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Author SHA1 Message Date
Johnathan Corgan d8cb4d407e FLP wire format revision and MMP link-layer measurement protocol 
## FLP Wire Format Revision

Replace the 1-byte discriminator with a structured wire format:

- 4-byte common prefix (ver+phase, flags, payload_len) and 16-byte
  established frame header with AEAD AAD binding
- 5-byte encrypted inner header (4-byte session-relative timestamp +
  1-byte message type) on all link messages
- Phase-based packet dispatch replacing discriminator-based dispatch
- SessionDatagram reassigned from type 0x40 to 0x00; add SenderReport
  (0x01) and ReceiverReport (0x02) message types for MMP
- SessionDatagram: rename hop_limit to ttl, add path_mtu field (u16 LE)
  with min(datagram.path_mtu, transport.mtu()) at forwarding
- Updated handshake packets (msg1: 87->90 bytes, msg2: 42->45 bytes)
- FIPS_OVERHEAD updated from 135 to 144 bytes

## MMP Link-Layer Measurement Protocol

Add the Metrics Measurement Protocol for link quality measurement
between FIPS peers. Measures RTT, loss, jitter, throughput, OWD trend,
and ETX from periodic sender/receiver reports exchanged over established
links.

Module layout:
- mmp/algorithms.rs: JitterEstimator, SrttEstimator, DualEwma, OwdTrend,
  SpinBit, ETX computation
- mmp/report.rs: SenderReport (48B) and ReceiverReport (68B) wire format
- mmp/sender.rs: per-peer TX counters and interval tracking
- mmp/receiver.rs: per-peer RX counters, jitter, loss, gap tracking
- mmp/metrics.rs: derived metrics from report processing (SRTT, goodput_bps)
- mmp/mod.rs: MmpMode (Full/Lightweight/Minimal), MmpConfig, MmpPeerState
- node/handlers/mmp.rs: report dispatch, timer-driven generation, operator
  logging (periodic + teardown)

Integration: per-frame TX/RX hooks in encrypted message handling, report
dispatch from link message router, timer-driven generation from tick
handler, and periodic operator logging with throughput formatting.

Three operating modes: Full (sender + receiver reports, spin bit, CE echo),
Lightweight (receiver reports only), Minimal (spin bit + CE echo only).

## Design Documentation

Updated FLP sections across all design documents to match the implemented
wire format, including revised overhead calculations and numeric values.

568 tests pass, clippy clean.
 2026-02-18 21:54:21 +00:00
Origami74andJohnathan Corgan d3477a7c0f Add explicit counter to DataPacket for out-of-order decryption 
Session-layer encryption used an implicit nonce counter with no counter
on the wire, requiring packets to arrive in exact order. Under bulk
transfer load (e.g., SCP), UDP packet loss or reordering permanently
desynchronized sender/receiver counters, causing all subsequent
decryption to fail with no recovery.

Add an 8-byte counter field to the DataPacket wire format and switch
from implicit-counter decrypt() to decrypt_with_replay_check() which
uses the explicit wire counter plus a 2048-packet sliding replay
window — the same pattern already used at the link layer.

Wire format: msg_type(1) + flags(1) + counter(8) + payload_len(2) = 12
bytes (was 4). FIPS_OVERHEAD updated 127 → 135 bytes accordingly.
 2026-02-17 00:33:01 +00:00
Origami74andJohnathan Corgan 852f561fa0 feat: implement ICMP Packet Too Big and TCP MSS clamping for MTU handling 
Add dual-approach MTU handling to prevent TCP connections from hanging
when packets exceed the transport MTU after FIPS encapsulation.

ICMPv6 Packet Too Big:
- Generate RFC 4443 PTB messages for oversized packets at TUN outbound
- Inject back via TUN for local delivery to the application
- Per-source rate limiting (100ms interval, 10s entry expiry)
- MTU check in handle_tun_outbound before session encapsulation

TCP MSS Clamping:
- Intercept SYN packets in run_tun_reader() (outbound)
- Intercept SYN-ACK packets in TunWriter (inbound)
- Clamp MSS option to fit within effective MTU (transport - 127 overhead)
- Recalculate TCP checksum after modification

Code organization:
- ICMP, TCP MSS, and rate limiter modules in upper/ alongside existing
  protocol-specific packet handling (dns.rs, tun.rs)
- Shared FIPS_OVERHEAD constant (127 bytes) and effective_ipv6_mtu()
  function in upper/icmp.rs
- Node::effective_ipv6_mtu() delegates to the shared function
- run_tun_reader() accepts actual transport MTU from config

Example config corrections:
- UDP transport MTU set to 1472 across all configs (correct max UDP
  payload for standard Ethernet: 1500 - 20 IPv4 - 8 UDP)
- Startup logging of effective MTU and max MSS values
 2026-02-16 21:33:21 +00:00
Johnathan Corgan 930f139787 Split cache.rs and config.rs into directory modules, create utils/ 
Module reorganization for three large single-file modules:

cache.rs (792 lines) split into cache/ directory:
- cache/mod.rs: CacheError, CacheStats, re-exports
- cache/entry.rs: CacheEntry with TTL/LRU tracking
- cache/coord_cache.rs: CoordCache (address-to-coordinate mappings)
- cache/route_cache.rs: RouteCache + CachedCoords (discovery routes)
- Added 22 new tests filling coverage gaps across all submodules

config.rs (1318 lines) split into config/ directory:
- config/mod.rs: ConfigError, IdentityConfig, Config struct with file
  loading/merge logic, all 24 integration tests
- config/node.rs: NodeConfig + 9 subsection structs (Limits, RateLimit,
  Retry, Cache, Discovery, Tree, Bloom, Session, Buffers)
- config/transport.rs: TransportInstances<T>, TransportsConfig, UdpConfig
- config/peer.rs: ConnectPolicy, PeerAddress, PeerConfig

DnsConfig and TunConfig moved to upper/config.rs to co-locate with the
upper layer components they configure (TUN interface, DNS responder).

index.rs moved to utils/index.rs as cross-cutting infrastructure that
serves both node and peer layers.
 2026-02-15 17:56:32 +00:00
Johnathan Corgan d71e48b0f2 Module reorganization, identity test coverage, design doc corrections 
Module reorganization:

- Split identity.rs (930 lines) into identity/ directory module:
  mod.rs, node_addr.rs, address.rs, peer.rs, local.rs, auth.rs,
  encoding.rs, tests.rs — following established bloom/, tree/, noise/
  pattern

- Group TUN, DNS, and ICMPv6 into upper/ module as the IPv6 adaptation
  layer: move tun.rs, icmp.rs, node/dns.rs into upper/

Identity test coverage (28 new tests, 52 total):

- Encoding error paths: invalid npub/nsec length, bad hex input
- NodeAddr: Debug, Display, as_slice, AsRef, Hash
- FipsAddress: from_slice, From trait, Debug, Display, Eq+Hash
- PeerIdentity: from_pubkey_full, pubkey_full parity paths, Debug
- Identity: keypair, pubkey_full, Debug
- AuthChallenge: from_bytes

Design doc corrections (fips-software-architecture.md):

- Identity struct: npub+nsec fields → keypair: Keypair with accessors
- Node struct: TunInterface → TunState, Transport → TransportHandle,
  Peer → PeerSlot
- Peer section: monolithic Peer → two-phase PeerSlot (PeerConnection +
  ActivePeer) with HandshakeState/ConnectivityState
- ActivePeer: npub → identity: PeerIdentity, ancestry Vec → Option,
  declaration/inbound_filter wrapped in Option
- BloomState: add 4 missing fields, fix update_debounce type
- DiscoveredPeer: field name and type corrections
 2026-02-15 17:11:58 +00:00