Unbounded actor mailboxes enable OOM DoS across all actors

[intendednull]

Problem

All actor mailboxes in crates/actor/src/runtime.rs:108-120 use tokio::sync::mpsc::unbounded_channel() and futures_channel::mpsc::unbounded(). No actor has backpressure or capacity limits.

This affects every actor in the system:

• Worker: NetworkActor, StateActor, HeartbeatActor, SyncActor
• Client: StateActor instances for ServerState, DagState, ChatMeta, etc.

A malicious peer flooding gossip messages causes unbounded mailbox growth in the NetworkActor, which forwards to StateActor, causing cascading OOM.

Impact

• Any actor can be OOM-crashed by sustained message flooding
• No backpressure — producers never slow down
• Affects both worker and client actor systems

Suggested fix

Replace unbounded_channel() with bounded channels:

let (tx, rx) = tokio::sync::mpsc::channel(10_000); // Bounded with backpressure

Or add per-actor message count metrics and drop/log when threshold exceeded.

Location

• crates/actor/src/runtime.rs:108-120

References

Found during deep implementation audit (pass 2)