P2P (`podseq-p2p`)

The p2p crate handles block propagation between the sequencer and full nodes. It is built on Commonware primitives.

Stack#

Primitive	Role
`commonware-p2p`	Authenticated, encrypted peer connections and peer discovery via the `authenticated::discovery` module.
`commonware-broadcast`	Buffered broadcast engine for block data (deduplication, caching, pull-by-digest).
`commonware-cryptography`	ed25519 peer identity keys.
`commonware-runtime` (tokio)	Commonware's tokio backend, shared with the node binary for coexistence.

Two-channel protocol#

Two p2p channels are registered on the discovery network:

Channel	ID	Purpose
Broadcast (buffered)	0	Full blocks. The broadcast engine caches blocks per peer and serves them by digest.
Announce (raw)	1	40-byte `(height, digest)` notifications. The sequencer sends these so full nodes know which digests to pull.

Flow#

Sequencer produces a block → signs it → persists it →
broadcast(block) on channel 0 + announce(height, digest) on channel 1.
Full node polls channel 1 (async, 100ms timeout) → on receiving an
announce, calls receive(digest) on channel 0 → pulls the block from the
broadcast cache → verifies signature → applies to Reth as an optimistic head only. p2p blocks are never marked safe or finalized.
DA sync is the verification path. Every height is fetched from the Sui Registry → Walrus. If the block was already pulled in via p2p (and matches canonical DA block), it is only finalized: the safe/finalized fork-choice pointers advance without re-submitting the payload. Only a mismatch (sequencer equivocation) re-applies the canonical DA block and reorgs onto it. p2p reduces latency to head; finality always comes from DA. If a p2p announce is dropped, the block still arrives through DA.

Public API#

P2pConfig: identity key path, listen address, bootstrap peers.
P2pNode::new(context, config): creates the network, registers channels, starts the broadcast engine and background tasks. Returns broadcaster + receiver.
BlockBroadcaster: broadcast(block) and announce(height, digest).
BlockReceiver: poll_next() (announce channel) and receive(digest) (pull from broadcast cache).

Configuration#

[p2p]
key_path = "p2p.key"             # 64-char hex ed25519 seed
listen_addr = "0.0.0.0:9000"     # socket to bind
dialable_addr = "1.2.3.4:9000"   # optional, for NAT
bootstrap_peers = [              # optional
  "abc123...@1.2.3.4:9000",
]

The identity key is generated automatically on first start and persisted to key_path.