The DNS name can now also contain the DoT server name. It's not longer a
binary IP address only.

Extend NML3ConfigData to account for that. To track the additional
data, use the string representation. The alternative to have a separate
type that contains the parsed information would be cumbersome too.

A DAD failure is in most cases a symptom of a network
misconfiguration; as such it must be logged in the default
configuration (info level).

While at it, fix other log messages.

Since we evaluate platform changes in a idle handler, there can be
multiple DAD failure at the same time that must generate a single
ndisc.configuration-change signal.

The function is unused at the moment.

We already have src/linux-headers, where we have complete copies of linux
user space headers. Of course that exists, because we want to use certain
features and don't depend on the installed kernel headers. Which works
well, because kernel user space API is stable, and we anyway want to
support compiling against a newer kernel and run against an older (e.g.
in a container). So having our copy of newer kernel headers is merely
as if we compiled against as newer kernel.

Add "src/nm-compat-headers" which has a similar purpose, but a different
approach. Instead of replacing the included header entirely, include
the system header and patch it with #define.

Use this for "linux/if_addr.h". Of course, the approach here is that we
no longer include <linux/if_addr.h> directly, but instead include
"nm-compat-headers/linux/if_addr.h".

These variants provide additional nm_assert() checks, and are thus
preferable.

Note that we cannot just blindly replace &g_array_index() with
&nm_g_array_index(), because the latter would not allow getting a
pointer at index [arr->len]. That might be a valid (though uncommon)
usecase. The correct replacement of &g_array_index() is thus
nm_g_array_index_p().

I checked the code manually and replaced uses of nm_g_array_index_p()
with &nm_g_array_index(), if that was a safe thing to do. The latter
seems preferable, because it is familar to &g_array_index().

- name things related to `in_addr_t`, `struct in6_addr`, `NMIPAddr` as
  `nm_ip4_addr_*()`, `nm_ip6_addr_*()`, `nm_ip_addr_*()`, respectively.

- we have a wrapper `nm_inet_ntop()` for `inet_ntop()`. This name
  of our wrapper is chosen to be familiar with the libc underlying
  function. With this, also name functions that are about string
  representations of addresses `nm_inet_*()`, `nm_inet4_*()`,
  `nm_inet6_*()`. For example, `nm_inet_parse_str()`,
  `nm_inet_is_normalized()`.

<<<<

  R() {
     git grep -l "$1" | xargs sed -i "s/\<$1\>/$2/g"
  }

  R NM_CMP_DIRECT_IN4ADDR_SAME_PREFIX          NM_CMP_DIRECT_IP4_ADDR_SAME_PREFIX
  R NM_CMP_DIRECT_IN6ADDR_SAME_PREFIX          NM_CMP_DIRECT_IP6_ADDR_SAME_PREFIX
  R NM_UTILS_INET_ADDRSTRLEN                   NM_INET_ADDRSTRLEN
  R _nm_utils_inet4_ntop                       nm_inet4_ntop
  R _nm_utils_inet6_ntop                       nm_inet6_ntop
  R _nm_utils_ip4_get_default_prefix           nm_ip4_addr_get_default_prefix
  R _nm_utils_ip4_get_default_prefix0          nm_ip4_addr_get_default_prefix0
  R _nm_utils_ip4_netmask_to_prefix            nm_ip4_addr_netmask_to_prefix
  R _nm_utils_ip4_prefix_to_netmask            nm_ip4_addr_netmask_from_prefix
  R nm_utils_inet4_ntop_dup                    nm_inet4_ntop_dup
  R nm_utils_inet6_ntop_dup                    nm_inet6_ntop_dup
  R nm_utils_inet_ntop                         nm_inet_ntop
  R nm_utils_inet_ntop_dup                     nm_inet_ntop_dup
  R nm_utils_ip4_address_clear_host_address    nm_ip4_addr_clear_host_address
  R nm_utils_ip4_address_is_link_local         nm_ip4_addr_is_link_local
  R nm_utils_ip4_address_is_loopback           nm_ip4_addr_is_loopback
  R nm_utils_ip4_address_is_zeronet            nm_ip4_addr_is_zeronet
  R nm_utils_ip4_address_same_prefix           nm_ip4_addr_same_prefix
  R nm_utils_ip4_address_same_prefix_cmp       nm_ip4_addr_same_prefix_cmp
  R nm_utils_ip6_address_clear_host_address    nm_ip6_addr_clear_host_address
  R nm_utils_ip6_address_same_prefix           nm_ip6_addr_same_prefix
  R nm_utils_ip6_address_same_prefix_cmp       nm_ip6_addr_same_prefix_cmp
  R nm_utils_ip6_is_ula                        nm_ip6_addr_is_ula
  R nm_utils_ip_address_same_prefix            nm_ip_addr_same_prefix
  R nm_utils_ip_address_same_prefix_cmp        nm_ip_addr_same_prefix_cmp
  R nm_utils_ip_is_site_local                  nm_ip_addr_is_site_local
  R nm_utils_ipaddr_is_normalized              nm_inet_is_normalized
  R nm_utils_ipaddr_is_valid                   nm_inet_is_valid
  R nm_utils_ipx_address_clear_host_address    nm_ip_addr_clear_host_address
  R nm_utils_parse_inaddr                      nm_inet_parse_str
  R nm_utils_parse_inaddr_bin                  nm_inet_parse_bin
  R nm_utils_parse_inaddr_bin_full             nm_inet_parse_bin_full
  R nm_utils_parse_inaddr_prefix               nm_inet_parse_with_prefix_str
  R nm_utils_parse_inaddr_prefix_bin           nm_inet_parse_with_prefix_bin
  R test_nm_utils_ip6_address_same_prefix      test_nm_ip_addr_same_prefix

  ./contrib/scripts/nm-code-format.sh -F

Dunno why this happens. Just silence it.

  nm:ERROR:../src/core/ndisc/tests/test-ndisc-fake.c:649:test_dns_solicit_loop: assertion failed (data.counter == 3): (2 == 3)

(cherry picked from commit cb98616e026d9547279d7b2576f9e0245f5f7360)

nmp_utils_lifetime_get() calculates the lifetime of addresses,
and it bases the result on a "now" timestamp.

If you have two addresses and calculate their expiry, then we want to
base it on top of the same "now" timestamp, meaning, we should
only call nm_utils_get_monotonic_timestamp_sec() once. This is also a
performance optimization. But much more importantly, when we make a
comparison at a certain moment, we need that all sides have the same
understanding of the current timestamp.

But nmp_utils_lifetime_get() does not always require the now timestamp.
And the caller doesn't know, whether it will need it (short of knowing
how nmp_utils_lifetime_get() is implemented). So, make the now parameter
an in/out argument. If we pass in an already valid now timestamp, use
that. Otherwise, fetch the current time and also return it.

(cherry picked from commit deb37401e95d4ea0025e406424c8da7c10bc9712)

We use clang-format for automatic formatting of our source files.
Since clang-format is actively maintained software, the actual
formatting depends on the used version of clang-format. That is
unfortunate and painful, but really unavoidable unless clang-format
would be strictly bug-compatible.

So the version that we must use is from the current Fedora release, which
is also tested by our gitlab-ci. Previously, we were using Fedora 34 with
clang-tools-extra-12.0.1-1.fc34.x86_64.

As Fedora 35 comes along, we need to update our formatting as Fedora 35
comes with version "13.0.0~rc1-1.fc35".
An alternative would be to freeze on version 12, but that has different
problems (like, it's cumbersome to rebuild clang 12 on Fedora 35 and it
would be cumbersome for our developers which are on Fedora 35 to use a
clang that they cannot easily install).

The (differently painful) solution is to reformat from time to time, as we
switch to a new Fedora (and thus clang) version.
Usually we would expect that such a reformatting brings minor changes.
But this time, the changes are huge. That is mentioned in the release
notes [1] as

  Makes PointerAligment: Right working with AlignConsecutiveDeclarations. (Fixes https://llvm.org/PR27353)

[1] https://releases.llvm.org/13.0.0/tools/clang/docs/ReleaseNotes.html#clang-format

Fixes-test: @ipv6_token