glm-5.1
5c820a41e9
Add 10 new tasks under tasks/architecture/ for Phase 0a (ADR writing): - 9 ADR tasks (026-034) with dependency-ordered structure - 1 review checkpoint task before Phase 0b spec writing ADR dependency graph (3 generations): Gen 1 (parallel): 026, 029, 030, 031, 032, 034 Gen 2 (depends on 029): 027, 028 Gen 3 (depends on 027+028): 033 Gen 4: review checkpoint Also mark all 34 prior implementation tasks as completed — they were finished but still showing as pending in the taskgraph.
64 lines
3.6 KiB
Markdown
64 lines
3.6 KiB
Markdown
---
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id: client/channel-manager
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name: Implement ChannelManager — SSH session management, channel opens, reconnection
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status: completed
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depends_on:
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- auth/client-auth-handler
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- transport/trait-and-types
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- auth/error-types
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scope: moderate
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risk: high
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impact: component
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level: implementation
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---
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## Description
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Implement the `ChannelManager` that owns the `Arc<client::Handle<ClientHandler>>` and provides the core client methods:
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- `open_direct_tcpip(host, port)` — open a tunnel channel to a remote host
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- `open_streamlocal(socket_path)` — open a tunnel to a Unix socket (stub for now)
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- `request_tcpip_forward(addr, port)` — request remote listening
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- `cancel_tcpip_forward(addr, port)` — cancel remote listening
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Most importantly, the channel manager handles **reconnection** on transport failure:
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1. Detect via `handle.is_closed()` or transport read error
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2. Exponential backoff reconnect (1s, 2s, 4s, ... max 30s)
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3. Re-establish transport connection (call `transport.connect()` again)
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4. Re-authenticate SSH session
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5. Notify SOCKS5 server and port forwards (in-flight connections fail, new connections work)
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Reconnection is always enabled. The backoff caps at 30 seconds and continues indefinitely.
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## Acceptance Criteria
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- [x] `crates/alknet-core/src/client/channel_manager.rs` exports `ChannelManager`
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- [x] `ChannelManager` holds: `Arc<Transport>`, `Arc<ClientAuthConfig>`, `Arc<client::Handle<ClientHandler>>` (behind RwLock for reconnection)
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- [x] `ChannelManager::new()` establishes initial transport connection, authenticates, returns manager
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- [x] `open_direct_tcpip(host, port)` — opens SSH channel to target
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- [x] `request_tcpip_forward(addr, port)` — sends `tcpip_forward` request
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- [x] `cancel_tcpip_forward(addr, port)` — sends `cancel_tcpip_forward` request
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- [x] Reconnection detection: monitors `handle.is_closed()`, triggers reconnect on failure
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- [x] Exponential backoff: 1s, 2s, 4s, 8s, 16s, 30s (cap), continues indefinitely
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- [x] Full reconnect: new transport stream, new SSH session over it (ADR-004)
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- [x] After reconnect: port forward listeners (`-L`, `-R`) re-registered with new session
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- [x] In-flight connections on old session fail gracefully (channel errors, not session-wide)
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- [x] Unit tests: channel open, reconnection trigger, backoff timing, forward re-registration
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## References
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- docs/architecture/client.md — Channel Manager section, Reconnection section
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- docs/architecture/decisions/004-ssh-over-transport.md — full reconnect, not "SSH reconnects over same transport"
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## Notes
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- Converted `client.rs` (single file) to directory module: `client/mod.rs` + `client/channel_manager.rs`
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- Used `russh::keys::PrivateKey` and `russh::keys::PublicKey` (not the nonexistent `russh::key::KeyPair`)
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- Reconnection monitor runs as a spawned tokio task that polls `handle.is_closed()` every 1s
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- On reconnect: creates new transport stream + new SSH session (ADR-004 full reconnect)
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- `ForwardRequest` struct tracks registered port forwards for re-registration after reconnect
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- In-flight channels on old session naturally fail with `ChannelError::ChannelClosed` since the handle is replaced
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## Summary
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Implemented `ChannelManager` in `crates/alknet-core/src/client/channel_manager.rs` with SSH session management, channel opens (`open_direct_tcpip`), port forward requests (`request_tcpip_forward`/`cancel_tcpip_forward`), and automatic reconnection with exponential backoff (1s→30s cap). Full reconnect per ADR-004 creates new transport stream + new SSH session. Port forwards are re-registered after successful reconnect. 8 unit tests covering backoff timing, forward tracking, transport failure, and reconnection detection. |