Thankfully, it turns out that HTTPBoot carries the same flexibility
as PXE with respect to no-ip answer being merged with an IP answer.
As a bonus, it actually is simpler than PXE, allowing skipping of udp
port 4011. Of course, we still want to support PXE boot, so that will
need to be implemented.
filename is ignored if pxeclient anyway. This will provide a
consistent approach for boot file for dhcp-elsewhere and
fixed ip clients alike.
Also add some TODO about how to enable DHCPREQUEST
processing when the time comes, as today the code skipping
option parsing for DISCOVER packets trips up the ability
to continue. We must make sure we don't call discovery
handler again for REQUEST after doing so for DISCOVER.
It d oesn't quite work, but it looks convincing. UDP checksum may
need to be added, and beyond that explore changes to the payload since
it is likely not enough DHCP was provided.
First, IP level sendto doesn't give the freedom to send 25.255.255.255
out of the interface desired. So have to go link layer.
Second, while python can do sendto, we have the interface index number
from recvmsg (which was ctypes). python expects the name instead
(wwhich it promptly turns... back into the index we start with). I
could have added code to get the name using some syscalls which would
have been work and produced more system calls, or added the code to
directly use sendto, which would also be efficient at runtime.
So I chose to use ctypes for both recvmsg and sendto here.
The plan is to have 'discovery'
data only on DISCOVER, but
still parse and be able to react to
REQUEST packets.
Additionally add the attributes
to control deployment state and
permissible protocols.
We have now done IP_PKTINFO, but there is a potential TODO
if wanting to properly honor unicast request.
For now, will just do always-broadcast as the options to do unicast
are more complex to do (either construct the packets or inject neigh
entry manually)
