[BUG] Three-body connections produces messages duplication

[picolino]

🐛 Bug Report

Imagine we have SSC applications connections structure like that:

  ┌────── A ──────┐
  │               │
  │               │
 msg1            msg1
  │               │
  │               │
  ▼               ▼
  B ───────────── C

If A produces msg1, it sends it to B and C according to configured known peers (KnownRemotePeers property in appsettings.yaml). B and C both recieves this message and if they knows about each other - they retranslate same message to each other what produces messages duplication.

  ┌────── A ──────┐
  │               │
  │               │
  │               │
  │               │
  B ──── msg1 ──► C
  ▲               │
  └───── msg1 ────┘

Expected behavior

We should retranslate message, but on client side should exists something like messages deduplication, that will prevent from handle and retranslate messages that already have been delivered to it.

Reproduction steps

1. Prepare three separated machines
2. Setup KnownRemotePeers into appsettings.yaml to connect all three machines with each others.
   Each machine should know about both others
3. Launch app on first machine
4. Launch app on second machine
5. Launch app on third machine
6. Send message from one machine
7. See message duplication on both other machines

Version: 1.0.0

[picolino]

Additional case:

Imagine we have 2 RDP servers that knows about each other (KnownPeers are filled) and every server has several users that uses this application. This architecture produces multiple messages duplication and cross-network multiple packages sending.

Current architecture

Seems like we should separate machines from each other by this logic:

1. Application trying to listen remote packages using tcp listener on specific port.
2. If application listener enables correctly - then this application should connect to known peers.
3. If application listener cannot been enabled (port already in use by another application instance for example) - then it should not connect to remote peers.
4. Both applications should connect to local peers through unix socket no matter what happening with network connectivity.

Fixed architecture