Aleksandr Bogomiakov
e701986a39
Plain WG and QUIC can be blocked or severely degraded while the iroh control connection still works. Add an awg carrier with one independent UDP socket, WireGuard engine and randomized masking profile per network/peer attempt. The smaller endpoint id negotiates fresh outer keys, PSK, header protection, header ranges, padding and signature templates through private authenticated control messages. Restart or fallback reentry generates a new profile; ordinary rekeying preserves the current profile. No pair parameters enter signed state, capabilities, persistent storage or public message events. Private payloads and serialized control buffers redact and zeroize themselves. Adapt the bounded packet masking engine from RunaRoo/AmneziaWG-RS at commit 51579a7d6e8882d1d8d6d00822f09e18a9423b73, retaining its Apache license and provenance. Declare WTFPL AND Apache-2.0 in package metadata to cover both new glue and the adapted source. Reuse boringtun instead of upstream's Node/global executors and interface machinery. This is Tsunagi AWG wire version 1, with standard WG headers restored before authentication; external Amnezia server compatibility is not implemented. DNS/SIP signature generators vary fields instead of replaying captures. Each attempt closes independently, bounds allocation, queues, candidates and fragment assemblies, and supports the full 64 KiB carrier contract using UDP packets at most 1200 bytes. Yield between fragment batches so large messages do not starve local socket readers. Keep carrier encryption separate from end-to-end tunnels so multihop relays still forward opaque ciphertext. The system owns the sole interface, signed addresses and admission. Plugins receive neither network secrets nor paths. Expose a bounded opaque control sender at the transport boundary; core control messages remain outside protocol crates. Optional STUN on the pair's actual socket adds IPv4 public candidates in CLI direct/relay mode, with a finite query deadline and an off/alternate-server option. Local mode remains offline. Symmetric NAT, IPv6-only paths and arbitrary UDP blocking can still require fallback; no AWG-over-QUIC or hidden AWG relay is introduced. Default carrier order is wg, awg, wg-quic, tcp-tls. Advance the fallback cycle after setup failures and sustained runtime loss, even after earlier cooldowns expire. Authenticated delivery probes traverse the actual encrypted tunnel, fit the interface MTU and never enter the TUN. Retire after a 20-second warmup and at least 60% loss over at least 15 completed recent observations. Preserve logical tunnels and control sessions while explicitly closing physical links, including TCP reader/writer tasks. Retain the newest private probe settings across independently queued control negotiation and inbound installation. CLI/tray reports keep end-to-end protocol and actual carrier separate. Control ALPN/version becomes tsunagi/ctrl/6 for the new private message; upgrade all members together. Data ALPN/envelopes remain version 5. Network identity derivation, transcript encoding, device identities, signed records, saved network configuration and release versions are unchanged. Validation on Linux through nix develop: - cargo fmt --all -- --check - cargo clippy --locked --workspace --all-targets -- -D warnings - cargo test --locked --workspace --all-targets, with the inherited TSUNAGI_CONTROL_SOCKET override removed: 504 passed, 2 pre-existing ignored Tests use real iroh membership, SQLite, UDP sockets and WireGuard encryption with memory TUNs. Cover three independent pairs, full-size IP and carrier frames, restart freshness/socket release, 80% carrier datagram loss, fallback to real iroh, fresh retries with working delivery checks, unequal small MTUs, malformed negotiations/profiles, role and resource bounds, probe forgery and STUN parsing. Earlier compile/lint iterations and focused tests caught RNG API/initializer mistakes, a retry assertion racing path installation, and a large-fragment burst overflowing loopback buffers; corrected before these successful checks. Normalized upstream license line endings for diff checks. Public NAT/STUN connectivity, actual DPI effectiveness, WAN performance, per-pair memory measurement, macOS/Windows, privileged TUN operations and manual tray interaction were not exercised.
6.6 KiB
Pairwise Amnezia transport
The CLI's default carrier preference is wg,awg,wg-quic,tcp-tls. To select
AWG explicitly:
tsng up --protocol awg
tsng up --protocol wg,awg,wg-quic,tcp-tls
awg is Tsunagi AWG wire version 1. Its packet masking engine is adapted from
RunaRoo/AmneziaWG-RS, with the pinned
source and license recorded in
UPSTREAM.md. It uses the existing boringtun
Noise/WireGuard implementation instead of upstream's Node, global executors
and OS interface machinery. Compatibility with ordinary Amnezia servers is
not implemented: this carrier connects authenticated Tsunagi members.
Negotiation and lifetime
There is one independent UDP socket and cancellable packet-engine task per
(network, peer) pair. The smaller endpoint id initiates, following the same
rule as other data carriers. Both sides must announce enabled AWG wire version
- An authenticated iroh control session is required throughout; AWG supplies no alternate discovery or membership mechanism.
Every open generates new masking parameters, a header-protection key, an
outer WireGuard key pair and a PSK. The initiator sends a private Offer with
a random attempt id, its public key, candidate socket addresses and the shared
profile. The responder validates it, creates its own fresh key pair and socket,
and returns an Answer naming that attempt. Both send masked handshakes and
encrypted delivery probes to the candidates. Only authenticated WireGuard
data, not a STUN response or an incoming UDP address alone, verifies a path.
Negotiation payloads are bounded at 4096 bytes (a caller can lower the limit), redacted in Debug, excluded from public message events and erased on drop. They are never capabilities, signed records, cache entries or exported status. At most 128 pairs are admitted per transport, with bounded command/data queues, at most 32 candidates per attempt and finite establishment deadlines. Stale answers and duplicate offers are rejected; a new attempt replaces and closes an older pair engine. Cancellation, peer departure, network deactivation and shutdown retire sockets without waiting for a remote reader.
A process restart, a failed setup, or a complete fallback cycle returning to AWG starts fresh negotiation. Normal WireGuard rekeying within a live attempt keeps that attempt's masking profile. A failed pair does not reconfigure other pairs or other networks. A full mesh of 15 members uses 14 engines per member and 105 independent pairs in total; it does not create additional system interfaces.
Masking
Each profile randomizes disjoint H1–H4 header ranges, a 12–48-byte S1–S4 prefix, a ChaCha20 header-protection key, handshake trailers, junk packet count/lengths, and extra content padding. Prefix lengths are equal within one profile so header detection has one offset. A fresh random nonce is in every packet's prefix; handshake headers and transport headers/counters are protected. The standard WireGuard header is restored before boringtun authenticates a message. This preserves boringtun's standard MAC calculations, which is another reason this is a Tsunagi-specific AWG wire version.
Before a handshake, an I1 signature packet is generated from either a complete DNS query or SIP OPTIONS template, with fresh identifiers and consistent length fields, followed by random junk packets. I2–I5 are unused in this version. The templates are structural generators, not replayed captures. QUIC imitation is not selected. Masking can change DPI classification; it is not a promise of indistinguishability or that any particular firewall will admit it.
Packets, NAT and fallback
The pair engine carries opaque relay envelopes inside authenticated outer WG packets. It fragments those envelopes into bounded chunks and expires incomplete assemblies; a logical datagram is bounded at 64 KiB and an outer UDP packet is at most 1200 bytes. The encapsulated IPv4 headers are internal framing only: no interface or OS address is created for a pair. Overlay addresses, routing, ownership checks and end-to-end encryption remain independent. A relay decrypts its own adjacent AWG carrier to forward opaque end-to-end ciphertext, never the destination's IP packet.
Local IPv4 candidates and simultaneous encrypted probes provide direct UDP
connectivity. In direct/relay reach mode the CLI also uses
stun.l.google.com:19302 to discover a server-reflexive address on this pair's
socket, with a 1.2-second bound. A STUN result is only a candidate. Local reach
mode makes no STUN request. Configure or disable it with
-o awg:stun=HOST:PORT or -o awg:stun=off. Failed discovery still permits local
candidates. IPv6-only paths, symmetric NAT and networks blocking arbitrary UDP
may fail AWG and fall back; there is no AWG-over-QUIC substitution or AWG TURN
relay hidden behind its name.
Data delivery checks go through the actual end-to-end encrypted tunnel, once per second, independently of control-plane RTT. Requests and replies bind a fresh private marker/key to the sender's endpoint id. Unanswered requests expire after three seconds. After a 20-second warmup, at least 15 completed observations and at least 60% loss in the last 20 observations retire a carrier. Probes are consumed locally after source/destination admission and never enter the TUN. AWG additionally checks encrypted outer delivery throughout the pair lifetime.
Setup failure or persistent runtime loss advances to the next mutually supported
carrier in the initiator's order. Earlier expired cooldowns do not jump ahead of
untried carriers. Retry cooldowns remain bounded; reaching AWG again negotiates
new parameters. Control sessions and the logical end-to-end tunnel survive a
carrier change. Status names the end-to-end protocol and the actual carrier
separately, so wg over awg is a valid result.
Control wire version 6 introduces the private transport message. All members
must upgrade together; device identities, network ids, handshake transcript
encoding, signed state and stored network configuration are unchanged. Data
ALPN remains tsunagi/data/5; the relay envelope is unchanged.
Verification
The default rootless, offline tests use real iroh endpoints, membership proofs, SQLite, UDP sockets, masked WireGuard handshakes, end-to-end encryption and memory TUNs. They cover independent three-member pairs, full-size bidirectional packets, restart freshness/socket release, 80% runtime datagram loss, fallback to real iroh and fresh negotiation on retry, plus malformed profiles/messages, role checks, probe forgery and STUN response parsing. These tests do not establish DPI effectiveness, WAN throughput, public NAT traversal or per-pair memory cost.