zonemaster.es/zonemaster-ldns/ldns/lua/rns-specs

* Classes of Manglement

from higher to lower level:
	- deliberately mess up a resolver ability to recurse
	- move RRsets to different sections
	- fiddle with the ID
	- add/delete RRs
		- remove glue, add wrong glue
		- add fake signatures
	- split up RRsets
	== mess with the final packet ==
	- distort the compression pointers in the final packet
	- swap bytes in the final packet
	- swap bits in the final packet

Based on a simple ldns-based nameserver.

A configuration file is needed to tell it what to do. Some form
of random stuff is also required.

Ideally what I want is that you "program" you nameserver to mangle
the packets.

The mangle stage should be seen as a lego system, where you can connect
different boxes together and push the assembled packet through it.

So RNS should be able to deal with raw packets, so you can put it
IN FRONT of another nameserver or it can directly deal with a ldns_packet*.       

Best way would be to build RNS is as a filter that can be put between the
resolver and nameserver. Or, if running on localhost, all answers can be
sent to a special IP of the resolver you want to test.

** Mangle Blocks

Each mangle function is effectively called from the configuration file.
From the config file a mangle-engine is built. The packet is then put
through this engine. After that a binary blob (with a length) comes 
out. This blob is then sent out to the network.

* Design of RNS

You program the engine in Lua by using ldns building blocks.

I must be able to call C ldns functions from lua and pass data
from and to the functions.

:Binary filter:

Steps:
1. suck in a packet
  b: check ip dst address
2. mangle it according to the configuration file
3. rebuilt and put out the new packet. (Or binary blob, or whatever)

* Implementation

A bunch of blob/packet functions-in/out.

So blob_out* lua_mangle_remove_rr(blob_in*, random, extra args??);

See are then chained together by the lua code.

:Packet Mangling:

These are the four basic operations:

Transpose: 	switching 2 elements
Substitute: 	replace an element with another one 
		(could be random)
Add: 		add an element
Remove: 	remove an element

Each operation can be done on a different level, we distinguish between the
following levels:

packet-level: 	the header bits, number of rr in a specific section,
rr-level: 	placement of rrs (which section)
byte-level: 	handle specific bytes, like the compression pointers (2
		bytes)
bit-level: 	handle specific bits

All 4 operation can be applied at all levels, this gives us 16 degrees of
freedom in the packet mangling. (ghe ghe :-) )

To keep matters interesting some sort of randomness is required in some
step, otherwise each packet is mangled in the same way. Also this
randomness together with the Lua script needs to be logged so the 
actual mangling can be replayed.

:Packet Mangling: address the different elements:
We need a way to address our elements:

elements: (network order)
	bytes: numbered from 0 till the end of the packet
	bits: within each byte numbered from 0 till 7
	sections: numbered from the start of the packet (mnemonics?)
	rr: numbered in each section

Ambivalent on whether we need something like addresses: section_answer?
ldns_* provides it. Should we use that?????

::Packet Mangling Implementation::
Example:

Suppose we have a mangling operation that mangles RR (at the rr-level):
transpose_rr(packet, rr1_position, rr2_position) 

The 2 rr's are now flipped. We could also use rand0 for the position
thereby letting the system decide. All these mangling functions should
this log what they do.

:: Short Term Implementation ::

Try to switch 2 rrs from one section to another. Complex addressing of
a packet <Section, RR number> probably.... Section can be random, RR number
can be random.


:: Addressing ::
everything is numbered from 0 to n-1, so n objects
this is how things go in side the packet too, so it is the easiest

:: Lua Implementation ::
RR level -> ldns stuff
Packet level -> ldns stuff
Byte level -> Lua string
Bit level -> Lua string, but add C bit ops