Adds the new lua alerts API

scripts/lua/modules/alert_api.lua

@@ -0,0 +1,57 @@
+--
+-- (C) 2014-16 - ntop.org
+--
+--[[
+This file contains an API the programmer can use to generate custom alerts
+
+ntopng alerts are a very generic concept that are represented using lua tables.
+The only two mandatory keys that must exist in every alert lua table are 'alert_level'
+and 'alert_type', respectively. The remaining keys are custom and a user can choose
+to save as many fields as he/she wish.
+
+'alert_type' must be an integer number that uniquely identifies the alert type.
+This integer number can be obtained using the helper function alertType as follows:
+
+alertType("under_attack"))
+alertType("tcp_syn_floow"))
+alertType("flows_flood"))
+
+'alert_severity' must be an integer number that uniquely identifies the alert severity.
+This integer number can be obtained using the helper function alertSeverity as follows:
+
+Alerts are fired using function fire_alert that takes the interface id as the first argument
+and the alert lua table as the second argument.
+
+alertSeverity("info")
+alertSeverity("warning")
+alertSeverity("error")
+
+
+Examples of alerts generation are:
+
+fire_alert(0,
+	   {['ifid']=0,
+	      ['alert_type']=alertType("under_attack"),
+	      ['alert_severity']=alertSeverity("warning"),
+	      ['seen']=os.time(), ['msg']="this is a test alert"})
+
+fire_alert(0, {['ifid']=0, ['alert_type']=2, ['alert_severity']=1, ['custom_field']=os.time(), ['custom_info']="test"})
+--]]
+
+dirs = ntop.getDirs()
+package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+
+if (ntop.isPro()) then
+  package.path = dirs.installdir .. "/pro/scripts/callbacks/?.lua;" .. package.path
+end
+
+require "lua_utils"
+
+function fire_alert(ifid, alert)
+   ntop.storeAlert(ifid, alert)
+end
+
+--fire_alert(0, {['ifid']=0, ['alert_type']=2, ['alert_severity']=1, ['seen']=os.time(), ['msg']="simone"})
+--tprint(alertSeverity("warning"))
+--tprint(alertType("under_attack"))
+