Agent: Return boolean from "should_monkey_run()"

A function named "should_monkey_run()" should let you know whether or
not monkey should run. Before this commit, the function was responsible
for flow control, as it raised a PlannedShutdownException, resulting in
the shutdown of the monkey agent.

monkey/infection_monkey/control.py

@@ -22,7 +22,6 @@ from infection_monkey.config import GUID, WormConfiguration
 from infection_monkey.network.info import check_internet_access, local_ips
 from infection_monkey.transport.http import HTTPConnectProxy
 from infection_monkey.transport.tcp import TcpProxy
-from infection_monkey.utils.exceptions.planned_shutdown_exception import PlannedShutdownException
 
 requests.packages.urllib3.disable_warnings()
 
@@ -401,10 +400,8 @@ class ControlClient(object):
             and ControlClient.can_island_see_port(vulnerable_port)
             and WormConfiguration.started_on_island
         ):
-            raise PlannedShutdownException(
-                "Monkey shouldn't run on current machine "
-                "(it will be exploited later with more depth)."
-            )
+            return False
+
         return True
 
     @staticmethod

monkey/infection_monkey/monkey.py

@@ -125,7 +125,12 @@ class InfectionMonkey(object):
             if is_running_on_island():
                 WormConfiguration.started_on_island = True
                 ControlClient.report_start_on_island()
-            ControlClient.should_monkey_run(self._opts.vulnerable_port)
+
+            if not ControlClient.should_monkey_run(self._opts.vulnerable_port):
+                raise PlannedShutdownException(
+                    "Monkey shouldn't run on current machine "
+                    "(it will be exploited later with more depth)."
+                )
 
             if firewall.is_enabled():
                 firewall.add_firewall_rule()