ferravexferravex-net
Original dependency-free bounded binary codecs, native UDP sockets and reusable networking building blocks.
Protocol version 2
Every packet starts with FERRAVEX, a one-byte version (PROTOCOL_VERSION = 2) and a one-byte kind. Integers and float bit patterns are little-endian. Packets exceeding 1,200 bytes, truncated fields, invalid numeric values, unknown versions/kinds and trailing bytes are rejected. Version 1 peers are deliberately incompatible and must upgrade together.
| Kind | Direction | Payload after the header |
|---|---|---|
| 1 | Client → server | Hello: nonce u64 |
| 2 | Client → server | Input: session u64, count u8, 1-6 existing input frames |
| 3 | Server → client | Welcome: nonce u64, session u64, player ID u8, tick u32 |
| 4 | Server → client | Full snapshot: session, tick, acknowledged input sequence/validity, bounded player list |
| 5 | Server → client | ReliableEvent: session u64, sequence u64, payload length u16, payload |
| 6 | Client → server | EventAck: session u64, individual sequence u64 |
Reliable event payloads are capped at 900 bytes, so a maximal event packet occupies 924 bytes. Session cookies must be nonzero. The ferravex-fps session implements actual transmission, ACKs, retry and consumption; this crate's codec does not send automatically.
reliable::EventSender bounds pending events at 256 and retries after 100 ms when polled with a monotonic clock. EventReceiver uses a 256-sequence window and returns each delivered event once in order. ACK only when receive succeeds, including duplicates. Individual acknowledgments ensure that acknowledging a newer event never hides loss of an older one.
delta::Delta provides sparse byte differences with full-payload fallback and exact baseline validation. history::History provides bounded ordered samples and interpolation brackets; ClockSync provides timestamp offset/RTT estimates. These are standalone building blocks. The current native FPS session does not exchange snapshot-delta baselines, clock-sync timestamps, or client shot times.
UDP is development/LAN transport with no encryption, identity authentication, NAT traversal, congestion controller or internet abuse mitigation. Session cookies isolate connection state; they are not an authentication or encryption protocol.