Two consumers may share a name; they must not share a delivery subject

novox/hq 04-ISSUES/146. A push consumer delivers onto an ordinary subject and everything subscribed to it gets a copy. The controller holds a consumer called 'controller' on CONTROL and another called 'controller' on EVENTS, and both were given _DELIVER.controller — so the one process, holding both subscriptions, acted on every message twice. Measured: one enrolment published, one message in the stream, one delivery, no redelivery, and the controller enrolled the machine twice — the second minting a credential that replaced the one the machine had just been handed, which is why it then reconnected for ever as a user whose password the mesh had rotated. Every report and every followed event doubled the same way, silently. The stream goes in the subject because the pair is what identifies a consumer. A subscriber's permission gains the same shape, keeping the bare name so an existing consumer keeps working until the next assertion moves it.
2026-09-29 21:32:33 +02:00
parent bc31745607
commit 3fbf658c16
5 changed files with 69 additions and 5 deletions
@@ -184,7 +184,20 @@ func (j *JetStream) EnsureConsumer(c Consumer) error {
 	// without the other is refused by the server with a message that does not say which half is
 	// missing.
 	if c.Queue != "" || c.Push {
-		want.DeliverSubject = "_DELIVER." + c.Name
+		// **Per consumer, which means per stream as well as per name** (novox/hq 04-ISSUES/146).
+		// A push consumer delivers onto an ordinary subject, and everything subscribed to that
+		// subject gets a copy. The controller holds a consumer called `controller` on CONTROL and
+		// another called `controller` on EVENTS, and both were given `_DELIVER.controller` — so the
+		// one process, holding both subscriptions, acted on every message twice. It enrolled a
+		// joining machine twice from one request, minting a second credential that replaced the one
+		// the machine had just been given; the same doubling applied to every report and every
+		// event the controller follows.
+		//
+		// The stream is in the name because the pair is what identifies a consumer — the server
+		// scopes a durable's name to its stream, and this subject is the only place that scoping
+		// was dropped. Already within what the controller may subscribe (`_DELIVER.controller.>`),
+		// so no permission moves.
+		want.DeliverSubject = DeliverSubjectFor(c)
 	}

 	switch _, err := j.js.ConsumerInfo(c.Stream, c.Name); {
@@ -269,7 +269,13 @@ func PermissionsFor(p Principal) (Permissions, error) {
 			"mesh.control." + p.Node + ".>",
 			"$JS.API.CONSUMER.INFO.NODES." + p.Node,
 		}
-		sub = []string{"mesh.node." + p.Node + ".declare", "_DELIVER." + p.Node}
+		// The deliver subject carries the stream as well as the consumer's name, so what a
+		// subscriber is permitted has to carry it too (novox/hq 04-ISSUES/146). The bare name
+		// stays: an existing consumer keeps delivering where it always did until the controller's
+		// next assertion moves it, and a permission that only allowed the new shape would refuse
+		// every node in the mesh for exactly as long as that took.
+		sub = []string{"mesh.node." + p.Node + ".declare",
+			"_DELIVER." + p.Node, "_DELIVER." + p.Node + ".>"}

 	case KindModule:
 		// 1. Its own namespace: it publishes its events there and serves its tools there. Nothing
@@ -323,7 +329,7 @@ func PermissionsFor(p Principal) (Permissions, error) {
 			// take work over the new bus was refused the asking (2026-09-28).
 			worker := "SEAT_" + upperSnake(s.Name) + "_worker"
 			stream := seatStreamName(s.Name)
-			sub = append(sub, "_DELIVER."+worker)
+			sub = append(sub, "_DELIVER."+worker, "_DELIVER."+worker+".>")
 			pub = append(pub, "$JS.API.CONSUMER.INFO."+stream+"."+worker, "$JS.ACK."+stream+"."+worker+".>")
 			for _, a := range s.Accepts {
 				sub = append(sub, seatSubject(s, "accept", a))
@@ -94,6 +94,24 @@ func MeshStreams() []Stream {
 	}
 }

+// DeliverSubjectFor is where a push consumer's messages land.
+//
+// **Per consumer, which means per stream as well as per name** (novox/hq 04-ISSUES/146). A push
+// consumer delivers onto an ordinary subject, and everything subscribed to that subject gets a
+// copy. The controller holds a consumer called `controller` on CONTROL and another called
+// `controller` on EVENTS; while both were given `_DELIVER.controller`, the one process holding
+// both subscriptions acted on every message twice — a joining machine was enrolled twice from one
+// request, and the second enrolment minted a credential that replaced the one the machine had just
+// been handed. Every report and every followed event doubled the same way, silently: nothing is
+// redelivered, no count is wrong, the work simply happens twice.
+//
+// The stream belongs in it because the pair is what identifies a consumer — the server scopes a
+// durable's name to its stream, and this subject was the one place that scoping was dropped. It
+// stays inside what a controller may already subscribe (`_DELIVER.controller.>`).
+func DeliverSubjectFor(c Consumer) string {
+	return "_DELIVER." + c.Name + "." + c.Stream
+}
+
 // An Asserter is the part of a JetStream connection stream assertion needs. Narrow on purpose: it
 // keeps this testable without a server, and keeps the client library out of everything that only
 // wants to know what the streams are.
@@ -233,3 +233,30 @@ func containsStep(steps []string, want string) bool {
 	}
 	return false
 }
+
+// **Two consumers may share a name, and must not share a delivery subject** (novox/hq
+// 04-ISSUES/146).
+//
+// A push consumer delivers onto an ordinary subject and everything subscribed to it gets a copy.
+// The controller holds a consumer called `controller` on CONTROL and another called `controller` on
+// EVENTS; while both were given `_DELIVER.controller`, the one process holding both subscriptions
+// acted on every message twice — a joining machine enrolled twice from one request, with the second
+// enrolment minting a credential that replaced the one the machine had just been handed.
+//
+// Checked here rather than against a server because it is a property of what the mesh asks for, and
+// because the failure it produces is silent: every count is right, nothing is redelivered, and the
+// work simply happens twice.
+func TestNoTwoConsumersDeliverOntoTheSameSubject(t *testing.T) {
+	seen := map[string]string{}
+	for _, c := range MeshConsumers() {
+		if !c.Push && c.Queue == "" {
+			continue
+		}
+		subject := DeliverSubjectFor(c)
+		if other, taken := seen[subject]; taken {
+			t.Errorf("%s on %s and %s deliver onto %s, so whoever holds both acts on every "+
+				"message twice", c.Name, c.Stream, other, subject)
+		}
+		seen[subject] = c.Name + " on " + c.Stream
+	}
+}
@@ -34,11 +34,11 @@ accounts {
      } }
      { user: "node.one", password: "$2a$11$nnnnnnnnnnnnnnnnnnnnnn", permissions: {
        publish: { allow: ["$JS.ACK.NODES.one.>", "$JS.API.CONSUMER.INFO.NODES.one", "mesh.control.one.>"] }
-        subscribe: { allow: ["_DELIVER.one", "_INBOX.node.one.>", "mesh.node.one.declare"] }
+        subscribe: { allow: ["_DELIVER.one", "_DELIVER.one.>", "_INBOX.node.one.>", "mesh.node.one.declare"] }
      } }
      { user: "one.telegram", password: "$2a$11$tttttttttttttttttttttt", permissions: {
        publish: { allow: ["$JS.ACK.EVENTS.one_telegram.>", "$JS.ACK.SEAT_TELEGRAM_SENDER.SEAT_TELEGRAM_SENDER_worker.>", "$JS.API.CONSUMER.INFO.EVENTS.one_telegram", "$JS.API.CONSUMER.INFO.SEAT_TELEGRAM_SENDER.SEAT_TELEGRAM_SENDER_worker", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_telegram", "mesh.seat.telegram-sender.event.delivered", "mesh.seat.telegram-sender.event.failed"] }
-        subscribe: { allow: ["_DELIVER.SEAT_TELEGRAM_SENDER_worker", "_INBOX.one.telegram.>", "mesh.mod.telegram.tool.>", "mesh.seat.telegram-sender.accept.send"] }
+        subscribe: { allow: ["_DELIVER.SEAT_TELEGRAM_SENDER_worker", "_DELIVER.SEAT_TELEGRAM_SENDER_worker.>", "_INBOX.one.telegram.>", "mesh.mod.telegram.tool.>", "mesh.seat.telegram-sender.accept.send"] }
        allow_responses: { max: 1, ttl: "1m" }
      } }
      { user: "two.audit", password: "$2a$11$aaaaaaaaaaaaaaaaaaaaaa", permissions: {