Fixes #4416 Implement recipient/endpoint shell script (#4688)

* Fixes #4416 implement shell script endpoint

* removed debugging code

* Removed for windows env

scripts/plugins/endpoints/shell_alert_endpoint/alert_endpoints/shell.lua

@@ -0,0 +1,160 @@
+--
+-- (C) 2018 - ntop.org
+--
+
+require "lua_utils"
+local json = require "dkjson"
+
+local endpoint_key = "shell_alert_endpoint"
+
+
+local shell = {
+    name = "Shell",
+    endpoint_params = {
+      { param_name = "shell_script" },
+      -- TODO: configure severity (Errors, Errors and Warnings, All)
+    },
+    endpoint_template = {
+      plugin_key = endpoint_key,
+      template_name = "shell_endpoint.template"
+    },
+    recipient_params = {
+      { param_name = "shell_options" },
+    },
+    recipient_template = {
+      plugin_key = endpoint_key,
+      template_name = "shell_recipient.template"
+    },
+	
+    windows_exclude = false,
+}
+
+shell.EXPORT_FREQUENCY = 5
+
+-- ##############################################
+
+-- @brief Returns the desided formatted output for recipient params
+function shell.format_recipient_params(recipient_params)
+   return string.format("(%s)", shell.name)
+end
+
+-- ##############################################
+
+local function recipient2sendMessageSettings(recipient)
+  local settings = {
+    path    = recipient.endpoint_conf.shell_script,
+    options = recipient.recipient_params.shell_options,
+  }
+
+  return settings
+end
+
+-- ##############################################
+
+function shell.setup()
+  local is_enabled = true
+
+  global_state = {}
+
+  return(is_enabled)
+end
+
+-- ##############################################
+
+function shell.sendMessage(alerts, settings)
+
+  if isEmptyString(settings.path) then
+    return false
+  end
+  
+  local msg = json.encode(alerts)
+
+  local cmd = settings.path .. " " .. settings.options .. " " .. msg
+
+  local tmp_file = io.popen(cmd .. ' \necho _$?')
+  local tmp_read = tmp_file:read'*a'
+  local exit_code = tmp_read:match'.*%D(%d+)'+0
+  tmp_file:close()
+
+  if(exit_code == 0) then
+    return true
+  end
+
+  return false
+end
+
+-- ##############################################
+
+function shell.dequeueRecipientAlerts(recipient, budget, high_priority)
+  local start_time = os.time()
+  local sent = 0
+  local more_available = true
+  local budget_used = 0
+  local MAX_ALERTS_PER_REQUEST = 1
+
+  local settings = recipient2sendMessageSettings(recipient)
+
+  local return_msg = {}
+  -- Dequeue alerts up to budget x MAX_ALERTS_PER_REQUEST
+  -- Note: in this case budget is the number of script messages to send
+  while budget_used <= budget and more_available do
+
+    local diff = os.time() - start_time
+    if diff >= shell.EXPORT_FREQUENCY then
+      break
+    end
+
+    -- Dequeue MAX_ALERTS_PER_REQUEST notifications
+    local notifications = {}
+    for i = 1, MAX_ALERTS_PER_REQUEST do
+       local notification = ntop.recipient_dequeue(recipient.recipient_id, high_priority)
+       if notification then 
+	  notifications[#notifications + 1] = notification
+       else
+	  break
+       end
+    end
+
+    if not notifications or #notifications == 0 then
+      more_available = false
+      break
+    end
+
+    local alerts = {}
+
+    for _, json_message in ipairs(notifications) do
+      local alert = json.decode(json_message)
+      table.insert(alerts, alert)
+    end
+
+    if not telegram.sendMessage(alerts, settings) then
+      return {success=false, error_message="- unable to execute the script"}
+    end
+
+    -- Remove the processed messages from the queue
+    budget_used = budget_used + #notifications
+    sent = sent + 1
+  end
+
+  return {success = true, more_available = more_available}
+end
+
+-- ##############################################
+
+function shell.runTest(recipient)
+  local message_info
+
+  local settings = recipient2sendMessageSettings(recipient)
+  local success = shell.sendMessage({}, settings)
+
+  if not success then
+    message_info = i18n("shell_alert_endpoint.shell_send_error")
+  end
+
+  return success, message_info
+end
+
+-- ##############################################
+
+return shell
+