clang generates internal calls for some _chk symbol, so add internal
aliases for them, and stub some with rtld-stubbed-symbols to avoid
ld.so linker issues.

Reviewed-by: Sam James <sam@gentoo.org>

The clang default to warning for missing fall-through and it does
not support all comment-like annotation that gcc does.  Use C23
[[fallthrough]] annotation instead.
proper attribute instead.

Reviewed-by: Collin Funk <collin.funk1@gmail.com>

We need to use __sz, not sz, as we do elsewhere.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Checked on aarch64-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Collin Funk <collin.funk1@gmail.com>
Reviewed-by: DJ Delorie <dj@redhat.com>

Add function __inet_pton_chk which calls __chk_fail when the size of
argument dst is too small.   inet_pton is redirected to __inet_pton_chk
or __inet_pton_warn when _FORTIFY_SOURCE is > 0.

Also add tests to debug/tst-fortify.c, update the abilist with
__inet_pton_chk and mention inet_pton fortification in maint.texi.

Co-authored-by: Frédéric Bérat <fberat@redhat.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>

- Create the __inet_ntop_chk routine that verifies that the builtin size
of the destination buffer is at least as big as the size given by the
user.
- Redirect calls from inet_ntop to __inet_ntop_chk or __inet_ntop_warn
- Update the abilist for this new routine
- Update the manual to mention the new fortification

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Make sure that numbers never overflow uint32_t in inet_network to
properly validate octets encountered in IPv4 addresses.

Avoid malloca in NSS networks file code because /etc/networks lines
can be arbitrarily long. Instead of handcrafting the input for
inet_network by adding ".0" octets if they are missing, just left shift
the result. Also, do not accept invalid entries, but ignore the line
instead.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>

Adds commonly used IPv6 packet header macros similar to what is available
on NetBSD and FreeBSD in sys/netinet/ip6.h and Android in
libc/include/netinet/ip6.h

Usage example IPV6_VERSION_MASK and IPV6_VERSION:

    if ((ip6->ip6_vfc & IPV6_VERSION_MASK) == IPV6_VERSION)
        return true;

Usage example IPV6_FLOWINFO_MASK:

    ip6->ip6_flow = (flow & IPV6_FLOWINFO_MASK);

The relevant standard is RFC2460 (Internet Protocol, Version 6
Specification). It defines the Internet Protocol version (IPV6_VERSION)
and reduced the size of the flow label field from 24 to 20 bits
(IPV6_FLOWLABEL_MASK). The traffic class and flow label fields together
make up the flow information (IPV6_FLOWINFO_MASK).

Tested on x86_64 GNU/Linux

Signed-off-by: Dan Luedtke <danrl@google.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Since tst-deadline.c is an internal test, compile tst-deadline.c with
-Wno-ignored-attributes for Clang to silence -Werror,-Wunknown-attributes
errors.  Also suppress -Wmaybe-uninitialized only for GCC in net-internal.h.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>