The missing parentheses around the additions when calculating optlen
in the previous code can cause an out-of-bound read of up to 228 bytes
if no DHCP_OPTEND is found in the message (the calculation basically
evaluated to `- 20 + 8 + 240`).
Since the buffer for the received packet (via pf_handler_t) is located
on the stack, this shouldn't cause much of an issue in practice.
Tobias Brunner
8f22345542