while previously we could compare NMNDiscPreference
directly according to their priority, we now need _preference_to_priority().
On the other hand, we could omit translate_preference() -- but actually,
we still have _route_preference_coerce() because pref comes from libndp
and is thus untrusted. We still have to range check it.

We have the timestamp nm_utils_get_monotonic_time_s(), which should be
gint32 type. Then we also have timestamps in the NMNDisc* objects, which
consist of guint32 timestamp and lifetime.

Cleanup handling the times and calculation of the timestamps by using
the correct integer type consistently and ensuring that no integer overflow
occurs.