glm-5.1
d3633b7839
Update four existing specs (overview, server, napi-and-pubsub, call-protocol) to reflect Phase 0 decisions: three-layer model, IdentityProvider, ForwardingPolicy, OperationEnv, static/dynamic config split. Review all 9 Phase 0a ADRs (026-034) for consistency. Fix 4 critical issues from architecture review: missing OQ-SVC-05 in open-questions.md, deprecated hub terminology, undefined AuthService and noq terms. Replace inline OQ text with cross-references per format rules. Add ConfigServiceImpl definition to configuration.md. Port absolute workspace paths to project-relative links by copying referenced docs (feasibility, certbot, fail2ban, event_source_types) into docs/research/.
31 lines
1.9 KiB
Markdown
31 lines
1.9 KiB
Markdown
# ADR-003: iroh Stream via tokio::io::join
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## Status
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Accepted
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## Context
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iroh's QUIC implementation provides separate `RecvStream` (implements `AsyncRead`) and `SendStream` (implements `AsyncWrite`) for each bidirectional channel opened via `open_bi()` / `accept_bi()`. russh's `connect_stream()` and `run_stream()` require a single type implementing both `AsyncRead` and `AsyncWrite`.
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Options considered:
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1. `tokio::io::join(recv, send)` — Combines the two halves into `Join<RecvStream, SendStream>` which implements both traits.
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2. Custom `IrohStream` wrapper — A struct with `recv` and `send` fields that delegates `AsyncRead` to `recv` and `AsyncWrite` to `send`.
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3. Using iroh's `Connection` directly — Opening a new `open_bi()` for each SSH channel instead of running SSH over a single stream.
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## Decision
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Use `tokio::io::join(recv_stream, send_stream)` (Option 1).
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One line of code, correct trait implementations, no custom types needed. The `Join<A, B>` type implements `AsyncRead` using `A` and `AsyncWrite` using `B`, which maps directly to iroh's split stream model.
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If profiling later shows overhead (unlikely — it's just method dispatch), we can switch to a custom wrapper. But YAGNI until demonstrated.
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Option 3 was rejected because it would require modifying russh to understand iroh connections. The whole point of the transport trait is that SSH doesn't know about iroh.
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## Consequences
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- **Positive**: Minimal code. One line to bridge iroh and russh.
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- **Positive**: No custom types to maintain.
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- **Positive**: Correct `AsyncRead` + `AsyncWrite` behavior — `Poll::Pending` on one half doesn't affect the other.
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- **Negative**: None identified. The `Join` type is a standard tokio combinator with well-tested semantics.
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## References
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- [transport.md](../transport.md)
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- [Feasibility assessment §11](../../research/feasibility/ssh-tunnel-vpn-alternative-feasibility.md) |