Management framework: expand notify_agent_hello event arguments

This swaps the host event argument for the Broker ID. The latter is more useful,
since the sending agent doesn't necessarily know its IP address as visible to
the controller, and the controller can pull up the full Broker context via the
ID.

It also adds an explicit argument to the event to indicate whether the agent
connected to the controller or vice versa. This simplifies the controller's
internal logic.

Also minor tweaks to logging to show Broker IDs.

scripts/policy/frameworks/management/agent/api.zeek

@@ -145,17 +145,20 @@ export {
 	## The agent sends this event upon peering as a "check-in", informing
 	## the controller that an agent of the given name is now available to
 	## communicate with. It is a controller-level equivalent of
-	## `:zeek:see:`Broker::peer_added`.
+	## `:zeek:see:`Broker::peer_added` and triggered by it.
 	##
 	## instance: an instance name, really the agent's name as per
 	##    :zeek:see:`Management::Agent::get_name`.
 	##
-	## host: the IP address of the agent. (This may change in the future.)
+	## id: the Broker ID of the agent.
+	##
+	## connecting: true if this agent connected to the controller,
+	##    false if the controller connected to the agent.
 	##
 	## api_version: the API version of this agent.
 	##
-	global notify_agent_hello: event(instance: string, host: addr,
+	global notify_agent_hello: event(instance: string, id: string,
-	    api_version: count);
+	    connecting: bool, api_version: count);
 
 
 	# The following are not yet implemented.

scripts/policy/frameworks/management/agent/main.zeek

@@ -694,7 +694,8 @@ event Broker::peer_added(peer: Broker::EndpointInfo, msg: string)
 
 	Broker::publish(agent_topic(),
 	    Management::Agent::API::notify_agent_hello,
-	    epi$id, to_addr(epi$network$address),
+	    epi$id, Broker::node_id(),
+	    Management::Agent::controller$address != "0.0.0.0",
 	    Management::Agent::API::version);
 	}
 
@@ -736,5 +737,5 @@ event zeek_init()
 	# If the controller connects to us, it also uses this port.
 	Broker::listen(cat(epi$network$address), epi$network$bound_port);
 
-	Management::Log::info("agent is live");
+	Management::Log::info(fmt("agent is live, Broker ID %s", Broker::node_id()));
 	}

scripts/policy/frameworks/management/controller/main.zeek

@@ -273,9 +273,10 @@ event Management::Controller::API::notify_agents_ready(instances: set[string])
 	send_config_to_agents(req, req$set_configuration_state$config);
 	}
 
-event Management::Agent::API::notify_agent_hello(instance: string, host: addr, api_version: count)
+event Management::Agent::API::notify_agent_hello(instance: string, id: string, connecting: bool, api_version: count)
 	{
-	Management::Log::info(fmt("rx Management::Agent::API::notify_agent_hello %s %s", instance, host));
+	Management::Log::info(fmt("rx Management::Agent::API::notify_agent_hello %s %s %s",
+	    instance, id, connecting));
 
 	# When an agent checks in with a mismatching API version, we log the
 	# fact and drop its state, if any.
@@ -283,7 +284,7 @@ event Management::Agent::API::notify_agent_hello(instance: string, host: addr, a
 		{
 		Management::Log::warning(
 		    fmt("instance %s/%s has checked in with incompatible API version %s",
-		        instance, host, api_version));
+		        instance, id, api_version));
 
 		if ( instance in g_instances )
 			drop_instance(g_instances[instance]);
@@ -882,5 +883,5 @@ event zeek_init()
 	Broker::subscribe(Management::Agent::topic_prefix);
 	Broker::subscribe(Management::Controller::topic);
 
-	Management::Log::info("controller is live");
+	Management::Log::info(fmt("controller is live, Broker ID %s", Broker::node_id()));
 	}

testing/btest/Baseline/scripts.policy.frameworks.management.controller.agent-checkin/zeek.nodes.controller.stdout

@@ -1,2 +1,2 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-notify_agent_hello agent 127.0.0.1 1
+notify_agent_hello agent 1

testing/btest/scripts/policy/frameworks/management/controller/agent-checkin.zeek

@@ -40,14 +40,12 @@ event zeek_init()
 		}
 	}
 
-event Management::Agent::API::notify_agent_hello(instance: string, host: addr, api_version: count)
+event Management::Agent::API::notify_agent_hello(instance: string, id: string, connecting: bool, api_version: count)
 	{
 	if ( Management::role == Management::CONTROLLER )
 		{
-		# On rare occasion it can happen that we log this twice, which'll need
-		# investigating. For now we ensure we only do so once.
 		if ( ! logged )
-			print(fmt("notify_agent_hello %s %s %s", instance, host, api_version));
+			print(fmt("notify_agent_hello %s %s", instance, api_version));
 
 		logged = T;