This is similar to TAKE_PTR() but operates on file descriptors, and thus
assigns -1 to the fd parameter after returning it.
Removes 60 lines from our codebase. Pretty good too I think.
Commit f11cba7479 ("libsystemd-network: fix unaligned loads (issue #7654)")
changed the way in which the MAC address is read to use native endiannes:
htobe32(*((uint32_t *)x) -> unaligned_read_ne32(x)
This is wrong because loads done with BPF_LD + BPF_ABS are big-endian, as it
can be seen for the ethertype and arp-operation loads above in the
filter. Also, the same commit changed:
htobe32(*((unsigned int *)x) -> unaligned_read_be32(x)
in _bind_raw_socket(), which is the correct form.
The commit broke IPv4LL in presence of loops, as the sender now considers its
own packets as conflicting.
Fixes: f11cba7479
We currently process every ARP packet, but we should only care about the ones
relating to our IP address.
Also rename ipv4ll helpers to apr-utils.[ch], and rework the helpers a bit.
