Closes the residual the 0004 hardening deferred: the NATS authenticator
can now confine a registered peer to the subjects of the rooms it
belongs to, instead of letting any registered identity sub/pub on any
subject. The dynamic-membership reconnection model the audit named is
provided by client.RefreshSession.
pkg/busauth:
- verifyNkey factors out the shared nkey verification.
- NewNkeyAuthenticatorACL + PermissionsFunc: an authenticator that, after
authorizing, derives and RegisterUser()s per-subject permissions. A
derivation error denies the connection (fail closed).
pkg/membership:
- SubjectACLFor(store) maps a signing pubkey to the subjects it may use:
the subject of every room it belongs to, plus the client infrastructure
subjects (_INBOX.>, $JS.API.> for request/reply and the persisted plane).
pkg/client:
- RefreshSession() rebuilds the data-plane connection so the authenticator
re-derives permissions after a membership change (NATS freezes
permissions at connect time). It retains the seeds/options to reconnect;
active subscriptions are dropped and must be re-made (documented).
Tests (DoD: isolation + refresh):
- TestSubjectACLIsolation: alice (member of room.A) may sub/pub room.A but
is DENIED sub and pub on room.B (permissions violation), and never reads
bob's room.B traffic; bob never receives alice's cross-room publish.
- TestRefreshSessionGainsNewRoom: alice has no permission for room B until
she is added and calls RefreshSession; the reconnect grants the subject
and she then receives room B traffic.
Scope note: the per-subject ACL authenticator is opt-in (NewServer/
membershipd keep the open authenticator by default) and is wired in with
the decentralized boot path; auto-RefreshSession on every membership
change (fully transparent) remains for 0003f. Master behavior unchanged.
Add high-availability cluster support to the embedded NATS server
(issue 0003a, first phase of decentralization).
pkg/embeddednats:
- ServerConfig gains ServerName (unique per node, required by JetStream
RAFT) and an optional *ClusterConfig (cluster name, route host/port,
peer route URLs, shared-secret Username/Password, and a mutual-TLS
*tls.Config). applyClusterOpts maps it onto server.Options.Cluster +
Routes. Nil Cluster keeps the legacy standalone server.
pkg/busauth:
- RouteTLSConfig builds the route layer's mutual-TLS config: the node
presents its CA-signed certificate AND verifies the peer's certificate
against the bus CA (RequireAndVerifyClientCert), reusing the issue-0001
CA. Routes authenticate NODES, never the client nkey authenticator.
cmd/membershipd:
- Cluster flags (--cluster-name/--server-name/--cluster-port/--routes/
--cluster-user/--cluster-pass/--route-tls-cert/-key/-ca) wire a node
into the cluster. validateClusterConfig refuses a public cluster
without a route secret and complete mutual route TLS, and rejects
partial route-TLS flags (all-or-nothing). splitRoutes parses the CSV.
Tests (DoD: golden + 2 edge + error path):
- TestClusterForwardsAcrossNodes: 2-node cluster forwards a client
subject from one node to a subscriber on the other.
- TestClusterThreeNodesForward: 3-node (HA shape) cross-node forwarding.
- TestClusterMutualTLSForwards: forwarding over mutual-TLS routes.
- TestClusterRejectsBadRouteAuth: wrong cluster password -> no route.
- TestClusterRejectsUnsignedNode: cert not signed by the bus CA -> no route.
- TestClusterConfigPolicy / TestSplitRoutes: boot-guard + CSV parsing.
Master stays green: standalone (no --cluster-name) is unchanged.
client/tls_test: mints a throwaway CA + server cert in-memory; a client
pinning the CA completes the handshake and operates (golden), a client
without the CA fails the handshake (error path). busauth/tls_test: golden
load of a CA PEM and a server keypair, plus error paths (missing file,
non-PEM). Harness body extracted to bootHarness(ctrlMode, natsAuth, natsTLS).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
busauth.LoadCATLSConfig turns a ca.crt path into a *tls.Config trusting only
that private CA (clients must pin it; the system roots would reject a
self-signed server cert). busauth.ServerTLSConfig loads the server keypair.
client.Options gains TLS; NewWithOptions calls nats.Secure when set, so the
data-plane connection is encrypted and the server pinned.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
busauth.NewNkeyAuthenticator verifies a client's nkey signature over the
server nonce (decoding like nats-server: raw-url then std base64), maps the
nkey to its Ed25519 hex, and consults an injected IsAuthorized predicate.
Checking on every connection (rather than a static Options.Nkeys map) means
revoking a user denies its next connection with no restart. embeddednats
gains StartHostAuth(auth) and sets AlwaysEnableNonce so the server advertises
the nonce nkey clients need; Start/StartHost stay open (auth=nil) for dev.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
A NATS nkey is an Ed25519 keypair, so the bus reuses each peer's signing
identity for the data plane instead of minting new key material. ClientNkey
derives the user nkey public string and a nonce-signing callback from the
peer's Ed25519 private key (its first 32 bytes are the nkey seed);
SignPubHexFromNkey maps a presented nkey back to the allowlist's hex key;
NkeyPublicFromSignPub is the public-only derivation.
This is NATS-specific transport glue kept in the app, not promoted to the
registry, to avoid pulling nats-io/nkeys into the multi-domain registry
module. The dedicated round-trip test runs first (spec requirement): it
proves the nkey signature equals the identity's raw Ed25519 signature and
that the nkey maps back to the identity's hex.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
agent
egutierrez