Option 58 is optional, and dhcp_state.renewal is only ever written by
parse_opts(), so a server that leaves it out keeps it at zero. The ACK
handler then sets dhcp_timer to zero, and the callback treats a zero timer
in LEASING as time to renew, so it sends a REQUEST on the next pass.
That REQUEST does set a 30 second timeout, but the ACK that answers it
comes back through the same path and zeroes the timer again, so the two
sides trade REQUEST and ACK as fast as the round trip allows, with the
console printing the whole lease each time round.
RFC 2131 has the client renew at half the lease when the server does not
say, so use that, and fall back to a fixed value if there is no lease
either. Both only fill in a value that is missing: a server that asks for a
short renewal still gets exactly what it asked for, which a blanket lower
bound would have overridden.
Not reproduced here, that needs a server configured without the option.
The id was built and checked with HTONS(), which casts to 16 bits, so the
top half of the 32-bit transaction id was thrown away and the rest byte
swapped. The id is opaque: the client only has to receive its own value
back, so there is no byte order to honour and no reason to narrow it.
Assign and compare the field directly, so the full 32-bit id round-trips.
The guard read `if (!DHCP_P->tid == HTONS(...))`. Unary `!` binds tighter
than `==`, so this evaluated `(!tid) == HTONS(id)`, i.e. `(tid ? 0 : 1) ==
HTONS(id)`, which is false for any non-zero id and never returns. The reply
was therefore accepted regardless of its transaction id, so a broadcast
reply meant for another client on the segment was parsed as ours.
Compare the field directly. The id is stored network-order in the packet
and host-order in the state, matching the HTONS() used when the request is
built, so `DHCP_P->tid != HTONS(dhcp_state.transaction_id)` is the intended
test.
Send the configured hostname on discover and request so the DHCP server
can register the device (e.g. in local DNS). Skipped while the hostname
is still empty, i.e. before set_hostname_default() has run.
We use the SoC's UUID to generate a fixed MAC for a particular
switch device. The MAC generated uses a Realtek prefix and then
is followed by 3 bytes genertaed from the first 3 bytes of the
UUID xored with the last byte in order to prevent being able
to deduce the UUID from the public MAC.
d00f
René van Dorst
bloqaudio
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logicog
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