added http error handling page

scripts/lua/http_status_code.lua

@@ -0,0 +1,45 @@
+--
+-- (C) 2020 - ntop.org
+--
+
+-- This page shows the HTTP errors that a user can get
+-- example: 404, 403, ...
+
+dirs = ntop.getDirs()
+package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+
+require("lua_utils")
+local page_utils = require("page_utils")
+
+sendHTTPContentTypeHeader('text/html')
+page_utils.print_header()
+
+local status_code = _GET["status_code"] or 200
+local referal_url = _GET["referal_url"] or '/'
+
+local error_descriptions = {
+    [404] = "Page not found!",
+    [403] = "Forbidden page!",
+    [200] = "Success!",
+}
+
+dofile(dirs.installdir .. "/scripts/lua/inc/menu.lua")
+
+print([[
+    <div class='row mb-4'>
+        <div class='col'>
+            <i class="fas fa-exclamation-triangle"></i>
+            <h2 class='text-center status-code-title mt-3 mb-1'>]].. status_code ..[[</h2>
+            <h3 class='text-center mt-1 mb-3 text-muted'>Ops! Something went wrong!</h3>
+            <p class='text-center mt-3 mb-4 lead'>
+                ]].. error_descriptions[status_code] ..[[
+            </p>
+            <a class='text-center d-block mb-5' href="]]..referal_url..[[">
+                <i class="fas fa-arrow-left"></i>
+                Bring me back
+            </a>
+        </div>
+    </div>
+]])
+
+dofile(dirs.installdir .. "/scripts/lua/inc/footer.lua")