mctpd: keep UUID on static-EID re-enrollment

src/mctpd.c

@@ -2237,7 +2237,6 @@ static void free_peers(struct ctx *ctx)
 static int change_peer_eid(struct peer *peer, mctp_eid_t new_eid)
 {
 	struct net *n = NULL;
-	int rc;
 
 	if (!mctp_eid_is_valid_unicast(new_eid))
 		return -EINVAL;
@@ -2256,15 +2255,17 @@ static int change_peer_eid(struct peer *peer, mctp_eid_t new_eid)
 	if (n->peers[new_eid])
 		return -EEXIST;
 
-	/* publish & unpublish will update peer->path */
+	/* The object path contains the EID, so the peer is left unpublished
+	 * and the caller is responsible for publishing: publish_peer
+	 * registers the UUID vtable only when peer->uuid is already known,
+	 * so publishing before query_peer_properties has run would
+	 * permanently hide the UUID interface (the assign-mismatch paths
+	 * reach here before the properties are queried). */
 	unpublish_peer(peer);
 	n->peers[new_eid] = n->peers[peer->eid];
 	n->peers[peer->eid] = NULL;
 	peer->eid = new_eid;
 	add_peer_route(peer);
-	rc = publish_peer(peer);
-	if (rc)
-		return rc;
 
 	return 0;
 }
@@ -3813,6 +3814,15 @@ static int peer_endpoint_recover(sd_event_source *s, uint64_t usec,
 			if (rc < 0) {
 				goto reclaim;
 			}
+			/* change_peer_eid() leaves the peer unpublished; the
+			 * object path moves with the EID. The properties were
+			 * queried when the peer was first set up, so
+			 * publishing here re-registers the full interface
+			 * set. */
+			rc = publish_peer(peer);
+			if (rc < 0) {
+				goto reschedule;
+			}
 		}
 	}
 

tests/test_mctpd.py

@@ -8,6 +8,7 @@
     mctpd_mctp_network_obj,
     mctpd_mctp_endpoint_common_obj,
     mctpd_mctp_endpoint_control_obj,
+    mctpd_mctp_endpoint_obj,
     mctpd_mctp_base_iface_obj,
 )
 from mctpenv import (
@@ -732,6 +733,46 @@ async def handle_mctp_control(self, sock, src_addr, msg):
     assert eid == ep.eid
 
 
+async def test_assign_endpoint_vary_set_eid_uuid(dbus, mctpd):
+    """An endpoint that holds its current EID and reports it in the Set
+    Endpoint ID response takes the EID-change path, where the UUID query only
+    completes after the object would first be published; the endpoint object
+    must still expose the UUID interface, same as a plain enrollment.
+    """
+
+    class VaryEndpoint(Endpoint):
+        async def handle_mctp_control(self, sock, src_addr, msg):
+            flags, opcode = msg[0:2]
+            if opcode != 1:
+                return await super().handle_mctp_control(sock, src_addr, msg)
+            dst_addr = MCTPSockAddr.for_ep_resp(self, src_addr, sock.addr_ext)
+            self.eid = msg[3] + 1
+            msg = bytes(
+                [
+                    flags & 0x1F,  # Rsp
+                    0x01,  # opcode: Set Endpoint ID
+                    0x00,  # cc: success
+                    0x00,  # assignment accepted, no pool
+                    self.eid,  # set EID: valid, but not what was assigned
+                    0x00,  # pool size: 0
+                ]
+            )
+            await sock.send(dst_addr, msg)
+
+    iface = mctpd.system.interfaces[0]
+    ep = VaryEndpoint(iface, bytes([0x1E]))
+    mctpd.network.add_endpoint(ep)
+    mctp = await mctpd_mctp_iface_obj(dbus, iface)
+
+    eid, _, path, _ = await mctp.call_assign_endpoint(ep.lladdr)
+
+    assert eid == ep.eid
+    uuid_i = await mctpd_mctp_endpoint_obj(
+        dbus, path, "xyz.openbmc_project.Common.UUID"
+    )
+    assert await uuid_i.get_uuid() == str(ep.uuid)
+
+
 async def test_setup_endpoint_conflicting_set_eid_response(dbus, mctpd):
     """During a SetupEndpoint's Set Endpoint ID exchange, return a response
     that indicates that the EID has been set, but report a different set EID in