Announce Architecture

The announce command manages a long-running swarm session, coordinating DHT presence and optionally handling incoming connections.

Initialization Flow

1. Identity Generation: A KeyPair is either generated randomly or derived from a seed.
2. Swarm Setup: A SwarmConfig is constructed with the identity and DHT configuration. Firewall settings are determined by the global config (Open if public=true, Consistent otherwise).
3. Joining Topic: The node joins the topic using JoinOpts { client: false }. This instructs the DHT to act as a server for this topic, making the node discoverable to lookup queries.
4. Flushing: The node waits for the join operation to flush, ensuring at least one announcement has reached the DHT.

Metadata Persistence

If the --data flag is provided, the node performs an initial mutable_put to the DHT.

• Storage: The data is signed by the node’s private key and stored at the node’s public key address on the DHT.
• Sequence: The seq field is set to the current Unix epoch in seconds.
• Lifecycle: A background task triggers every 600 seconds to re-put the data, preventing expiration and keeping the DHT record fresh.

Connection Management

When a peer discovers this node via lookup, they may attempt to open a direct UDX connection.

• Accepting: The announce loop listens on the conn_rx channel for incoming connections.
• Modes:
  • Default: Incoming connections are immediately dropped to minimize resource usage.
  • Echo Mode (--ping): Connections are accepted and passed to the Echo Protocol handler.

Shutdown Sequence

The command remains active until it receives a termination signal (SIGINT or SIGTERM) or the --duration timer expires.

1. Unannounce: The node sends a leave request to the DHT for the active topic.
2. Cleanup: The background refresh task is aborted, and the swarm handle is destroyed.
3. Exit: The process exits with code 0.