glm-5.1
dad8224686
Docs: - README.md: index with doc table, ADR table, lifecycle definitions - overview.md: purpose, exports, dependencies, constraints - transport.md: Transport trait, TCP/TLS/iroh implementations, stream join - client.md: SOCKS5 server, port forwarding, channel manager, reconnection - server.md: auth, channel handling, stealth mode, outbound proxy - tun-shim.md: separate privileged process, virtual DNS, --unshare mode - napi-and-pubsub.md: NAPI wrapper, pubsub event target adapter ADRs: - 001: Pluggable transport via AsyncRead+AsyncWrite trait - 002: TUN shim as separate process - 003: iroh stream via tokio::io::join - 004: SSH runs over transport, not alongside - 005: SOCKS5 as primary interface, TUN as add-on - 006(007): NAPI exposes single duplex stream Open questions: 11 items covering TLS certs, iroh relay defaults, Windows TUN, auth expansion, NAPI surface, TCP reconstruction
26 lines
2.1 KiB
Markdown
26 lines
2.1 KiB
Markdown
# ADR-001: Pluggable Transport via AsyncRead+AsyncWrite Trait
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## Status
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Accepted
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## Context
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Wraith needs to support multiple transport modes (TCP, TLS, iroh) for SSH sessions. Each mode has different connection establishment logic but produces the same result: a bidirectional byte stream. Without an abstraction, each transport would need its own SSH connection code path.
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russh's `client::connect_stream()` and `server::run_stream()` both accept `AsyncRead + AsyncWrite + Unpin + Send`, meaning SSH is already transport-agnostic at the API level. The design question is whether to enshrine this in wraith's own type system or handle each transport case-by-case.
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## Decision
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Define a `Transport` trait that produces `AsyncRead + AsyncWrite + Unpin + Send` streams. Each transport (TCP, TLS, iroh) implements this trait. The SSH layer calls `transport.connect()` and passes the result to `russh::client::connect_stream()`.
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On the server side, define a `TransportAcceptor` trait that produces incoming streams. Each acceptor (TCP listener, TLS listener, iroh endpoint) implements this trait. The server calls `acceptor.accept()` and passes the result to `russh::server::run_stream()`.
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This makes adding a new transport (e.g., WebSocket, QUIC directly) a matter of implementing the trait, not modifying SSH code.
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## Consequences
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- **Positive**: Clean separation between transport and protocol. Adding transports is additive. SSH code is transport-agnostic.
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- **Positive**: Testing is simplified — mock transports can produce in-memory streams.
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- **Negative**: Slight indirection for the single-transport case (just TCP). The trait boilerplate is minimal though.
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- **Negative**: The trait must be object-safe if we want dynamic dispatch. Using `impl Trait` in function signatures avoids this but limits runtime transport selection. CLI-selected transport needs dynamic dispatch: `Box<dyn Transport<Stream = Box<dyn AsyncRead+AsyncWrite+Unpin+Send>>>`.
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## References
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- [transport.md](../transport.md)
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- [Feasibility assessment §3](../../../../conversations/research/ssh-tunnel-vpn-alternative-feasibility.md) |