feat(agent): reseed verb — host-fed entropy, CRNG reseed, machine-id regen#4
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…regen Cloned/restored VMs resume from byte-identical snapshot memory, so their CRNG state (and /etc/machine-id) is identical across all clones unless something perturbs it post-boot. Adds a second wire-protocol verb, reseed, so the host can push fresh entropy and order a CRNG reseed (+ optional machine-id regen) over the same vsock connection used for exec.
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What
New wire verb
reseed— the second verb afterexec. After a VM clone/restore, N guests share byte-identical snapshot memory, hence byte-identical CRNG state (colliding TLS keys/UUIDs). The host sends areseedframe carrying fresh entropy; the agent:RNDADDENTROPY(hand-builtrand_pool_info: entropy bits + buf size + payload, native-endian),RNDRESEEDCRNG,/var/lib/systemd/random-seed,/etc/machine-id(regen_machine_id— clone sets it, same-VM restore doesn't; skipped silently where the file doesn't exist, e.g. Android).Response reuses the existing terminal frames (
MsgExit/MsgError). Non-Linux GOOSes answer with a sentinel error (build-tag stub, same pattern astransport_other.go). Old agents reject the unknown frame type via the existing first-frame check — graceful degradation for free.Client side:
client.Reseed(ctx, conn, entropy, regenMachineID); the connection prologue shared withRunis extracted intoopenSession.Validation
make lint: 0 issues × {linux, darwin, windows}make test: agent 84.9% / client 21.2% coverage, race-enabled; new tests: dispatch (reseed first-frame, unknown-type rejection), protocol round-trip, client success/error/non-zero-exitrand_pool_infolayout (bits vs bytes), single-fd ioctl sequence, one-terminal-frame invariant, ctx-cancel conn teardown