Module peer_seq 

Per-peer monotonic sequence counters and a 64-entry sliding-window replay detector.

Outbound: PeerSeqSender

Each local-node-to-peer direction has a distinct counter. Sent frames carry strictly-increasing sequence numbers starting from 1. 0 is reserved as a sentinel meaning “never sent”.

Inbound: PeerSeqWindow

A 64-bit bitmap anchored at last_accepted_seq. Frame with sequence n is:

• accepted and window advanced if n > last_accepted_seq
• accepted and bit set if last_accepted_seq - 63 <= n < last_accepted_seq and the bit was previously unset
• rejected as replay if the bit was already set, or if n is older than the window

The window model is identical to IPsec AH/ESP (RFC 4303 §3.4.3). 64 entries is the standard default — large enough that legitimate reordering in-flight (rare over one QUIC stream but possible across QUIC streams) is tolerated, and small enough to fit in a single u64.

Structs

PeerSeqSender

Outbound monotonic counter for this AuthContext. One counter total — not one per target — because the receiver’s replay window is keyed by the sender’s local_node_id. If this sender used a per-target counter, two distinct targets’ traffic would share the same window on any node that receives from both: seq=1 from target=A and seq=1 from target=B collide in the receiver’s window[sender_id]. A single counter makes every outbound seq globally unique per sender.

PeerSeqWindow

Per-peer inbound sliding-window replay detector. One window per (local_node, remote_peer) pair.

Constants

REPLAY_WINDOW

Size of the inbound replay-detection window.