Add rest endpoint to get interface dscp stats

scripts/lua/rest/v1/get/interface/dscp/stats.lua

@@ -0,0 +1,48 @@
+--
+-- (C) 2013-20 - ntop.org
+--
+
+local dirs = ntop.getDirs()
+package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+
+require "lua_utils"
+local rest_utils = require("rest_utils")
+local dscp_consts = require "dscp_consts"
+
+--
+-- Read DSCP statistics on an interface
+-- Example: curl -u admin:admin -d '{"ifid": "1"}' http://localhost:3000/lua/rest/v1/get/interface/dscp/stats.lua
+--
+-- NOTE: in case of invalid login, no error is returned but redirected to login
+--
+
+sendHTTPContentTypeHeader('text/html')
+
+local rc = rest_utils.consts_ok
+local res = {}
+
+local ifid = _GET["ifid"]
+
+if isEmptyString(ifid) then
+   rc = rest_utils.consts_invalid_interface
+   print(rest_utils.rc(rc))
+   return
+end
+
+interface.select(ifid)
+
+local stats = interface.getStats()
+
+if stats == nil then
+   print(rest_utils.rc(rest_utils.consts_internal_error))
+   return
+end
+
+for key, value in pairsByKeys(stats.dscp, asc) do
+   res[#res + 1] = {
+      label = dscp_consts.ds_precedence_descr(key),
+      value = value['packets.rcvd'] + value['packets.sent']
+   }
+end
+
+print(rest_utils.rc(rc, res))