cluster/serializer/broker: Do not send empty metadata vectors around

Event when there's no metadata attached to an event, we'd still use the
constructor passing an empty metadata vector, resulting in an on-the-wire
representation with an empty trailing vector.

Particularly visible when just snooping events via websocat. There also
seems to be some bug with the timestamp -1 handling.

src/cluster/serializer/broker/Serializer.cc

@@ -66,8 +66,8 @@ std::optional<broker::zeek::Event> detail::to_broker_event(const zeek::cluster::
     }
 
     // Convert metadata from the cluster::detail::Event event to broker's event metadata format.
-    broker::vector broker_meta;
     if ( const auto* meta = ev.Metadata(); meta != nullptr ) {
+        broker::vector broker_meta;
         broker_meta.reserve(meta->size());
 
         for ( const auto& m : *meta ) {
@@ -81,9 +81,11 @@ std::optional<broker::zeek::Event> detail::to_broker_event(const zeek::cluster::
                                       obj_desc_short(m.Val()).c_str());
             }
         }
+
+        return broker::zeek::Event(ev.HandlerName(), xs, broker_meta);
     }
 
-    return broker::zeek::Event(ev.HandlerName(), xs, broker_meta);
+    return broker::zeek::Event(ev.HandlerName(), xs);
 }
 
 std::optional<zeek::cluster::Event> detail::to_zeek_event(const broker::zeek::Event& ev) {

testing/btest/Baseline/cluster.websocket.metadata/..client-metadata-from-client..stderr

@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.

testing/btest/Baseline/cluster.websocket.metadata/..client-metadata-from-client.out

@@ -0,0 +1,5 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Connected!
+ack {'type': 'ack', 'endpoint': 'endpoint', 'version': 'endpoint'}
+ping {'type': 'data-message', 'topic': '/test/pings/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'ping'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two'}, {'@data-type': 'count', 'data': 42}]}, {'@data-type': 'vector', 'data': [{'@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'timestamp', 'data': '1970-01-01T01:42:42'}]}]}]}]}
+pong {'type': 'data-message', 'topic': '/test/pongs/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'pong'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two fourty-two'}, {'@data-type': 'count', 'data': 84}]}, {'@data-type': 'vector', 'data': [{'@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'timestamp', 'data': '1970-01-01T01:42:42.000'}]}]}]}]}

testing/btest/Baseline/cluster.websocket.metadata/..client-metadata..stderr

@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.

testing/btest/Baseline/cluster.websocket.metadata/..client-metadata.out

@@ -0,0 +1,5 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Connected!
+ack {'type': 'ack', 'endpoint': 'endpoint', 'version': 'endpoint'}
+ping {'type': 'data-message', 'topic': '/test/pings/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'ping'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two'}, {'@data-type': 'count', 'data': 42}]}]}]}
+pong {'type': 'data-message', 'topic': '/test/pongs/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'pong'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two fourty-two'}, {'@data-type': 'count', 'data': 84}]}, {'@data-type': 'vector', 'data': [{'@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'timestamp', 'data': '1969-12-31T23:59:59.000'}]}]}]}]}

testing/btest/Baseline/cluster.websocket.metadata/..client-no-metadata..stderr

@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.

testing/btest/Baseline/cluster.websocket.metadata/..client-no-metadata.out

@@ -0,0 +1,5 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Connected!
+ack {'type': 'ack', 'endpoint': 'endpoint', 'version': 'endpoint'}
+ping {'type': 'data-message', 'topic': '/test/pings/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'ping'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two'}, {'@data-type': 'count', 'data': 42}]}]}]}
+pong {'type': 'data-message', 'topic': '/test/pongs/', '@data-type': 'vector', 'data': [{'@data-type': 'count', 'data': 1}, {'@data-type': 'count', 'data': 1}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'pong'}, {'@data-type': 'vector', 'data': [{'@data-type': 'string', 'data': 'fourty-two fourty-two'}, {'@data-type': 'count', 'data': 84}]}]}]}

testing/btest/Baseline/cluster.websocket.metadata/..manager-metadata-from-client..stderr

@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+<params>, line 1: received termination signal

testing/btest/Baseline/cluster.websocket.metadata/..manager-metadata-from-client.out

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Cluster::websocket_client_added, [/test/pongs/, /zeek/wstest/ws1/]
+ping: fourty-two, 42 (metadata=[[id=EventMetadata::NETWORK_TIMESTAMP, val=6162.0]]), sending pong...
+Cluster::websocket_client_lost

testing/btest/Baseline/cluster.websocket.metadata/..manager-metadata..stderr

@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+<params>, line 1: received termination signal

testing/btest/Baseline/cluster.websocket.metadata/..manager-metadata.out

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Cluster::websocket_client_added, [/test/pongs/, /zeek/wstest/ws1/]
+ping: fourty-two, 42 (metadata=[]), sending pong...
+Cluster::websocket_client_lost

testing/btest/Baseline/cluster.websocket.metadata/..manager-no-metadata..stderr

@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+received termination signal

testing/btest/Baseline/cluster.websocket.metadata/..manager-no-metadata.out

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Cluster::websocket_client_added, [/test/pongs/, /zeek/wstest/ws1/]
+ping: fourty-two, 42 (metadata=[]), sending pong...
+Cluster::websocket_client_lost

testing/btest/cluster/websocket/bad-event-args.zeek

@@ -105,7 +105,7 @@ def run(ws_url):
         # This should be good ping(string, count)
         ws.send(json.dumps(make_ping([{"@data-type": "string", "data": "Hello"}, {"@data-type": "count", "data": 42}])))
         pong = json.loads(ws.recv())
-        name, args, _ = pong["data"][2]["data"]
+        name, args = pong["data"][2]["data"]
         print("pong", name, args)
 
         # This one fails again

testing/btest/cluster/websocket/metadata.zeek

@@ -0,0 +1,121 @@
+# @TEST-DOC: Run a single node cluster (manager) with a websocket server and have a single client connect to check the metadata it receives.
+#
+# @TEST-REQUIRES: have-zeromq
+# @TEST-REQUIRES: python3 -c 'import websockets.sync'
+#
+# @TEST-GROUP: cluster-zeromq
+#
+# @TEST-PORT: XPUB_PORT
+# @TEST-PORT: XSUB_PORT
+# @TEST-PORT: LOG_PULL_PORT
+# @TEST-PORT: WEBSOCKET_PORT
+#
+# @TEST-EXEC: cp $FILES/zeromq/cluster-layout-simple.zeek cluster-layout.zeek
+# @TEST-EXEC: cp $FILES/zeromq/test-bootstrap.zeek zeromq-test-bootstrap.zeek
+# @TEST-EXEC: cp $FILES/ws/wstest.py .
+#
+# @TEST-EXEC: zeek -b --parse-only manager.zeek
+# @TEST-EXEC: python3 -m py_compile client.py
+#
+# @TEST-EXEC: btest-bg-run manager-no-metadata "ZEEKPATH=$ZEEKPATH:.. && CLUSTER_NODE=manager zeek -b ../manager.zeek >out"
+# @TEST-EXEC: btest-bg-run client-no-metadata "python3 ../client.py >out"
+#
+# @TEST-EXEC: btest-bg-wait 30
+# @TEST-EXEC: btest-diff ./manager-no-metadata/out
+# @TEST-EXEC: btest-diff ./manager-no-metadata/.stderr
+# @TEST-EXEC: btest-diff ./client-no-metadata/out
+# @TEST-EXEC: btest-diff ./client-no-metadata/.stderr
+#
+# @TEST-EXEC: btest-bg-run manager-metadata "ZEEKPATH=$ZEEKPATH:.. && CLUSTER_NODE=manager zeek -b ../manager.zeek EventMetadata::add_network_timestamp=T >out"
+# @TEST-EXEC: btest-bg-run client-metadata "python3 ../client.py >out"
+#
+# @TEST-EXEC: btest-bg-wait 30
+# @TEST-EXEC: btest-diff ./manager-metadata/out
+# @TEST-EXEC: btest-diff ./manager-metadata/.stderr
+# @TEST-EXEC: btest-diff ./client-metadata/out
+# @TEST-EXEC: btest-diff ./client-metadata/.stderr
+#
+# @TEST-EXEC: btest-bg-run manager-metadata-from-client "ZEEKPATH=$ZEEKPATH:.. && CLUSTER_NODE=manager zeek -b ../manager.zeek EventMetadata::add_network_timestamp=T >out"
+# @TEST-EXEC: btest-bg-run client-metadata-from-client "NETWORK_TIMESTAMP=1970-01-01T01:42:42 python3 ../client.py >out"
+
+# @TEST-EXEC: btest-bg-wait 30
+# @TEST-EXEC: btest-diff ./manager-metadata-from-client/out
+# @TEST-EXEC: btest-diff ./manager-metadata-from-client/.stderr
+# @TEST-EXEC: btest-diff ./client-metadata-from-client/out
+# @TEST-EXEC: btest-diff ./client-metadata-from-client/.stderr
+
+
+# @TEST-START-FILE manager.zeek
+@load ./zeromq-test-bootstrap
+redef exit_only_after_terminate = T;
+
+redef allow_network_time_forward = F;
+
+global ping: event(msg: string, c: count) &is_used;
+global pong: event(msg: string, c: count) &is_used;
+
+event zeek_init()
+	{
+	set_network_time(double_to_time(4711.0));
+
+	Cluster::subscribe("/test/pings/");
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	}
+
+event ping(msg: string, n: count) &is_used
+	{
+	print fmt("ping: %s, %s (metadata=%s), sending pong...", msg, n, EventMetadata::current_all());
+	Cluster::publish("/test/pongs/", pong, msg + " " + msg, n + n);
+	}
+
+event Cluster::websocket_client_added(info: Cluster::EndpointInfo, subscriptions: string_vec)
+	{
+	print "Cluster::websocket_client_added", subscriptions;
+	}
+
+event Cluster::websocket_client_lost(info: Cluster::EndpointInfo, code: count, reason: string)
+	{
+	print "Cluster::websocket_client_lost";
+	terminate();
+	}
+# @TEST-END-FILE
+
+
+# @TEST-START-FILE client.py
+import os
+import wstest
+
+def run(ws_url):
+    with wstest.connect("ws1", ws_url) as c:
+        print("Connected!")
+        ack = c.hello_v1(["/test/pongs/"])
+        assert "type" in ack
+        assert ack["type"] == "ack"
+        assert "endpoint" in ack
+        assert "version" in ack
+
+        ack["endpoint"] = "endpoint"
+        ack["version"] = "endpoint"
+        print("ack", ack)
+        ping = wstest.build_event_v1("/test/pings/", "ping", ["fourty-two", 42])
+
+        if ts_str := os.environ.get("NETWORK_TIMESTAMP"):
+            # Sneak timestamp metadata into the ping if the env variable is set
+            ping["data"][2]["data"] += [{
+                "@data-type": "vector",
+                "data": [{
+                    "@data-type": "vector", "data": [
+                        {"@data-type": "count", "data": 1},
+                        {"@data-type": "timestamp", "data": ts_str}
+                    ],
+                }]
+            }]
+
+        print("ping", ping)
+        c.send_json(ping)
+        pong = c.recv_json()
+        print("pong", pong)
+
+if __name__ == "__main__":
+    wstest.main(run, wstest.WS4_URL_V1)
+# @TEST-END-FILE