UDP connect() to 255.255.255.255:67 sets the socket's source-filter to
broadcast peers only. The DHCP server (e.g. QEMU SLIRP at 10.0.2.2)
responds from its own IP, which the filter rejects. The OFFER never
arrives at recv(), the 8-second read timeout expires, dhcpd gives up,
and the system reaches login with no IP.
Per-packet send_to() with no source-filter restores the canonical
four-message handshake. Applied at all four broadcast points:
DISCOVER, REQUEST, RENEW, REBIND.
Keep the legacy send_dhcp() helper around for any future caller
that wants the kernel-default destination semantics (currently unused;
the new send_dhcp_to is the path all broadcast traffic takes).
Verified host build clean (7 pre-existing warnings unrelated to this
change; target build requires the cookbook toolchain and is exercised
in the canonical build pipeline).
Red Bear OS
29166263bb