---
status: draft
last_updated: 2026-09-25 (the assembly layer landed + the cross-cutting
assembly integration suite; the protocol core landed + the cross-cutting
integration suite 2026-09-24; the rfc1928 doc's targeted fork 2026-09-22; the
vendor extraction amendment ADR-011 §Amendment 2026-09-21; Phase 1
initial draft 2026-09-20 — the OQ-SK ledger promoted into ADRs
001-012 and open-questions.md)
---
# alksocks — Architecture
A SOCKS5 (RFC 1928) producer/consumer protocol crate on alkcall
channels: an arbitrary-egress proxy service that never binds a port
unless explicitly configured to — the `alk/socks5`-family
producer/consumer protocol crate, the sibling of alktty
(`alk/tty`) and alktunnels (`alk/tunnel`). Where alktunnels
realizes the `-L`/`-R` forwarding flavors, alksocks realizes the
`-D` flavor (dynamic / SOCKS5 proxy). This directory holds the
architecture spec docs and the ADRs.
## Current State
Phase 1 (Architecture) — the **protocol core and the assembly layer
are implemented**. Phase
0 (`docs/research/phase-0.md`) is converged (2026-09-14) and
POC-complete (all numbered POCs passed or were dropped with the scope
decision); the OQ-SK ledger's Phase 1 inputs are collected and
promoted into ADRs 001–014. All docs are `draft` — they transition
to `reviewed` when their open questions resolve and the architecture
review passes.
The landed surface: the RFC 1928 core in `src/rfc1928/` (the targeted
fork, ADR-013 — the vendor group's six tasks landed and passed the
extraction review), the ASSOCIATE datagram frame codec (`src/wire.rs`,
ADR-003), the open-op params + typed error surface (`src/params.rs` /
`src/error.rs`, ADR-001), the three seam types (`src/egress.rs`,
ADR-004), the producer half (`src/producer.rs` — the session-gate
establisher, the command-dispatch pump, the three commands, the scope
gates), and the consumer half (`src/consumer.rs` — the
connect/associate/bind session types with teardown ownership). The
assembly layer (batch 2) landed with it: the `local` providers
(`src/local/` — tcp_dial / udp_egress / bind_accept, the producer-side
`ProducerDoor`, ADR-008/009), the front doors (`src/door.rs` — the
NoAuth raw-pipe + RFC 1929 cred-bearing TCP door, the BIND door, the
UDP door, ADR-005/003/014), and the composed providers
(`src/composed/` — the direct-op egress + the bind-first accept over
alktunnels 0.2.0, ADR-007/008). Both cross-cutting integration suites
pin the behavior end to end: `tests/core-integration.rs` (the
protocol core) and `tests/assembly-integration.rs` (the assembly
layer — the full `-D` story through the doors, the composed variant
set, mixed assembly, the assembly teardown matrix).
## Documents
| [overview.md](overview.md) | draft | Crate purpose, the resource model in brief, dependencies, feature gates, module map |
| [wire.md](wire.md) | draft | The wire format: the open op (trivial params — ADR-001), the phase model, the data planes (CONNECT pass-through / ASSOCIATE frames / BIND phases), sentinels |
| [producer.md](producer.md) | draft | The producer half: the session-gate establisher, command dispatch, the three seams (dial/egress/accept), scope gates, the local backend |
| [consumer.md](consumer.md) | draft | The consumer half: the channels-native sessions (connect/associate/bind), the front doors, door auth (ADR-005), teardown ownership |
| [vendor.md](rfc1928.md) | draft | The RFC 1928 core: the targeted fork of fast-socks5's `T`-generic subset (ADR-013; the extraction mechanics in ADR-011) — the fork's scope, the deliberate modifications, the maintenance posture |
| [bast.md](bast.md) | draft | The BAST document for the ASSOCIATE datagram frame (ADR-003); pass-through stages have no binary framing to describe |
| [open-questions.md](open-questions.md) | draft | Centralized OQ tracker (OQ-SK-01..09 promoted; new questions as OQ-SK2-06.. — the SK2 numbering is not contiguous from 01, working-draft numbers were consumed) |
## ADR Table
| [001](decisions/001-alpn-and-open-op.md) | ALPN, Open Op, and Trivial Params | Accepted |
| [002](decisions/002-protocol-base.md) | Protocol Base — the Vendored fast-socks5 Typestate Subset | Accepted |
| [003](decisions/003-udp-handle-swap.md) | The Handle Swap — one Channel per Association, Frames In-Band | Accepted |
| [004](decisions/004-dial-callback-shape.md) | The Dial-Callback Shape — Function, not Trait, at Three Seams | Accepted |
| [005](decisions/005-auth-split-by-door.md) | Auth Mapping — "Both," Split by the Door | Accepted |
| [006](decisions/006-access-control.md) | Access-Control Posture — the Open Gate Plus the Command Gate | Accepted |
| [007](decisions/007-bind-in-base.md) | BIND in the Base Crate — the Phase Model Extended | Accepted |
| [008](decisions/008-provider-defaults.md) | Egress/Accept Provider Defaults — Local Socket and Composed (Direct Op) | Accepted |
| [009](decisions/009-feature-gates.md) | Feature-Gate Layout — `local` and the Composition Boundary | Accepted (amended 2026-09-21) |
| [010](decisions/010-channel-capacity.md) | Channel Capacity — Proxy-Workload Recommendation, Not a Wire Change | Accepted |
| [011](decisions/011-inline-vendor.md) | the Inline Vendor — fast-socks5's `T`-Generic Subset, In-Tree | Superseded by ADR-013 (extraction mechanics remain authoritative) |
| [012](decisions/012-target-policy.md) | Target Policy and the Virtual-Subnet Translation Layer | Accepted |
| [013](decisions/013-targeted-fork.md) | The Targeted Fork — the Extracted Subset Is Owned, Not Vendored | Accepted |
Upstream ADRs (alkcall/alktunnels/alknet) are referenced by their own
numbers and are NOT ported — the alkcall originals at
`/workspace/@alkdev/alkcall/docs/architecture/decisions/` remain
authoritative for the shared surfaces (establishment, channels wire
format, `pump_bidi`, identity seam, the channel caps).
## Key Design Principles
1. **The protocol never binds.** The SOCKS5 service is a produced,
ACL-scoped resource on a channels connection ("ALPN as a
service"); kernel binds exist only as the two explicit, optional,
feature-gated assembly shapes (the producer's local backend; the
consumer's front door). The binding decision belongs to the
caller. The UDP ASSOCIATE "bind" is virtualized as the channel
(the handle swap, ADR-003).
2. **The RFC conversation is the data plane.** One ALPN, one open
op, trivial params (ADR-001); the phase model needs no mode byte
— the reply synchronizes the switch; no in-band control
vocabulary (the escape hatch is a new ALPN, never a framing
change).
3. **The seams are functions, not traits** (ADR-004): DialFn /
EgressFactory / BindAcceptFactory at the three I/O planes; the
protocol layer never names a substrate type; ownership rides the
handle structurally.
4. **Auth is split by the door** (ADR-005): producer = the identity
seam; the front door = RFC 1929 + the credential→identity static
mapping.
5. **Two grants, clean separation** (ADR-006): `socks5:open`
(egress) and `socks5:bind` (ingress listeners) — never implied by
each other; target policy = the dialer.
6. **Backpressure and limits are inherited, not redefined** (the
alkcall channels invariants); the one-channel-per-session
convention holds for all three commands; the proxy-workload cap
posture is ADR-010 (config, not wire).
7. **Wasm-clean default crate** (ADR-009): the default crate is
protocol-only; the RFC 1928 core is an extraction with zero
kernel-net code — there is no `net` feature (ADR-011 §Amendment);
`local` is opt-in and non-wasm; `composed` rides alktunnels'
wasm-clean default (verified with the wasm check at
implementation).
8. **The RFC 1928 core is owned** (ADR-013, superseding ADR-011's
vendor posture): the extracted `T`-generic subset is a targeted
fork (`src/rfc1928/`, fork point `5b18d4d`) — project
conventions apply unconditionally, the lint-allow/verbatim
apparatus is dissolved; `/workspace/fast-socks5` stays the
differential-testing behavioral reference and the only place the
full upstream surface (the kernel-net region) exists; nothing
waits on upstream and nothing is absorbed from it (a future
upstream fix is a hand-port, guarded by the differential suite).
## Document Lifecycle
| `draft` | Under active development; may change significantly | → `reviewed` when the doc's open questions resolve |
| `reviewed` | Architecture is final; implementation may begin | → `stable` when implementation is complete and verified |
| `stable` | Locked; changes require review, may warrant an ADR | → `deprecated` when superseded |
| `deprecated` | Superseded; kept for reference | Removed when no longer referenced |
## References
- Phase 0: `docs/research/phase-0.md` (the OQ ledger + convergence),
the POC findings files, `docs/research/iroh-socks5-eval.md`
- The SDD process: `docs/sdd_process.md` (Phase 1's process; the
task format; the deferred-OQ blocker-task half)
- Upstream: alkcall ADR-037/039/047/049/050/040/041/051, ledger
CF-005/CF-006; alktunnels ADR-003/004/006/007/008 + the graduation
research; alknet ADR-078/090
- Siblings: alktty (`/workspace/@alkdev/alktty`),
alktunnels (`/workspace/@alkdev/alktunnels`)
- Reference checkout: `/workspace/fast-socks5` (v1.0.0, MIT,
third-party — the differential-testing reference)
- RFC 1928, RFC 1929; tun2proxy (`/workspace/tun2proxy`)