Module caps 

The frozen version-1 protocol constants and the message-level cap checks (SPEC §7.1, §7.2).

These are the wire contract — an implementation is conformant only if it enforces exactly these values. Senders MUST never exceed the list caps; receivers MUST reject (never truncate) an over-cap message with a violation strike. The PexEngine enforces both directions: it caps its own outgoing messages, and it rejects over-cap inbound ones.

Constants

PEX_ARRIVAL_GRACE

The receiver’s enforcement tolerance, in seconds — absorbs scheduling + clock skew (SPEC §6.4).

PEX_DEFAULT_INTERVAL

Default declared send interval, in seconds (SPEC §6.2).

PEX_MAX_ADDED

Maximum entries in a pex_delta.added list.

PEX_MAX_ADDRESSES

Maximum addresses per peer entry.

PEX_MAX_DROPPED

Maximum ids in a pex_delta.dropped list.

PEX_MAX_ENTRY_AGE

Maximum last_seen age (seconds) an entry may be advertised with; older entries are not advertised (sender) and skipped on receive (SPEC §3.3, §8.2).

PEX_MAX_FLAGS

Maximum flags per peer entry (and per handshake).

PEX_MAX_FLAG_LEN

Maximum characters per flag token.

PEX_MAX_FRAME

Maximum message body bytes (256 KiB) — matches the DHT / dig-nat wire bound. A frame claiming a larger body MUST be rejected before allocating or reading the body (SPEC §4.1, §7.2).

PEX_MAX_HINTS

Hard ceiling on the engine-global hints map (SPEC §9.2, §11.3) — the deduplicated best hint per peer_id across all links. Bounds total memory when many links each contribute distinct peer_ids. Oldest-last_seen entries are evicted first once the cap is reached.

PEX_MAX_INTERVAL

Interval ceiling for declarations, in seconds.

PEX_MAX_RECEIVED_PER_LINK

Hard ceiling on a single link’s received accumulator (SPEC §9.2, §11.3) — the set of peer_ids that link has told us, kept for dropped attribution. Bounds per-link memory from an authenticated peer that streams an unbounded number of distinct fresh peer_ids over the link’s lifetime; a single message is already capped by PEX_MAX_ADDED/PEX_MAX_SNAPSHOT, but that does not bound the cumulative total across many messages. Oldest-last_seen entries are evicted first once the cap is reached.

PEX_MAX_SNAPSHOT

Maximum entries in a pex_snapshot.peers list.

PEX_MIN_INTERVAL

Hard interval floor, in seconds — a sender MUST NOT declare (nor be enforced) below this.

PEX_VERSION

The PEX wire version this crate implements (SPEC §7.1).

PEX_VIOLATION_LIMIT

Strikes on a direction before it is muted / the peer may be disconnected (SPEC §7.1, §11.2).

Functions

frame_within_bound

Whether a frame body of len bytes is within PEX_MAX_FRAME. A caller MUST check this before allocating or reading the body (the stream binding checks the length prefix; the relay binding checks the WebSocket payload length).