Enhanced the host Lua API for host checks

scripts/callbacks/checks/hosts/custom_host_lua_script.lua.sample

@@ -10,6 +10,30 @@
 --       that ntopng has in memory
 --
 
+-- the function below is for *DEBUG ONLY* purposes to test the implementation
+function dump_host()
+   local dirs = ntop.getDirs()
+   package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+   require "lua_utils"
+
+   local rsp = {}
+
+   rsp.ip                  = host.ip()
+   rsp.mac                 = host.mac()
+   rsp.name                = host.name()
+   rsp.vlan_id             = host.vlan_id()
+   rsp.is_unicast          = host.is_unicast()
+   rsp.is_multicast        = host.is_multicast()
+   rsp.is_broadcast        = host.is_broadcast()
+   rsp.is_blacklisted      = host.is_blacklisted()
+   rsp.bytes_sent          = host.bytes_sent()
+   rsp.bytes_rcvd          = host.bytes_rcvd()
+   rsp.bytes               = host.bytes()
+   rsp.l7                  = host.l7()
+
+   io.write("----------------------------\n")
+   tprint(rsp)
+end
 
 
 -- the function below shows an example of how a host alert is triggered
@@ -21,5 +45,12 @@ function trigger_dummy_alert()
    host.triggerAlert(score, message)
 end
 
+-- dump_host()
+
+-- Set this host as already visited in case we want to visit it once
+-- With this call, a host is visited only once. Do not call the method below
+-- if you want to visit the host periodically
+host.skipVisitedHost()
+
 -- IMPORTANT: do not forget this return at the end of the script
 return(0)