Reorganize the node module tree by concept rather than by
message-handling verb, as the first step of the node runtime
decomposition. Pure relocation: no wire, config, metric, or log
semantics change; the lib test count is unchanged (1577 passed).
Moves (git mv, 100% rename similarity):
- handlers/{forwarding,rx_loop,connected_udp,dispatch,encrypted}.rs
-> node/dataplane/ — the whole RX hot path (the select! run loop,
transit/local forwarding, the link-message router, the RX decrypt
path with responder K-bit cutover + roam writes, and connected-UDP
fast-path activation) now lives in one home.
- node/session.rs -> node/session/mod.rs — establishes the session
concept home for the data/state types. The message-behavior file
handlers/session.rs stays put for now (folds in with the later FSP
session step).
The IK/XX-divergent establishment files (handlers/{handshake,rekey,
timeout}.rs) and the deferred-home files (handlers/{mmp,lookup}.rs)
deliberately stay in handlers/, to move once rather than twice.
Every module is reached through impl Node methods, so no call site or
re-export shim was needed. Updated in lockstep with the moves: the
module_path!-derived tracing targets in the two mesh-lab compose-trace
overlays, a structural test's include_str! source path, doc-comments
in proto/routing and the mesh-lab docs, and the stale source-location
citations (node/handlers/{forwarding,rx_loop,encrypted}.rs and
node/session.rs) in doc-comments and the discovery design doc.
Johnathan Corgan