Since we don't need the error value, and the buffer is allocated with a fixed
size, the whole logic provided by in_addr_to_string() becomes unnecessary, so
it's enough to wrap inet_ntop() directly.
inet_ntop() can only fail with ENOSPC. But we specify a buffer that is supposed
to be large enough, so this should never fail. A bunch of tests of this are added.
This allows all the wrappers like strna(), strnull(), strempty() to be dropped.
The guard of 'if (DEBUG_LOGGING)' can be dropped from around log_debug(),
because log_debug() implements the check outside of the function call. But
log_link_debug() does not, so it we need it to avoid unnecessary evaluation of
the formatting.
In the documentation, using the term "managed" for both the RA flag and
the DHCPv6 mode is confusing because the mode is referred to as
"solicit" both in the official DHCPv6 documentation (see RFC 8415) and
in the WithoutRA option.
Furthermore, calling the other RA flag "other information" or "other
address configuration" is confusing because its official name is simply
"other configuration" (see RFC 4861 and RFC 5175) and it isn't used to
assign IP addresses.
Rewrite the documentation for DHCPv6Client and WithoutRA to make it
clear that getting the "managed" RA flag triggers the same kind of DHCP
request as WithoutRA=solicit, whereas getting the "other configuration"
RA flag triggers the same kind of DHCP request as
WithoutRA=information-request.
The LLDP spec (IEEE 802.1AB) requires the three mandatory TLVs (Chassis
ID, Port ID, and TTL) to be the first three TLVs in the packet, in that
specific order, whereas systemd put the TTL near the end of the packet.
This violation caused the ethernet switch in our office to discard these
packets as malformed, and Wireshark's packet parser also chokes on them.
We reject too-short packets in client_receive_message_raw(), so
the packets that dhcp_packet_verify_headers() gets are of sufficient size.
But let's add an assert to clarify this for the reader.
Closes#23223.
Let's raise our supported baseline a bit: CLOCK_BOOTTIME started to work
with timerfd in kernel 3.15 (i.e. back in 2014), let's require support
for it now.
This will raise our baseline only modestly from 3.13 → 3.15.
