Milestones 2+3 completed (NLnet-funded project "R5N (2021-02-038)")

[Bernd Fix]

Dear GNUnet community,

I am happy to announce the completion of milestones 2 and 3 for the "Go 
implementation of the R5N DHT" which is a NLnet-funded project "R5N 
(2021-02-038)".

The source code is written for Go1.18+ (it makes use of generics in some 
places); it can be found in the GNUnet Repository at 
"https://git.gnunet.org/gnunet-go.git/"; with tag "v0.1.30" in the master 
branch.

As others started to (re-)use `gnunet-go` in their own code base (see 
https://git.taler.net/taldir.git/ for example), the README contains a 
final chapter on how to easily integrate `gnunet-go` into your own 
projects. If you are a developer, you might want to take a look at that 
documentation.


The code for Milestones 2 and 3 covers the following areas:

# Milestone 2

## Bloomfilter

with optional mutator to randomize recurring filters. 
[`gnunet/service/dht/blocks/filters.go`]

## Service messages

defined DHT_P2P_GET, DHT_P2P_PUT, DHT_P2P_RESULT and DHT_P2P_HELLO 
messages [`gnunet/message/msg_dht_p2p.go`] and implemented handling 
[`gnunet/service/dht/messages.go`]

## Managing routing tables:

* processing messages for peer visibility
* add/update peers
* remove dead peers
* handling of expired peers
* Recursive lookup
* Approximate lookup
* Replication

see [`gnunet/service/dht/routingtable.go`]

# Milestone 3

## Path signatures

creating, tracking and verifying path signatures 
[`gnunet/service/dht/path`] and integration of pathes into 
DHT-P2P-GET/PUT/RESULT processes [`gnunet/service/dht/messages.go`]

We are now ready to start intergration tests between the Go- and C-based 
implementations which for sure will uncover quite a few undiscovered 
bugs and glitches.

I think that the Go implementation (as a clean-room implementation only 
based on the LSD0004 draft of the protocol) helped a lot in ironing out 
the protocol; draft- and code-wise. If one day the Go implementation 
speaks TNG, it will be possible to run GNUnet as a pure-Go 
implementation with GNS support.

Cheers, Bernd.